Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

13 files changed, 10449 insertions, 0 deletions

diff --git a/vendor/gimli/src/write/abbrev.rs b/vendor/gimli/src/write/abbrev.rs
new file mode 100644
index 0000000..7cdfa96
--- /dev/null
+++ b/vendor/gimli/src/write/abbrev.rs
@@ -0,0 +1,188 @@
+use alloc::vec::Vec;
+use indexmap::IndexSet;
+use std::ops::{Deref, DerefMut};
+
+use crate::common::{DebugAbbrevOffset, SectionId};
+use crate::constants;
+use crate::write::{Result, Section, Writer};
+
+/// A table of abbreviations that will be stored in a `.debug_abbrev` section.
+// Requirements:
+// - values are `Abbreviation`
+// - insertion returns an abbreviation code for use in writing a DIE
+// - inserting a duplicate returns the code of the existing value
+#[derive(Debug, Default)]
+pub(crate) struct AbbreviationTable {
+    abbrevs: IndexSet<Abbreviation>,
+}
+
+impl AbbreviationTable {
+    /// Add an abbreviation to the table and return its code.
+    pub fn add(&mut self, abbrev: Abbreviation) -> u64 {
+        let (code, _) = self.abbrevs.insert_full(abbrev);
+        // Code must be non-zero
+        (code + 1) as u64
+    }
+
+    /// Write the abbreviation table to the `.debug_abbrev` section.
+    pub fn write<W: Writer>(&self, w: &mut DebugAbbrev<W>) -> Result<()> {
+        for (code, abbrev) in self.abbrevs.iter().enumerate() {
+            w.write_uleb128((code + 1) as u64)?;
+            abbrev.write(w)?;
+        }
+        // Null abbreviation code
+        w.write_u8(0)
+    }
+}
+
+/// An abbreviation describes the shape of a `DebuggingInformationEntry`'s type:
+/// its tag type, whether it has children, and its set of attributes.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub(crate) struct Abbreviation {
+    tag: constants::DwTag,
+    has_children: bool,
+    attributes: Vec<AttributeSpecification>,
+}
+
+impl Abbreviation {
+    /// Construct a new `Abbreviation`.
+    #[inline]
+    pub fn new(
+        tag: constants::DwTag,
+        has_children: bool,
+        attributes: Vec<AttributeSpecification>,
+    ) -> Abbreviation {
+        Abbreviation {
+            tag,
+            has_children,
+            attributes,
+        }
+    }
+
+    /// Write the abbreviation to the `.debug_abbrev` section.
+    pub fn write<W: Writer>(&self, w: &mut DebugAbbrev<W>) -> Result<()> {
+        w.write_uleb128(self.tag.0.into())?;
+        w.write_u8(if self.has_children {
+            constants::DW_CHILDREN_yes.0
+        } else {
+            constants::DW_CHILDREN_no.0
+        })?;
+        for attr in &self.attributes {
+            attr.write(w)?;
+        }
+        // Null name and form
+        w.write_u8(0)?;
+        w.write_u8(0)
+    }
+}
+
+/// The description of an attribute in an abbreviated type.
+// TODO: support implicit const
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub(crate) struct AttributeSpecification {
+    name: constants::DwAt,
+    form: constants::DwForm,
+}
+
+impl AttributeSpecification {
+    /// Construct a new `AttributeSpecification`.
+    #[inline]
+    pub fn new(name: constants::DwAt, form: constants::DwForm) -> AttributeSpecification {
+        AttributeSpecification { name, form }
+    }
+
+    /// Write the attribute specification to the `.debug_abbrev` section.
+    #[inline]
+    pub fn write<W: Writer>(&self, w: &mut DebugAbbrev<W>) -> Result<()> {
+        w.write_uleb128(self.name.0.into())?;
+        w.write_uleb128(self.form.0.into())
+    }
+}
+
+define_section!(
+    DebugAbbrev,
+    DebugAbbrevOffset,
+    "A writable `.debug_abbrev` section."
+);
+
+#[cfg(test)]
+#[cfg(feature = "read")]
+mod tests {
+    use super::*;
+    use crate::constants;
+    use crate::read;
+    use crate::write::EndianVec;
+    use crate::LittleEndian;
+
+    #[test]
+    fn test_abbreviation_table() {
+        let mut abbrevs = AbbreviationTable::default();
+        let abbrev1 = Abbreviation::new(
+            constants::DW_TAG_subprogram,
+            false,
+            vec![AttributeSpecification::new(
+                constants::DW_AT_name,
+                constants::DW_FORM_string,
+            )],
+        );
+        let abbrev2 = Abbreviation::new(
+            constants::DW_TAG_compile_unit,
+            true,
+            vec![
+                AttributeSpecification::new(constants::DW_AT_producer, constants::DW_FORM_strp),
+                AttributeSpecification::new(constants::DW_AT_language, constants::DW_FORM_data2),
+            ],
+        );
+        let code1 = abbrevs.add(abbrev1.clone());
+        assert_eq!(code1, 1);
+        let code2 = abbrevs.add(abbrev2.clone());
+        assert_eq!(code2, 2);
+        assert_eq!(abbrevs.add(abbrev1.clone()), code1);
+        assert_eq!(abbrevs.add(abbrev2.clone()), code2);
+
+        let mut debug_abbrev = DebugAbbrev::from(EndianVec::new(LittleEndian));
+        let debug_abbrev_offset = debug_abbrev.offset();
+        assert_eq!(debug_abbrev_offset, DebugAbbrevOffset(0));
+        abbrevs.write(&mut debug_abbrev).unwrap();
+        assert_eq!(debug_abbrev.offset(), DebugAbbrevOffset(17));
+
+        let read_debug_abbrev = read::DebugAbbrev::new(debug_abbrev.slice(), LittleEndian);
+        let read_abbrevs = read_debug_abbrev
+            .abbreviations(debug_abbrev_offset)
+            .unwrap();
+
+        let read_abbrev1 = read_abbrevs.get(code1).unwrap();
+        assert_eq!(abbrev1.tag, read_abbrev1.tag());
+        assert_eq!(abbrev1.has_children, read_abbrev1.has_children());
+        assert_eq!(abbrev1.attributes.len(), read_abbrev1.attributes().len());
+        assert_eq!(
+            abbrev1.attributes[0].name,
+            read_abbrev1.attributes()[0].name()
+        );
+        assert_eq!(
+            abbrev1.attributes[0].form,
+            read_abbrev1.attributes()[0].form()
+        );
+
+        let read_abbrev2 = read_abbrevs.get(code2).unwrap();
+        assert_eq!(abbrev2.tag, read_abbrev2.tag());
+        assert_eq!(abbrev2.has_children, read_abbrev2.has_children());
+        assert_eq!(abbrev2.attributes.len(), read_abbrev2.attributes().len());
+        assert_eq!(
+            abbrev2.attributes[0].name,
+            read_abbrev2.attributes()[0].name()
+        );
+        assert_eq!(
+            abbrev2.attributes[0].form,
+            read_abbrev2.attributes()[0].form()
+        );
+        assert_eq!(
+            abbrev2.attributes[1].name,
+            read_abbrev2.attributes()[1].name()
+        );
+        assert_eq!(
+            abbrev2.attributes[1].form,
+            read_abbrev2.attributes()[1].form()
+        );
+    }
+}
diff --git a/vendor/gimli/src/write/cfi.rs b/vendor/gimli/src/write/cfi.rs
new file mode 100644
index 0000000..5e108f1
--- /dev/null
+++ b/vendor/gimli/src/write/cfi.rs
@@ -0,0 +1,1050 @@
+use alloc::vec::Vec;
+use indexmap::IndexSet;
+use std::ops::{Deref, DerefMut};
+
+use crate::common::{DebugFrameOffset, EhFrameOffset, Encoding, Format, Register, SectionId};
+use crate::constants;
+use crate::write::{Address, BaseId, Error, Expression, Result, Section, Writer};
+
+define_section!(
+    DebugFrame,
+    DebugFrameOffset,
+    "A writable `.debug_frame` section."
+);
+
+define_section!(EhFrame, EhFrameOffset, "A writable `.eh_frame` section.");
+
+define_id!(CieId, "An identifier for a CIE in a `FrameTable`.");
+
+/// A table of frame description entries.
+#[derive(Debug, Default)]
+pub struct FrameTable {
+    /// Base id for CIEs.
+    base_id: BaseId,
+    /// The common information entries.
+    cies: IndexSet<CommonInformationEntry>,
+    /// The frame description entries.
+    fdes: Vec<(CieId, FrameDescriptionEntry)>,
+}
+
+impl FrameTable {
+    /// Add a CIE and return its id.
+    ///
+    /// If the CIE already exists, then return the id of the existing CIE.
+    pub fn add_cie(&mut self, cie: CommonInformationEntry) -> CieId {
+        let (index, _) = self.cies.insert_full(cie);
+        CieId::new(self.base_id, index)
+    }
+
+    /// The number of CIEs.
+    pub fn cie_count(&self) -> usize {
+        self.cies.len()
+    }
+
+    /// Add a FDE.
+    ///
+    /// Does not check for duplicates.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the CIE id is invalid.
+    pub fn add_fde(&mut self, cie: CieId, fde: FrameDescriptionEntry) {
+        debug_assert_eq!(self.base_id, cie.base_id);
+        self.fdes.push((cie, fde));
+    }
+
+    /// The number of FDEs.
+    pub fn fde_count(&self) -> usize {
+        self.fdes.len()
+    }
+
+    /// Write the frame table entries to the given `.debug_frame` section.
+    pub fn write_debug_frame<W: Writer>(&self, w: &mut DebugFrame<W>) -> Result<()> {
+        self.write(&mut w.0, false)
+    }
+
+    /// Write the frame table entries to the given `.eh_frame` section.
+    pub fn write_eh_frame<W: Writer>(&self, w: &mut EhFrame<W>) -> Result<()> {
+        self.write(&mut w.0, true)
+    }
+
+    fn write<W: Writer>(&self, w: &mut W, eh_frame: bool) -> Result<()> {
+        let mut cie_offsets = vec![None; self.cies.len()];
+        for (cie_id, fde) in &self.fdes {
+            let cie_index = cie_id.index;
+            let cie = self.cies.get_index(cie_index).unwrap();
+            let cie_offset = match cie_offsets[cie_index] {
+                Some(offset) => offset,
+                None => {
+                    // Only write CIEs as they are referenced.
+                    let offset = cie.write(w, eh_frame)?;
+                    cie_offsets[cie_index] = Some(offset);
+                    offset
+                }
+            };
+
+            fde.write(w, eh_frame, cie_offset, cie)?;
+        }
+        // TODO: write length 0 terminator for eh_frame?
+        Ok(())
+    }
+}
+
+/// A common information entry. This contains information that is shared between FDEs.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct CommonInformationEntry {
+    encoding: Encoding,
+
+    /// A constant that is factored out of code offsets.
+    ///
+    /// This should be set to the minimum instruction length.
+    /// Writing a code offset that is not a multiple of this factor will generate an error.
+    code_alignment_factor: u8,
+
+    /// A constant that is factored out of data offsets.
+    ///
+    /// This should be set to the minimum data alignment for the frame.
+    /// Writing a data offset that is not a multiple of this factor will generate an error.
+    data_alignment_factor: i8,
+
+    /// The return address register. This might not correspond to an actual machine register.
+    return_address_register: Register,
+
+    /// The address of the personality function and its encoding.
+    pub personality: Option<(constants::DwEhPe, Address)>,
+
+    /// The encoding to use for the LSDA address in FDEs.
+    ///
+    /// If set then all FDEs which use this CIE must have a LSDA address.
+    pub lsda_encoding: Option<constants::DwEhPe>,
+
+    /// The encoding to use for addresses in FDEs.
+    pub fde_address_encoding: constants::DwEhPe,
+
+    /// True for signal trampolines.
+    pub signal_trampoline: bool,
+
+    /// The initial instructions upon entry to this function.
+    instructions: Vec<CallFrameInstruction>,
+}
+
+impl CommonInformationEntry {
+    /// Create a new common information entry.
+    ///
+    /// The encoding version must be a CFI version, not a DWARF version.
+    pub fn new(
+        encoding: Encoding,
+        code_alignment_factor: u8,
+        data_alignment_factor: i8,
+        return_address_register: Register,
+    ) -> Self {
+        CommonInformationEntry {
+            encoding,
+            code_alignment_factor,
+            data_alignment_factor,
+            return_address_register,
+            personality: None,
+            lsda_encoding: None,
+            fde_address_encoding: constants::DW_EH_PE_absptr,
+            signal_trampoline: false,
+            instructions: Vec::new(),
+        }
+    }
+
+    /// Add an initial instruction.
+    pub fn add_instruction(&mut self, instruction: CallFrameInstruction) {
+        self.instructions.push(instruction);
+    }
+
+    fn has_augmentation(&self) -> bool {
+        self.personality.is_some()
+            || self.lsda_encoding.is_some()
+            || self.signal_trampoline
+            || self.fde_address_encoding != constants::DW_EH_PE_absptr
+    }
+
+    /// Returns the section offset of the CIE.
+    fn write<W: Writer>(&self, w: &mut W, eh_frame: bool) -> Result<usize> {
+        let encoding = self.encoding;
+        let offset = w.len();
+
+        let length_offset = w.write_initial_length(encoding.format)?;
+        let length_base = w.len();
+
+        if eh_frame {
+            w.write_u32(0)?;
+        } else {
+            match encoding.format {
+                Format::Dwarf32 => w.write_u32(0xffff_ffff)?,
+                Format::Dwarf64 => w.write_u64(0xffff_ffff_ffff_ffff)?,
+            }
+        }
+
+        if eh_frame {
+            if encoding.version != 1 {
+                return Err(Error::UnsupportedVersion(encoding.version));
+            };
+        } else {
+            match encoding.version {
+                1 | 3 | 4 => {}
+                _ => return Err(Error::UnsupportedVersion(encoding.version)),
+            };
+        }
+        w.write_u8(encoding.version as u8)?;
+
+        let augmentation = self.has_augmentation();
+        if augmentation {
+            w.write_u8(b'z')?;
+            if self.lsda_encoding.is_some() {
+                w.write_u8(b'L')?;
+            }
+            if self.personality.is_some() {
+                w.write_u8(b'P')?;
+            }
+            if self.fde_address_encoding != constants::DW_EH_PE_absptr {
+                w.write_u8(b'R')?;
+            }
+            if self.signal_trampoline {
+                w.write_u8(b'S')?;
+            }
+        }
+        w.write_u8(0)?;
+
+        if encoding.version >= 4 {
+            w.write_u8(encoding.address_size)?;
+            // TODO: segment_selector_size
+            w.write_u8(0)?;
+        }
+
+        w.write_uleb128(self.code_alignment_factor.into())?;
+        w.write_sleb128(self.data_alignment_factor.into())?;
+
+        if !eh_frame && encoding.version == 1 {
+            let register = self.return_address_register.0 as u8;
+            if u16::from(register) != self.return_address_register.0 {
+                return Err(Error::ValueTooLarge);
+            }
+            w.write_u8(register)?;
+        } else {
+            w.write_uleb128(self.return_address_register.0.into())?;
+        }
+
+        if augmentation {
+            let augmentation_length_offset = w.len();
+            w.write_u8(0)?;
+            let augmentation_length_base = w.len();
+
+            if let Some(eh_pe) = self.lsda_encoding {
+                w.write_u8(eh_pe.0)?;
+            }
+            if let Some((eh_pe, address)) = self.personality {
+                w.write_u8(eh_pe.0)?;
+                w.write_eh_pointer(address, eh_pe, encoding.address_size)?;
+            }
+            if self.fde_address_encoding != constants::DW_EH_PE_absptr {
+                w.write_u8(self.fde_address_encoding.0)?;
+            }
+
+            let augmentation_length = (w.len() - augmentation_length_base) as u64;
+            debug_assert!(augmentation_length < 0x80);
+            w.write_udata_at(augmentation_length_offset, augmentation_length, 1)?;
+        }
+
+        for instruction in &self.instructions {
+            instruction.write(w, encoding, self)?;
+        }
+
+        write_nop(
+            w,
+            encoding.format.word_size() as usize + w.len() - length_base,
+            encoding.address_size,
+        )?;
+
+        let length = (w.len() - length_base) as u64;
+        w.write_initial_length_at(length_offset, length, encoding.format)?;
+
+        Ok(offset)
+    }
+}
+
+/// A frame description entry. There should be one FDE per function.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FrameDescriptionEntry {
+    /// The initial address of the function.
+    address: Address,
+
+    /// The length in bytes of the function.
+    length: u32,
+
+    /// The address of the LSDA.
+    pub lsda: Option<Address>,
+
+    /// The instructions for this function, ordered by offset.
+    instructions: Vec<(u32, CallFrameInstruction)>,
+}
+
+impl FrameDescriptionEntry {
+    /// Create a new frame description entry for a function.
+    pub fn new(address: Address, length: u32) -> Self {
+        FrameDescriptionEntry {
+            address,
+            length,
+            lsda: None,
+            instructions: Vec::new(),
+        }
+    }
+
+    /// Add an instruction.
+    ///
+    /// Instructions must be added in increasing order of offset, or writing will fail.
+    pub fn add_instruction(&mut self, offset: u32, instruction: CallFrameInstruction) {
+        debug_assert!(self.instructions.last().map(|x| x.0).unwrap_or(0) <= offset);
+        self.instructions.push((offset, instruction));
+    }
+
+    fn write<W: Writer>(
+        &self,
+        w: &mut W,
+        eh_frame: bool,
+        cie_offset: usize,
+        cie: &CommonInformationEntry,
+    ) -> Result<()> {
+        let encoding = cie.encoding;
+        let length_offset = w.write_initial_length(encoding.format)?;
+        let length_base = w.len();
+
+        if eh_frame {
+            // .eh_frame uses a relative offset which doesn't need relocation.
+            w.write_udata((w.len() - cie_offset) as u64, 4)?;
+        } else {
+            w.write_offset(
+                cie_offset,
+                SectionId::DebugFrame,
+                encoding.format.word_size(),
+            )?;
+        }
+
+        if cie.fde_address_encoding != constants::DW_EH_PE_absptr {
+            w.write_eh_pointer(
+                self.address,
+                cie.fde_address_encoding,
+                encoding.address_size,
+            )?;
+            w.write_eh_pointer_data(
+                self.length.into(),
+                cie.fde_address_encoding.format(),
+                encoding.address_size,
+            )?;
+        } else {
+            w.write_address(self.address, encoding.address_size)?;
+            w.write_udata(self.length.into(), encoding.address_size)?;
+        }
+
+        if cie.has_augmentation() {
+            let mut augmentation_length = 0u64;
+            if self.lsda.is_some() {
+                augmentation_length += u64::from(encoding.address_size);
+            }
+            w.write_uleb128(augmentation_length)?;
+
+            debug_assert_eq!(self.lsda.is_some(), cie.lsda_encoding.is_some());
+            if let (Some(lsda), Some(lsda_encoding)) = (self.lsda, cie.lsda_encoding) {
+                w.write_eh_pointer(lsda, lsda_encoding, encoding.address_size)?;
+            }
+        }
+
+        let mut prev_offset = 0;
+        for (offset, instruction) in &self.instructions {
+            write_advance_loc(w, cie.code_alignment_factor, prev_offset, *offset)?;
+            prev_offset = *offset;
+            instruction.write(w, encoding, cie)?;
+        }
+
+        write_nop(
+            w,
+            encoding.format.word_size() as usize + w.len() - length_base,
+            encoding.address_size,
+        )?;
+
+        let length = (w.len() - length_base) as u64;
+        w.write_initial_length_at(length_offset, length, encoding.format)?;
+
+        Ok(())
+    }
+}
+
+/// An instruction in a frame description entry.
+///
+/// This may be a CFA definition, a register rule, or some other directive.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[non_exhaustive]
+pub enum CallFrameInstruction {
+    /// Define the CFA rule to use the provided register and offset.
+    Cfa(Register, i32),
+    /// Update the CFA rule to use the provided register. The offset is unchanged.
+    CfaRegister(Register),
+    /// Update the CFA rule to use the provided offset. The register is unchanged.
+    CfaOffset(i32),
+    /// Define the CFA rule to use the provided expression.
+    CfaExpression(Expression),
+
+    /// Restore the initial rule for the register.
+    Restore(Register),
+    /// The previous value of the register is not recoverable.
+    Undefined(Register),
+    /// The register has not been modified.
+    SameValue(Register),
+    /// The previous value of the register is saved at address CFA + offset.
+    Offset(Register, i32),
+    /// The previous value of the register is CFA + offset.
+    ValOffset(Register, i32),
+    /// The previous value of the register is stored in another register.
+    Register(Register, Register),
+    /// The previous value of the register is saved at address given by the expression.
+    Expression(Register, Expression),
+    /// The previous value of the register is given by the expression.
+    ValExpression(Register, Expression),
+
+    /// Push all register rules onto a stack.
+    RememberState,
+    /// Pop all register rules off the stack.
+    RestoreState,
+    /// The size of the arguments that have been pushed onto the stack.
+    ArgsSize(u32),
+
+    /// AAarch64 extension: negate the `RA_SIGN_STATE` pseudo-register.
+    NegateRaState,
+}
+
+impl CallFrameInstruction {
+    fn write<W: Writer>(
+        &self,
+        w: &mut W,
+        encoding: Encoding,
+        cie: &CommonInformationEntry,
+    ) -> Result<()> {
+        match *self {
+            CallFrameInstruction::Cfa(register, offset) => {
+                if offset < 0 {
+                    let offset = factored_data_offset(offset, cie.data_alignment_factor)?;
+                    w.write_u8(constants::DW_CFA_def_cfa_sf.0)?;
+                    w.write_uleb128(register.0.into())?;
+                    w.write_sleb128(offset.into())?;
+                } else {
+                    // Unfactored offset.
+                    w.write_u8(constants::DW_CFA_def_cfa.0)?;
+                    w.write_uleb128(register.0.into())?;
+                    w.write_uleb128(offset as u64)?;
+                }
+            }
+            CallFrameInstruction::CfaRegister(register) => {
+                w.write_u8(constants::DW_CFA_def_cfa_register.0)?;
+                w.write_uleb128(register.0.into())?;
+            }
+            CallFrameInstruction::CfaOffset(offset) => {
+                if offset < 0 {
+                    let offset = factored_data_offset(offset, cie.data_alignment_factor)?;
+                    w.write_u8(constants::DW_CFA_def_cfa_offset_sf.0)?;
+                    w.write_sleb128(offset.into())?;
+                } else {
+                    // Unfactored offset.
+                    w.write_u8(constants::DW_CFA_def_cfa_offset.0)?;
+                    w.write_uleb128(offset as u64)?;
+                }
+            }
+            CallFrameInstruction::CfaExpression(ref expression) => {
+                w.write_u8(constants::DW_CFA_def_cfa_expression.0)?;
+                w.write_uleb128(expression.size(encoding, None) as u64)?;
+                expression.write(w, None, encoding, None)?;
+            }
+            CallFrameInstruction::Restore(register) => {
+                if register.0 < 0x40 {
+                    w.write_u8(constants::DW_CFA_restore.0 | register.0 as u8)?;
+                } else {
+                    w.write_u8(constants::DW_CFA_restore_extended.0)?;
+                    w.write_uleb128(register.0.into())?;
+                }
+            }
+            CallFrameInstruction::Undefined(register) => {
+                w.write_u8(constants::DW_CFA_undefined.0)?;
+                w.write_uleb128(register.0.into())?;
+            }
+            CallFrameInstruction::SameValue(register) => {
+                w.write_u8(constants::DW_CFA_same_value.0)?;
+                w.write_uleb128(register.0.into())?;
+            }
+            CallFrameInstruction::Offset(register, offset) => {
+                let offset = factored_data_offset(offset, cie.data_alignment_factor)?;
+                if offset < 0 {
+                    w.write_u8(constants::DW_CFA_offset_extended_sf.0)?;
+                    w.write_uleb128(register.0.into())?;
+                    w.write_sleb128(offset.into())?;
+                } else if register.0 < 0x40 {
+                    w.write_u8(constants::DW_CFA_offset.0 | register.0 as u8)?;
+                    w.write_uleb128(offset as u64)?;
+                } else {
+                    w.write_u8(constants::DW_CFA_offset_extended.0)?;
+                    w.write_uleb128(register.0.into())?;
+                    w.write_uleb128(offset as u64)?;
+                }
+            }
+            CallFrameInstruction::ValOffset(register, offset) => {
+                let offset = factored_data_offset(offset, cie.data_alignment_factor)?;
+                if offset < 0 {
+                    w.write_u8(constants::DW_CFA_val_offset_sf.0)?;
+                    w.write_uleb128(register.0.into())?;
+                    w.write_sleb128(offset.into())?;
+                } else {
+                    w.write_u8(constants::DW_CFA_val_offset.0)?;
+                    w.write_uleb128(register.0.into())?;
+                    w.write_uleb128(offset as u64)?;
+                }
+            }
+            CallFrameInstruction::Register(register1, register2) => {
+                w.write_u8(constants::DW_CFA_register.0)?;
+                w.write_uleb128(register1.0.into())?;
+                w.write_uleb128(register2.0.into())?;
+            }
+            CallFrameInstruction::Expression(register, ref expression) => {
+                w.write_u8(constants::DW_CFA_expression.0)?;
+                w.write_uleb128(register.0.into())?;
+                w.write_uleb128(expression.size(encoding, None) as u64)?;
+                expression.write(w, None, encoding, None)?;
+            }
+            CallFrameInstruction::ValExpression(register, ref expression) => {
+                w.write_u8(constants::DW_CFA_val_expression.0)?;
+                w.write_uleb128(register.0.into())?;
+                w.write_uleb128(expression.size(encoding, None) as u64)?;
+                expression.write(w, None, encoding, None)?;
+            }
+            CallFrameInstruction::RememberState => {
+                w.write_u8(constants::DW_CFA_remember_state.0)?;
+            }
+            CallFrameInstruction::RestoreState => {
+                w.write_u8(constants::DW_CFA_restore_state.0)?;
+            }
+            CallFrameInstruction::ArgsSize(size) => {
+                w.write_u8(constants::DW_CFA_GNU_args_size.0)?;
+                w.write_uleb128(size.into())?;
+            }
+            CallFrameInstruction::NegateRaState => {
+                w.write_u8(constants::DW_CFA_AARCH64_negate_ra_state.0)?;
+            }
+        }
+        Ok(())
+    }
+}
+
+fn write_advance_loc<W: Writer>(
+    w: &mut W,
+    code_alignment_factor: u8,
+    prev_offset: u32,
+    offset: u32,
+) -> Result<()> {
+    if offset == prev_offset {
+        return Ok(());
+    }
+    let delta = factored_code_delta(prev_offset, offset, code_alignment_factor)?;
+    if delta < 0x40 {
+        w.write_u8(constants::DW_CFA_advance_loc.0 | delta as u8)?;
+    } else if delta < 0x100 {
+        w.write_u8(constants::DW_CFA_advance_loc1.0)?;
+        w.write_u8(delta as u8)?;
+    } else if delta < 0x10000 {
+        w.write_u8(constants::DW_CFA_advance_loc2.0)?;
+        w.write_u16(delta as u16)?;
+    } else {
+        w.write_u8(constants::DW_CFA_advance_loc4.0)?;
+        w.write_u32(delta)?;
+    }
+    Ok(())
+}
+
+fn write_nop<W: Writer>(w: &mut W, len: usize, align: u8) -> Result<()> {
+    debug_assert_eq!(align & (align - 1), 0);
+    let tail_len = (!len + 1) & (align as usize - 1);
+    for _ in 0..tail_len {
+        w.write_u8(constants::DW_CFA_nop.0)?;
+    }
+    Ok(())
+}
+
+fn factored_code_delta(prev_offset: u32, offset: u32, factor: u8) -> Result<u32> {
+    if offset < prev_offset {
+        return Err(Error::InvalidFrameCodeOffset(offset));
+    }
+    let delta = offset - prev_offset;
+    let factor = u32::from(factor);
+    let factored_delta = delta / factor;
+    if delta != factored_delta * factor {
+        return Err(Error::InvalidFrameCodeOffset(offset));
+    }
+    Ok(factored_delta)
+}
+
+fn factored_data_offset(offset: i32, factor: i8) -> Result<i32> {
+    let factor = i32::from(factor);
+    let factored_offset = offset / factor;
+    if offset != factored_offset * factor {
+        return Err(Error::InvalidFrameDataOffset(offset));
+    }
+    Ok(factored_offset)
+}
+
+#[cfg(feature = "read")]
+pub(crate) mod convert {
+    use super::*;
+    use crate::read::{self, Reader};
+    use crate::write::{ConvertError, ConvertResult};
+    use std::collections::{hash_map, HashMap};
+
+    impl FrameTable {
+        /// Create a frame table by reading the data in the given section.
+        ///
+        /// `convert_address` is a function to convert read addresses into the `Address`
+        /// type. For non-relocatable addresses, this function may simply return
+        /// `Address::Constant(address)`. For relocatable addresses, it is the caller's
+        /// responsibility to determine the symbol and addend corresponding to the address
+        /// and return `Address::Symbol { symbol, addend }`.
+        pub fn from<R, Section>(
+            frame: &Section,
+            convert_address: &dyn Fn(u64) -> Option<Address>,
+        ) -> ConvertResult<FrameTable>
+        where
+            R: Reader<Offset = usize>,
+            Section: read::UnwindSection<R>,
+            Section::Offset: read::UnwindOffset<usize>,
+        {
+            let bases = read::BaseAddresses::default().set_eh_frame(0);
+
+            let mut frame_table = FrameTable::default();
+
+            let mut cie_ids = HashMap::new();
+            let mut entries = frame.entries(&bases);
+            while let Some(entry) = entries.next()? {
+                let partial = match entry {
+                    read::CieOrFde::Cie(_) => continue,
+                    read::CieOrFde::Fde(partial) => partial,
+                };
+
+                // TODO: is it worth caching the parsed CIEs? It would be better if FDEs only
+                // stored a reference.
+                let from_fde = partial.parse(Section::cie_from_offset)?;
+                let from_cie = from_fde.cie();
+                let cie_id = match cie_ids.entry(from_cie.offset()) {
+                    hash_map::Entry::Occupied(o) => *o.get(),
+                    hash_map::Entry::Vacant(e) => {
+                        let cie =
+                            CommonInformationEntry::from(from_cie, frame, &bases, convert_address)?;
+                        let cie_id = frame_table.add_cie(cie);
+                        e.insert(cie_id);
+                        cie_id
+                    }
+                };
+                let fde = FrameDescriptionEntry::from(&from_fde, frame, &bases, convert_address)?;
+                frame_table.add_fde(cie_id, fde);
+            }
+
+            Ok(frame_table)
+        }
+    }
+
+    impl CommonInformationEntry {
+        fn from<R, Section>(
+            from_cie: &read::CommonInformationEntry<R>,
+            frame: &Section,
+            bases: &read::BaseAddresses,
+            convert_address: &dyn Fn(u64) -> Option<Address>,
+        ) -> ConvertResult<CommonInformationEntry>
+        where
+            R: Reader<Offset = usize>,
+            Section: read::UnwindSection<R>,
+            Section::Offset: read::UnwindOffset<usize>,
+        {
+            let mut cie = CommonInformationEntry::new(
+                from_cie.encoding(),
+                from_cie.code_alignment_factor() as u8,
+                from_cie.data_alignment_factor() as i8,
+                from_cie.return_address_register(),
+            );
+
+            cie.personality = match from_cie.personality_with_encoding() {
+                // We treat these the same because the encoding already determines
+                // whether it is indirect.
+                Some((eh_pe, read::Pointer::Direct(p)))
+                | Some((eh_pe, read::Pointer::Indirect(p))) => {
+                    let address = convert_address(p).ok_or(ConvertError::InvalidAddress)?;
+                    Some((eh_pe, address))
+                }
+                _ => None,
+            };
+            cie.lsda_encoding = from_cie.lsda_encoding();
+            cie.fde_address_encoding = from_cie
+                .fde_address_encoding()
+                .unwrap_or(constants::DW_EH_PE_absptr);
+            cie.signal_trampoline = from_cie.is_signal_trampoline();
+
+            let mut offset = 0;
+            let mut from_instructions = from_cie.instructions(frame, bases);
+            while let Some(from_instruction) = from_instructions.next()? {
+                if let Some(instruction) = CallFrameInstruction::from(
+                    from_instruction,
+                    from_cie,
+                    convert_address,
+                    &mut offset,
+                )? {
+                    cie.instructions.push(instruction);
+                }
+            }
+            Ok(cie)
+        }
+    }
+
+    impl FrameDescriptionEntry {
+        fn from<R, Section>(
+            from_fde: &read::FrameDescriptionEntry<R>,
+            frame: &Section,
+            bases: &read::BaseAddresses,
+            convert_address: &dyn Fn(u64) -> Option<Address>,
+        ) -> ConvertResult<FrameDescriptionEntry>
+        where
+            R: Reader<Offset = usize>,
+            Section: read::UnwindSection<R>,
+            Section::Offset: read::UnwindOffset<usize>,
+        {
+            let address =
+                convert_address(from_fde.initial_address()).ok_or(ConvertError::InvalidAddress)?;
+            let length = from_fde.len() as u32;
+            let mut fde = FrameDescriptionEntry::new(address, length);
+
+            match from_fde.lsda() {
+                // We treat these the same because the encoding already determines
+                // whether it is indirect.
+                Some(read::Pointer::Direct(p)) | Some(read::Pointer::Indirect(p)) => {
+                    let address = convert_address(p).ok_or(ConvertError::InvalidAddress)?;
+                    fde.lsda = Some(address);
+                }
+                None => {}
+            }
+
+            let from_cie = from_fde.cie();
+            let mut offset = 0;
+            let mut from_instructions = from_fde.instructions(frame, bases);
+            while let Some(from_instruction) = from_instructions.next()? {
+                if let Some(instruction) = CallFrameInstruction::from(
+                    from_instruction,
+                    from_cie,
+                    convert_address,
+                    &mut offset,
+                )? {
+                    fde.instructions.push((offset, instruction));
+                }
+            }
+
+            Ok(fde)
+        }
+    }
+
+    impl CallFrameInstruction {
+        fn from<R: Reader<Offset = usize>>(
+            from_instruction: read::CallFrameInstruction<R>,
+            from_cie: &read::CommonInformationEntry<R>,
+            convert_address: &dyn Fn(u64) -> Option<Address>,
+            offset: &mut u32,
+        ) -> ConvertResult<Option<CallFrameInstruction>> {
+            let convert_expression =
+                |x| Expression::from(x, from_cie.encoding(), None, None, None, convert_address);
+            // TODO: validate integer type conversions
+            Ok(Some(match from_instruction {
+                read::CallFrameInstruction::SetLoc { .. } => {
+                    return Err(ConvertError::UnsupportedCfiInstruction);
+                }
+                read::CallFrameInstruction::AdvanceLoc { delta } => {
+                    *offset += delta * from_cie.code_alignment_factor() as u32;
+                    return Ok(None);
+                }
+                read::CallFrameInstruction::DefCfa { register, offset } => {
+                    CallFrameInstruction::Cfa(register, offset as i32)
+                }
+                read::CallFrameInstruction::DefCfaSf {
+                    register,
+                    factored_offset,
+                } => {
+                    let offset = factored_offset * from_cie.data_alignment_factor();
+                    CallFrameInstruction::Cfa(register, offset as i32)
+                }
+                read::CallFrameInstruction::DefCfaRegister { register } => {
+                    CallFrameInstruction::CfaRegister(register)
+                }
+
+                read::CallFrameInstruction::DefCfaOffset { offset } => {
+                    CallFrameInstruction::CfaOffset(offset as i32)
+                }
+                read::CallFrameInstruction::DefCfaOffsetSf { factored_offset } => {
+                    let offset = factored_offset * from_cie.data_alignment_factor();
+                    CallFrameInstruction::CfaOffset(offset as i32)
+                }
+                read::CallFrameInstruction::DefCfaExpression { expression } => {
+                    CallFrameInstruction::CfaExpression(convert_expression(expression)?)
+                }
+                read::CallFrameInstruction::Undefined { register } => {
+                    CallFrameInstruction::Undefined(register)
+                }
+                read::CallFrameInstruction::SameValue { register } => {
+                    CallFrameInstruction::SameValue(register)
+                }
+                read::CallFrameInstruction::Offset {
+                    register,
+                    factored_offset,
+                } => {
+                    let offset = factored_offset as i64 * from_cie.data_alignment_factor();
+                    CallFrameInstruction::Offset(register, offset as i32)
+                }
+                read::CallFrameInstruction::OffsetExtendedSf {
+                    register,
+                    factored_offset,
+                } => {
+                    let offset = factored_offset * from_cie.data_alignment_factor();
+                    CallFrameInstruction::Offset(register, offset as i32)
+                }
+                read::CallFrameInstruction::ValOffset {
+                    register,
+                    factored_offset,
+                } => {
+                    let offset = factored_offset as i64 * from_cie.data_alignment_factor();
+                    CallFrameInstruction::ValOffset(register, offset as i32)
+                }
+                read::CallFrameInstruction::ValOffsetSf {
+                    register,
+                    factored_offset,
+                } => {
+                    let offset = factored_offset * from_cie.data_alignment_factor();
+                    CallFrameInstruction::ValOffset(register, offset as i32)
+                }
+                read::CallFrameInstruction::Register {
+                    dest_register,
+                    src_register,
+                } => CallFrameInstruction::Register(dest_register, src_register),
+                read::CallFrameInstruction::Expression {
+                    register,
+                    expression,
+                } => CallFrameInstruction::Expression(register, convert_expression(expression)?),
+                read::CallFrameInstruction::ValExpression {
+                    register,
+                    expression,
+                } => CallFrameInstruction::ValExpression(register, convert_expression(expression)?),
+                read::CallFrameInstruction::Restore { register } => {
+                    CallFrameInstruction::Restore(register)
+                }
+                read::CallFrameInstruction::RememberState => CallFrameInstruction::RememberState,
+                read::CallFrameInstruction::RestoreState => CallFrameInstruction::RestoreState,
+                read::CallFrameInstruction::ArgsSize { size } => {
+                    CallFrameInstruction::ArgsSize(size as u32)
+                }
+                read::CallFrameInstruction::NegateRaState => CallFrameInstruction::NegateRaState,
+                read::CallFrameInstruction::Nop => return Ok(None),
+            }))
+        }
+    }
+}
+
+#[cfg(test)]
+#[cfg(feature = "read")]
+mod tests {
+    use super::*;
+    use crate::arch::X86_64;
+    use crate::read;
+    use crate::write::EndianVec;
+    use crate::{LittleEndian, Vendor};
+
+    #[test]
+    fn test_frame_table() {
+        for &version in &[1, 3, 4] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+                    let mut frames = FrameTable::default();
+
+                    let cie1 = CommonInformationEntry::new(encoding, 1, 8, X86_64::RA);
+                    let cie1_id = frames.add_cie(cie1.clone());
+                    assert_eq!(cie1_id, frames.add_cie(cie1.clone()));
+
+                    let mut cie2 = CommonInformationEntry::new(encoding, 1, 8, X86_64::RA);
+                    cie2.lsda_encoding = Some(constants::DW_EH_PE_absptr);
+                    cie2.personality =
+                        Some((constants::DW_EH_PE_absptr, Address::Constant(0x1234)));
+                    cie2.signal_trampoline = true;
+                    let cie2_id = frames.add_cie(cie2.clone());
+                    assert_ne!(cie1_id, cie2_id);
+                    assert_eq!(cie2_id, frames.add_cie(cie2.clone()));
+
+                    let fde1 = FrameDescriptionEntry::new(Address::Constant(0x1000), 0x10);
+                    frames.add_fde(cie1_id, fde1.clone());
+
+                    let fde2 = FrameDescriptionEntry::new(Address::Constant(0x2000), 0x20);
+                    frames.add_fde(cie1_id, fde2.clone());
+
+                    let mut fde3 = FrameDescriptionEntry::new(Address::Constant(0x3000), 0x30);
+                    fde3.lsda = Some(Address::Constant(0x3300));
+                    frames.add_fde(cie2_id, fde3.clone());
+
+                    let mut fde4 = FrameDescriptionEntry::new(Address::Constant(0x4000), 0x40);
+                    fde4.lsda = Some(Address::Constant(0x4400));
+                    frames.add_fde(cie2_id, fde4.clone());
+
+                    let mut cie3 = CommonInformationEntry::new(encoding, 1, 8, X86_64::RA);
+                    cie3.fde_address_encoding = constants::DW_EH_PE_pcrel;
+                    cie3.lsda_encoding = Some(constants::DW_EH_PE_pcrel);
+                    cie3.personality = Some((constants::DW_EH_PE_pcrel, Address::Constant(0x1235)));
+                    cie3.signal_trampoline = true;
+                    let cie3_id = frames.add_cie(cie3.clone());
+                    assert_ne!(cie2_id, cie3_id);
+                    assert_eq!(cie3_id, frames.add_cie(cie3.clone()));
+
+                    let mut fde5 = FrameDescriptionEntry::new(Address::Constant(0x5000), 0x50);
+                    fde5.lsda = Some(Address::Constant(0x5500));
+                    frames.add_fde(cie3_id, fde5.clone());
+
+                    // Test writing `.debug_frame`.
+                    let mut debug_frame = DebugFrame::from(EndianVec::new(LittleEndian));
+                    frames.write_debug_frame(&mut debug_frame).unwrap();
+
+                    let mut read_debug_frame =
+                        read::DebugFrame::new(debug_frame.slice(), LittleEndian);
+                    read_debug_frame.set_address_size(address_size);
+                    let convert_frames = FrameTable::from(&read_debug_frame, &|address| {
+                        Some(Address::Constant(address))
+                    })
+                    .unwrap();
+                    assert_eq!(frames.cies, convert_frames.cies);
+                    assert_eq!(frames.fdes.len(), convert_frames.fdes.len());
+                    for (a, b) in frames.fdes.iter().zip(convert_frames.fdes.iter()) {
+                        assert_eq!(a.1, b.1);
+                    }
+
+                    if version == 1 {
+                        // Test writing `.eh_frame`.
+                        let mut eh_frame = EhFrame::from(EndianVec::new(LittleEndian));
+                        frames.write_eh_frame(&mut eh_frame).unwrap();
+
+                        let mut read_eh_frame = read::EhFrame::new(eh_frame.slice(), LittleEndian);
+                        read_eh_frame.set_address_size(address_size);
+                        let convert_frames = FrameTable::from(&read_eh_frame, &|address| {
+                            Some(Address::Constant(address))
+                        })
+                        .unwrap();
+                        assert_eq!(frames.cies, convert_frames.cies);
+                        assert_eq!(frames.fdes.len(), convert_frames.fdes.len());
+                        for (a, b) in frames.fdes.iter().zip(convert_frames.fdes.iter()) {
+                            assert_eq!(a.1, b.1);
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn test_frame_instruction() {
+        let mut expression = Expression::new();
+        expression.op_constu(0);
+
+        let cie_instructions = [
+            CallFrameInstruction::Cfa(X86_64::RSP, 8),
+            CallFrameInstruction::Offset(X86_64::RA, -8),
+        ];
+
+        let fde_instructions = [
+            (0, CallFrameInstruction::Cfa(X86_64::RSP, 0)),
+            (0, CallFrameInstruction::Cfa(X86_64::RSP, -8)),
+            (2, CallFrameInstruction::CfaRegister(X86_64::RBP)),
+            (4, CallFrameInstruction::CfaOffset(8)),
+            (4, CallFrameInstruction::CfaOffset(0)),
+            (4, CallFrameInstruction::CfaOffset(-8)),
+            (6, CallFrameInstruction::CfaExpression(expression.clone())),
+            (8, CallFrameInstruction::Restore(Register(1))),
+            (8, CallFrameInstruction::Restore(Register(101))),
+            (10, CallFrameInstruction::Undefined(Register(2))),
+            (12, CallFrameInstruction::SameValue(Register(3))),
+            (14, CallFrameInstruction::Offset(Register(4), 16)),
+            (14, CallFrameInstruction::Offset(Register(104), 16)),
+            (16, CallFrameInstruction::ValOffset(Register(5), -24)),
+            (16, CallFrameInstruction::ValOffset(Register(5), 24)),
+            (18, CallFrameInstruction::Register(Register(6), Register(7))),
+            (
+                20,
+                CallFrameInstruction::Expression(Register(8), expression.clone()),
+            ),
+            (
+                22,
+                CallFrameInstruction::ValExpression(Register(9), expression.clone()),
+            ),
+            (24 + 0x80, CallFrameInstruction::RememberState),
+            (26 + 0x280, CallFrameInstruction::RestoreState),
+            (28 + 0x20280, CallFrameInstruction::ArgsSize(23)),
+        ];
+
+        let fde_instructions_aarch64 = [(0, CallFrameInstruction::NegateRaState)];
+
+        for &version in &[1, 3, 4] {
+            for &address_size in &[4, 8] {
+                for &vendor in &[Vendor::Default, Vendor::AArch64] {
+                    for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                        let encoding = Encoding {
+                            format,
+                            version,
+                            address_size,
+                        };
+                        let mut frames = FrameTable::default();
+
+                        let mut cie = CommonInformationEntry::new(encoding, 2, 8, X86_64::RA);
+                        for i in &cie_instructions {
+                            cie.add_instruction(i.clone());
+                        }
+                        let cie_id = frames.add_cie(cie);
+
+                        let mut fde = FrameDescriptionEntry::new(Address::Constant(0x1000), 0x10);
+                        for (o, i) in &fde_instructions {
+                            fde.add_instruction(*o, i.clone());
+                        }
+                        frames.add_fde(cie_id, fde);
+
+                        if vendor == Vendor::AArch64 {
+                            let mut fde =
+                                FrameDescriptionEntry::new(Address::Constant(0x2000), 0x10);
+                            for (o, i) in &fde_instructions_aarch64 {
+                                fde.add_instruction(*o, i.clone());
+                            }
+                            frames.add_fde(cie_id, fde);
+                        }
+
+                        let mut debug_frame = DebugFrame::from(EndianVec::new(LittleEndian));
+                        frames.write_debug_frame(&mut debug_frame).unwrap();
+
+                        let mut read_debug_frame =
+                            read::DebugFrame::new(debug_frame.slice(), LittleEndian);
+                        read_debug_frame.set_address_size(address_size);
+                        read_debug_frame.set_vendor(vendor);
+                        let frames = FrameTable::from(&read_debug_frame, &|address| {
+                            Some(Address::Constant(address))
+                        })
+                        .unwrap();
+
+                        assert_eq!(
+                            &frames.cies.get_index(0).unwrap().instructions,
+                            &cie_instructions
+                        );
+                        assert_eq!(&frames.fdes[0].1.instructions, &fde_instructions);
+                        if vendor == Vendor::AArch64 {
+                            assert_eq!(&frames.fdes[1].1.instructions, &fde_instructions_aarch64);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/vendor/gimli/src/write/dwarf.rs b/vendor/gimli/src/write/dwarf.rs
new file mode 100644
index 0000000..ea50712
--- /dev/null
+++ b/vendor/gimli/src/write/dwarf.rs
@@ -0,0 +1,138 @@
+use alloc::vec::Vec;
+
+use crate::common::Encoding;
+use crate::write::{
+    AbbreviationTable, LineProgram, LineStringTable, Result, Sections, StringTable, Unit,
+    UnitTable, Writer,
+};
+
+/// Writable DWARF information for more than one unit.
+#[derive(Debug, Default)]
+pub struct Dwarf {
+    /// A table of units. These are primarily stored in the `.debug_info` section,
+    /// but they also contain information that is stored in other sections.
+    pub units: UnitTable,
+
+    /// Extra line number programs that are not associated with a unit.
+    ///
+    /// These should only be used when generating DWARF5 line-only debug
+    /// information.
+    pub line_programs: Vec<LineProgram>,
+
+    /// A table of strings that will be stored in the `.debug_line_str` section.
+    pub line_strings: LineStringTable,
+
+    /// A table of strings that will be stored in the `.debug_str` section.
+    pub strings: StringTable,
+}
+
+impl Dwarf {
+    /// Create a new `Dwarf` instance.
+    #[inline]
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Write the DWARF information to the given sections.
+    pub fn write<W: Writer>(&mut self, sections: &mut Sections<W>) -> Result<()> {
+        let line_strings = self.line_strings.write(&mut sections.debug_line_str)?;
+        let strings = self.strings.write(&mut sections.debug_str)?;
+        self.units.write(sections, &line_strings, &strings)?;
+        for line_program in &self.line_programs {
+            line_program.write(
+                &mut sections.debug_line,
+                line_program.encoding(),
+                &line_strings,
+                &strings,
+            )?;
+        }
+        Ok(())
+    }
+}
+
+/// Writable DWARF information for a single unit.
+#[derive(Debug)]
+pub struct DwarfUnit {
+    /// A unit. This is primarily stored in the `.debug_info` section,
+    /// but also contains information that is stored in other sections.
+    pub unit: Unit,
+
+    /// A table of strings that will be stored in the `.debug_line_str` section.
+    pub line_strings: LineStringTable,
+
+    /// A table of strings that will be stored in the `.debug_str` section.
+    pub strings: StringTable,
+}
+
+impl DwarfUnit {
+    /// Create a new `DwarfUnit`.
+    ///
+    /// Note: you should set `self.unit.line_program` after creation.
+    /// This cannot be done earlier because it may need to reference
+    /// `self.line_strings`.
+    pub fn new(encoding: Encoding) -> Self {
+        let unit = Unit::new(encoding, LineProgram::none());
+        DwarfUnit {
+            unit,
+            line_strings: LineStringTable::default(),
+            strings: StringTable::default(),
+        }
+    }
+
+    /// Write the DWARf information to the given sections.
+    pub fn write<W: Writer>(&mut self, sections: &mut Sections<W>) -> Result<()> {
+        let line_strings = self.line_strings.write(&mut sections.debug_line_str)?;
+        let strings = self.strings.write(&mut sections.debug_str)?;
+
+        let abbrev_offset = sections.debug_abbrev.offset();
+        let mut abbrevs = AbbreviationTable::default();
+
+        self.unit.write(
+            sections,
+            abbrev_offset,
+            &mut abbrevs,
+            &line_strings,
+            &strings,
+        )?;
+        // None should exist because we didn't give out any UnitId.
+        assert!(sections.debug_info_refs.is_empty());
+        assert!(sections.debug_loc_refs.is_empty());
+        assert!(sections.debug_loclists_refs.is_empty());
+
+        abbrevs.write(&mut sections.debug_abbrev)?;
+        Ok(())
+    }
+}
+
+#[cfg(feature = "read")]
+pub(crate) mod convert {
+    use super::*;
+    use crate::read::{self, Reader};
+    use crate::write::{Address, ConvertResult};
+
+    impl Dwarf {
+        /// Create a `write::Dwarf` by converting a `read::Dwarf`.
+        ///
+        /// `convert_address` is a function to convert read addresses into the `Address`
+        /// type. For non-relocatable addresses, this function may simply return
+        /// `Address::Constant(address)`. For relocatable addresses, it is the caller's
+        /// responsibility to determine the symbol and addend corresponding to the address
+        /// and return `Address::Symbol { symbol, addend }`.
+        pub fn from<R: Reader<Offset = usize>>(
+            dwarf: &read::Dwarf<R>,
+            convert_address: &dyn Fn(u64) -> Option<Address>,
+        ) -> ConvertResult<Dwarf> {
+            let mut line_strings = LineStringTable::default();
+            let mut strings = StringTable::default();
+            let units = UnitTable::from(dwarf, &mut line_strings, &mut strings, convert_address)?;
+            // TODO: convert the line programs that were not referenced by a unit.
+            let line_programs = Vec::new();
+            Ok(Dwarf {
+                units,
+                line_programs,
+                line_strings,
+                strings,
+            })
+        }
+    }
+}
diff --git a/vendor/gimli/src/write/endian_vec.rs b/vendor/gimli/src/write/endian_vec.rs
new file mode 100644
index 0000000..7b04060
--- /dev/null
+++ b/vendor/gimli/src/write/endian_vec.rs
@@ -0,0 +1,117 @@
+use alloc::vec::Vec;
+use std::mem;
+
+use crate::endianity::Endianity;
+use crate::write::{Error, Result, Writer};
+
+/// A `Vec<u8>` with endianity metadata.
+///
+/// This implements the `Writer` trait, which is used for all writing of DWARF sections.
+#[derive(Debug, Clone)]
+pub struct EndianVec<Endian>
+where
+    Endian: Endianity,
+{
+    vec: Vec<u8>,
+    endian: Endian,
+}
+
+impl<Endian> EndianVec<Endian>
+where
+    Endian: Endianity,
+{
+    /// Construct an empty `EndianVec` with the given endianity.
+    pub fn new(endian: Endian) -> EndianVec<Endian> {
+        EndianVec {
+            vec: Vec::new(),
+            endian,
+        }
+    }
+
+    /// Return a reference to the raw slice.
+    pub fn slice(&self) -> &[u8] {
+        &self.vec
+    }
+
+    /// Convert into a `Vec<u8>`.
+    pub fn into_vec(self) -> Vec<u8> {
+        self.vec
+    }
+
+    /// Take any written data out of the `EndianVec`, leaving an empty `Vec` in its place.
+    pub fn take(&mut self) -> Vec<u8> {
+        let mut vec = Vec::new();
+        mem::swap(&mut self.vec, &mut vec);
+        vec
+    }
+}
+
+impl<Endian> Writer for EndianVec<Endian>
+where
+    Endian: Endianity,
+{
+    type Endian = Endian;
+
+    #[inline]
+    fn endian(&self) -> Self::Endian {
+        self.endian
+    }
+
+    #[inline]
+    fn len(&self) -> usize {
+        self.vec.len()
+    }
+
+    fn write(&mut self, bytes: &[u8]) -> Result<()> {
+        self.vec.extend(bytes);
+        Ok(())
+    }
+
+    fn write_at(&mut self, offset: usize, bytes: &[u8]) -> Result<()> {
+        if offset > self.vec.len() {
+            return Err(Error::OffsetOutOfBounds);
+        }
+        let to = &mut self.vec[offset..];
+        if bytes.len() > to.len() {
+            return Err(Error::LengthOutOfBounds);
+        }
+        let to = &mut to[..bytes.len()];
+        to.copy_from_slice(bytes);
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::LittleEndian;
+
+    #[test]
+    fn test_endian_vec() {
+        let mut w = EndianVec::new(LittleEndian);
+        assert_eq!(w.endian(), LittleEndian);
+        assert_eq!(w.len(), 0);
+
+        w.write(&[1, 2]).unwrap();
+        assert_eq!(w.slice(), &[1, 2]);
+        assert_eq!(w.len(), 2);
+
+        w.write(&[3, 4, 5]).unwrap();
+        assert_eq!(w.slice(), &[1, 2, 3, 4, 5]);
+        assert_eq!(w.len(), 5);
+
+        w.write_at(0, &[6, 7]).unwrap();
+        assert_eq!(w.slice(), &[6, 7, 3, 4, 5]);
+        assert_eq!(w.len(), 5);
+
+        w.write_at(3, &[8, 9]).unwrap();
+        assert_eq!(w.slice(), &[6, 7, 3, 8, 9]);
+        assert_eq!(w.len(), 5);
+
+        assert_eq!(w.write_at(4, &[6, 7]), Err(Error::LengthOutOfBounds));
+        assert_eq!(w.write_at(5, &[6, 7]), Err(Error::LengthOutOfBounds));
+        assert_eq!(w.write_at(6, &[6, 7]), Err(Error::OffsetOutOfBounds));
+
+        assert_eq!(w.into_vec(), vec![6, 7, 3, 8, 9]);
+    }
+}
diff --git a/vendor/gimli/src/write/line.rs b/vendor/gimli/src/write/line.rs
new file mode 100644
index 0000000..c88b735
--- /dev/null
+++ b/vendor/gimli/src/write/line.rs
@@ -0,0 +1,1957 @@
+use alloc::vec::Vec;
+use indexmap::{IndexMap, IndexSet};
+use std::ops::{Deref, DerefMut};
+
+use crate::common::{DebugLineOffset, Encoding, Format, LineEncoding, SectionId};
+use crate::constants;
+use crate::leb128;
+use crate::write::{
+    Address, DebugLineStrOffsets, DebugStrOffsets, Error, LineStringId, LineStringTable, Result,
+    Section, StringId, Writer,
+};
+
+/// The number assigned to the first special opcode.
+//
+// We output all instructions for all DWARF versions, since readers
+// should be able to ignore instructions they don't support.
+const OPCODE_BASE: u8 = 13;
+
+/// A line number program.
+#[derive(Debug, Clone)]
+pub struct LineProgram {
+    /// True if this line program was created with `LineProgram::none()`.
+    none: bool,
+    encoding: Encoding,
+    line_encoding: LineEncoding,
+
+    /// A list of source directory path names.
+    ///
+    /// If a path is relative, then the directory is located relative to the working
+    /// directory of the compilation unit.
+    ///
+    /// The first entry is for the working directory of the compilation unit.
+    directories: IndexSet<LineString>,
+
+    /// A list of source file entries.
+    ///
+    /// Each entry has a path name and a directory.
+    ///
+    /// If a path is a relative, then the file is located relative to the
+    /// directory. Otherwise the directory is meaningless.
+    ///
+    /// Does not include comp_file, even for version >= 5.
+    files: IndexMap<(LineString, DirectoryId), FileInfo>,
+
+    /// The primary source file of the compilation unit.
+    /// This is required for version >= 5, but we never reference it elsewhere
+    /// because DWARF defines DW_AT_decl_file=0 to mean not specified.
+    comp_file: (LineString, FileInfo),
+
+    /// True if the file entries may have valid timestamps.
+    ///
+    /// Entries may still have a timestamp of 0 even if this is set.
+    /// For version <= 4, this is ignored.
+    /// For version 5, this controls whether to emit `DW_LNCT_timestamp`.
+    pub file_has_timestamp: bool,
+
+    /// True if the file entries may have valid sizes.
+    ///
+    /// Entries may still have a size of 0 even if this is set.
+    /// For version <= 4, this is ignored.
+    /// For version 5, this controls whether to emit `DW_LNCT_size`.
+    pub file_has_size: bool,
+
+    /// True if the file entries have valid MD5 checksums.
+    ///
+    /// For version <= 4, this is ignored.
+    /// For version 5, this controls whether to emit `DW_LNCT_MD5`.
+    pub file_has_md5: bool,
+
+    prev_row: LineRow,
+    row: LineRow,
+    // TODO: this probably should be either rows or sequences instead
+    instructions: Vec<LineInstruction>,
+    in_sequence: bool,
+}
+
+impl LineProgram {
+    /// Create a new `LineProgram`.
+    ///
+    /// `comp_dir` defines the working directory of the compilation unit,
+    /// and must be the same as the `DW_AT_comp_dir` attribute
+    /// of the compilation unit DIE.
+    ///
+    /// `comp_file` and `comp_file_info` define the primary source file
+    /// of the compilation unit and must be the same as the `DW_AT_name`
+    /// attribute of the compilation unit DIE.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `line_encoding.line_base` > 0.
+    ///
+    /// Panics if `line_encoding.line_base` + `line_encoding.line_range` <= 0.
+    ///
+    /// Panics if `comp_dir` is empty or contains a null byte.
+    ///
+    /// Panics if `comp_file` is empty or contains a null byte.
+    pub fn new(
+        encoding: Encoding,
+        line_encoding: LineEncoding,
+        comp_dir: LineString,
+        comp_file: LineString,
+        comp_file_info: Option<FileInfo>,
+    ) -> LineProgram {
+        // We require a special opcode for a line advance of 0.
+        // See the debug_asserts in generate_row().
+        assert!(line_encoding.line_base <= 0);
+        assert!(line_encoding.line_base + line_encoding.line_range as i8 > 0);
+        let mut program = LineProgram {
+            none: false,
+            encoding,
+            line_encoding,
+            directories: IndexSet::new(),
+            files: IndexMap::new(),
+            comp_file: (comp_file, comp_file_info.unwrap_or_default()),
+            prev_row: LineRow::initial_state(line_encoding),
+            row: LineRow::initial_state(line_encoding),
+            instructions: Vec::new(),
+            in_sequence: false,
+            file_has_timestamp: false,
+            file_has_size: false,
+            file_has_md5: false,
+        };
+        // For all DWARF versions, directory index 0 is comp_dir.
+        // For version <= 4, the entry is implicit. We still add
+        // it here so that we use it, but we don't emit it.
+        program.add_directory(comp_dir);
+        program
+    }
+
+    /// Create a new `LineProgram` with no fields set.
+    ///
+    /// This can be used when the `LineProgram` will not be used.
+    ///
+    /// You should not attempt to add files or line instructions to
+    /// this line program, or write it to the `.debug_line` section.
+    pub fn none() -> Self {
+        let line_encoding = LineEncoding::default();
+        LineProgram {
+            none: true,
+            encoding: Encoding {
+                format: Format::Dwarf32,
+                version: 2,
+                address_size: 0,
+            },
+            line_encoding,
+            directories: IndexSet::new(),
+            files: IndexMap::new(),
+            comp_file: (LineString::String(Vec::new()), FileInfo::default()),
+            prev_row: LineRow::initial_state(line_encoding),
+            row: LineRow::initial_state(line_encoding),
+            instructions: Vec::new(),
+            in_sequence: false,
+            file_has_timestamp: false,
+            file_has_size: false,
+            file_has_md5: false,
+        }
+    }
+
+    /// Return true if this line program was created with `LineProgram::none()`.
+    #[inline]
+    pub fn is_none(&self) -> bool {
+        self.none
+    }
+
+    /// Return the encoding parameters for this line program.
+    #[inline]
+    pub fn encoding(&self) -> Encoding {
+        self.encoding
+    }
+
+    /// Return the DWARF version for this line program.
+    #[inline]
+    pub fn version(&self) -> u16 {
+        self.encoding.version
+    }
+
+    /// Return the address size in bytes for this line program.
+    #[inline]
+    pub fn address_size(&self) -> u8 {
+        self.encoding.address_size
+    }
+
+    /// Return the DWARF format for this line program.
+    #[inline]
+    pub fn format(&self) -> Format {
+        self.encoding.format
+    }
+
+    /// Return the id for the working directory of the compilation unit.
+    #[inline]
+    pub fn default_directory(&self) -> DirectoryId {
+        DirectoryId(0)
+    }
+
+    /// Add a directory entry and return its id.
+    ///
+    /// If the directory already exists, then return the id of the existing entry.
+    ///
+    /// If the path is relative, then the directory is located relative to the working
+    /// directory of the compilation unit.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `directory` is empty or contains a null byte.
+    pub fn add_directory(&mut self, directory: LineString) -> DirectoryId {
+        if let LineString::String(ref val) = directory {
+            // For DWARF version <= 4, directories must not be empty.
+            // The first directory isn't emitted so skip the check for it.
+            if self.encoding.version <= 4 && !self.directories.is_empty() {
+                assert!(!val.is_empty());
+            }
+            assert!(!val.contains(&0));
+        }
+        let (index, _) = self.directories.insert_full(directory);
+        DirectoryId(index)
+    }
+
+    /// Get a reference to a directory entry.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `id` is invalid.
+    pub fn get_directory(&self, id: DirectoryId) -> &LineString {
+        self.directories.get_index(id.0).unwrap()
+    }
+
+    /// Add a file entry and return its id.
+    ///
+    /// If the file already exists, then return the id of the existing entry.
+    ///
+    /// If the file path is relative, then the file is located relative
+    /// to the directory. Otherwise the directory is meaningless, but it
+    /// is still used as a key for file entries.
+    ///
+    /// If `info` is `None`, then new entries are assigned
+    /// default information, and existing entries are unmodified.
+    ///
+    /// If `info` is not `None`, then it is always assigned to the
+    /// entry, even if the entry already exists.
+    ///
+    /// # Panics
+    ///
+    /// Panics if 'file' is empty or contains a null byte.
+    pub fn add_file(
+        &mut self,
+        file: LineString,
+        directory: DirectoryId,
+        info: Option<FileInfo>,
+    ) -> FileId {
+        if let LineString::String(ref val) = file {
+            assert!(!val.is_empty());
+            assert!(!val.contains(&0));
+        }
+
+        let key = (file, directory);
+        let index = if let Some(info) = info {
+            let (index, _) = self.files.insert_full(key, info);
+            index
+        } else {
+            let entry = self.files.entry(key);
+            let index = entry.index();
+            entry.or_default();
+            index
+        };
+        FileId::new(index)
+    }
+
+    /// Get a reference to a file entry.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `id` is invalid.
+    pub fn get_file(&self, id: FileId) -> (&LineString, DirectoryId) {
+        match id.index() {
+            None => (&self.comp_file.0, DirectoryId(0)),
+            Some(index) => self
+                .files
+                .get_index(index)
+                .map(|entry| (&(entry.0).0, (entry.0).1))
+                .unwrap(),
+        }
+    }
+
+    /// Get a reference to the info for a file entry.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `id` is invalid.
+    pub fn get_file_info(&self, id: FileId) -> &FileInfo {
+        match id.index() {
+            None => &self.comp_file.1,
+            Some(index) => self.files.get_index(index).map(|entry| entry.1).unwrap(),
+        }
+    }
+
+    /// Get a mutable reference to the info for a file entry.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `id` is invalid.
+    pub fn get_file_info_mut(&mut self, id: FileId) -> &mut FileInfo {
+        match id.index() {
+            None => &mut self.comp_file.1,
+            Some(index) => self
+                .files
+                .get_index_mut(index)
+                .map(|entry| entry.1)
+                .unwrap(),
+        }
+    }
+
+    /// Begin a new sequence and set its base address.
+    ///
+    /// # Panics
+    ///
+    /// Panics if a sequence has already begun.
+    pub fn begin_sequence(&mut self, address: Option<Address>) {
+        assert!(!self.in_sequence);
+        self.in_sequence = true;
+        if let Some(address) = address {
+            self.instructions.push(LineInstruction::SetAddress(address));
+        }
+    }
+
+    /// End the sequence, and reset the row to its default values.
+    ///
+    /// Only the `address_offset` and op_index` fields of the current row are used.
+    ///
+    /// # Panics
+    ///
+    /// Panics if a sequence has not begun.
+    pub fn end_sequence(&mut self, address_offset: u64) {
+        assert!(self.in_sequence);
+        self.in_sequence = false;
+        self.row.address_offset = address_offset;
+        let op_advance = self.op_advance();
+        if op_advance != 0 {
+            self.instructions
+                .push(LineInstruction::AdvancePc(op_advance));
+        }
+        self.instructions.push(LineInstruction::EndSequence);
+        self.prev_row = LineRow::initial_state(self.line_encoding);
+        self.row = LineRow::initial_state(self.line_encoding);
+    }
+
+    /// Return true if a sequence has begun.
+    #[inline]
+    pub fn in_sequence(&self) -> bool {
+        self.in_sequence
+    }
+
+    /// Returns a reference to the data for the current row.
+    #[inline]
+    pub fn row(&mut self) -> &mut LineRow {
+        &mut self.row
+    }
+
+    /// Generates the line number information instructions for the current row.
+    ///
+    /// After the instructions are generated, it sets `discriminator` to 0, and sets
+    /// `basic_block`, `prologue_end`, and `epilogue_begin` to false.
+    ///
+    /// # Panics
+    ///
+    /// Panics if a sequence has not begun.
+    /// Panics if the address_offset decreases.
+    pub fn generate_row(&mut self) {
+        assert!(self.in_sequence);
+
+        // Output fields that are reset on every row.
+        if self.row.discriminator != 0 {
+            self.instructions
+                .push(LineInstruction::SetDiscriminator(self.row.discriminator));
+            self.row.discriminator = 0;
+        }
+        if self.row.basic_block {
+            self.instructions.push(LineInstruction::SetBasicBlock);
+            self.row.basic_block = false;
+        }
+        if self.row.prologue_end {
+            self.instructions.push(LineInstruction::SetPrologueEnd);
+            self.row.prologue_end = false;
+        }
+        if self.row.epilogue_begin {
+            self.instructions.push(LineInstruction::SetEpilogueBegin);
+            self.row.epilogue_begin = false;
+        }
+
+        // Output fields that are not reset on every row.
+        if self.row.is_statement != self.prev_row.is_statement {
+            self.instructions.push(LineInstruction::NegateStatement);
+        }
+        if self.row.file != self.prev_row.file {
+            self.instructions
+                .push(LineInstruction::SetFile(self.row.file));
+        }
+        if self.row.column != self.prev_row.column {
+            self.instructions
+                .push(LineInstruction::SetColumn(self.row.column));
+        }
+        if self.row.isa != self.prev_row.isa {
+            self.instructions
+                .push(LineInstruction::SetIsa(self.row.isa));
+        }
+
+        // Advance the line, address, and operation index.
+        let line_base = i64::from(self.line_encoding.line_base) as u64;
+        let line_range = u64::from(self.line_encoding.line_range);
+        let line_advance = self.row.line as i64 - self.prev_row.line as i64;
+        let op_advance = self.op_advance();
+
+        // Default to special advances of 0.
+        let special_base = u64::from(OPCODE_BASE);
+        // TODO: handle lack of special opcodes for 0 line advance
+        debug_assert!(self.line_encoding.line_base <= 0);
+        debug_assert!(self.line_encoding.line_base + self.line_encoding.line_range as i8 >= 0);
+        let special_default = special_base.wrapping_sub(line_base);
+        let mut special = special_default;
+        let mut use_special = false;
+
+        if line_advance != 0 {
+            let special_line = (line_advance as u64).wrapping_sub(line_base);
+            if special_line < line_range {
+                special = special_base + special_line;
+                use_special = true;
+            } else {
+                self.instructions
+                    .push(LineInstruction::AdvanceLine(line_advance));
+            }
+        }
+
+        if op_advance != 0 {
+            // Using ConstAddPc can save a byte.
+            let (special_op_advance, const_add_pc) = if special + op_advance * line_range <= 255 {
+                (op_advance, false)
+            } else {
+                let op_range = (255 - special_base) / line_range;
+                (op_advance - op_range, true)
+            };
+
+            let special_op = special_op_advance * line_range;
+            if special + special_op <= 255 {
+                special += special_op;
+                use_special = true;
+                if const_add_pc {
+                    self.instructions.push(LineInstruction::ConstAddPc);
+                }
+            } else {
+                self.instructions
+                    .push(LineInstruction::AdvancePc(op_advance));
+            }
+        }
+
+        if use_special && special != special_default {
+            debug_assert!(special >= special_base);
+            debug_assert!(special <= 255);
+            self.instructions
+                .push(LineInstruction::Special(special as u8));
+        } else {
+            self.instructions.push(LineInstruction::Copy);
+        }
+
+        self.prev_row = self.row;
+    }
+
+    fn op_advance(&self) -> u64 {
+        debug_assert!(self.row.address_offset >= self.prev_row.address_offset);
+        let mut address_advance = self.row.address_offset - self.prev_row.address_offset;
+        if self.line_encoding.minimum_instruction_length != 1 {
+            debug_assert_eq!(
+                self.row.address_offset % u64::from(self.line_encoding.minimum_instruction_length),
+                0
+            );
+            address_advance /= u64::from(self.line_encoding.minimum_instruction_length);
+        }
+        address_advance * u64::from(self.line_encoding.maximum_operations_per_instruction)
+            + self.row.op_index
+            - self.prev_row.op_index
+    }
+
+    /// Returns true if the line number program has no instructions.
+    ///
+    /// Does not check the file or directory entries.
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.instructions.is_empty()
+    }
+
+    /// Write the line number program to the given section.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `self.is_none()`.
+    pub fn write<W: Writer>(
+        &self,
+        w: &mut DebugLine<W>,
+        encoding: Encoding,
+        debug_line_str_offsets: &DebugLineStrOffsets,
+        debug_str_offsets: &DebugStrOffsets,
+    ) -> Result<DebugLineOffset> {
+        assert!(!self.is_none());
+
+        if encoding.version < self.version()
+            || encoding.format != self.format()
+            || encoding.address_size != self.address_size()
+        {
+            return Err(Error::IncompatibleLineProgramEncoding);
+        }
+
+        let offset = w.offset();
+
+        let length_offset = w.write_initial_length(self.format())?;
+        let length_base = w.len();
+
+        if self.version() < 2 || self.version() > 5 {
+            return Err(Error::UnsupportedVersion(self.version()));
+        }
+        w.write_u16(self.version())?;
+
+        if self.version() >= 5 {
+            w.write_u8(self.address_size())?;
+            // Segment selector size.
+            w.write_u8(0)?;
+        }
+
+        let header_length_offset = w.len();
+        w.write_udata(0, self.format().word_size())?;
+        let header_length_base = w.len();
+
+        w.write_u8(self.line_encoding.minimum_instruction_length)?;
+        if self.version() >= 4 {
+            w.write_u8(self.line_encoding.maximum_operations_per_instruction)?;
+        } else if self.line_encoding.maximum_operations_per_instruction != 1 {
+            return Err(Error::NeedVersion(4));
+        };
+        w.write_u8(if self.line_encoding.default_is_stmt {
+            1
+        } else {
+            0
+        })?;
+        w.write_u8(self.line_encoding.line_base as u8)?;
+        w.write_u8(self.line_encoding.line_range)?;
+        w.write_u8(OPCODE_BASE)?;
+        w.write(&[0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1])?;
+
+        if self.version() <= 4 {
+            // The first directory is stored as DW_AT_comp_dir.
+            for dir in self.directories.iter().skip(1) {
+                dir.write(
+                    w,
+                    constants::DW_FORM_string,
+                    self.encoding,
+                    debug_line_str_offsets,
+                    debug_str_offsets,
+                )?;
+            }
+            w.write_u8(0)?;
+
+            for ((file, dir), info) in self.files.iter() {
+                file.write(
+                    w,
+                    constants::DW_FORM_string,
+                    self.encoding,
+                    debug_line_str_offsets,
+                    debug_str_offsets,
+                )?;
+                w.write_uleb128(dir.0 as u64)?;
+                w.write_uleb128(info.timestamp)?;
+                w.write_uleb128(info.size)?;
+            }
+            w.write_u8(0)?;
+        } else {
+            // Directory entry formats (only ever 1).
+            w.write_u8(1)?;
+            w.write_uleb128(u64::from(constants::DW_LNCT_path.0))?;
+            let dir_form = self.directories.get_index(0).unwrap().form();
+            w.write_uleb128(dir_form.0.into())?;
+
+            // Directory entries.
+            w.write_uleb128(self.directories.len() as u64)?;
+            for dir in self.directories.iter() {
+                dir.write(
+                    w,
+                    dir_form,
+                    self.encoding,
+                    debug_line_str_offsets,
+                    debug_str_offsets,
+                )?;
+            }
+
+            // File name entry formats.
+            let count = 2
+                + if self.file_has_timestamp { 1 } else { 0 }
+                + if self.file_has_size { 1 } else { 0 }
+                + if self.file_has_md5 { 1 } else { 0 };
+            w.write_u8(count)?;
+            w.write_uleb128(u64::from(constants::DW_LNCT_path.0))?;
+            let file_form = self.comp_file.0.form();
+            w.write_uleb128(file_form.0.into())?;
+            w.write_uleb128(u64::from(constants::DW_LNCT_directory_index.0))?;
+            w.write_uleb128(constants::DW_FORM_udata.0.into())?;
+            if self.file_has_timestamp {
+                w.write_uleb128(u64::from(constants::DW_LNCT_timestamp.0))?;
+                w.write_uleb128(constants::DW_FORM_udata.0.into())?;
+            }
+            if self.file_has_size {
+                w.write_uleb128(u64::from(constants::DW_LNCT_size.0))?;
+                w.write_uleb128(constants::DW_FORM_udata.0.into())?;
+            }
+            if self.file_has_md5 {
+                w.write_uleb128(u64::from(constants::DW_LNCT_MD5.0))?;
+                w.write_uleb128(constants::DW_FORM_data16.0.into())?;
+            }
+
+            // File name entries.
+            w.write_uleb128(self.files.len() as u64 + 1)?;
+            let mut write_file = |file: &LineString, dir: DirectoryId, info: &FileInfo| {
+                file.write(
+                    w,
+                    file_form,
+                    self.encoding,
+                    debug_line_str_offsets,
+                    debug_str_offsets,
+                )?;
+                w.write_uleb128(dir.0 as u64)?;
+                if self.file_has_timestamp {
+                    w.write_uleb128(info.timestamp)?;
+                }
+                if self.file_has_size {
+                    w.write_uleb128(info.size)?;
+                }
+                if self.file_has_md5 {
+                    w.write(&info.md5)?;
+                }
+                Ok(())
+            };
+            write_file(&self.comp_file.0, DirectoryId(0), &self.comp_file.1)?;
+            for ((file, dir), info) in self.files.iter() {
+                write_file(file, *dir, info)?;
+            }
+        }
+
+        let header_length = (w.len() - header_length_base) as u64;
+        w.write_udata_at(
+            header_length_offset,
+            header_length,
+            self.format().word_size(),
+        )?;
+
+        for instruction in &self.instructions {
+            instruction.write(w, self.address_size())?;
+        }
+
+        let length = (w.len() - length_base) as u64;
+        w.write_initial_length_at(length_offset, length, self.format())?;
+
+        Ok(offset)
+    }
+}
+
+/// A row in the line number table that corresponds to a machine instruction.
+#[derive(Debug, Clone, Copy)]
+pub struct LineRow {
+    /// The offset of the instruction from the start address of the sequence.
+    pub address_offset: u64,
+    /// The index of an operation within a VLIW instruction.
+    ///
+    /// The index of the first operation is 0.
+    /// Set to 0 for non-VLIW instructions.
+    pub op_index: u64,
+
+    /// The source file corresponding to the instruction.
+    pub file: FileId,
+    /// The line number within the source file.
+    ///
+    /// Lines are numbered beginning at 1. Set to 0 if there is no source line.
+    pub line: u64,
+    /// The column number within the source line.
+    ///
+    /// Columns are numbered beginning at 1. Set to 0 for the "left edge" of the line.
+    pub column: u64,
+    /// An additional discriminator used to distinguish between source locations.
+    /// This value is assigned arbitrarily by the DWARF producer.
+    pub discriminator: u64,
+
+    /// Set to true if the instruction is a recommended breakpoint for a statement.
+    pub is_statement: bool,
+    /// Set to true if the instruction is the beginning of a basic block.
+    pub basic_block: bool,
+    /// Set to true if the instruction is a recommended breakpoint at the entry of a
+    /// function.
+    pub prologue_end: bool,
+    /// Set to true if the instruction is a recommended breakpoint prior to the exit of
+    /// a function.
+    pub epilogue_begin: bool,
+
+    /// The instruction set architecture of the instruction.
+    ///
+    /// Set to 0 for the default ISA. Other values are defined by the architecture ABI.
+    pub isa: u64,
+}
+
+impl LineRow {
+    /// Return the initial state as specified in the DWARF standard.
+    fn initial_state(line_encoding: LineEncoding) -> Self {
+        LineRow {
+            address_offset: 0,
+            op_index: 0,
+
+            file: FileId::initial_state(),
+            line: 1,
+            column: 0,
+            discriminator: 0,
+
+            is_statement: line_encoding.default_is_stmt,
+            basic_block: false,
+            prologue_end: false,
+            epilogue_begin: false,
+
+            isa: 0,
+        }
+    }
+}
+
+/// An instruction in a line number program.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum LineInstruction {
+    // Special opcodes
+    Special(u8),
+
+    // Standard opcodes
+    Copy,
+    AdvancePc(u64),
+    AdvanceLine(i64),
+    SetFile(FileId),
+    SetColumn(u64),
+    NegateStatement,
+    SetBasicBlock,
+    ConstAddPc,
+    // DW_LNS_fixed_advance_pc is not supported.
+    SetPrologueEnd,
+    SetEpilogueBegin,
+    SetIsa(u64),
+
+    // Extended opcodes
+    EndSequence,
+    // TODO: this doubles the size of this enum.
+    SetAddress(Address),
+    // DW_LNE_define_file is not supported.
+    SetDiscriminator(u64),
+}
+
+impl LineInstruction {
+    /// Write the line number instruction to the given section.
+    fn write<W: Writer>(self, w: &mut DebugLine<W>, address_size: u8) -> Result<()> {
+        use self::LineInstruction::*;
+        match self {
+            Special(val) => w.write_u8(val)?,
+            Copy => w.write_u8(constants::DW_LNS_copy.0)?,
+            AdvancePc(val) => {
+                w.write_u8(constants::DW_LNS_advance_pc.0)?;
+                w.write_uleb128(val)?;
+            }
+            AdvanceLine(val) => {
+                w.write_u8(constants::DW_LNS_advance_line.0)?;
+                w.write_sleb128(val)?;
+            }
+            SetFile(val) => {
+                w.write_u8(constants::DW_LNS_set_file.0)?;
+                w.write_uleb128(val.raw())?;
+            }
+            SetColumn(val) => {
+                w.write_u8(constants::DW_LNS_set_column.0)?;
+                w.write_uleb128(val)?;
+            }
+            NegateStatement => w.write_u8(constants::DW_LNS_negate_stmt.0)?,
+            SetBasicBlock => w.write_u8(constants::DW_LNS_set_basic_block.0)?,
+            ConstAddPc => w.write_u8(constants::DW_LNS_const_add_pc.0)?,
+            SetPrologueEnd => w.write_u8(constants::DW_LNS_set_prologue_end.0)?,
+            SetEpilogueBegin => w.write_u8(constants::DW_LNS_set_epilogue_begin.0)?,
+            SetIsa(val) => {
+                w.write_u8(constants::DW_LNS_set_isa.0)?;
+                w.write_uleb128(val)?;
+            }
+            EndSequence => {
+                w.write_u8(0)?;
+                w.write_uleb128(1)?;
+                w.write_u8(constants::DW_LNE_end_sequence.0)?;
+            }
+            SetAddress(address) => {
+                w.write_u8(0)?;
+                w.write_uleb128(1 + u64::from(address_size))?;
+                w.write_u8(constants::DW_LNE_set_address.0)?;
+                w.write_address(address, address_size)?;
+            }
+            SetDiscriminator(val) => {
+                let mut bytes = [0u8; 10];
+                // bytes is long enough so this will never fail.
+                let len = leb128::write::unsigned(&mut { &mut bytes[..] }, val).unwrap();
+                w.write_u8(0)?;
+                w.write_uleb128(1 + len as u64)?;
+                w.write_u8(constants::DW_LNE_set_discriminator.0)?;
+                w.write(&bytes[..len])?;
+            }
+        }
+        Ok(())
+    }
+}
+
+/// A string value for use in defining paths in line number programs.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum LineString {
+    /// A slice of bytes representing a string. Must not include null bytes.
+    /// Not guaranteed to be UTF-8 or anything like that.
+    String(Vec<u8>),
+
+    /// A reference to a string in the `.debug_str` section.
+    StringRef(StringId),
+
+    /// A reference to a string in the `.debug_line_str` section.
+    LineStringRef(LineStringId),
+}
+
+impl LineString {
+    /// Create a `LineString` using the normal form for the given encoding.
+    pub fn new<T>(val: T, encoding: Encoding, line_strings: &mut LineStringTable) -> Self
+    where
+        T: Into<Vec<u8>>,
+    {
+        let val = val.into();
+        if encoding.version <= 4 {
+            LineString::String(val)
+        } else {
+            LineString::LineStringRef(line_strings.add(val))
+        }
+    }
+
+    fn form(&self) -> constants::DwForm {
+        match *self {
+            LineString::String(..) => constants::DW_FORM_string,
+            LineString::StringRef(..) => constants::DW_FORM_strp,
+            LineString::LineStringRef(..) => constants::DW_FORM_line_strp,
+        }
+    }
+
+    fn write<W: Writer>(
+        &self,
+        w: &mut DebugLine<W>,
+        form: constants::DwForm,
+        encoding: Encoding,
+        debug_line_str_offsets: &DebugLineStrOffsets,
+        debug_str_offsets: &DebugStrOffsets,
+    ) -> Result<()> {
+        if form != self.form() {
+            return Err(Error::LineStringFormMismatch);
+        }
+
+        match *self {
+            LineString::String(ref val) => {
+                if encoding.version <= 4 {
+                    debug_assert!(!val.is_empty());
+                }
+                w.write(val)?;
+                w.write_u8(0)?;
+            }
+            LineString::StringRef(val) => {
+                if encoding.version < 5 {
+                    return Err(Error::NeedVersion(5));
+                }
+                w.write_offset(
+                    debug_str_offsets.get(val).0,
+                    SectionId::DebugStr,
+                    encoding.format.word_size(),
+                )?;
+            }
+            LineString::LineStringRef(val) => {
+                if encoding.version < 5 {
+                    return Err(Error::NeedVersion(5));
+                }
+                w.write_offset(
+                    debug_line_str_offsets.get(val).0,
+                    SectionId::DebugLineStr,
+                    encoding.format.word_size(),
+                )?;
+            }
+        }
+        Ok(())
+    }
+}
+
+/// An identifier for a directory in a `LineProgram`.
+///
+/// Defaults to the working directory of the compilation unit.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct DirectoryId(usize);
+
+// Force FileId access via the methods.
+mod id {
+    /// An identifier for a file in a `LineProgram`.
+    #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+    pub struct FileId(usize);
+
+    impl FileId {
+        /// Create a FileId given an index into `LineProgram::files`.
+        pub(crate) fn new(index: usize) -> Self {
+            FileId(index + 1)
+        }
+
+        /// The index of the file in `LineProgram::files`.
+        pub(super) fn index(self) -> Option<usize> {
+            if self.0 == 0 {
+                None
+            } else {
+                Some(self.0 - 1)
+            }
+        }
+
+        /// The initial state of the file register.
+        pub(super) fn initial_state() -> Self {
+            FileId(1)
+        }
+
+        /// The raw value used when writing.
+        pub(crate) fn raw(self) -> u64 {
+            self.0 as u64
+        }
+
+        /// The id for file index 0 in DWARF version 5.
+        /// Only used when converting.
+        // Used for tests only.
+        #[allow(unused)]
+        pub(super) fn zero() -> Self {
+            FileId(0)
+        }
+    }
+}
+pub use self::id::*;
+
+/// Extra information for file in a `LineProgram`.
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
+pub struct FileInfo {
+    /// The implementation defined timestamp of the last modification of the file,
+    /// or 0 if not available.
+    pub timestamp: u64,
+
+    /// The size of the file in bytes, or 0 if not available.
+    pub size: u64,
+
+    /// A 16-byte MD5 digest of the file contents.
+    ///
+    /// Only used if version >= 5 and `LineProgram::file_has_md5` is `true`.
+    pub md5: [u8; 16],
+}
+
+define_section!(
+    DebugLine,
+    DebugLineOffset,
+    "A writable `.debug_line` section."
+);
+
+#[cfg(feature = "read")]
+mod convert {
+    use super::*;
+    use crate::read::{self, Reader};
+    use crate::write::{self, ConvertError, ConvertResult};
+
+    impl LineProgram {
+        /// Create a line number program by reading the data from the given program.
+        ///
+        /// Return the program and a mapping from file index to `FileId`.
+        pub fn from<R: Reader<Offset = usize>>(
+            mut from_program: read::IncompleteLineProgram<R>,
+            dwarf: &read::Dwarf<R>,
+            line_strings: &mut write::LineStringTable,
+            strings: &mut write::StringTable,
+            convert_address: &dyn Fn(u64) -> Option<Address>,
+        ) -> ConvertResult<(LineProgram, Vec<FileId>)> {
+            // Create mappings in case the source has duplicate files or directories.
+            let mut dirs = Vec::new();
+            let mut files = Vec::new();
+
+            let mut program = {
+                let from_header = from_program.header();
+                let encoding = from_header.encoding();
+
+                let comp_dir = match from_header.directory(0) {
+                    Some(comp_dir) => LineString::from(comp_dir, dwarf, line_strings, strings)?,
+                    None => LineString::new(&[][..], encoding, line_strings),
+                };
+
+                let (comp_name, comp_file_info) = match from_header.file(0) {
+                    Some(comp_file) => {
+                        if comp_file.directory_index() != 0 {
+                            return Err(ConvertError::InvalidDirectoryIndex);
+                        }
+                        (
+                            LineString::from(comp_file.path_name(), dwarf, line_strings, strings)?,
+                            Some(FileInfo {
+                                timestamp: comp_file.timestamp(),
+                                size: comp_file.size(),
+                                md5: *comp_file.md5(),
+                            }),
+                        )
+                    }
+                    None => (LineString::new(&[][..], encoding, line_strings), None),
+                };
+
+                if from_header.line_base() > 0 {
+                    return Err(ConvertError::InvalidLineBase);
+                }
+                let mut program = LineProgram::new(
+                    encoding,
+                    from_header.line_encoding(),
+                    comp_dir,
+                    comp_name,
+                    comp_file_info,
+                );
+
+                let file_skip;
+                if from_header.version() <= 4 {
+                    // The first directory is implicit.
+                    dirs.push(DirectoryId(0));
+                    // A file index of 0 is invalid for version <= 4, but putting
+                    // something there makes the indexing easier.
+                    file_skip = 0;
+                    files.push(FileId::zero());
+                } else {
+                    // We don't add the first file to `files`, but still allow
+                    // it to be referenced from converted instructions.
+                    file_skip = 1;
+                    files.push(FileId::zero());
+                }
+
+                for from_dir in from_header.include_directories() {
+                    let from_dir =
+                        LineString::from(from_dir.clone(), dwarf, line_strings, strings)?;
+                    dirs.push(program.add_directory(from_dir));
+                }
+
+                program.file_has_timestamp = from_header.file_has_timestamp();
+                program.file_has_size = from_header.file_has_size();
+                program.file_has_md5 = from_header.file_has_md5();
+                for from_file in from_header.file_names().iter().skip(file_skip) {
+                    let from_name =
+                        LineString::from(from_file.path_name(), dwarf, line_strings, strings)?;
+                    let from_dir = from_file.directory_index();
+                    if from_dir >= dirs.len() as u64 {
+                        return Err(ConvertError::InvalidDirectoryIndex);
+                    }
+                    let from_dir = dirs[from_dir as usize];
+                    let from_info = Some(FileInfo {
+                        timestamp: from_file.timestamp(),
+                        size: from_file.size(),
+                        md5: *from_file.md5(),
+                    });
+                    files.push(program.add_file(from_name, from_dir, from_info));
+                }
+
+                program
+            };
+
+            // We can't use the `from_program.rows()` because that wouldn't let
+            // us preserve address relocations.
+            let mut from_row = read::LineRow::new(from_program.header());
+            let mut instructions = from_program.header().instructions();
+            let mut address = None;
+            while let Some(instruction) = instructions.next_instruction(from_program.header())? {
+                match instruction {
+                    read::LineInstruction::SetAddress(val) => {
+                        if program.in_sequence() {
+                            return Err(ConvertError::UnsupportedLineInstruction);
+                        }
+                        match convert_address(val) {
+                            Some(val) => address = Some(val),
+                            None => return Err(ConvertError::InvalidAddress),
+                        }
+                        from_row.execute(read::LineInstruction::SetAddress(0), &mut from_program);
+                    }
+                    read::LineInstruction::DefineFile(_) => {
+                        return Err(ConvertError::UnsupportedLineInstruction);
+                    }
+                    _ => {
+                        if from_row.execute(instruction, &mut from_program) {
+                            if !program.in_sequence() {
+                                program.begin_sequence(address);
+                                address = None;
+                            }
+                            if from_row.end_sequence() {
+                                program.end_sequence(from_row.address());
+                            } else {
+                                program.row().address_offset = from_row.address();
+                                program.row().op_index = from_row.op_index();
+                                program.row().file = {
+                                    let file = from_row.file_index();
+                                    if file >= files.len() as u64 {
+                                        return Err(ConvertError::InvalidFileIndex);
+                                    }
+                                    if file == 0 && program.version() <= 4 {
+                                        return Err(ConvertError::InvalidFileIndex);
+                                    }
+                                    files[file as usize]
+                                };
+                                program.row().line = match from_row.line() {
+                                    Some(line) => line.get(),
+                                    None => 0,
+                                };
+                                program.row().column = match from_row.column() {
+                                    read::ColumnType::LeftEdge => 0,
+                                    read::ColumnType::Column(val) => val.get(),
+                                };
+                                program.row().discriminator = from_row.discriminator();
+                                program.row().is_statement = from_row.is_stmt();
+                                program.row().basic_block = from_row.basic_block();
+                                program.row().prologue_end = from_row.prologue_end();
+                                program.row().epilogue_begin = from_row.epilogue_begin();
+                                program.row().isa = from_row.isa();
+                                program.generate_row();
+                            }
+                            from_row.reset(from_program.header());
+                        }
+                    }
+                };
+            }
+            Ok((program, files))
+        }
+    }
+
+    impl LineString {
+        fn from<R: Reader<Offset = usize>>(
+            from_attr: read::AttributeValue<R>,
+            dwarf: &read::Dwarf<R>,
+            line_strings: &mut write::LineStringTable,
+            strings: &mut write::StringTable,
+        ) -> ConvertResult<LineString> {
+            Ok(match from_attr {
+                read::AttributeValue::String(r) => LineString::String(r.to_slice()?.to_vec()),
+                read::AttributeValue::DebugStrRef(offset) => {
+                    let r = dwarf.debug_str.get_str(offset)?;
+                    let id = strings.add(r.to_slice()?);
+                    LineString::StringRef(id)
+                }
+                read::AttributeValue::DebugLineStrRef(offset) => {
+                    let r = dwarf.debug_line_str.get_str(offset)?;
+                    let id = line_strings.add(r.to_slice()?);
+                    LineString::LineStringRef(id)
+                }
+                _ => return Err(ConvertError::UnsupportedLineStringForm),
+            })
+        }
+    }
+}
+
+#[cfg(test)]
+#[cfg(feature = "read")]
+mod tests {
+    use super::*;
+    use crate::read;
+    use crate::write::{DebugLineStr, DebugStr, EndianVec, StringTable};
+    use crate::LittleEndian;
+
+    #[test]
+    fn test_line_program_table() {
+        let dir1 = LineString::String(b"dir1".to_vec());
+        let file1 = LineString::String(b"file1".to_vec());
+        let dir2 = LineString::String(b"dir2".to_vec());
+        let file2 = LineString::String(b"file2".to_vec());
+
+        let mut programs = Vec::new();
+        for &version in &[2, 3, 4, 5] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+                    let mut program = LineProgram::new(
+                        encoding,
+                        LineEncoding::default(),
+                        dir1.clone(),
+                        file1.clone(),
+                        None,
+                    );
+
+                    {
+                        assert_eq!(&dir1, program.get_directory(program.default_directory()));
+                        program.file_has_timestamp = true;
+                        program.file_has_size = true;
+                        if encoding.version >= 5 {
+                            program.file_has_md5 = true;
+                        }
+
+                        let dir_id = program.add_directory(dir2.clone());
+                        assert_eq!(&dir2, program.get_directory(dir_id));
+                        assert_eq!(dir_id, program.add_directory(dir2.clone()));
+
+                        let file_info = FileInfo {
+                            timestamp: 1,
+                            size: 2,
+                            md5: if encoding.version >= 5 {
+                                [3; 16]
+                            } else {
+                                [0; 16]
+                            },
+                        };
+                        let file_id = program.add_file(file2.clone(), dir_id, Some(file_info));
+                        assert_eq!((&file2, dir_id), program.get_file(file_id));
+                        assert_eq!(file_info, *program.get_file_info(file_id));
+
+                        program.get_file_info_mut(file_id).size = 3;
+                        assert_ne!(file_info, *program.get_file_info(file_id));
+                        assert_eq!(file_id, program.add_file(file2.clone(), dir_id, None));
+                        assert_ne!(file_info, *program.get_file_info(file_id));
+                        assert_eq!(
+                            file_id,
+                            program.add_file(file2.clone(), dir_id, Some(file_info))
+                        );
+                        assert_eq!(file_info, *program.get_file_info(file_id));
+
+                        programs.push((program, file_id, encoding));
+                    }
+                }
+            }
+        }
+
+        let debug_line_str_offsets = DebugLineStrOffsets::none();
+        let debug_str_offsets = DebugStrOffsets::none();
+        let mut debug_line = DebugLine::from(EndianVec::new(LittleEndian));
+        let mut debug_line_offsets = Vec::new();
+        for (program, _, encoding) in &programs {
+            debug_line_offsets.push(
+                program
+                    .write(
+                        &mut debug_line,
+                        *encoding,
+                        &debug_line_str_offsets,
+                        &debug_str_offsets,
+                    )
+                    .unwrap(),
+            );
+        }
+
+        let read_debug_line = read::DebugLine::new(debug_line.slice(), LittleEndian);
+
+        let convert_address = &|address| Some(Address::Constant(address));
+        for ((program, file_id, encoding), offset) in programs.iter().zip(debug_line_offsets.iter())
+        {
+            let read_program = read_debug_line
+                .program(
+                    *offset,
+                    encoding.address_size,
+                    Some(read::EndianSlice::new(b"dir1", LittleEndian)),
+                    Some(read::EndianSlice::new(b"file1", LittleEndian)),
+                )
+                .unwrap();
+
+            let dwarf = read::Dwarf::default();
+            let mut convert_line_strings = LineStringTable::default();
+            let mut convert_strings = StringTable::default();
+            let (convert_program, convert_files) = LineProgram::from(
+                read_program,
+                &dwarf,
+                &mut convert_line_strings,
+                &mut convert_strings,
+                convert_address,
+            )
+            .unwrap();
+            assert_eq!(convert_program.version(), program.version());
+            assert_eq!(convert_program.address_size(), program.address_size());
+            assert_eq!(convert_program.format(), program.format());
+
+            let convert_file_id = convert_files[file_id.raw() as usize];
+            let (file, dir) = program.get_file(*file_id);
+            let (convert_file, convert_dir) = convert_program.get_file(convert_file_id);
+            assert_eq!(file, convert_file);
+            assert_eq!(
+                program.get_directory(dir),
+                convert_program.get_directory(convert_dir)
+            );
+            assert_eq!(
+                program.get_file_info(*file_id),
+                convert_program.get_file_info(convert_file_id)
+            );
+        }
+    }
+
+    #[test]
+    fn test_line_row() {
+        let dir1 = &b"dir1"[..];
+        let file1 = &b"file1"[..];
+        let file2 = &b"file2"[..];
+        let convert_address = &|address| Some(Address::Constant(address));
+
+        let debug_line_str_offsets = DebugLineStrOffsets::none();
+        let debug_str_offsets = DebugStrOffsets::none();
+
+        for &version in &[2, 3, 4, 5] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+                    let line_base = -5;
+                    let line_range = 14;
+                    let neg_line_base = (-line_base) as u8;
+                    let mut program = LineProgram::new(
+                        encoding,
+                        LineEncoding {
+                            line_base,
+                            line_range,
+                            ..Default::default()
+                        },
+                        LineString::String(dir1.to_vec()),
+                        LineString::String(file1.to_vec()),
+                        None,
+                    );
+                    let dir_id = program.default_directory();
+                    program.add_file(LineString::String(file1.to_vec()), dir_id, None);
+                    let file_id =
+                        program.add_file(LineString::String(file2.to_vec()), dir_id, None);
+
+                    // Test sequences.
+                    {
+                        let mut program = program.clone();
+                        let address = Address::Constant(0x12);
+                        program.begin_sequence(Some(address));
+                        assert_eq!(
+                            program.instructions,
+                            vec![LineInstruction::SetAddress(address)]
+                        );
+                    }
+
+                    {
+                        let mut program = program.clone();
+                        program.begin_sequence(None);
+                        assert_eq!(program.instructions, Vec::new());
+                    }
+
+                    {
+                        let mut program = program.clone();
+                        program.begin_sequence(None);
+                        program.end_sequence(0x1234);
+                        assert_eq!(
+                            program.instructions,
+                            vec![
+                                LineInstruction::AdvancePc(0x1234),
+                                LineInstruction::EndSequence
+                            ]
+                        );
+                    }
+
+                    // Create a base program.
+                    program.begin_sequence(None);
+                    program.row.line = 0x1000;
+                    program.generate_row();
+                    let base_row = program.row;
+                    let base_instructions = program.instructions.clone();
+
+                    // Create test cases.
+                    let mut tests = Vec::new();
+
+                    let row = base_row;
+                    tests.push((row, vec![LineInstruction::Copy]));
+
+                    let mut row = base_row;
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((row, vec![LineInstruction::Special(OPCODE_BASE)]));
+
+                    let mut row = base_row;
+                    row.line += u64::from(line_range) - 1;
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((
+                        row,
+                        vec![LineInstruction::Special(OPCODE_BASE + line_range - 1)],
+                    ));
+
+                    let mut row = base_row;
+                    row.line += u64::from(line_range);
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((
+                        row,
+                        vec![
+                            LineInstruction::AdvanceLine(i64::from(line_range - neg_line_base)),
+                            LineInstruction::Copy,
+                        ],
+                    ));
+
+                    let mut row = base_row;
+                    row.address_offset = 1;
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((
+                        row,
+                        vec![LineInstruction::Special(OPCODE_BASE + line_range)],
+                    ));
+
+                    let op_range = (255 - OPCODE_BASE) / line_range;
+                    let mut row = base_row;
+                    row.address_offset = u64::from(op_range);
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((
+                        row,
+                        vec![LineInstruction::Special(
+                            OPCODE_BASE + op_range * line_range,
+                        )],
+                    ));
+
+                    let mut row = base_row;
+                    row.address_offset = u64::from(op_range);
+                    row.line += u64::from(255 - OPCODE_BASE - op_range * line_range);
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((row, vec![LineInstruction::Special(255)]));
+
+                    let mut row = base_row;
+                    row.address_offset = u64::from(op_range);
+                    row.line += u64::from(255 - OPCODE_BASE - op_range * line_range) + 1;
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((
+                        row,
+                        vec![LineInstruction::ConstAddPc, LineInstruction::Copy],
+                    ));
+
+                    let mut row = base_row;
+                    row.address_offset = u64::from(op_range);
+                    row.line += u64::from(255 - OPCODE_BASE - op_range * line_range) + 2;
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((
+                        row,
+                        vec![
+                            LineInstruction::ConstAddPc,
+                            LineInstruction::Special(OPCODE_BASE + 6),
+                        ],
+                    ));
+
+                    let mut row = base_row;
+                    row.address_offset = u64::from(op_range) * 2;
+                    row.line += u64::from(255 - OPCODE_BASE - op_range * line_range);
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((
+                        row,
+                        vec![LineInstruction::ConstAddPc, LineInstruction::Special(255)],
+                    ));
+
+                    let mut row = base_row;
+                    row.address_offset = u64::from(op_range) * 2;
+                    row.line += u64::from(255 - OPCODE_BASE - op_range * line_range) + 1;
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((
+                        row,
+                        vec![
+                            LineInstruction::AdvancePc(row.address_offset),
+                            LineInstruction::Copy,
+                        ],
+                    ));
+
+                    let mut row = base_row;
+                    row.address_offset = u64::from(op_range) * 2;
+                    row.line += u64::from(255 - OPCODE_BASE - op_range * line_range) + 2;
+                    row.line -= u64::from(neg_line_base);
+                    tests.push((
+                        row,
+                        vec![
+                            LineInstruction::AdvancePc(row.address_offset),
+                            LineInstruction::Special(OPCODE_BASE + 6),
+                        ],
+                    ));
+
+                    let mut row = base_row;
+                    row.address_offset = 0x1234;
+                    tests.push((
+                        row,
+                        vec![LineInstruction::AdvancePc(0x1234), LineInstruction::Copy],
+                    ));
+
+                    let mut row = base_row;
+                    row.line += 0x1234;
+                    tests.push((
+                        row,
+                        vec![LineInstruction::AdvanceLine(0x1234), LineInstruction::Copy],
+                    ));
+
+                    let mut row = base_row;
+                    row.file = file_id;
+                    tests.push((
+                        row,
+                        vec![LineInstruction::SetFile(file_id), LineInstruction::Copy],
+                    ));
+
+                    let mut row = base_row;
+                    row.column = 0x1234;
+                    tests.push((
+                        row,
+                        vec![LineInstruction::SetColumn(0x1234), LineInstruction::Copy],
+                    ));
+
+                    let mut row = base_row;
+                    row.discriminator = 0x1234;
+                    tests.push((
+                        row,
+                        vec![
+                            LineInstruction::SetDiscriminator(0x1234),
+                            LineInstruction::Copy,
+                        ],
+                    ));
+
+                    let mut row = base_row;
+                    row.is_statement = !row.is_statement;
+                    tests.push((
+                        row,
+                        vec![LineInstruction::NegateStatement, LineInstruction::Copy],
+                    ));
+
+                    let mut row = base_row;
+                    row.basic_block = true;
+                    tests.push((
+                        row,
+                        vec![LineInstruction::SetBasicBlock, LineInstruction::Copy],
+                    ));
+
+                    let mut row = base_row;
+                    row.prologue_end = true;
+                    tests.push((
+                        row,
+                        vec![LineInstruction::SetPrologueEnd, LineInstruction::Copy],
+                    ));
+
+                    let mut row = base_row;
+                    row.epilogue_begin = true;
+                    tests.push((
+                        row,
+                        vec![LineInstruction::SetEpilogueBegin, LineInstruction::Copy],
+                    ));
+
+                    let mut row = base_row;
+                    row.isa = 0x1234;
+                    tests.push((
+                        row,
+                        vec![LineInstruction::SetIsa(0x1234), LineInstruction::Copy],
+                    ));
+
+                    for test in tests {
+                        // Test generate_row().
+                        let mut program = program.clone();
+                        program.row = test.0;
+                        program.generate_row();
+                        assert_eq!(
+                            &program.instructions[base_instructions.len()..],
+                            &test.1[..]
+                        );
+
+                        // Test LineProgram::from().
+                        let mut debug_line = DebugLine::from(EndianVec::new(LittleEndian));
+                        let debug_line_offset = program
+                            .write(
+                                &mut debug_line,
+                                encoding,
+                                &debug_line_str_offsets,
+                                &debug_str_offsets,
+                            )
+                            .unwrap();
+
+                        let read_debug_line =
+                            read::DebugLine::new(debug_line.slice(), LittleEndian);
+                        let read_program = read_debug_line
+                            .program(
+                                debug_line_offset,
+                                address_size,
+                                Some(read::EndianSlice::new(dir1, LittleEndian)),
+                                Some(read::EndianSlice::new(file1, LittleEndian)),
+                            )
+                            .unwrap();
+
+                        let dwarf = read::Dwarf::default();
+                        let mut convert_line_strings = LineStringTable::default();
+                        let mut convert_strings = StringTable::default();
+                        let (convert_program, _convert_files) = LineProgram::from(
+                            read_program,
+                            &dwarf,
+                            &mut convert_line_strings,
+                            &mut convert_strings,
+                            convert_address,
+                        )
+                        .unwrap();
+                        assert_eq!(
+                            &convert_program.instructions[base_instructions.len()..],
+                            &test.1[..]
+                        );
+                    }
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn test_line_instruction() {
+        let dir1 = &b"dir1"[..];
+        let file1 = &b"file1"[..];
+
+        let debug_line_str_offsets = DebugLineStrOffsets::none();
+        let debug_str_offsets = DebugStrOffsets::none();
+
+        for &version in &[2, 3, 4, 5] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+                    let mut program = LineProgram::new(
+                        encoding,
+                        LineEncoding::default(),
+                        LineString::String(dir1.to_vec()),
+                        LineString::String(file1.to_vec()),
+                        None,
+                    );
+                    let dir_id = program.default_directory();
+                    let file_id =
+                        program.add_file(LineString::String(file1.to_vec()), dir_id, None);
+
+                    for &(ref inst, ref expect_inst) in &[
+                        (
+                            LineInstruction::Special(OPCODE_BASE),
+                            read::LineInstruction::Special(OPCODE_BASE),
+                        ),
+                        (
+                            LineInstruction::Special(255),
+                            read::LineInstruction::Special(255),
+                        ),
+                        (LineInstruction::Copy, read::LineInstruction::Copy),
+                        (
+                            LineInstruction::AdvancePc(0x12),
+                            read::LineInstruction::AdvancePc(0x12),
+                        ),
+                        (
+                            LineInstruction::AdvanceLine(0x12),
+                            read::LineInstruction::AdvanceLine(0x12),
+                        ),
+                        (
+                            LineInstruction::SetFile(file_id),
+                            read::LineInstruction::SetFile(file_id.raw()),
+                        ),
+                        (
+                            LineInstruction::SetColumn(0x12),
+                            read::LineInstruction::SetColumn(0x12),
+                        ),
+                        (
+                            LineInstruction::NegateStatement,
+                            read::LineInstruction::NegateStatement,
+                        ),
+                        (
+                            LineInstruction::SetBasicBlock,
+                            read::LineInstruction::SetBasicBlock,
+                        ),
+                        (
+                            LineInstruction::ConstAddPc,
+                            read::LineInstruction::ConstAddPc,
+                        ),
+                        (
+                            LineInstruction::SetPrologueEnd,
+                            read::LineInstruction::SetPrologueEnd,
+                        ),
+                        (
+                            LineInstruction::SetEpilogueBegin,
+                            read::LineInstruction::SetEpilogueBegin,
+                        ),
+                        (
+                            LineInstruction::SetIsa(0x12),
+                            read::LineInstruction::SetIsa(0x12),
+                        ),
+                        (
+                            LineInstruction::EndSequence,
+                            read::LineInstruction::EndSequence,
+                        ),
+                        (
+                            LineInstruction::SetAddress(Address::Constant(0x12)),
+                            read::LineInstruction::SetAddress(0x12),
+                        ),
+                        (
+                            LineInstruction::SetDiscriminator(0x12),
+                            read::LineInstruction::SetDiscriminator(0x12),
+                        ),
+                    ][..]
+                    {
+                        let mut program = program.clone();
+                        program.instructions.push(*inst);
+
+                        let mut debug_line = DebugLine::from(EndianVec::new(LittleEndian));
+                        let debug_line_offset = program
+                            .write(
+                                &mut debug_line,
+                                encoding,
+                                &debug_line_str_offsets,
+                                &debug_str_offsets,
+                            )
+                            .unwrap();
+
+                        let read_debug_line =
+                            read::DebugLine::new(debug_line.slice(), LittleEndian);
+                        let read_program = read_debug_line
+                            .program(
+                                debug_line_offset,
+                                address_size,
+                                Some(read::EndianSlice::new(dir1, LittleEndian)),
+                                Some(read::EndianSlice::new(file1, LittleEndian)),
+                            )
+                            .unwrap();
+                        let read_header = read_program.header();
+                        let mut read_insts = read_header.instructions();
+                        assert_eq!(
+                            *expect_inst,
+                            read_insts.next_instruction(read_header).unwrap().unwrap()
+                        );
+                        assert_eq!(None, read_insts.next_instruction(read_header).unwrap());
+                    }
+                }
+            }
+        }
+    }
+
+    // Test that the address/line advance is correct. We don't test for optimality.
+    #[test]
+    fn test_advance() {
+        let encoding = Encoding {
+            format: Format::Dwarf32,
+            version: 4,
+            address_size: 8,
+        };
+
+        let dir1 = &b"dir1"[..];
+        let file1 = &b"file1"[..];
+
+        let addresses = 0..50;
+        let lines = -10..25i64;
+
+        let debug_line_str_offsets = DebugLineStrOffsets::none();
+        let debug_str_offsets = DebugStrOffsets::none();
+
+        for minimum_instruction_length in vec![1, 4] {
+            for maximum_operations_per_instruction in vec![1, 3] {
+                for line_base in vec![-5, 0] {
+                    for line_range in vec![10, 20] {
+                        let line_encoding = LineEncoding {
+                            minimum_instruction_length,
+                            maximum_operations_per_instruction,
+                            line_base,
+                            line_range,
+                            default_is_stmt: true,
+                        };
+                        let mut program = LineProgram::new(
+                            encoding,
+                            line_encoding,
+                            LineString::String(dir1.to_vec()),
+                            LineString::String(file1.to_vec()),
+                            None,
+                        );
+                        for address_advance in addresses.clone() {
+                            program.begin_sequence(Some(Address::Constant(0x1000)));
+                            program.row().line = 0x10000;
+                            program.generate_row();
+                            for line_advance in lines.clone() {
+                                {
+                                    let row = program.row();
+                                    row.address_offset +=
+                                        address_advance * u64::from(minimum_instruction_length);
+                                    row.line = row.line.wrapping_add(line_advance as u64);
+                                }
+                                program.generate_row();
+                            }
+                            let address_offset = program.row().address_offset
+                                + u64::from(minimum_instruction_length);
+                            program.end_sequence(address_offset);
+                        }
+
+                        let mut debug_line = DebugLine::from(EndianVec::new(LittleEndian));
+                        let debug_line_offset = program
+                            .write(
+                                &mut debug_line,
+                                encoding,
+                                &debug_line_str_offsets,
+                                &debug_str_offsets,
+                            )
+                            .unwrap();
+
+                        let read_debug_line =
+                            read::DebugLine::new(debug_line.slice(), LittleEndian);
+                        let read_program = read_debug_line
+                            .program(
+                                debug_line_offset,
+                                8,
+                                Some(read::EndianSlice::new(dir1, LittleEndian)),
+                                Some(read::EndianSlice::new(file1, LittleEndian)),
+                            )
+                            .unwrap();
+
+                        let mut rows = read_program.rows();
+                        for address_advance in addresses.clone() {
+                            let mut address;
+                            let mut line;
+                            {
+                                let row = rows.next_row().unwrap().unwrap().1;
+                                address = row.address();
+                                line = row.line().unwrap().get();
+                            }
+                            assert_eq!(address, 0x1000);
+                            assert_eq!(line, 0x10000);
+                            for line_advance in lines.clone() {
+                                let row = rows.next_row().unwrap().unwrap().1;
+                                assert_eq!(
+                                    row.address() - address,
+                                    address_advance * u64::from(minimum_instruction_length)
+                                );
+                                assert_eq!(
+                                    (row.line().unwrap().get() as i64) - (line as i64),
+                                    line_advance
+                                );
+                                address = row.address();
+                                line = row.line().unwrap().get();
+                            }
+                            let row = rows.next_row().unwrap().unwrap().1;
+                            assert!(row.end_sequence());
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn test_line_string() {
+        let version = 5;
+
+        let file = b"file1";
+
+        let mut strings = StringTable::default();
+        let string_id = strings.add("file2");
+        let mut debug_str = DebugStr::from(EndianVec::new(LittleEndian));
+        let debug_str_offsets = strings.write(&mut debug_str).unwrap();
+
+        let mut line_strings = LineStringTable::default();
+        let line_string_id = line_strings.add("file3");
+        let mut debug_line_str = DebugLineStr::from(EndianVec::new(LittleEndian));
+        let debug_line_str_offsets = line_strings.write(&mut debug_line_str).unwrap();
+
+        for &address_size in &[4, 8] {
+            for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                let encoding = Encoding {
+                    format,
+                    version,
+                    address_size,
+                };
+
+                for (file, expect_file) in vec![
+                    (
+                        LineString::String(file.to_vec()),
+                        read::AttributeValue::String(read::EndianSlice::new(file, LittleEndian)),
+                    ),
+                    (
+                        LineString::StringRef(string_id),
+                        read::AttributeValue::DebugStrRef(debug_str_offsets.get(string_id)),
+                    ),
+                    (
+                        LineString::LineStringRef(line_string_id),
+                        read::AttributeValue::DebugLineStrRef(
+                            debug_line_str_offsets.get(line_string_id),
+                        ),
+                    ),
+                ] {
+                    let program = LineProgram::new(
+                        encoding,
+                        LineEncoding::default(),
+                        LineString::String(b"dir".to_vec()),
+                        file,
+                        None,
+                    );
+
+                    let mut debug_line = DebugLine::from(EndianVec::new(LittleEndian));
+                    let debug_line_offset = program
+                        .write(
+                            &mut debug_line,
+                            encoding,
+                            &debug_line_str_offsets,
+                            &debug_str_offsets,
+                        )
+                        .unwrap();
+
+                    let read_debug_line = read::DebugLine::new(debug_line.slice(), LittleEndian);
+                    let read_program = read_debug_line
+                        .program(debug_line_offset, address_size, None, None)
+                        .unwrap();
+                    let read_header = read_program.header();
+                    assert_eq!(read_header.file(0).unwrap().path_name(), expect_file);
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn test_missing_comp_dir() {
+        let debug_line_str_offsets = DebugLineStrOffsets::none();
+        let debug_str_offsets = DebugStrOffsets::none();
+
+        for &version in &[2, 3, 4, 5] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+                    let program = LineProgram::new(
+                        encoding,
+                        LineEncoding::default(),
+                        LineString::String(Vec::new()),
+                        LineString::String(Vec::new()),
+                        None,
+                    );
+
+                    let mut debug_line = DebugLine::from(EndianVec::new(LittleEndian));
+                    let debug_line_offset = program
+                        .write(
+                            &mut debug_line,
+                            encoding,
+                            &debug_line_str_offsets,
+                            &debug_str_offsets,
+                        )
+                        .unwrap();
+
+                    let read_debug_line = read::DebugLine::new(debug_line.slice(), LittleEndian);
+                    let read_program = read_debug_line
+                        .program(
+                            debug_line_offset,
+                            address_size,
+                            // Testing missing comp_dir/comp_name.
+                            None,
+                            None,
+                        )
+                        .unwrap();
+
+                    let dwarf = read::Dwarf::default();
+                    let mut convert_line_strings = LineStringTable::default();
+                    let mut convert_strings = StringTable::default();
+                    let convert_address = &|address| Some(Address::Constant(address));
+                    LineProgram::from(
+                        read_program,
+                        &dwarf,
+                        &mut convert_line_strings,
+                        &mut convert_strings,
+                        convert_address,
+                    )
+                    .unwrap();
+                }
+            }
+        }
+    }
+}
diff --git a/vendor/gimli/src/write/loc.rs b/vendor/gimli/src/write/loc.rs
new file mode 100644
index 0000000..6dfe45a
--- /dev/null
+++ b/vendor/gimli/src/write/loc.rs
@@ -0,0 +1,550 @@
+use alloc::vec::Vec;
+use indexmap::IndexSet;
+use std::ops::{Deref, DerefMut};
+
+use crate::common::{Encoding, LocationListsOffset, SectionId};
+use crate::write::{
+    Address, BaseId, DebugInfoReference, Error, Expression, Result, Section, Sections, UnitOffsets,
+    Writer,
+};
+
+define_section!(
+    DebugLoc,
+    LocationListsOffset,
+    "A writable `.debug_loc` section."
+);
+define_section!(
+    DebugLocLists,
+    LocationListsOffset,
+    "A writable `.debug_loclists` section."
+);
+
+define_offsets!(
+    LocationListOffsets: LocationListId => LocationListsOffset,
+    "The section offsets of a series of location lists within the `.debug_loc` or `.debug_loclists` sections."
+);
+
+define_id!(
+    LocationListId,
+    "An identifier for a location list in a `LocationListTable`."
+);
+
+/// A table of location lists that will be stored in a `.debug_loc` or `.debug_loclists` section.
+#[derive(Debug, Default)]
+pub struct LocationListTable {
+    base_id: BaseId,
+    locations: IndexSet<LocationList>,
+}
+
+impl LocationListTable {
+    /// Add a location list to the table.
+    pub fn add(&mut self, loc_list: LocationList) -> LocationListId {
+        let (index, _) = self.locations.insert_full(loc_list);
+        LocationListId::new(self.base_id, index)
+    }
+
+    /// Write the location list table to the appropriate section for the given DWARF version.
+    pub(crate) fn write<W: Writer>(
+        &self,
+        sections: &mut Sections<W>,
+        encoding: Encoding,
+        unit_offsets: Option<&UnitOffsets>,
+    ) -> Result<LocationListOffsets> {
+        if self.locations.is_empty() {
+            return Ok(LocationListOffsets::none());
+        }
+
+        match encoding.version {
+            2..=4 => self.write_loc(
+                &mut sections.debug_loc,
+                &mut sections.debug_loc_refs,
+                encoding,
+                unit_offsets,
+            ),
+            5 => self.write_loclists(
+                &mut sections.debug_loclists,
+                &mut sections.debug_loclists_refs,
+                encoding,
+                unit_offsets,
+            ),
+            _ => Err(Error::UnsupportedVersion(encoding.version)),
+        }
+    }
+
+    /// Write the location list table to the `.debug_loc` section.
+    fn write_loc<W: Writer>(
+        &self,
+        w: &mut DebugLoc<W>,
+        refs: &mut Vec<DebugInfoReference>,
+        encoding: Encoding,
+        unit_offsets: Option<&UnitOffsets>,
+    ) -> Result<LocationListOffsets> {
+        let address_size = encoding.address_size;
+        let mut offsets = Vec::new();
+        for loc_list in self.locations.iter() {
+            offsets.push(w.offset());
+            for loc in &loc_list.0 {
+                // Note that we must ensure none of the ranges have both begin == 0 and end == 0.
+                // We do this by ensuring that begin != end, which is a bit more restrictive
+                // than required, but still seems reasonable.
+                match *loc {
+                    Location::BaseAddress { address } => {
+                        let marker = !0 >> (64 - address_size * 8);
+                        w.write_udata(marker, address_size)?;
+                        w.write_address(address, address_size)?;
+                    }
+                    Location::OffsetPair {
+                        begin,
+                        end,
+                        ref data,
+                    } => {
+                        if begin == end {
+                            return Err(Error::InvalidRange);
+                        }
+                        w.write_udata(begin, address_size)?;
+                        w.write_udata(end, address_size)?;
+                        write_expression(&mut w.0, refs, encoding, unit_offsets, data)?;
+                    }
+                    Location::StartEnd {
+                        begin,
+                        end,
+                        ref data,
+                    } => {
+                        if begin == end {
+                            return Err(Error::InvalidRange);
+                        }
+                        w.write_address(begin, address_size)?;
+                        w.write_address(end, address_size)?;
+                        write_expression(&mut w.0, refs, encoding, unit_offsets, data)?;
+                    }
+                    Location::StartLength {
+                        begin,
+                        length,
+                        ref data,
+                    } => {
+                        let end = match begin {
+                            Address::Constant(begin) => Address::Constant(begin + length),
+                            Address::Symbol { symbol, addend } => Address::Symbol {
+                                symbol,
+                                addend: addend + length as i64,
+                            },
+                        };
+                        if begin == end {
+                            return Err(Error::InvalidRange);
+                        }
+                        w.write_address(begin, address_size)?;
+                        w.write_address(end, address_size)?;
+                        write_expression(&mut w.0, refs, encoding, unit_offsets, data)?;
+                    }
+                    Location::DefaultLocation { .. } => {
+                        return Err(Error::InvalidRange);
+                    }
+                }
+            }
+            w.write_udata(0, address_size)?;
+            w.write_udata(0, address_size)?;
+        }
+        Ok(LocationListOffsets {
+            base_id: self.base_id,
+            offsets,
+        })
+    }
+
+    /// Write the location list table to the `.debug_loclists` section.
+    fn write_loclists<W: Writer>(
+        &self,
+        w: &mut DebugLocLists<W>,
+        refs: &mut Vec<DebugInfoReference>,
+        encoding: Encoding,
+        unit_offsets: Option<&UnitOffsets>,
+    ) -> Result<LocationListOffsets> {
+        let mut offsets = Vec::new();
+
+        if encoding.version != 5 {
+            return Err(Error::NeedVersion(5));
+        }
+
+        let length_offset = w.write_initial_length(encoding.format)?;
+        let length_base = w.len();
+
+        w.write_u16(encoding.version)?;
+        w.write_u8(encoding.address_size)?;
+        w.write_u8(0)?; // segment_selector_size
+        w.write_u32(0)?; // offset_entry_count (when set to zero DW_FORM_rnglistx can't be used, see section 7.28)
+                         // FIXME implement DW_FORM_rnglistx writing and implement the offset entry list
+
+        for loc_list in self.locations.iter() {
+            offsets.push(w.offset());
+            for loc in &loc_list.0 {
+                match *loc {
+                    Location::BaseAddress { address } => {
+                        w.write_u8(crate::constants::DW_LLE_base_address.0)?;
+                        w.write_address(address, encoding.address_size)?;
+                    }
+                    Location::OffsetPair {
+                        begin,
+                        end,
+                        ref data,
+                    } => {
+                        w.write_u8(crate::constants::DW_LLE_offset_pair.0)?;
+                        w.write_uleb128(begin)?;
+                        w.write_uleb128(end)?;
+                        write_expression(&mut w.0, refs, encoding, unit_offsets, data)?;
+                    }
+                    Location::StartEnd {
+                        begin,
+                        end,
+                        ref data,
+                    } => {
+                        w.write_u8(crate::constants::DW_LLE_start_end.0)?;
+                        w.write_address(begin, encoding.address_size)?;
+                        w.write_address(end, encoding.address_size)?;
+                        write_expression(&mut w.0, refs, encoding, unit_offsets, data)?;
+                    }
+                    Location::StartLength {
+                        begin,
+                        length,
+                        ref data,
+                    } => {
+                        w.write_u8(crate::constants::DW_LLE_start_length.0)?;
+                        w.write_address(begin, encoding.address_size)?;
+                        w.write_uleb128(length)?;
+                        write_expression(&mut w.0, refs, encoding, unit_offsets, data)?;
+                    }
+                    Location::DefaultLocation { ref data } => {
+                        w.write_u8(crate::constants::DW_LLE_default_location.0)?;
+                        write_expression(&mut w.0, refs, encoding, unit_offsets, data)?;
+                    }
+                }
+            }
+
+            w.write_u8(crate::constants::DW_LLE_end_of_list.0)?;
+        }
+
+        let length = (w.len() - length_base) as u64;
+        w.write_initial_length_at(length_offset, length, encoding.format)?;
+
+        Ok(LocationListOffsets {
+            base_id: self.base_id,
+            offsets,
+        })
+    }
+}
+
+/// A locations list that will be stored in a `.debug_loc` or `.debug_loclists` section.
+#[derive(Clone, Debug, Eq, PartialEq, Hash)]
+pub struct LocationList(pub Vec<Location>);
+
+/// A single location.
+#[derive(Clone, Debug, Eq, PartialEq, Hash)]
+pub enum Location {
+    /// DW_LLE_base_address
+    BaseAddress {
+        /// Base address.
+        address: Address,
+    },
+    /// DW_LLE_offset_pair
+    OffsetPair {
+        /// Start of range relative to base address.
+        begin: u64,
+        /// End of range relative to base address.
+        end: u64,
+        /// Location description.
+        data: Expression,
+    },
+    /// DW_LLE_start_end
+    StartEnd {
+        /// Start of range.
+        begin: Address,
+        /// End of range.
+        end: Address,
+        /// Location description.
+        data: Expression,
+    },
+    /// DW_LLE_start_length
+    StartLength {
+        /// Start of range.
+        begin: Address,
+        /// Length of range.
+        length: u64,
+        /// Location description.
+        data: Expression,
+    },
+    /// DW_LLE_default_location
+    DefaultLocation {
+        /// Location description.
+        data: Expression,
+    },
+}
+
+fn write_expression<W: Writer>(
+    w: &mut W,
+    refs: &mut Vec<DebugInfoReference>,
+    encoding: Encoding,
+    unit_offsets: Option<&UnitOffsets>,
+    val: &Expression,
+) -> Result<()> {
+    let size = val.size(encoding, unit_offsets) as u64;
+    if encoding.version <= 4 {
+        w.write_udata(size, 2)?;
+    } else {
+        w.write_uleb128(size)?;
+    }
+    val.write(w, Some(refs), encoding, unit_offsets)?;
+    Ok(())
+}
+
+#[cfg(feature = "read")]
+mod convert {
+    use super::*;
+
+    use crate::read::{self, Reader};
+    use crate::write::{ConvertError, ConvertResult, ConvertUnitContext};
+
+    impl LocationList {
+        /// Create a location list by reading the data from the give location list iter.
+        pub(crate) fn from<R: Reader<Offset = usize>>(
+            mut from: read::RawLocListIter<R>,
+            context: &ConvertUnitContext<R>,
+        ) -> ConvertResult<Self> {
+            let mut have_base_address = context.base_address != Address::Constant(0);
+            let convert_address =
+                |x| (context.convert_address)(x).ok_or(ConvertError::InvalidAddress);
+            let convert_expression = |x| {
+                Expression::from(
+                    x,
+                    context.unit.encoding(),
+                    Some(context.dwarf),
+                    Some(context.unit),
+                    Some(context.entry_ids),
+                    context.convert_address,
+                )
+            };
+            let mut loc_list = Vec::new();
+            while let Some(from_loc) = from.next()? {
+                let loc = match from_loc {
+                    read::RawLocListEntry::AddressOrOffsetPair { begin, end, data } => {
+                        // These were parsed as addresses, even if they are offsets.
+                        let begin = convert_address(begin)?;
+                        let end = convert_address(end)?;
+                        let data = convert_expression(data)?;
+                        match (begin, end) {
+                            (Address::Constant(begin_offset), Address::Constant(end_offset)) => {
+                                if have_base_address {
+                                    Location::OffsetPair {
+                                        begin: begin_offset,
+                                        end: end_offset,
+                                        data,
+                                    }
+                                } else {
+                                    Location::StartEnd { begin, end, data }
+                                }
+                            }
+                            _ => {
+                                if have_base_address {
+                                    // At least one of begin/end is an address, but we also have
+                                    // a base address. Adding addresses is undefined.
+                                    return Err(ConvertError::InvalidRangeRelativeAddress);
+                                }
+                                Location::StartEnd { begin, end, data }
+                            }
+                        }
+                    }
+                    read::RawLocListEntry::BaseAddress { addr } => {
+                        have_base_address = true;
+                        let address = convert_address(addr)?;
+                        Location::BaseAddress { address }
+                    }
+                    read::RawLocListEntry::BaseAddressx { addr } => {
+                        have_base_address = true;
+                        let address = convert_address(context.dwarf.address(context.unit, addr)?)?;
+                        Location::BaseAddress { address }
+                    }
+                    read::RawLocListEntry::StartxEndx { begin, end, data } => {
+                        let begin = convert_address(context.dwarf.address(context.unit, begin)?)?;
+                        let end = convert_address(context.dwarf.address(context.unit, end)?)?;
+                        let data = convert_expression(data)?;
+                        Location::StartEnd { begin, end, data }
+                    }
+                    read::RawLocListEntry::StartxLength {
+                        begin,
+                        length,
+                        data,
+                    } => {
+                        let begin = convert_address(context.dwarf.address(context.unit, begin)?)?;
+                        let data = convert_expression(data)?;
+                        Location::StartLength {
+                            begin,
+                            length,
+                            data,
+                        }
+                    }
+                    read::RawLocListEntry::OffsetPair { begin, end, data } => {
+                        let data = convert_expression(data)?;
+                        Location::OffsetPair { begin, end, data }
+                    }
+                    read::RawLocListEntry::StartEnd { begin, end, data } => {
+                        let begin = convert_address(begin)?;
+                        let end = convert_address(end)?;
+                        let data = convert_expression(data)?;
+                        Location::StartEnd { begin, end, data }
+                    }
+                    read::RawLocListEntry::StartLength {
+                        begin,
+                        length,
+                        data,
+                    } => {
+                        let begin = convert_address(begin)?;
+                        let data = convert_expression(data)?;
+                        Location::StartLength {
+                            begin,
+                            length,
+                            data,
+                        }
+                    }
+                    read::RawLocListEntry::DefaultLocation { data } => {
+                        let data = convert_expression(data)?;
+                        Location::DefaultLocation { data }
+                    }
+                };
+                // In some cases, existing data may contain begin == end, filtering
+                // these out.
+                match loc {
+                    Location::StartLength { length, .. } if length == 0 => continue,
+                    Location::StartEnd { begin, end, .. } if begin == end => continue,
+                    Location::OffsetPair { begin, end, .. } if begin == end => continue,
+                    _ => (),
+                }
+                loc_list.push(loc);
+            }
+            Ok(LocationList(loc_list))
+        }
+    }
+}
+
+#[cfg(test)]
+#[cfg(feature = "read")]
+mod tests {
+    use super::*;
+    use crate::common::{
+        DebugAbbrevOffset, DebugAddrBase, DebugInfoOffset, DebugLocListsBase, DebugRngListsBase,
+        DebugStrOffsetsBase, Format,
+    };
+    use crate::read;
+    use crate::write::{
+        ConvertUnitContext, EndianVec, LineStringTable, RangeListTable, StringTable,
+    };
+    use crate::LittleEndian;
+    use std::collections::HashMap;
+    use std::sync::Arc;
+
+    #[test]
+    fn test_loc_list() {
+        let mut line_strings = LineStringTable::default();
+        let mut strings = StringTable::default();
+        let mut expression = Expression::new();
+        expression.op_constu(0);
+
+        for &version in &[2, 3, 4, 5] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+
+                    let mut loc_list = LocationList(vec![
+                        Location::StartLength {
+                            begin: Address::Constant(6666),
+                            length: 7777,
+                            data: expression.clone(),
+                        },
+                        Location::StartEnd {
+                            begin: Address::Constant(4444),
+                            end: Address::Constant(5555),
+                            data: expression.clone(),
+                        },
+                        Location::BaseAddress {
+                            address: Address::Constant(1111),
+                        },
+                        Location::OffsetPair {
+                            begin: 2222,
+                            end: 3333,
+                            data: expression.clone(),
+                        },
+                    ]);
+                    if version >= 5 {
+                        loc_list.0.push(Location::DefaultLocation {
+                            data: expression.clone(),
+                        });
+                    }
+
+                    let mut locations = LocationListTable::default();
+                    let loc_list_id = locations.add(loc_list.clone());
+
+                    let mut sections = Sections::new(EndianVec::new(LittleEndian));
+                    let loc_list_offsets = locations.write(&mut sections, encoding, None).unwrap();
+                    assert!(sections.debug_loc_refs.is_empty());
+                    assert!(sections.debug_loclists_refs.is_empty());
+
+                    let read_debug_loc =
+                        read::DebugLoc::new(sections.debug_loc.slice(), LittleEndian);
+                    let read_debug_loclists =
+                        read::DebugLocLists::new(sections.debug_loclists.slice(), LittleEndian);
+                    let read_loc = read::LocationLists::new(read_debug_loc, read_debug_loclists);
+                    let offset = loc_list_offsets.get(loc_list_id);
+                    let read_loc_list = read_loc.raw_locations(offset, encoding).unwrap();
+
+                    let dwarf = read::Dwarf {
+                        locations: read_loc,
+                        ..Default::default()
+                    };
+                    let unit = read::Unit {
+                        header: read::UnitHeader::new(
+                            encoding,
+                            0,
+                            read::UnitType::Compilation,
+                            DebugAbbrevOffset(0),
+                            DebugInfoOffset(0).into(),
+                            read::EndianSlice::default(),
+                        ),
+                        abbreviations: Arc::new(read::Abbreviations::default()),
+                        name: None,
+                        comp_dir: None,
+                        low_pc: 0,
+                        str_offsets_base: DebugStrOffsetsBase(0),
+                        addr_base: DebugAddrBase(0),
+                        loclists_base: DebugLocListsBase(0),
+                        rnglists_base: DebugRngListsBase(0),
+                        line_program: None,
+                        dwo_id: None,
+                    };
+                    let context = ConvertUnitContext {
+                        dwarf: &dwarf,
+                        unit: &unit,
+                        line_strings: &mut line_strings,
+                        strings: &mut strings,
+                        ranges: &mut RangeListTable::default(),
+                        locations: &mut locations,
+                        convert_address: &|address| Some(Address::Constant(address)),
+                        base_address: Address::Constant(0),
+                        line_program_offset: None,
+                        line_program_files: Vec::new(),
+                        entry_ids: &HashMap::new(),
+                    };
+                    let convert_loc_list = LocationList::from(read_loc_list, &context).unwrap();
+
+                    if version <= 4 {
+                        loc_list.0[0] = Location::StartEnd {
+                            begin: Address::Constant(6666),
+                            end: Address::Constant(6666 + 7777),
+                            data: expression.clone(),
+                        };
+                    }
+                    assert_eq!(loc_list, convert_loc_list);
+                }
+            }
+        }
+    }
+}
diff --git a/vendor/gimli/src/write/mod.rs b/vendor/gimli/src/write/mod.rs
new file mode 100644
index 0000000..47ba631
--- /dev/null
+++ b/vendor/gimli/src/write/mod.rs
@@ -0,0 +1,425 @@
+//! Write DWARF debugging information.
+//!
+//! ## API Structure
+//!
+//! This module works by building up a representation of the debugging information
+//! in memory, and then writing it all at once. It supports two major use cases:
+//!
+//! * Use the [`DwarfUnit`](./struct.DwarfUnit.html) type when writing DWARF
+//! for a single compilation unit.
+//!
+//! * Use the [`Dwarf`](./struct.Dwarf.html) type when writing DWARF for multiple
+//! compilation units.
+//!
+//! The module also supports reading in DWARF debugging information and writing it out
+//! again, possibly after modifying it. Create a [`read::Dwarf`](../read/struct.Dwarf.html)
+//! instance, and then use [`Dwarf::from`](./struct.Dwarf.html#method.from) to convert
+//! it to a writable instance.
+//!
+//! ## Example Usage
+//!
+//! Write a compilation unit containing only the top level DIE.
+//!
+//! ```rust
+//! use gimli::write::{
+//!     Address, AttributeValue, DwarfUnit, EndianVec, Error, Range, RangeList, Sections,
+//! };
+//!
+//! fn example() -> Result<(), Error> {
+//!     // Choose the encoding parameters.
+//!     let encoding = gimli::Encoding {
+//!         format: gimli::Format::Dwarf32,
+//!         version: 5,
+//!         address_size: 8,
+//!     };
+//!     // Create a container for a single compilation unit.
+//!     let mut dwarf = DwarfUnit::new(encoding);
+//!     // Set a range attribute on the root DIE.
+//!     let range_list = RangeList(vec![Range::StartLength {
+//!         begin: Address::Constant(0x100),
+//!         length: 42,
+//!     }]);
+//!     let range_list_id = dwarf.unit.ranges.add(range_list);
+//!     let root = dwarf.unit.root();
+//!     dwarf.unit.get_mut(root).set(
+//!         gimli::DW_AT_ranges,
+//!         AttributeValue::RangeListRef(range_list_id),
+//!     );
+//!     // Create a `Vec` for each DWARF section.
+//!     let mut sections = Sections::new(EndianVec::new(gimli::LittleEndian));
+//!     // Finally, write the DWARF data to the sections.
+//!     dwarf.write(&mut sections)?;
+//!     sections.for_each(|id, data| {
+//!         // Here you can add the data to the output object file.
+//!         Ok(())
+//!     })
+//! }
+//! # fn main() {
+//! #     example().unwrap();
+//! # }
+
+use std::error;
+use std::fmt;
+use std::result;
+
+use crate::constants;
+
+mod endian_vec;
+pub use self::endian_vec::*;
+
+mod writer;
+pub use self::writer::*;
+
+#[macro_use]
+mod section;
+pub use self::section::*;
+
+macro_rules! define_id {
+    ($name:ident, $docs:expr) => {
+        #[doc=$docs]
+        #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+        pub struct $name {
+            base_id: BaseId,
+            index: usize,
+        }
+
+        impl $name {
+            #[inline]
+            fn new(base_id: BaseId, index: usize) -> Self {
+                $name { base_id, index }
+            }
+        }
+    };
+}
+
+macro_rules! define_offsets {
+    ($offsets:ident: $id:ident => $offset:ident, $off_doc:expr) => {
+        #[doc=$off_doc]
+        #[derive(Debug)]
+        pub struct $offsets {
+            base_id: BaseId,
+            // We know ids start at 0.
+            offsets: Vec<$offset>,
+        }
+
+        impl $offsets {
+            /// Return an empty list of offsets.
+            #[inline]
+            pub fn none() -> Self {
+                $offsets {
+                    base_id: BaseId::default(),
+                    offsets: Vec::new(),
+                }
+            }
+
+            /// Get the offset
+            ///
+            /// # Panics
+            ///
+            /// Panics if `id` is invalid.
+            #[inline]
+            pub fn get(&self, id: $id) -> $offset {
+                debug_assert_eq!(self.base_id, id.base_id);
+                self.offsets[id.index]
+            }
+
+            /// Return the number of offsets.
+            #[inline]
+            pub fn count(&self) -> usize {
+                self.offsets.len()
+            }
+        }
+    };
+}
+
+mod abbrev;
+pub use self::abbrev::*;
+
+mod cfi;
+pub use self::cfi::*;
+
+mod dwarf;
+pub use self::dwarf::*;
+
+mod line;
+pub use self::line::*;
+
+mod loc;
+pub use self::loc::*;
+
+mod op;
+pub use self::op::*;
+
+mod range;
+pub use self::range::*;
+
+mod str;
+pub use self::str::*;
+
+mod unit;
+pub use self::unit::*;
+
+/// An error that occurred when writing.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Error {
+    /// The given offset is out of bounds.
+    OffsetOutOfBounds,
+    /// The given length is out of bounds.
+    LengthOutOfBounds,
+    /// The attribute value is an invalid for writing.
+    InvalidAttributeValue,
+    /// The value is too large for the encoding form.
+    ValueTooLarge,
+    /// Unsupported word size.
+    UnsupportedWordSize(u8),
+    /// Unsupported DWARF version.
+    UnsupportedVersion(u16),
+    /// The unit length is too large for the requested DWARF format.
+    InitialLengthOverflow,
+    /// The address is invalid.
+    InvalidAddress,
+    /// The reference is invalid.
+    InvalidReference,
+    /// A requested feature requires a different DWARF version.
+    NeedVersion(u16),
+    /// Strings in line number program have mismatched forms.
+    LineStringFormMismatch,
+    /// The range is empty or otherwise invalid.
+    InvalidRange,
+    /// The line number program encoding is incompatible with the unit encoding.
+    IncompatibleLineProgramEncoding,
+    /// Could not encode code offset for a frame instruction.
+    InvalidFrameCodeOffset(u32),
+    /// Could not encode data offset for a frame instruction.
+    InvalidFrameDataOffset(i32),
+    /// Unsupported eh_frame pointer encoding.
+    UnsupportedPointerEncoding(constants::DwEhPe),
+    /// Unsupported reference in CFI expression.
+    UnsupportedCfiExpressionReference,
+    /// Unsupported forward reference in expression.
+    UnsupportedExpressionForwardReference,
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
+        match *self {
+            Error::OffsetOutOfBounds => write!(f, "The given offset is out of bounds."),
+            Error::LengthOutOfBounds => write!(f, "The given length is out of bounds."),
+            Error::InvalidAttributeValue => {
+                write!(f, "The attribute value is an invalid for writing.")
+            }
+            Error::ValueTooLarge => write!(f, "The value is too large for the encoding form."),
+            Error::UnsupportedWordSize(size) => write!(f, "Unsupported word size: {}", size),
+            Error::UnsupportedVersion(version) => {
+                write!(f, "Unsupported DWARF version: {}", version)
+            }
+            Error::InitialLengthOverflow => write!(
+                f,
+                "The unit length is too large for the requested DWARF format."
+            ),
+            Error::InvalidAddress => write!(f, "The address is invalid."),
+            Error::InvalidReference => write!(f, "The reference is invalid."),
+            Error::NeedVersion(version) => write!(
+                f,
+                "A requested feature requires a DWARF version {}.",
+                version
+            ),
+            Error::LineStringFormMismatch => {
+                write!(f, "Strings in line number program have mismatched forms.")
+            }
+            Error::InvalidRange => write!(f, "The range is empty or otherwise invalid."),
+            Error::IncompatibleLineProgramEncoding => write!(
+                f,
+                "The line number program encoding is incompatible with the unit encoding."
+            ),
+            Error::InvalidFrameCodeOffset(offset) => write!(
+                f,
+                "Could not encode code offset ({}) for a frame instruction.",
+                offset,
+            ),
+            Error::InvalidFrameDataOffset(offset) => write!(
+                f,
+                "Could not encode data offset ({}) for a frame instruction.",
+                offset,
+            ),
+            Error::UnsupportedPointerEncoding(eh_pe) => {
+                write!(f, "Unsupported eh_frame pointer encoding ({}).", eh_pe)
+            }
+            Error::UnsupportedCfiExpressionReference => {
+                write!(f, "Unsupported reference in CFI expression.")
+            }
+            Error::UnsupportedExpressionForwardReference => {
+                write!(f, "Unsupported forward reference in expression.")
+            }
+        }
+    }
+}
+
+impl error::Error for Error {}
+
+/// The result of a write.
+pub type Result<T> = result::Result<T, Error>;
+
+/// An address.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum Address {
+    /// A fixed address that does not require relocation.
+    Constant(u64),
+    /// An address that is relative to a symbol which may be relocated.
+    Symbol {
+        /// The symbol that the address is relative to.
+        ///
+        /// The meaning of this value is decided by the writer, but
+        /// will typically be an index into a symbol table.
+        symbol: usize,
+        /// The offset of the address relative to the symbol.
+        ///
+        /// This will typically be used as the addend in a relocation.
+        addend: i64,
+    },
+}
+
+/// A reference to a `.debug_info` entry.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum Reference {
+    /// An external symbol.
+    ///
+    /// The meaning of this value is decided by the writer, but
+    /// will typically be an index into a symbol table.
+    Symbol(usize),
+    /// An entry in the same section.
+    ///
+    /// This only supports references in units that are emitted together.
+    Entry(UnitId, UnitEntryId),
+}
+
+// This type is only used in debug assertions.
+#[cfg(not(debug_assertions))]
+type BaseId = ();
+
+#[cfg(debug_assertions)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+struct BaseId(usize);
+
+#[cfg(debug_assertions)]
+impl Default for BaseId {
+    fn default() -> Self {
+        use std::sync::atomic;
+        static BASE_ID: atomic::AtomicUsize = atomic::AtomicUsize::new(0);
+        BaseId(BASE_ID.fetch_add(1, atomic::Ordering::Relaxed))
+    }
+}
+
+#[cfg(feature = "read")]
+mod convert {
+    use super::*;
+    use crate::read;
+
+    pub(crate) use super::unit::convert::*;
+
+    /// An error that occurred when converting a read value into a write value.
+    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+    pub enum ConvertError {
+        /// An error occurred when reading.
+        Read(read::Error),
+        /// Writing of this attribute value is not implemented yet.
+        UnsupportedAttributeValue,
+        /// This attribute value is an invalid name/form combination.
+        InvalidAttributeValue,
+        /// A `.debug_info` reference does not refer to a valid entry.
+        InvalidDebugInfoOffset,
+        /// An address could not be converted.
+        InvalidAddress,
+        /// Writing this line number instruction is not implemented yet.
+        UnsupportedLineInstruction,
+        /// Writing this form of line string is not implemented yet.
+        UnsupportedLineStringForm,
+        /// A `.debug_line` file index is invalid.
+        InvalidFileIndex,
+        /// A `.debug_line` directory index is invalid.
+        InvalidDirectoryIndex,
+        /// A `.debug_line` line base is invalid.
+        InvalidLineBase,
+        /// A `.debug_line` reference is invalid.
+        InvalidLineRef,
+        /// A `.debug_info` unit entry reference is invalid.
+        InvalidUnitRef,
+        /// A `.debug_info` reference is invalid.
+        InvalidDebugInfoRef,
+        /// Invalid relative address in a range list.
+        InvalidRangeRelativeAddress,
+        /// Writing this CFI instruction is not implemented yet.
+        UnsupportedCfiInstruction,
+        /// Writing indirect pointers is not implemented yet.
+        UnsupportedIndirectAddress,
+        /// Writing this expression operation is not implemented yet.
+        UnsupportedOperation,
+        /// Operation branch target is invalid.
+        InvalidBranchTarget,
+        /// Writing this unit type is not supported yet.
+        UnsupportedUnitType,
+    }
+
+    impl fmt::Display for ConvertError {
+        fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
+            use self::ConvertError::*;
+            match *self {
+                Read(ref e) => e.fmt(f),
+                UnsupportedAttributeValue => {
+                    write!(f, "Writing of this attribute value is not implemented yet.")
+                }
+                InvalidAttributeValue => write!(
+                    f,
+                    "This attribute value is an invalid name/form combination."
+                ),
+                InvalidDebugInfoOffset => write!(
+                    f,
+                    "A `.debug_info` reference does not refer to a valid entry."
+                ),
+                InvalidAddress => write!(f, "An address could not be converted."),
+                UnsupportedLineInstruction => write!(
+                    f,
+                    "Writing this line number instruction is not implemented yet."
+                ),
+                UnsupportedLineStringForm => write!(
+                    f,
+                    "Writing this form of line string is not implemented yet."
+                ),
+                InvalidFileIndex => write!(f, "A `.debug_line` file index is invalid."),
+                InvalidDirectoryIndex => write!(f, "A `.debug_line` directory index is invalid."),
+                InvalidLineBase => write!(f, "A `.debug_line` line base is invalid."),
+                InvalidLineRef => write!(f, "A `.debug_line` reference is invalid."),
+                InvalidUnitRef => write!(f, "A `.debug_info` unit entry reference is invalid."),
+                InvalidDebugInfoRef => write!(f, "A `.debug_info` reference is invalid."),
+                InvalidRangeRelativeAddress => {
+                    write!(f, "Invalid relative address in a range list.")
+                }
+                UnsupportedCfiInstruction => {
+                    write!(f, "Writing this CFI instruction is not implemented yet.")
+                }
+                UnsupportedIndirectAddress => {
+                    write!(f, "Writing indirect pointers is not implemented yet.")
+                }
+                UnsupportedOperation => write!(
+                    f,
+                    "Writing this expression operation is not implemented yet."
+                ),
+                InvalidBranchTarget => write!(f, "Operation branch target is invalid."),
+                UnsupportedUnitType => write!(f, "Writing this unit type is not supported yet."),
+            }
+        }
+    }
+
+    impl error::Error for ConvertError {}
+
+    impl From<read::Error> for ConvertError {
+        fn from(e: read::Error) -> Self {
+            ConvertError::Read(e)
+        }
+    }
+
+    /// The result of a conversion.
+    pub type ConvertResult<T> = result::Result<T, ConvertError>;
+}
+#[cfg(feature = "read")]
+pub use self::convert::*;
diff --git a/vendor/gimli/src/write/op.rs b/vendor/gimli/src/write/op.rs
new file mode 100644
index 0000000..287083b
--- /dev/null
+++ b/vendor/gimli/src/write/op.rs
@@ -0,0 +1,1618 @@
+use alloc::boxed::Box;
+use alloc::vec::Vec;
+
+use crate::common::{Encoding, Register};
+use crate::constants::{self, DwOp};
+use crate::leb128::write::{sleb128_size, uleb128_size};
+use crate::write::{
+    Address, DebugInfoReference, Error, Reference, Result, UnitEntryId, UnitOffsets, Writer,
+};
+
+/// The bytecode for a DWARF expression or location description.
+#[derive(Debug, Default, Clone, PartialEq, Eq, Hash)]
+pub struct Expression {
+    operations: Vec<Operation>,
+}
+
+impl Expression {
+    /// Create an empty expression.
+    #[inline]
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Create an expression from raw bytecode.
+    ///
+    /// This does not support operations that require references, such as `DW_OP_addr`.
+    #[inline]
+    pub fn raw(bytecode: Vec<u8>) -> Self {
+        Expression {
+            operations: vec![Operation::Raw(bytecode)],
+        }
+    }
+
+    /// Add an operation to the expression.
+    ///
+    /// This should only be used for operations that have no explicit operands.
+    pub fn op(&mut self, opcode: DwOp) {
+        self.operations.push(Operation::Simple(opcode));
+    }
+
+    /// Add a `DW_OP_addr` operation to the expression.
+    pub fn op_addr(&mut self, address: Address) {
+        self.operations.push(Operation::Address(address));
+    }
+
+    /// Add a `DW_OP_constu` operation to the expression.
+    ///
+    /// This may be emitted as a smaller equivalent operation.
+    pub fn op_constu(&mut self, value: u64) {
+        self.operations.push(Operation::UnsignedConstant(value));
+    }
+
+    /// Add a `DW_OP_consts` operation to the expression.
+    ///
+    /// This may be emitted as a smaller equivalent operation.
+    pub fn op_consts(&mut self, value: i64) {
+        self.operations.push(Operation::SignedConstant(value));
+    }
+
+    /// Add a `DW_OP_const_type` or `DW_OP_GNU_const_type` operation to the expression.
+    pub fn op_const_type(&mut self, base: UnitEntryId, value: Box<[u8]>) {
+        self.operations.push(Operation::ConstantType(base, value));
+    }
+
+    /// Add a `DW_OP_fbreg` operation to the expression.
+    pub fn op_fbreg(&mut self, offset: i64) {
+        self.operations.push(Operation::FrameOffset(offset));
+    }
+
+    /// Add a `DW_OP_bregx` operation to the expression.
+    ///
+    /// This may be emitted as a smaller equivalent operation.
+    pub fn op_breg(&mut self, register: Register, offset: i64) {
+        self.operations
+            .push(Operation::RegisterOffset(register, offset));
+    }
+
+    /// Add a `DW_OP_regval_type` or `DW_OP_GNU_regval_type` operation to the expression.
+    ///
+    /// This may be emitted as a smaller equivalent operation.
+    pub fn op_regval_type(&mut self, register: Register, base: UnitEntryId) {
+        self.operations
+            .push(Operation::RegisterType(register, base));
+    }
+
+    /// Add a `DW_OP_pick` operation to the expression.
+    ///
+    /// This may be emitted as a `DW_OP_dup` or `DW_OP_over` operation.
+    pub fn op_pick(&mut self, index: u8) {
+        self.operations.push(Operation::Pick(index));
+    }
+
+    /// Add a `DW_OP_deref` operation to the expression.
+    pub fn op_deref(&mut self) {
+        self.operations.push(Operation::Deref { space: false });
+    }
+
+    /// Add a `DW_OP_xderef` operation to the expression.
+    pub fn op_xderef(&mut self) {
+        self.operations.push(Operation::Deref { space: true });
+    }
+
+    /// Add a `DW_OP_deref_size` operation to the expression.
+    pub fn op_deref_size(&mut self, size: u8) {
+        self.operations
+            .push(Operation::DerefSize { size, space: false });
+    }
+
+    /// Add a `DW_OP_xderef_size` operation to the expression.
+    pub fn op_xderef_size(&mut self, size: u8) {
+        self.operations
+            .push(Operation::DerefSize { size, space: true });
+    }
+
+    /// Add a `DW_OP_deref_type` or `DW_OP_GNU_deref_type` operation to the expression.
+    pub fn op_deref_type(&mut self, size: u8, base: UnitEntryId) {
+        self.operations.push(Operation::DerefType {
+            size,
+            base,
+            space: false,
+        });
+    }
+
+    /// Add a `DW_OP_xderef_type` operation to the expression.
+    pub fn op_xderef_type(&mut self, size: u8, base: UnitEntryId) {
+        self.operations.push(Operation::DerefType {
+            size,
+            base,
+            space: true,
+        });
+    }
+
+    /// Add a `DW_OP_plus_uconst` operation to the expression.
+    pub fn op_plus_uconst(&mut self, value: u64) {
+        self.operations.push(Operation::PlusConstant(value));
+    }
+
+    /// Add a `DW_OP_skip` operation to the expression.
+    ///
+    /// Returns the index of the operation. The caller must call `set_target` with
+    /// this index to set the target of the branch.
+    pub fn op_skip(&mut self) -> usize {
+        let index = self.next_index();
+        self.operations.push(Operation::Skip(!0));
+        index
+    }
+
+    /// Add a `DW_OP_bra` operation to the expression.
+    ///
+    /// Returns the index of the operation. The caller must call `set_target` with
+    /// this index to set the target of the branch.
+    pub fn op_bra(&mut self) -> usize {
+        let index = self.next_index();
+        self.operations.push(Operation::Branch(!0));
+        index
+    }
+
+    /// Return the index that will be assigned to the next operation.
+    ///
+    /// This can be passed to `set_target`.
+    #[inline]
+    pub fn next_index(&self) -> usize {
+        self.operations.len()
+    }
+
+    /// Set the target of a `DW_OP_skip` or `DW_OP_bra` operation .
+    pub fn set_target(&mut self, operation: usize, new_target: usize) {
+        debug_assert!(new_target <= self.next_index());
+        debug_assert_ne!(operation, new_target);
+        match self.operations[operation] {
+            Operation::Skip(ref mut target) | Operation::Branch(ref mut target) => {
+                *target = new_target;
+            }
+            _ => unimplemented!(),
+        }
+    }
+
+    /// Add a `DW_OP_call4` operation to the expression.
+    pub fn op_call(&mut self, entry: UnitEntryId) {
+        self.operations.push(Operation::Call(entry));
+    }
+
+    /// Add a `DW_OP_call_ref` operation to the expression.
+    pub fn op_call_ref(&mut self, entry: Reference) {
+        self.operations.push(Operation::CallRef(entry));
+    }
+
+    /// Add a `DW_OP_convert` or `DW_OP_GNU_convert` operation to the expression.
+    ///
+    /// `base` is the DIE of the base type, or `None` for the generic type.
+    pub fn op_convert(&mut self, base: Option<UnitEntryId>) {
+        self.operations.push(Operation::Convert(base));
+    }
+
+    /// Add a `DW_OP_reinterpret` or `DW_OP_GNU_reinterpret` operation to the expression.
+    ///
+    /// `base` is the DIE of the base type, or `None` for the generic type.
+    pub fn op_reinterpret(&mut self, base: Option<UnitEntryId>) {
+        self.operations.push(Operation::Reinterpret(base));
+    }
+
+    /// Add a `DW_OP_entry_value` or `DW_OP_GNU_entry_value` operation to the expression.
+    pub fn op_entry_value(&mut self, expression: Expression) {
+        self.operations.push(Operation::EntryValue(expression));
+    }
+
+    /// Add a `DW_OP_regx` operation to the expression.
+    ///
+    /// This may be emitted as a smaller equivalent operation.
+    pub fn op_reg(&mut self, register: Register) {
+        self.operations.push(Operation::Register(register));
+    }
+
+    /// Add a `DW_OP_implicit_value` operation to the expression.
+    pub fn op_implicit_value(&mut self, data: Box<[u8]>) {
+        self.operations.push(Operation::ImplicitValue(data));
+    }
+
+    /// Add a `DW_OP_implicit_pointer` or `DW_OP_GNU_implicit_pointer` operation to the expression.
+    pub fn op_implicit_pointer(&mut self, entry: Reference, byte_offset: i64) {
+        self.operations
+            .push(Operation::ImplicitPointer { entry, byte_offset });
+    }
+
+    /// Add a `DW_OP_piece` operation to the expression.
+    pub fn op_piece(&mut self, size_in_bytes: u64) {
+        self.operations.push(Operation::Piece { size_in_bytes });
+    }
+
+    /// Add a `DW_OP_bit_piece` operation to the expression.
+    pub fn op_bit_piece(&mut self, size_in_bits: u64, bit_offset: u64) {
+        self.operations.push(Operation::BitPiece {
+            size_in_bits,
+            bit_offset,
+        });
+    }
+
+    /// Add a `DW_OP_GNU_parameter_ref` operation to the expression.
+    pub fn op_gnu_parameter_ref(&mut self, entry: UnitEntryId) {
+        self.operations.push(Operation::ParameterRef(entry));
+    }
+
+    /// Add a `DW_OP_WASM_location 0x0` operation to the expression.
+    pub fn op_wasm_local(&mut self, index: u32) {
+        self.operations.push(Operation::WasmLocal(index));
+    }
+
+    /// Add a `DW_OP_WASM_location 0x1` operation to the expression.
+    pub fn op_wasm_global(&mut self, index: u32) {
+        self.operations.push(Operation::WasmGlobal(index));
+    }
+
+    /// Add a `DW_OP_WASM_location 0x2` operation to the expression.
+    pub fn op_wasm_stack(&mut self, index: u32) {
+        self.operations.push(Operation::WasmStack(index));
+    }
+
+    pub(crate) fn size(&self, encoding: Encoding, unit_offsets: Option<&UnitOffsets>) -> usize {
+        let mut size = 0;
+        for operation in &self.operations {
+            size += operation.size(encoding, unit_offsets);
+        }
+        size
+    }
+
+    pub(crate) fn write<W: Writer>(
+        &self,
+        w: &mut W,
+        mut refs: Option<&mut Vec<DebugInfoReference>>,
+        encoding: Encoding,
+        unit_offsets: Option<&UnitOffsets>,
+    ) -> Result<()> {
+        // TODO: only calculate offsets if needed?
+        let mut offsets = Vec::with_capacity(self.operations.len());
+        let mut offset = w.len();
+        for operation in &self.operations {
+            offsets.push(offset);
+            offset += operation.size(encoding, unit_offsets);
+        }
+        offsets.push(offset);
+        for (operation, offset) in self.operations.iter().zip(offsets.iter().copied()) {
+            debug_assert_eq!(w.len(), offset);
+            operation.write(w, refs.as_deref_mut(), encoding, unit_offsets, &offsets)?;
+        }
+        Ok(())
+    }
+}
+
+/// A single DWARF operation.
+//
+// This type is intentionally not public so that we can change the
+// representation of expressions as needed.
+//
+// Variants are listed in the order they appear in Section 2.5.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+enum Operation {
+    /// Raw bytecode.
+    ///
+    /// Does not support references.
+    Raw(Vec<u8>),
+    /// An operation that has no explicit operands.
+    ///
+    /// Represents:
+    /// - `DW_OP_drop`, `DW_OP_swap`, `DW_OP_rot`
+    /// - `DW_OP_push_object_address`, `DW_OP_form_tls_address`, `DW_OP_call_frame_cfa`
+    /// - `DW_OP_abs`, `DW_OP_and`, `DW_OP_div`, `DW_OP_minus`, `DW_OP_mod`, `DW_OP_mul`,
+    ///   `DW_OP_neg`, `DW_OP_not`, `DW_OP_or`, `DW_OP_plus`, `DW_OP_shl`, `DW_OP_shr`,
+    ///   `DW_OP_shra`, `DW_OP_xor`
+    /// - `DW_OP_le`, `DW_OP_ge`, `DW_OP_eq`, `DW_OP_lt`, `DW_OP_gt`, `DW_OP_ne`
+    /// - `DW_OP_nop`
+    /// - `DW_OP_stack_value`
+    Simple(DwOp),
+    /// Relocate the address if needed, and push it on the stack.
+    ///
+    /// Represents `DW_OP_addr`.
+    Address(Address),
+    /// Push an unsigned constant value on the stack.
+    ///
+    /// Represents `DW_OP_constu`.
+    UnsignedConstant(u64),
+    /// Push a signed constant value on the stack.
+    ///
+    /// Represents `DW_OP_consts`.
+    SignedConstant(i64),
+    /* TODO: requires .debug_addr write support
+    /// Read the address at the given index in `.debug_addr, relocate the address if needed,
+    /// and push it on the stack.
+    ///
+    /// Represents `DW_OP_addrx`.
+    AddressIndex(DebugAddrIndex<Offset>),
+    /// Read the address at the given index in `.debug_addr, and push it on the stack.
+    /// Do not relocate the address.
+    ///
+    /// Represents `DW_OP_constx`.
+    ConstantIndex(DebugAddrIndex<Offset>),
+    */
+    /// Interpret the value bytes as a constant of a given type, and push it on the stack.
+    ///
+    /// Represents `DW_OP_const_type`.
+    ConstantType(UnitEntryId, Box<[u8]>),
+    /// Compute the frame base (using `DW_AT_frame_base`), add the
+    /// given offset, and then push the resulting sum on the stack.
+    ///
+    /// Represents `DW_OP_fbreg`.
+    FrameOffset(i64),
+    /// Find the contents of the given register, add the offset, and then
+    /// push the resulting sum on the stack.
+    ///
+    /// Represents `DW_OP_bregx`.
+    RegisterOffset(Register, i64),
+    /// Interpret the contents of the given register as a value of the given type,
+    /// and push it on the stack.
+    ///
+    /// Represents `DW_OP_regval_type`.
+    RegisterType(Register, UnitEntryId),
+    /// Copy the item at a stack index and push it on top of the stack.
+    ///
+    /// Represents `DW_OP_pick`, `DW_OP_dup`, and `DW_OP_over`.
+    Pick(u8),
+    /// Pop the topmost value of the stack, dereference it, and push the
+    /// resulting value.
+    ///
+    /// Represents `DW_OP_deref` and `DW_OP_xderef`.
+    Deref {
+        /// True if the dereference operation takes an address space
+        /// argument from the stack; false otherwise.
+        space: bool,
+    },
+    /// Pop the topmost value of the stack, dereference it to obtain a value
+    /// of the given size, and push the resulting value.
+    ///
+    /// Represents `DW_OP_deref_size` and `DW_OP_xderef_size`.
+    DerefSize {
+        /// True if the dereference operation takes an address space
+        /// argument from the stack; false otherwise.
+        space: bool,
+        /// The size of the data to dereference.
+        size: u8,
+    },
+    /// Pop the topmost value of the stack, dereference it to obtain a value
+    /// of the given type, and push the resulting value.
+    ///
+    /// Represents `DW_OP_deref_type` and `DW_OP_xderef_type`.
+    DerefType {
+        /// True if the dereference operation takes an address space
+        /// argument from the stack; false otherwise.
+        space: bool,
+        /// The size of the data to dereference.
+        size: u8,
+        /// The DIE of the base type, or `None` for the generic type.
+        base: UnitEntryId,
+    },
+    /// Add an unsigned constant to the topmost value on the stack.
+    ///
+    /// Represents `DW_OP_plus_uconst`.
+    PlusConstant(u64),
+    /// Unconditional branch to the target location.
+    ///
+    /// The value is the index within the expression of the operation to branch to.
+    /// This will be converted to a relative offset when writing.
+    ///
+    /// Represents `DW_OP_skip`.
+    Skip(usize),
+    /// Branch to the target location if the top of stack is nonzero.
+    ///
+    /// The value is the index within the expression of the operation to branch to.
+    /// This will be converted to a relative offset when writing.
+    ///
+    /// Represents `DW_OP_bra`.
+    Branch(usize),
+    /// Evaluate a DWARF expression as a subroutine.
+    ///
+    /// The expression comes from the `DW_AT_location` attribute of the indicated DIE.
+    ///
+    /// Represents `DW_OP_call4`.
+    Call(UnitEntryId),
+    /// Evaluate an external DWARF expression as a subroutine.
+    ///
+    /// The expression comes from the `DW_AT_location` attribute of the indicated DIE,
+    /// which may be in another compilation unit or shared object.
+    ///
+    /// Represents `DW_OP_call_ref`.
+    CallRef(Reference),
+    /// Pop the top stack entry, convert it to a different type, and push it on the stack.
+    ///
+    /// Represents `DW_OP_convert`.
+    Convert(Option<UnitEntryId>),
+    /// Pop the top stack entry, reinterpret the bits in its value as a different type,
+    /// and push it on the stack.
+    ///
+    /// Represents `DW_OP_reinterpret`.
+    Reinterpret(Option<UnitEntryId>),
+    /// Evaluate an expression at the entry to the current subprogram, and push it on the stack.
+    ///
+    /// Represents `DW_OP_entry_value`.
+    EntryValue(Expression),
+    // FIXME: EntryRegister
+    /// Indicate that this piece's location is in the given register.
+    ///
+    /// Completes the piece or expression.
+    ///
+    /// Represents `DW_OP_regx`.
+    Register(Register),
+    /// The object has no location, but has a known constant value.
+    ///
+    /// Completes the piece or expression.
+    ///
+    /// Represents `DW_OP_implicit_value`.
+    ImplicitValue(Box<[u8]>),
+    /// The object is a pointer to a value which has no actual location, such as
+    /// an implicit value or a stack value.
+    ///
+    /// Completes the piece or expression.
+    ///
+    /// Represents `DW_OP_implicit_pointer`.
+    ImplicitPointer {
+        /// The DIE of the value that this is an implicit pointer into.
+        entry: Reference,
+        /// The byte offset into the value that the implicit pointer points to.
+        byte_offset: i64,
+    },
+    /// Terminate a piece.
+    ///
+    /// Represents `DW_OP_piece`.
+    Piece {
+        /// The size of this piece in bytes.
+        size_in_bytes: u64,
+    },
+    /// Terminate a piece with a size in bits.
+    ///
+    /// Represents `DW_OP_bit_piece`.
+    BitPiece {
+        /// The size of this piece in bits.
+        size_in_bits: u64,
+        /// The bit offset of this piece.
+        bit_offset: u64,
+    },
+    /// This represents a parameter that was optimized out.
+    ///
+    /// The entry is the definition of the parameter, and is matched to
+    /// the `DW_TAG_GNU_call_site_parameter` in the caller that also
+    /// points to the same definition of the parameter.
+    ///
+    /// Represents `DW_OP_GNU_parameter_ref`.
+    ParameterRef(UnitEntryId),
+    /// The index of a local in the currently executing function.
+    ///
+    /// Represents `DW_OP_WASM_location 0x00`.
+    WasmLocal(u32),
+    /// The index of a global.
+    ///
+    /// Represents `DW_OP_WASM_location 0x01`.
+    WasmGlobal(u32),
+    /// The index of an item on the operand stack.
+    ///
+    /// Represents `DW_OP_WASM_location 0x02`.
+    WasmStack(u32),
+}
+
+impl Operation {
+    fn size(&self, encoding: Encoding, unit_offsets: Option<&UnitOffsets>) -> usize {
+        let base_size = |base| {
+            // Errors are handled during writes.
+            match unit_offsets {
+                Some(offsets) => uleb128_size(offsets.unit_offset(base)),
+                None => 0,
+            }
+        };
+        1 + match *self {
+            Operation::Raw(ref bytecode) => return bytecode.len(),
+            Operation::Simple(_) => 0,
+            Operation::Address(_) => encoding.address_size as usize,
+            Operation::UnsignedConstant(value) => {
+                if value < 32 {
+                    0
+                } else {
+                    uleb128_size(value)
+                }
+            }
+            Operation::SignedConstant(value) => sleb128_size(value),
+            Operation::ConstantType(base, ref value) => base_size(base) + 1 + value.len(),
+            Operation::FrameOffset(offset) => sleb128_size(offset),
+            Operation::RegisterOffset(register, offset) => {
+                if register.0 < 32 {
+                    sleb128_size(offset)
+                } else {
+                    uleb128_size(register.0.into()) + sleb128_size(offset)
+                }
+            }
+            Operation::RegisterType(register, base) => {
+                uleb128_size(register.0.into()) + base_size(base)
+            }
+            Operation::Pick(index) => {
+                if index > 1 {
+                    1
+                } else {
+                    0
+                }
+            }
+            Operation::Deref { .. } => 0,
+            Operation::DerefSize { .. } => 1,
+            Operation::DerefType { base, .. } => 1 + base_size(base),
+            Operation::PlusConstant(value) => uleb128_size(value),
+            Operation::Skip(_) => 2,
+            Operation::Branch(_) => 2,
+            Operation::Call(_) => 4,
+            Operation::CallRef(_) => encoding.format.word_size() as usize,
+            Operation::Convert(base) => match base {
+                Some(base) => base_size(base),
+                None => 1,
+            },
+            Operation::Reinterpret(base) => match base {
+                Some(base) => base_size(base),
+                None => 1,
+            },
+            Operation::EntryValue(ref expression) => {
+                let length = expression.size(encoding, unit_offsets);
+                uleb128_size(length as u64) + length
+            }
+            Operation::Register(register) => {
+                if register.0 < 32 {
+                    0
+                } else {
+                    uleb128_size(register.0.into())
+                }
+            }
+            Operation::ImplicitValue(ref data) => uleb128_size(data.len() as u64) + data.len(),
+            Operation::ImplicitPointer { byte_offset, .. } => {
+                encoding.format.word_size() as usize + sleb128_size(byte_offset)
+            }
+            Operation::Piece { size_in_bytes } => uleb128_size(size_in_bytes),
+            Operation::BitPiece {
+                size_in_bits,
+                bit_offset,
+            } => uleb128_size(size_in_bits) + uleb128_size(bit_offset),
+            Operation::ParameterRef(_) => 4,
+            Operation::WasmLocal(index)
+            | Operation::WasmGlobal(index)
+            | Operation::WasmStack(index) => 1 + uleb128_size(index.into()),
+        }
+    }
+
+    pub(crate) fn write<W: Writer>(
+        &self,
+        w: &mut W,
+        refs: Option<&mut Vec<DebugInfoReference>>,
+        encoding: Encoding,
+        unit_offsets: Option<&UnitOffsets>,
+        offsets: &[usize],
+    ) -> Result<()> {
+        let entry_offset = |entry| match unit_offsets {
+            Some(offsets) => {
+                let offset = offsets.unit_offset(entry);
+                if offset == 0 {
+                    Err(Error::UnsupportedExpressionForwardReference)
+                } else {
+                    Ok(offset)
+                }
+            }
+            None => Err(Error::UnsupportedCfiExpressionReference),
+        };
+        match *self {
+            Operation::Raw(ref bytecode) => w.write(bytecode)?,
+            Operation::Simple(opcode) => w.write_u8(opcode.0)?,
+            Operation::Address(address) => {
+                w.write_u8(constants::DW_OP_addr.0)?;
+                w.write_address(address, encoding.address_size)?;
+            }
+            Operation::UnsignedConstant(value) => {
+                if value < 32 {
+                    w.write_u8(constants::DW_OP_lit0.0 + value as u8)?;
+                } else {
+                    w.write_u8(constants::DW_OP_constu.0)?;
+                    w.write_uleb128(value)?;
+                }
+            }
+            Operation::SignedConstant(value) => {
+                w.write_u8(constants::DW_OP_consts.0)?;
+                w.write_sleb128(value)?;
+            }
+            Operation::ConstantType(base, ref value) => {
+                if encoding.version >= 5 {
+                    w.write_u8(constants::DW_OP_const_type.0)?;
+                } else {
+                    w.write_u8(constants::DW_OP_GNU_const_type.0)?;
+                }
+                w.write_uleb128(entry_offset(base)?)?;
+                w.write_udata(value.len() as u64, 1)?;
+                w.write(value)?;
+            }
+            Operation::FrameOffset(offset) => {
+                w.write_u8(constants::DW_OP_fbreg.0)?;
+                w.write_sleb128(offset)?;
+            }
+            Operation::RegisterOffset(register, offset) => {
+                if register.0 < 32 {
+                    w.write_u8(constants::DW_OP_breg0.0 + register.0 as u8)?;
+                } else {
+                    w.write_u8(constants::DW_OP_bregx.0)?;
+                    w.write_uleb128(register.0.into())?;
+                }
+                w.write_sleb128(offset)?;
+            }
+            Operation::RegisterType(register, base) => {
+                if encoding.version >= 5 {
+                    w.write_u8(constants::DW_OP_regval_type.0)?;
+                } else {
+                    w.write_u8(constants::DW_OP_GNU_regval_type.0)?;
+                }
+                w.write_uleb128(register.0.into())?;
+                w.write_uleb128(entry_offset(base)?)?;
+            }
+            Operation::Pick(index) => match index {
+                0 => w.write_u8(constants::DW_OP_dup.0)?,
+                1 => w.write_u8(constants::DW_OP_over.0)?,
+                _ => {
+                    w.write_u8(constants::DW_OP_pick.0)?;
+                    w.write_u8(index)?;
+                }
+            },
+            Operation::Deref { space } => {
+                if space {
+                    w.write_u8(constants::DW_OP_xderef.0)?;
+                } else {
+                    w.write_u8(constants::DW_OP_deref.0)?;
+                }
+            }
+            Operation::DerefSize { space, size } => {
+                if space {
+                    w.write_u8(constants::DW_OP_xderef_size.0)?;
+                } else {
+                    w.write_u8(constants::DW_OP_deref_size.0)?;
+                }
+                w.write_u8(size)?;
+            }
+            Operation::DerefType { space, size, base } => {
+                if space {
+                    w.write_u8(constants::DW_OP_xderef_type.0)?;
+                } else {
+                    if encoding.version >= 5 {
+                        w.write_u8(constants::DW_OP_deref_type.0)?;
+                    } else {
+                        w.write_u8(constants::DW_OP_GNU_deref_type.0)?;
+                    }
+                }
+                w.write_u8(size)?;
+                w.write_uleb128(entry_offset(base)?)?;
+            }
+            Operation::PlusConstant(value) => {
+                w.write_u8(constants::DW_OP_plus_uconst.0)?;
+                w.write_uleb128(value)?;
+            }
+            Operation::Skip(target) => {
+                w.write_u8(constants::DW_OP_skip.0)?;
+                let offset = offsets[target] as i64 - (w.len() as i64 + 2);
+                w.write_sdata(offset, 2)?;
+            }
+            Operation::Branch(target) => {
+                w.write_u8(constants::DW_OP_bra.0)?;
+                let offset = offsets[target] as i64 - (w.len() as i64 + 2);
+                w.write_sdata(offset, 2)?;
+            }
+            Operation::Call(entry) => {
+                w.write_u8(constants::DW_OP_call4.0)?;
+                // TODO: this probably won't work in practice, because we may
+                // only know the offsets of base type DIEs at this point.
+                w.write_udata(entry_offset(entry)?, 4)?;
+            }
+            Operation::CallRef(entry) => {
+                w.write_u8(constants::DW_OP_call_ref.0)?;
+                let size = encoding.format.word_size();
+                match entry {
+                    Reference::Symbol(symbol) => w.write_reference(symbol, size)?,
+                    Reference::Entry(unit, entry) => {
+                        let refs = refs.ok_or(Error::InvalidReference)?;
+                        refs.push(DebugInfoReference {
+                            offset: w.len(),
+                            unit,
+                            entry,
+                            size,
+                        });
+                        w.write_udata(0, size)?;
+                    }
+                }
+            }
+            Operation::Convert(base) => {
+                if encoding.version >= 5 {
+                    w.write_u8(constants::DW_OP_convert.0)?;
+                } else {
+                    w.write_u8(constants::DW_OP_GNU_convert.0)?;
+                }
+                match base {
+                    Some(base) => w.write_uleb128(entry_offset(base)?)?,
+                    None => w.write_u8(0)?,
+                }
+            }
+            Operation::Reinterpret(base) => {
+                if encoding.version >= 5 {
+                    w.write_u8(constants::DW_OP_reinterpret.0)?;
+                } else {
+                    w.write_u8(constants::DW_OP_GNU_reinterpret.0)?;
+                }
+                match base {
+                    Some(base) => w.write_uleb128(entry_offset(base)?)?,
+                    None => w.write_u8(0)?,
+                }
+            }
+            Operation::EntryValue(ref expression) => {
+                if encoding.version >= 5 {
+                    w.write_u8(constants::DW_OP_entry_value.0)?;
+                } else {
+                    w.write_u8(constants::DW_OP_GNU_entry_value.0)?;
+                }
+                let length = expression.size(encoding, unit_offsets);
+                w.write_uleb128(length as u64)?;
+                expression.write(w, refs, encoding, unit_offsets)?;
+            }
+            Operation::Register(register) => {
+                if register.0 < 32 {
+                    w.write_u8(constants::DW_OP_reg0.0 + register.0 as u8)?;
+                } else {
+                    w.write_u8(constants::DW_OP_regx.0)?;
+                    w.write_uleb128(register.0.into())?;
+                }
+            }
+            Operation::ImplicitValue(ref data) => {
+                w.write_u8(constants::DW_OP_implicit_value.0)?;
+                w.write_uleb128(data.len() as u64)?;
+                w.write(data)?;
+            }
+            Operation::ImplicitPointer { entry, byte_offset } => {
+                if encoding.version >= 5 {
+                    w.write_u8(constants::DW_OP_implicit_pointer.0)?;
+                } else {
+                    w.write_u8(constants::DW_OP_GNU_implicit_pointer.0)?;
+                }
+                let size = if encoding.version == 2 {
+                    encoding.address_size
+                } else {
+                    encoding.format.word_size()
+                };
+                match entry {
+                    Reference::Symbol(symbol) => {
+                        w.write_reference(symbol, size)?;
+                    }
+                    Reference::Entry(unit, entry) => {
+                        let refs = refs.ok_or(Error::InvalidReference)?;
+                        refs.push(DebugInfoReference {
+                            offset: w.len(),
+                            unit,
+                            entry,
+                            size,
+                        });
+                        w.write_udata(0, size)?;
+                    }
+                }
+                w.write_sleb128(byte_offset)?;
+            }
+            Operation::Piece { size_in_bytes } => {
+                w.write_u8(constants::DW_OP_piece.0)?;
+                w.write_uleb128(size_in_bytes)?;
+            }
+            Operation::BitPiece {
+                size_in_bits,
+                bit_offset,
+            } => {
+                w.write_u8(constants::DW_OP_bit_piece.0)?;
+                w.write_uleb128(size_in_bits)?;
+                w.write_uleb128(bit_offset)?;
+            }
+            Operation::ParameterRef(entry) => {
+                w.write_u8(constants::DW_OP_GNU_parameter_ref.0)?;
+                w.write_udata(entry_offset(entry)?, 4)?;
+            }
+            Operation::WasmLocal(index) => {
+                w.write(&[constants::DW_OP_WASM_location.0, 0])?;
+                w.write_uleb128(index.into())?;
+            }
+            Operation::WasmGlobal(index) => {
+                w.write(&[constants::DW_OP_WASM_location.0, 1])?;
+                w.write_uleb128(index.into())?;
+            }
+            Operation::WasmStack(index) => {
+                w.write(&[constants::DW_OP_WASM_location.0, 2])?;
+                w.write_uleb128(index.into())?;
+            }
+        }
+        Ok(())
+    }
+}
+
+#[cfg(feature = "read")]
+pub(crate) mod convert {
+    use super::*;
+    use crate::common::UnitSectionOffset;
+    use crate::read::{self, Reader};
+    use crate::write::{ConvertError, ConvertResult, UnitEntryId, UnitId};
+    use std::collections::HashMap;
+
+    impl Expression {
+        /// Create an expression from the input expression.
+        pub fn from<R: Reader<Offset = usize>>(
+            from_expression: read::Expression<R>,
+            encoding: Encoding,
+            dwarf: Option<&read::Dwarf<R>>,
+            unit: Option<&read::Unit<R>>,
+            entry_ids: Option<&HashMap<UnitSectionOffset, (UnitId, UnitEntryId)>>,
+            convert_address: &dyn Fn(u64) -> Option<Address>,
+        ) -> ConvertResult<Expression> {
+            let convert_unit_offset = |offset: read::UnitOffset| -> ConvertResult<_> {
+                let entry_ids = entry_ids.ok_or(ConvertError::UnsupportedOperation)?;
+                let unit = unit.ok_or(ConvertError::UnsupportedOperation)?;
+                let id = entry_ids
+                    .get(&offset.to_unit_section_offset(unit))
+                    .ok_or(ConvertError::InvalidUnitRef)?;
+                Ok(id.1)
+            };
+            let convert_debug_info_offset = |offset| -> ConvertResult<_> {
+                // TODO: support relocations
+                let entry_ids = entry_ids.ok_or(ConvertError::UnsupportedOperation)?;
+                let id = entry_ids
+                    .get(&UnitSectionOffset::DebugInfoOffset(offset))
+                    .ok_or(ConvertError::InvalidDebugInfoRef)?;
+                Ok(Reference::Entry(id.0, id.1))
+            };
+
+            // Calculate offsets for use in branch/skip operations.
+            let mut offsets = Vec::new();
+            let mut offset = 0;
+            let mut from_operations = from_expression.clone().operations(encoding);
+            while from_operations.next()?.is_some() {
+                offsets.push(offset);
+                offset = from_operations.offset_from(&from_expression);
+            }
+            offsets.push(from_expression.0.len());
+
+            let mut from_operations = from_expression.clone().operations(encoding);
+            let mut operations = Vec::new();
+            while let Some(from_operation) = from_operations.next()? {
+                let operation = match from_operation {
+                    read::Operation::Deref {
+                        base_type,
+                        size,
+                        space,
+                    } => {
+                        if base_type.0 != 0 {
+                            let base = convert_unit_offset(base_type)?;
+                            Operation::DerefType { space, size, base }
+                        } else if size != encoding.address_size {
+                            Operation::DerefSize { space, size }
+                        } else {
+                            Operation::Deref { space }
+                        }
+                    }
+                    read::Operation::Drop => Operation::Simple(constants::DW_OP_drop),
+                    read::Operation::Pick { index } => Operation::Pick(index),
+                    read::Operation::Swap => Operation::Simple(constants::DW_OP_swap),
+                    read::Operation::Rot => Operation::Simple(constants::DW_OP_rot),
+                    read::Operation::Abs => Operation::Simple(constants::DW_OP_abs),
+                    read::Operation::And => Operation::Simple(constants::DW_OP_and),
+                    read::Operation::Div => Operation::Simple(constants::DW_OP_div),
+                    read::Operation::Minus => Operation::Simple(constants::DW_OP_minus),
+                    read::Operation::Mod => Operation::Simple(constants::DW_OP_mod),
+                    read::Operation::Mul => Operation::Simple(constants::DW_OP_mul),
+                    read::Operation::Neg => Operation::Simple(constants::DW_OP_neg),
+                    read::Operation::Not => Operation::Simple(constants::DW_OP_not),
+                    read::Operation::Or => Operation::Simple(constants::DW_OP_or),
+                    read::Operation::Plus => Operation::Simple(constants::DW_OP_plus),
+                    read::Operation::PlusConstant { value } => Operation::PlusConstant(value),
+                    read::Operation::Shl => Operation::Simple(constants::DW_OP_shl),
+                    read::Operation::Shr => Operation::Simple(constants::DW_OP_shr),
+                    read::Operation::Shra => Operation::Simple(constants::DW_OP_shra),
+                    read::Operation::Xor => Operation::Simple(constants::DW_OP_xor),
+                    read::Operation::Eq => Operation::Simple(constants::DW_OP_eq),
+                    read::Operation::Ge => Operation::Simple(constants::DW_OP_ge),
+                    read::Operation::Gt => Operation::Simple(constants::DW_OP_gt),
+                    read::Operation::Le => Operation::Simple(constants::DW_OP_le),
+                    read::Operation::Lt => Operation::Simple(constants::DW_OP_lt),
+                    read::Operation::Ne => Operation::Simple(constants::DW_OP_ne),
+                    read::Operation::Bra { target } => {
+                        let offset = from_operations
+                            .offset_from(&from_expression)
+                            .wrapping_add(i64::from(target) as usize);
+                        let index = offsets
+                            .binary_search(&offset)
+                            .map_err(|_| ConvertError::InvalidBranchTarget)?;
+                        Operation::Branch(index)
+                    }
+                    read::Operation::Skip { target } => {
+                        let offset = from_operations
+                            .offset_from(&from_expression)
+                            .wrapping_add(i64::from(target) as usize);
+                        let index = offsets
+                            .binary_search(&offset)
+                            .map_err(|_| ConvertError::InvalidBranchTarget)?;
+                        Operation::Skip(index)
+                    }
+                    read::Operation::UnsignedConstant { value } => {
+                        Operation::UnsignedConstant(value)
+                    }
+                    read::Operation::SignedConstant { value } => Operation::SignedConstant(value),
+                    read::Operation::Register { register } => Operation::Register(register),
+                    read::Operation::RegisterOffset {
+                        register,
+                        offset,
+                        base_type,
+                    } => {
+                        if base_type.0 != 0 {
+                            Operation::RegisterType(register, convert_unit_offset(base_type)?)
+                        } else {
+                            Operation::RegisterOffset(register, offset)
+                        }
+                    }
+                    read::Operation::FrameOffset { offset } => Operation::FrameOffset(offset),
+                    read::Operation::Nop => Operation::Simple(constants::DW_OP_nop),
+                    read::Operation::PushObjectAddress => {
+                        Operation::Simple(constants::DW_OP_push_object_address)
+                    }
+                    read::Operation::Call { offset } => match offset {
+                        read::DieReference::UnitRef(offset) => {
+                            Operation::Call(convert_unit_offset(offset)?)
+                        }
+                        read::DieReference::DebugInfoRef(offset) => {
+                            Operation::CallRef(convert_debug_info_offset(offset)?)
+                        }
+                    },
+                    read::Operation::TLS => Operation::Simple(constants::DW_OP_form_tls_address),
+                    read::Operation::CallFrameCFA => {
+                        Operation::Simple(constants::DW_OP_call_frame_cfa)
+                    }
+                    read::Operation::Piece {
+                        size_in_bits,
+                        bit_offset: None,
+                    } => Operation::Piece {
+                        size_in_bytes: size_in_bits / 8,
+                    },
+                    read::Operation::Piece {
+                        size_in_bits,
+                        bit_offset: Some(bit_offset),
+                    } => Operation::BitPiece {
+                        size_in_bits,
+                        bit_offset,
+                    },
+                    read::Operation::ImplicitValue { data } => {
+                        Operation::ImplicitValue(data.to_slice()?.into_owned().into())
+                    }
+                    read::Operation::StackValue => Operation::Simple(constants::DW_OP_stack_value),
+                    read::Operation::ImplicitPointer { value, byte_offset } => {
+                        let entry = convert_debug_info_offset(value)?;
+                        Operation::ImplicitPointer { entry, byte_offset }
+                    }
+                    read::Operation::EntryValue { expression } => {
+                        let expression = Expression::from(
+                            read::Expression(expression),
+                            encoding,
+                            dwarf,
+                            unit,
+                            entry_ids,
+                            convert_address,
+                        )?;
+                        Operation::EntryValue(expression)
+                    }
+                    read::Operation::ParameterRef { offset } => {
+                        let entry = convert_unit_offset(offset)?;
+                        Operation::ParameterRef(entry)
+                    }
+                    read::Operation::Address { address } => {
+                        let address =
+                            convert_address(address).ok_or(ConvertError::InvalidAddress)?;
+                        Operation::Address(address)
+                    }
+                    read::Operation::AddressIndex { index } => {
+                        let dwarf = dwarf.ok_or(ConvertError::UnsupportedOperation)?;
+                        let unit = unit.ok_or(ConvertError::UnsupportedOperation)?;
+                        let val = dwarf.address(unit, index)?;
+                        let address = convert_address(val).ok_or(ConvertError::InvalidAddress)?;
+                        Operation::Address(address)
+                    }
+                    read::Operation::ConstantIndex { index } => {
+                        let dwarf = dwarf.ok_or(ConvertError::UnsupportedOperation)?;
+                        let unit = unit.ok_or(ConvertError::UnsupportedOperation)?;
+                        let val = dwarf.address(unit, index)?;
+                        Operation::UnsignedConstant(val)
+                    }
+                    read::Operation::TypedLiteral { base_type, value } => {
+                        let entry = convert_unit_offset(base_type)?;
+                        Operation::ConstantType(entry, value.to_slice()?.into_owned().into())
+                    }
+                    read::Operation::Convert { base_type } => {
+                        if base_type.0 == 0 {
+                            Operation::Convert(None)
+                        } else {
+                            let entry = convert_unit_offset(base_type)?;
+                            Operation::Convert(Some(entry))
+                        }
+                    }
+                    read::Operation::Reinterpret { base_type } => {
+                        if base_type.0 == 0 {
+                            Operation::Reinterpret(None)
+                        } else {
+                            let entry = convert_unit_offset(base_type)?;
+                            Operation::Reinterpret(Some(entry))
+                        }
+                    }
+                    read::Operation::WasmLocal { index } => Operation::WasmLocal(index),
+                    read::Operation::WasmGlobal { index } => Operation::WasmGlobal(index),
+                    read::Operation::WasmStack { index } => Operation::WasmStack(index),
+                };
+                operations.push(operation);
+            }
+            Ok(Expression { operations })
+        }
+    }
+}
+
+#[cfg(test)]
+#[cfg(feature = "read")]
+mod tests {
+    use super::*;
+    use crate::common::{
+        DebugAbbrevOffset, DebugAddrBase, DebugInfoOffset, DebugLocListsBase, DebugRngListsBase,
+        DebugStrOffsetsBase, Format, SectionId,
+    };
+    use crate::read;
+    use crate::write::{
+        DebugLineStrOffsets, DebugStrOffsets, EndianVec, LineProgram, Sections, Unit, UnitTable,
+    };
+    use crate::LittleEndian;
+    use std::collections::HashMap;
+    use std::sync::Arc;
+
+    #[test]
+    fn test_operation() {
+        for &version in &[3, 4, 5] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+
+                    let mut units = UnitTable::default();
+                    let unit_id = units.add(Unit::new(encoding, LineProgram::none()));
+                    let unit = units.get_mut(unit_id);
+                    let entry_id = unit.add(unit.root(), constants::DW_TAG_base_type);
+                    let reference = Reference::Entry(unit_id, entry_id);
+
+                    let mut sections = Sections::new(EndianVec::new(LittleEndian));
+                    let debug_line_str_offsets = DebugLineStrOffsets::none();
+                    let debug_str_offsets = DebugStrOffsets::none();
+                    let debug_info_offsets = units
+                        .write(&mut sections, &debug_line_str_offsets, &debug_str_offsets)
+                        .unwrap();
+                    let unit_offsets = debug_info_offsets.unit_offsets(unit_id);
+                    let debug_info_offset = unit_offsets.debug_info_offset(entry_id);
+                    let entry_offset =
+                        read::UnitOffset(unit_offsets.unit_offset(entry_id) as usize);
+
+                    let mut reg_expression = Expression::new();
+                    reg_expression.op_reg(Register(23));
+
+                    let operations: &[(&dyn Fn(&mut Expression), Operation, read::Operation<_>)] =
+                        &[
+                            (
+                                &|x| x.op_deref(),
+                                Operation::Deref { space: false },
+                                read::Operation::Deref {
+                                    base_type: read::UnitOffset(0),
+                                    size: address_size,
+                                    space: false,
+                                },
+                            ),
+                            (
+                                &|x| x.op_xderef(),
+                                Operation::Deref { space: true },
+                                read::Operation::Deref {
+                                    base_type: read::UnitOffset(0),
+                                    size: address_size,
+                                    space: true,
+                                },
+                            ),
+                            (
+                                &|x| x.op_deref_size(2),
+                                Operation::DerefSize {
+                                    space: false,
+                                    size: 2,
+                                },
+                                read::Operation::Deref {
+                                    base_type: read::UnitOffset(0),
+                                    size: 2,
+                                    space: false,
+                                },
+                            ),
+                            (
+                                &|x| x.op_xderef_size(2),
+                                Operation::DerefSize {
+                                    space: true,
+                                    size: 2,
+                                },
+                                read::Operation::Deref {
+                                    base_type: read::UnitOffset(0),
+                                    size: 2,
+                                    space: true,
+                                },
+                            ),
+                            (
+                                &|x| x.op_deref_type(2, entry_id),
+                                Operation::DerefType {
+                                    space: false,
+                                    size: 2,
+                                    base: entry_id,
+                                },
+                                read::Operation::Deref {
+                                    base_type: entry_offset,
+                                    size: 2,
+                                    space: false,
+                                },
+                            ),
+                            (
+                                &|x| x.op_xderef_type(2, entry_id),
+                                Operation::DerefType {
+                                    space: true,
+                                    size: 2,
+                                    base: entry_id,
+                                },
+                                read::Operation::Deref {
+                                    base_type: entry_offset,
+                                    size: 2,
+                                    space: true,
+                                },
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_drop),
+                                Operation::Simple(constants::DW_OP_drop),
+                                read::Operation::Drop,
+                            ),
+                            (
+                                &|x| x.op_pick(0),
+                                Operation::Pick(0),
+                                read::Operation::Pick { index: 0 },
+                            ),
+                            (
+                                &|x| x.op_pick(1),
+                                Operation::Pick(1),
+                                read::Operation::Pick { index: 1 },
+                            ),
+                            (
+                                &|x| x.op_pick(2),
+                                Operation::Pick(2),
+                                read::Operation::Pick { index: 2 },
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_swap),
+                                Operation::Simple(constants::DW_OP_swap),
+                                read::Operation::Swap,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_rot),
+                                Operation::Simple(constants::DW_OP_rot),
+                                read::Operation::Rot,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_abs),
+                                Operation::Simple(constants::DW_OP_abs),
+                                read::Operation::Abs,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_and),
+                                Operation::Simple(constants::DW_OP_and),
+                                read::Operation::And,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_div),
+                                Operation::Simple(constants::DW_OP_div),
+                                read::Operation::Div,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_minus),
+                                Operation::Simple(constants::DW_OP_minus),
+                                read::Operation::Minus,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_mod),
+                                Operation::Simple(constants::DW_OP_mod),
+                                read::Operation::Mod,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_mul),
+                                Operation::Simple(constants::DW_OP_mul),
+                                read::Operation::Mul,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_neg),
+                                Operation::Simple(constants::DW_OP_neg),
+                                read::Operation::Neg,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_not),
+                                Operation::Simple(constants::DW_OP_not),
+                                read::Operation::Not,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_or),
+                                Operation::Simple(constants::DW_OP_or),
+                                read::Operation::Or,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_plus),
+                                Operation::Simple(constants::DW_OP_plus),
+                                read::Operation::Plus,
+                            ),
+                            (
+                                &|x| x.op_plus_uconst(23),
+                                Operation::PlusConstant(23),
+                                read::Operation::PlusConstant { value: 23 },
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_shl),
+                                Operation::Simple(constants::DW_OP_shl),
+                                read::Operation::Shl,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_shr),
+                                Operation::Simple(constants::DW_OP_shr),
+                                read::Operation::Shr,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_shra),
+                                Operation::Simple(constants::DW_OP_shra),
+                                read::Operation::Shra,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_xor),
+                                Operation::Simple(constants::DW_OP_xor),
+                                read::Operation::Xor,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_eq),
+                                Operation::Simple(constants::DW_OP_eq),
+                                read::Operation::Eq,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_ge),
+                                Operation::Simple(constants::DW_OP_ge),
+                                read::Operation::Ge,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_gt),
+                                Operation::Simple(constants::DW_OP_gt),
+                                read::Operation::Gt,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_le),
+                                Operation::Simple(constants::DW_OP_le),
+                                read::Operation::Le,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_lt),
+                                Operation::Simple(constants::DW_OP_lt),
+                                read::Operation::Lt,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_ne),
+                                Operation::Simple(constants::DW_OP_ne),
+                                read::Operation::Ne,
+                            ),
+                            (
+                                &|x| x.op_constu(23),
+                                Operation::UnsignedConstant(23),
+                                read::Operation::UnsignedConstant { value: 23 },
+                            ),
+                            (
+                                &|x| x.op_consts(-23),
+                                Operation::SignedConstant(-23),
+                                read::Operation::SignedConstant { value: -23 },
+                            ),
+                            (
+                                &|x| x.op_reg(Register(23)),
+                                Operation::Register(Register(23)),
+                                read::Operation::Register {
+                                    register: Register(23),
+                                },
+                            ),
+                            (
+                                &|x| x.op_reg(Register(123)),
+                                Operation::Register(Register(123)),
+                                read::Operation::Register {
+                                    register: Register(123),
+                                },
+                            ),
+                            (
+                                &|x| x.op_breg(Register(23), 34),
+                                Operation::RegisterOffset(Register(23), 34),
+                                read::Operation::RegisterOffset {
+                                    register: Register(23),
+                                    offset: 34,
+                                    base_type: read::UnitOffset(0),
+                                },
+                            ),
+                            (
+                                &|x| x.op_breg(Register(123), 34),
+                                Operation::RegisterOffset(Register(123), 34),
+                                read::Operation::RegisterOffset {
+                                    register: Register(123),
+                                    offset: 34,
+                                    base_type: read::UnitOffset(0),
+                                },
+                            ),
+                            (
+                                &|x| x.op_regval_type(Register(23), entry_id),
+                                Operation::RegisterType(Register(23), entry_id),
+                                read::Operation::RegisterOffset {
+                                    register: Register(23),
+                                    offset: 0,
+                                    base_type: entry_offset,
+                                },
+                            ),
+                            (
+                                &|x| x.op_fbreg(34),
+                                Operation::FrameOffset(34),
+                                read::Operation::FrameOffset { offset: 34 },
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_nop),
+                                Operation::Simple(constants::DW_OP_nop),
+                                read::Operation::Nop,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_push_object_address),
+                                Operation::Simple(constants::DW_OP_push_object_address),
+                                read::Operation::PushObjectAddress,
+                            ),
+                            (
+                                &|x| x.op_call(entry_id),
+                                Operation::Call(entry_id),
+                                read::Operation::Call {
+                                    offset: read::DieReference::UnitRef(entry_offset),
+                                },
+                            ),
+                            (
+                                &|x| x.op_call_ref(reference),
+                                Operation::CallRef(reference),
+                                read::Operation::Call {
+                                    offset: read::DieReference::DebugInfoRef(debug_info_offset),
+                                },
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_form_tls_address),
+                                Operation::Simple(constants::DW_OP_form_tls_address),
+                                read::Operation::TLS,
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_call_frame_cfa),
+                                Operation::Simple(constants::DW_OP_call_frame_cfa),
+                                read::Operation::CallFrameCFA,
+                            ),
+                            (
+                                &|x| x.op_piece(23),
+                                Operation::Piece { size_in_bytes: 23 },
+                                read::Operation::Piece {
+                                    size_in_bits: 23 * 8,
+                                    bit_offset: None,
+                                },
+                            ),
+                            (
+                                &|x| x.op_bit_piece(23, 34),
+                                Operation::BitPiece {
+                                    size_in_bits: 23,
+                                    bit_offset: 34,
+                                },
+                                read::Operation::Piece {
+                                    size_in_bits: 23,
+                                    bit_offset: Some(34),
+                                },
+                            ),
+                            (
+                                &|x| x.op_implicit_value(vec![23].into()),
+                                Operation::ImplicitValue(vec![23].into()),
+                                read::Operation::ImplicitValue {
+                                    data: read::EndianSlice::new(&[23], LittleEndian),
+                                },
+                            ),
+                            (
+                                &|x| x.op(constants::DW_OP_stack_value),
+                                Operation::Simple(constants::DW_OP_stack_value),
+                                read::Operation::StackValue,
+                            ),
+                            (
+                                &|x| x.op_implicit_pointer(reference, 23),
+                                Operation::ImplicitPointer {
+                                    entry: reference,
+                                    byte_offset: 23,
+                                },
+                                read::Operation::ImplicitPointer {
+                                    value: debug_info_offset,
+                                    byte_offset: 23,
+                                },
+                            ),
+                            (
+                                &|x| x.op_entry_value(reg_expression.clone()),
+                                Operation::EntryValue(reg_expression.clone()),
+                                read::Operation::EntryValue {
+                                    expression: read::EndianSlice::new(
+                                        &[constants::DW_OP_reg23.0],
+                                        LittleEndian,
+                                    ),
+                                },
+                            ),
+                            (
+                                &|x| x.op_gnu_parameter_ref(entry_id),
+                                Operation::ParameterRef(entry_id),
+                                read::Operation::ParameterRef {
+                                    offset: entry_offset,
+                                },
+                            ),
+                            (
+                                &|x| x.op_addr(Address::Constant(23)),
+                                Operation::Address(Address::Constant(23)),
+                                read::Operation::Address { address: 23 },
+                            ),
+                            (
+                                &|x| x.op_const_type(entry_id, vec![23].into()),
+                                Operation::ConstantType(entry_id, vec![23].into()),
+                                read::Operation::TypedLiteral {
+                                    base_type: entry_offset,
+                                    value: read::EndianSlice::new(&[23], LittleEndian),
+                                },
+                            ),
+                            (
+                                &|x| x.op_convert(None),
+                                Operation::Convert(None),
+                                read::Operation::Convert {
+                                    base_type: read::UnitOffset(0),
+                                },
+                            ),
+                            (
+                                &|x| x.op_convert(Some(entry_id)),
+                                Operation::Convert(Some(entry_id)),
+                                read::Operation::Convert {
+                                    base_type: entry_offset,
+                                },
+                            ),
+                            (
+                                &|x| x.op_reinterpret(None),
+                                Operation::Reinterpret(None),
+                                read::Operation::Reinterpret {
+                                    base_type: read::UnitOffset(0),
+                                },
+                            ),
+                            (
+                                &|x| x.op_reinterpret(Some(entry_id)),
+                                Operation::Reinterpret(Some(entry_id)),
+                                read::Operation::Reinterpret {
+                                    base_type: entry_offset,
+                                },
+                            ),
+                            (
+                                &|x| x.op_wasm_local(1000),
+                                Operation::WasmLocal(1000),
+                                read::Operation::WasmLocal { index: 1000 },
+                            ),
+                            (
+                                &|x| x.op_wasm_global(1000),
+                                Operation::WasmGlobal(1000),
+                                read::Operation::WasmGlobal { index: 1000 },
+                            ),
+                            (
+                                &|x| x.op_wasm_stack(1000),
+                                Operation::WasmStack(1000),
+                                read::Operation::WasmStack { index: 1000 },
+                            ),
+                        ];
+
+                    let mut expression = Expression::new();
+                    let start_index = expression.next_index();
+                    for (f, o, _) in operations {
+                        f(&mut expression);
+                        assert_eq!(expression.operations.last(), Some(o));
+                    }
+
+                    let bra_index = expression.op_bra();
+                    let skip_index = expression.op_skip();
+                    expression.op(constants::DW_OP_nop);
+                    let end_index = expression.next_index();
+                    expression.set_target(bra_index, start_index);
+                    expression.set_target(skip_index, end_index);
+
+                    let mut w = EndianVec::new(LittleEndian);
+                    let mut refs = Vec::new();
+                    expression
+                        .write(&mut w, Some(&mut refs), encoding, Some(&unit_offsets))
+                        .unwrap();
+                    for r in &refs {
+                        assert_eq!(r.unit, unit_id);
+                        assert_eq!(r.entry, entry_id);
+                        w.write_offset_at(
+                            r.offset,
+                            debug_info_offset.0,
+                            SectionId::DebugInfo,
+                            r.size,
+                        )
+                        .unwrap();
+                    }
+
+                    let read_expression =
+                        read::Expression(read::EndianSlice::new(w.slice(), LittleEndian));
+                    let mut read_operations = read_expression.operations(encoding);
+                    for (_, _, operation) in operations {
+                        assert_eq!(read_operations.next(), Ok(Some(*operation)));
+                    }
+
+                    // 4 = DW_OP_skip + i16 + DW_OP_nop
+                    assert_eq!(
+                        read_operations.next(),
+                        Ok(Some(read::Operation::Bra {
+                            target: -(w.len() as i16) + 4
+                        }))
+                    );
+                    // 1 = DW_OP_nop
+                    assert_eq!(
+                        read_operations.next(),
+                        Ok(Some(read::Operation::Skip { target: 1 }))
+                    );
+                    assert_eq!(read_operations.next(), Ok(Some(read::Operation::Nop)));
+                    assert_eq!(read_operations.next(), Ok(None));
+
+                    // Fake the unit.
+                    let unit = read::Unit {
+                        header: read::UnitHeader::new(
+                            encoding,
+                            0,
+                            read::UnitType::Compilation,
+                            DebugAbbrevOffset(0),
+                            DebugInfoOffset(0).into(),
+                            read::EndianSlice::new(&[], LittleEndian),
+                        ),
+                        abbreviations: Arc::new(read::Abbreviations::default()),
+                        name: None,
+                        comp_dir: None,
+                        low_pc: 0,
+                        str_offsets_base: DebugStrOffsetsBase(0),
+                        addr_base: DebugAddrBase(0),
+                        loclists_base: DebugLocListsBase(0),
+                        rnglists_base: DebugRngListsBase(0),
+                        line_program: None,
+                        dwo_id: None,
+                    };
+
+                    let mut entry_ids = HashMap::new();
+                    entry_ids.insert(debug_info_offset.into(), (unit_id, entry_id));
+                    let convert_expression = Expression::from(
+                        read_expression,
+                        encoding,
+                        None, /* dwarf */
+                        Some(&unit),
+                        Some(&entry_ids),
+                        &|address| Some(Address::Constant(address)),
+                    )
+                    .unwrap();
+                    let mut convert_operations = convert_expression.operations.iter();
+                    for (_, operation, _) in operations {
+                        assert_eq!(convert_operations.next(), Some(operation));
+                    }
+                    assert_eq!(
+                        convert_operations.next(),
+                        Some(&Operation::Branch(start_index))
+                    );
+                    assert_eq!(convert_operations.next(), Some(&Operation::Skip(end_index)));
+                    assert_eq!(
+                        convert_operations.next(),
+                        Some(&Operation::Simple(constants::DW_OP_nop))
+                    );
+                }
+            }
+        }
+    }
+}
diff --git a/vendor/gimli/src/write/range.rs b/vendor/gimli/src/write/range.rs
new file mode 100644
index 0000000..c707e1e
--- /dev/null
+++ b/vendor/gimli/src/write/range.rs
@@ -0,0 +1,416 @@
+use alloc::vec::Vec;
+use indexmap::IndexSet;
+use std::ops::{Deref, DerefMut};
+
+use crate::common::{Encoding, RangeListsOffset, SectionId};
+use crate::write::{Address, BaseId, Error, Result, Section, Sections, Writer};
+
+define_section!(
+    DebugRanges,
+    RangeListsOffset,
+    "A writable `.debug_ranges` section."
+);
+define_section!(
+    DebugRngLists,
+    RangeListsOffset,
+    "A writable `.debug_rnglists` section."
+);
+
+define_offsets!(
+    RangeListOffsets: RangeListId => RangeListsOffset,
+    "The section offsets of a series of range lists within the `.debug_ranges` or `.debug_rnglists` sections."
+);
+
+define_id!(
+    RangeListId,
+    "An identifier for a range list in a `RangeListTable`."
+);
+
+/// A table of range lists that will be stored in a `.debug_ranges` or `.debug_rnglists` section.
+#[derive(Debug, Default)]
+pub struct RangeListTable {
+    base_id: BaseId,
+    ranges: IndexSet<RangeList>,
+}
+
+impl RangeListTable {
+    /// Add a range list to the table.
+    pub fn add(&mut self, range_list: RangeList) -> RangeListId {
+        let (index, _) = self.ranges.insert_full(range_list);
+        RangeListId::new(self.base_id, index)
+    }
+
+    /// Write the range list table to the appropriate section for the given DWARF version.
+    pub(crate) fn write<W: Writer>(
+        &self,
+        sections: &mut Sections<W>,
+        encoding: Encoding,
+    ) -> Result<RangeListOffsets> {
+        if self.ranges.is_empty() {
+            return Ok(RangeListOffsets::none());
+        }
+
+        match encoding.version {
+            2..=4 => self.write_ranges(&mut sections.debug_ranges, encoding.address_size),
+            5 => self.write_rnglists(&mut sections.debug_rnglists, encoding),
+            _ => Err(Error::UnsupportedVersion(encoding.version)),
+        }
+    }
+
+    /// Write the range list table to the `.debug_ranges` section.
+    fn write_ranges<W: Writer>(
+        &self,
+        w: &mut DebugRanges<W>,
+        address_size: u8,
+    ) -> Result<RangeListOffsets> {
+        let mut offsets = Vec::new();
+        for range_list in self.ranges.iter() {
+            offsets.push(w.offset());
+            for range in &range_list.0 {
+                // Note that we must ensure none of the ranges have both begin == 0 and end == 0.
+                // We do this by ensuring that begin != end, which is a bit more restrictive
+                // than required, but still seems reasonable.
+                match *range {
+                    Range::BaseAddress { address } => {
+                        let marker = !0 >> (64 - address_size * 8);
+                        w.write_udata(marker, address_size)?;
+                        w.write_address(address, address_size)?;
+                    }
+                    Range::OffsetPair { begin, end } => {
+                        if begin == end {
+                            return Err(Error::InvalidRange);
+                        }
+                        w.write_udata(begin, address_size)?;
+                        w.write_udata(end, address_size)?;
+                    }
+                    Range::StartEnd { begin, end } => {
+                        if begin == end {
+                            return Err(Error::InvalidRange);
+                        }
+                        w.write_address(begin, address_size)?;
+                        w.write_address(end, address_size)?;
+                    }
+                    Range::StartLength { begin, length } => {
+                        let end = match begin {
+                            Address::Constant(begin) => Address::Constant(begin + length),
+                            Address::Symbol { symbol, addend } => Address::Symbol {
+                                symbol,
+                                addend: addend + length as i64,
+                            },
+                        };
+                        if begin == end {
+                            return Err(Error::InvalidRange);
+                        }
+                        w.write_address(begin, address_size)?;
+                        w.write_address(end, address_size)?;
+                    }
+                }
+            }
+            w.write_udata(0, address_size)?;
+            w.write_udata(0, address_size)?;
+        }
+        Ok(RangeListOffsets {
+            base_id: self.base_id,
+            offsets,
+        })
+    }
+
+    /// Write the range list table to the `.debug_rnglists` section.
+    fn write_rnglists<W: Writer>(
+        &self,
+        w: &mut DebugRngLists<W>,
+        encoding: Encoding,
+    ) -> Result<RangeListOffsets> {
+        let mut offsets = Vec::new();
+
+        if encoding.version != 5 {
+            return Err(Error::NeedVersion(5));
+        }
+
+        let length_offset = w.write_initial_length(encoding.format)?;
+        let length_base = w.len();
+
+        w.write_u16(encoding.version)?;
+        w.write_u8(encoding.address_size)?;
+        w.write_u8(0)?; // segment_selector_size
+        w.write_u32(0)?; // offset_entry_count (when set to zero DW_FORM_rnglistx can't be used, see section 7.28)
+                         // FIXME implement DW_FORM_rnglistx writing and implement the offset entry list
+
+        for range_list in self.ranges.iter() {
+            offsets.push(w.offset());
+            for range in &range_list.0 {
+                match *range {
+                    Range::BaseAddress { address } => {
+                        w.write_u8(crate::constants::DW_RLE_base_address.0)?;
+                        w.write_address(address, encoding.address_size)?;
+                    }
+                    Range::OffsetPair { begin, end } => {
+                        w.write_u8(crate::constants::DW_RLE_offset_pair.0)?;
+                        w.write_uleb128(begin)?;
+                        w.write_uleb128(end)?;
+                    }
+                    Range::StartEnd { begin, end } => {
+                        w.write_u8(crate::constants::DW_RLE_start_end.0)?;
+                        w.write_address(begin, encoding.address_size)?;
+                        w.write_address(end, encoding.address_size)?;
+                    }
+                    Range::StartLength { begin, length } => {
+                        w.write_u8(crate::constants::DW_RLE_start_length.0)?;
+                        w.write_address(begin, encoding.address_size)?;
+                        w.write_uleb128(length)?;
+                    }
+                }
+            }
+
+            w.write_u8(crate::constants::DW_RLE_end_of_list.0)?;
+        }
+
+        let length = (w.len() - length_base) as u64;
+        w.write_initial_length_at(length_offset, length, encoding.format)?;
+
+        Ok(RangeListOffsets {
+            base_id: self.base_id,
+            offsets,
+        })
+    }
+}
+
+/// A range list that will be stored in a `.debug_ranges` or `.debug_rnglists` section.
+#[derive(Clone, Debug, Eq, PartialEq, Hash)]
+pub struct RangeList(pub Vec<Range>);
+
+/// A single range.
+#[derive(Clone, Debug, Eq, PartialEq, Hash)]
+pub enum Range {
+    /// DW_RLE_base_address
+    BaseAddress {
+        /// Base address.
+        address: Address,
+    },
+    /// DW_RLE_offset_pair
+    OffsetPair {
+        /// Start of range relative to base address.
+        begin: u64,
+        /// End of range relative to base address.
+        end: u64,
+    },
+    /// DW_RLE_start_end
+    StartEnd {
+        /// Start of range.
+        begin: Address,
+        /// End of range.
+        end: Address,
+    },
+    /// DW_RLE_start_length
+    StartLength {
+        /// Start of range.
+        begin: Address,
+        /// Length of range.
+        length: u64,
+    },
+}
+
+#[cfg(feature = "read")]
+mod convert {
+    use super::*;
+
+    use crate::read::{self, Reader};
+    use crate::write::{ConvertError, ConvertResult, ConvertUnitContext};
+
+    impl RangeList {
+        /// Create a range list by reading the data from the give range list iter.
+        pub(crate) fn from<R: Reader<Offset = usize>>(
+            mut from: read::RawRngListIter<R>,
+            context: &ConvertUnitContext<R>,
+        ) -> ConvertResult<Self> {
+            let mut have_base_address = context.base_address != Address::Constant(0);
+            let convert_address =
+                |x| (context.convert_address)(x).ok_or(ConvertError::InvalidAddress);
+            let mut ranges = Vec::new();
+            while let Some(from_range) = from.next()? {
+                let range = match from_range {
+                    read::RawRngListEntry::AddressOrOffsetPair { begin, end } => {
+                        // These were parsed as addresses, even if they are offsets.
+                        let begin = convert_address(begin)?;
+                        let end = convert_address(end)?;
+                        match (begin, end) {
+                            (Address::Constant(begin_offset), Address::Constant(end_offset)) => {
+                                if have_base_address {
+                                    Range::OffsetPair {
+                                        begin: begin_offset,
+                                        end: end_offset,
+                                    }
+                                } else {
+                                    Range::StartEnd { begin, end }
+                                }
+                            }
+                            _ => {
+                                if have_base_address {
+                                    // At least one of begin/end is an address, but we also have
+                                    // a base address. Adding addresses is undefined.
+                                    return Err(ConvertError::InvalidRangeRelativeAddress);
+                                }
+                                Range::StartEnd { begin, end }
+                            }
+                        }
+                    }
+                    read::RawRngListEntry::BaseAddress { addr } => {
+                        have_base_address = true;
+                        let address = convert_address(addr)?;
+                        Range::BaseAddress { address }
+                    }
+                    read::RawRngListEntry::BaseAddressx { addr } => {
+                        have_base_address = true;
+                        let address = convert_address(context.dwarf.address(context.unit, addr)?)?;
+                        Range::BaseAddress { address }
+                    }
+                    read::RawRngListEntry::StartxEndx { begin, end } => {
+                        let begin = convert_address(context.dwarf.address(context.unit, begin)?)?;
+                        let end = convert_address(context.dwarf.address(context.unit, end)?)?;
+                        Range::StartEnd { begin, end }
+                    }
+                    read::RawRngListEntry::StartxLength { begin, length } => {
+                        let begin = convert_address(context.dwarf.address(context.unit, begin)?)?;
+                        Range::StartLength { begin, length }
+                    }
+                    read::RawRngListEntry::OffsetPair { begin, end } => {
+                        Range::OffsetPair { begin, end }
+                    }
+                    read::RawRngListEntry::StartEnd { begin, end } => {
+                        let begin = convert_address(begin)?;
+                        let end = convert_address(end)?;
+                        Range::StartEnd { begin, end }
+                    }
+                    read::RawRngListEntry::StartLength { begin, length } => {
+                        let begin = convert_address(begin)?;
+                        Range::StartLength { begin, length }
+                    }
+                };
+                // Filtering empty ranges out.
+                match range {
+                    Range::StartLength { length, .. } if length == 0 => continue,
+                    Range::StartEnd { begin, end, .. } if begin == end => continue,
+                    Range::OffsetPair { begin, end, .. } if begin == end => continue,
+                    _ => (),
+                }
+                ranges.push(range);
+            }
+            Ok(RangeList(ranges))
+        }
+    }
+}
+
+#[cfg(test)]
+#[cfg(feature = "read")]
+mod tests {
+    use super::*;
+    use crate::common::{
+        DebugAbbrevOffset, DebugAddrBase, DebugInfoOffset, DebugLocListsBase, DebugRngListsBase,
+        DebugStrOffsetsBase, Format,
+    };
+    use crate::read;
+    use crate::write::{
+        ConvertUnitContext, EndianVec, LineStringTable, LocationListTable, Range, RangeListTable,
+        StringTable,
+    };
+    use crate::LittleEndian;
+    use std::collections::HashMap;
+    use std::sync::Arc;
+
+    #[test]
+    fn test_range() {
+        let mut line_strings = LineStringTable::default();
+        let mut strings = StringTable::default();
+
+        for &version in &[2, 3, 4, 5] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+
+                    let mut range_list = RangeList(vec![
+                        Range::StartLength {
+                            begin: Address::Constant(6666),
+                            length: 7777,
+                        },
+                        Range::StartEnd {
+                            begin: Address::Constant(4444),
+                            end: Address::Constant(5555),
+                        },
+                        Range::BaseAddress {
+                            address: Address::Constant(1111),
+                        },
+                        Range::OffsetPair {
+                            begin: 2222,
+                            end: 3333,
+                        },
+                    ]);
+
+                    let mut ranges = RangeListTable::default();
+                    let range_list_id = ranges.add(range_list.clone());
+
+                    let mut sections = Sections::new(EndianVec::new(LittleEndian));
+                    let range_list_offsets = ranges.write(&mut sections, encoding).unwrap();
+
+                    let read_debug_ranges =
+                        read::DebugRanges::new(sections.debug_ranges.slice(), LittleEndian);
+                    let read_debug_rnglists =
+                        read::DebugRngLists::new(sections.debug_rnglists.slice(), LittleEndian);
+                    let read_ranges = read::RangeLists::new(read_debug_ranges, read_debug_rnglists);
+                    let offset = range_list_offsets.get(range_list_id);
+                    let read_range_list = read_ranges.raw_ranges(offset, encoding).unwrap();
+
+                    let dwarf = read::Dwarf {
+                        ranges: read_ranges,
+                        ..Default::default()
+                    };
+                    let unit = read::Unit {
+                        header: read::UnitHeader::new(
+                            encoding,
+                            0,
+                            read::UnitType::Compilation,
+                            DebugAbbrevOffset(0),
+                            DebugInfoOffset(0).into(),
+                            read::EndianSlice::default(),
+                        ),
+                        abbreviations: Arc::new(read::Abbreviations::default()),
+                        name: None,
+                        comp_dir: None,
+                        low_pc: 0,
+                        str_offsets_base: DebugStrOffsetsBase(0),
+                        addr_base: DebugAddrBase(0),
+                        loclists_base: DebugLocListsBase(0),
+                        rnglists_base: DebugRngListsBase(0),
+                        line_program: None,
+                        dwo_id: None,
+                    };
+                    let context = ConvertUnitContext {
+                        dwarf: &dwarf,
+                        unit: &unit,
+                        line_strings: &mut line_strings,
+                        strings: &mut strings,
+                        ranges: &mut ranges,
+                        locations: &mut LocationListTable::default(),
+                        convert_address: &|address| Some(Address::Constant(address)),
+                        base_address: Address::Constant(0),
+                        line_program_offset: None,
+                        line_program_files: Vec::new(),
+                        entry_ids: &HashMap::new(),
+                    };
+                    let convert_range_list = RangeList::from(read_range_list, &context).unwrap();
+
+                    if version <= 4 {
+                        range_list.0[0] = Range::StartEnd {
+                            begin: Address::Constant(6666),
+                            end: Address::Constant(6666 + 7777),
+                        };
+                    }
+                    assert_eq!(range_list, convert_range_list);
+                }
+            }
+        }
+    }
+}
diff --git a/vendor/gimli/src/write/section.rs b/vendor/gimli/src/write/section.rs
new file mode 100644
index 0000000..db5eb9a
--- /dev/null
+++ b/vendor/gimli/src/write/section.rs
@@ -0,0 +1,172 @@
+use std::ops::DerefMut;
+use std::result;
+use std::vec::Vec;
+
+use crate::common::SectionId;
+use crate::write::{
+    DebugAbbrev, DebugFrame, DebugInfo, DebugInfoReference, DebugLine, DebugLineStr, DebugLoc,
+    DebugLocLists, DebugRanges, DebugRngLists, DebugStr, EhFrame, Writer,
+};
+
+macro_rules! define_section {
+    ($name:ident, $offset:ident, $docs:expr) => {
+        #[doc=$docs]
+        #[derive(Debug, Default)]
+        pub struct $name<W: Writer>(pub W);
+
+        impl<W: Writer> $name<W> {
+            /// Return the offset of the next write.
+            pub fn offset(&self) -> $offset {
+                $offset(self.len())
+            }
+        }
+
+        impl<W: Writer> From<W> for $name<W> {
+            #[inline]
+            fn from(w: W) -> Self {
+                $name(w)
+            }
+        }
+
+        impl<W: Writer> Deref for $name<W> {
+            type Target = W;
+
+            #[inline]
+            fn deref(&self) -> &W {
+                &self.0
+            }
+        }
+
+        impl<W: Writer> DerefMut for $name<W> {
+            #[inline]
+            fn deref_mut(&mut self) -> &mut W {
+                &mut self.0
+            }
+        }
+
+        impl<W: Writer> Section<W> for $name<W> {
+            #[inline]
+            fn id(&self) -> SectionId {
+                SectionId::$name
+            }
+        }
+    };
+}
+
+/// Functionality common to all writable DWARF sections.
+pub trait Section<W: Writer>: DerefMut<Target = W> {
+    /// Returns the DWARF section kind for this type.
+    fn id(&self) -> SectionId;
+
+    /// Returns the ELF section name for this type.
+    fn name(&self) -> &'static str {
+        self.id().name()
+    }
+}
+
+/// All of the writable DWARF sections.
+#[derive(Debug, Default)]
+pub struct Sections<W: Writer> {
+    /// The `.debug_abbrev` section.
+    pub debug_abbrev: DebugAbbrev<W>,
+    /// The `.debug_info` section.
+    pub debug_info: DebugInfo<W>,
+    /// The `.debug_line` section.
+    pub debug_line: DebugLine<W>,
+    /// The `.debug_line_str` section.
+    pub debug_line_str: DebugLineStr<W>,
+    /// The `.debug_ranges` section.
+    pub debug_ranges: DebugRanges<W>,
+    /// The `.debug_rnglists` section.
+    pub debug_rnglists: DebugRngLists<W>,
+    /// The `.debug_loc` section.
+    pub debug_loc: DebugLoc<W>,
+    /// The `.debug_loclists` section.
+    pub debug_loclists: DebugLocLists<W>,
+    /// The `.debug_str` section.
+    pub debug_str: DebugStr<W>,
+    /// The `.debug_frame` section.
+    pub debug_frame: DebugFrame<W>,
+    /// The `.eh_frame` section.
+    pub eh_frame: EhFrame<W>,
+    /// Unresolved references in the `.debug_info` section.
+    pub(crate) debug_info_refs: Vec<DebugInfoReference>,
+    /// Unresolved references in the `.debug_loc` section.
+    pub(crate) debug_loc_refs: Vec<DebugInfoReference>,
+    /// Unresolved references in the `.debug_loclists` section.
+    pub(crate) debug_loclists_refs: Vec<DebugInfoReference>,
+}
+
+impl<W: Writer + Clone> Sections<W> {
+    /// Create a new `Sections` using clones of the given `section`.
+    pub fn new(section: W) -> Self {
+        Sections {
+            debug_abbrev: DebugAbbrev(section.clone()),
+            debug_info: DebugInfo(section.clone()),
+            debug_line: DebugLine(section.clone()),
+            debug_line_str: DebugLineStr(section.clone()),
+            debug_ranges: DebugRanges(section.clone()),
+            debug_rnglists: DebugRngLists(section.clone()),
+            debug_loc: DebugLoc(section.clone()),
+            debug_loclists: DebugLocLists(section.clone()),
+            debug_str: DebugStr(section.clone()),
+            debug_frame: DebugFrame(section.clone()),
+            eh_frame: EhFrame(section),
+            debug_info_refs: Vec::new(),
+            debug_loc_refs: Vec::new(),
+            debug_loclists_refs: Vec::new(),
+        }
+    }
+}
+
+impl<W: Writer> Sections<W> {
+    /// For each section, call `f` once with a shared reference.
+    pub fn for_each<F, E>(&self, mut f: F) -> result::Result<(), E>
+    where
+        F: FnMut(SectionId, &W) -> result::Result<(), E>,
+    {
+        macro_rules! f {
+            ($s:expr) => {
+                f($s.id(), &$s)
+            };
+        }
+        // Ordered so that earlier sections do not reference later sections.
+        f!(self.debug_abbrev)?;
+        f!(self.debug_str)?;
+        f!(self.debug_line_str)?;
+        f!(self.debug_line)?;
+        f!(self.debug_ranges)?;
+        f!(self.debug_rnglists)?;
+        f!(self.debug_loc)?;
+        f!(self.debug_loclists)?;
+        f!(self.debug_info)?;
+        f!(self.debug_frame)?;
+        f!(self.eh_frame)?;
+        Ok(())
+    }
+
+    /// For each section, call `f` once with a mutable reference.
+    pub fn for_each_mut<F, E>(&mut self, mut f: F) -> result::Result<(), E>
+    where
+        F: FnMut(SectionId, &mut W) -> result::Result<(), E>,
+    {
+        macro_rules! f {
+            ($s:expr) => {
+                f($s.id(), &mut $s)
+            };
+        }
+        // Ordered so that earlier sections do not reference later sections.
+        f!(self.debug_abbrev)?;
+        f!(self.debug_str)?;
+        f!(self.debug_line_str)?;
+        f!(self.debug_line)?;
+        f!(self.debug_ranges)?;
+        f!(self.debug_rnglists)?;
+        f!(self.debug_loc)?;
+        f!(self.debug_loclists)?;
+        f!(self.debug_info)?;
+        f!(self.debug_frame)?;
+        f!(self.eh_frame)?;
+        Ok(())
+    }
+}
diff --git a/vendor/gimli/src/write/str.rs b/vendor/gimli/src/write/str.rs
new file mode 100644
index 0000000..83285c0
--- /dev/null
+++ b/vendor/gimli/src/write/str.rs
@@ -0,0 +1,172 @@
+use alloc::vec::Vec;
+use indexmap::IndexSet;
+use std::ops::{Deref, DerefMut};
+
+use crate::common::{DebugLineStrOffset, DebugStrOffset, SectionId};
+use crate::write::{BaseId, Result, Section, Writer};
+
+// Requirements:
+// - values are `[u8]`, null bytes are not allowed
+// - insertion returns a fixed id
+// - inserting a duplicate returns the id of the existing value
+// - able to convert an id to a section offset
+// Optional?
+// - able to get an existing value given an id
+//
+// Limitations of current implementation (using IndexSet):
+// - inserting requires either an allocation for duplicates,
+//   or a double lookup for non-duplicates
+// - doesn't preserve offsets when updating an existing `.debug_str` section
+//
+// Possible changes:
+// - calculate offsets as we add values, and use that as the id.
+//   This would avoid the need for DebugStrOffsets but would make it
+//   hard to implement `get`.
+macro_rules! define_string_table {
+    ($name:ident, $id:ident, $section:ident, $offsets:ident, $docs:expr) => {
+        #[doc=$docs]
+        #[derive(Debug, Default)]
+        pub struct $name {
+            base_id: BaseId,
+            strings: IndexSet<Vec<u8>>,
+        }
+
+        impl $name {
+            /// Add a string to the string table and return its id.
+            ///
+            /// If the string already exists, then return the id of the existing string.
+            ///
+            /// # Panics
+            ///
+            /// Panics if `bytes` contains a null byte.
+            pub fn add<T>(&mut self, bytes: T) -> $id
+            where
+                T: Into<Vec<u8>>,
+            {
+                let bytes = bytes.into();
+                assert!(!bytes.contains(&0));
+                let (index, _) = self.strings.insert_full(bytes);
+                $id::new(self.base_id, index)
+            }
+
+            /// Return the number of strings in the table.
+            #[inline]
+            pub fn count(&self) -> usize {
+                self.strings.len()
+            }
+
+            /// Get a reference to a string in the table.
+            ///
+            /// # Panics
+            ///
+            /// Panics if `id` is invalid.
+            pub fn get(&self, id: $id) -> &[u8] {
+                debug_assert_eq!(self.base_id, id.base_id);
+                self.strings.get_index(id.index).map(Vec::as_slice).unwrap()
+            }
+
+            /// Write the string table to the `.debug_str` section.
+            ///
+            /// Returns the offsets at which the strings are written.
+            pub fn write<W: Writer>(&self, w: &mut $section<W>) -> Result<$offsets> {
+                let mut offsets = Vec::new();
+                for bytes in self.strings.iter() {
+                    offsets.push(w.offset());
+                    w.write(bytes)?;
+                    w.write_u8(0)?;
+                }
+
+                Ok($offsets {
+                    base_id: self.base_id,
+                    offsets,
+                })
+            }
+        }
+    };
+}
+
+define_id!(StringId, "An identifier for a string in a `StringTable`.");
+
+define_string_table!(
+    StringTable,
+    StringId,
+    DebugStr,
+    DebugStrOffsets,
+    "A table of strings that will be stored in a `.debug_str` section."
+);
+
+define_section!(DebugStr, DebugStrOffset, "A writable `.debug_str` section.");
+
+define_offsets!(
+    DebugStrOffsets: StringId => DebugStrOffset,
+    "The section offsets of all strings within a `.debug_str` section."
+);
+
+define_id!(
+    LineStringId,
+    "An identifier for a string in a `LineStringTable`."
+);
+
+define_string_table!(
+    LineStringTable,
+    LineStringId,
+    DebugLineStr,
+    DebugLineStrOffsets,
+    "A table of strings that will be stored in a `.debug_line_str` section."
+);
+
+define_section!(
+    DebugLineStr,
+    DebugLineStrOffset,
+    "A writable `.debug_line_str` section."
+);
+
+define_offsets!(
+    DebugLineStrOffsets: LineStringId => DebugLineStrOffset,
+    "The section offsets of all strings within a `.debug_line_str` section."
+);
+
+#[cfg(test)]
+#[cfg(feature = "read")]
+mod tests {
+    use super::*;
+    use crate::read;
+    use crate::write::EndianVec;
+    use crate::LittleEndian;
+
+    #[test]
+    fn test_string_table() {
+        let mut strings = StringTable::default();
+        assert_eq!(strings.count(), 0);
+        let id1 = strings.add(&b"one"[..]);
+        let id2 = strings.add(&b"two"[..]);
+        assert_eq!(strings.add(&b"one"[..]), id1);
+        assert_eq!(strings.add(&b"two"[..]), id2);
+        assert_eq!(strings.get(id1), &b"one"[..]);
+        assert_eq!(strings.get(id2), &b"two"[..]);
+        assert_eq!(strings.count(), 2);
+
+        let mut debug_str = DebugStr::from(EndianVec::new(LittleEndian));
+        let offsets = strings.write(&mut debug_str).unwrap();
+        assert_eq!(debug_str.slice(), b"one\0two\0");
+        assert_eq!(offsets.get(id1), DebugStrOffset(0));
+        assert_eq!(offsets.get(id2), DebugStrOffset(4));
+        assert_eq!(offsets.count(), 2);
+    }
+
+    #[test]
+    fn test_string_table_read() {
+        let mut strings = StringTable::default();
+        let id1 = strings.add(&b"one"[..]);
+        let id2 = strings.add(&b"two"[..]);
+
+        let mut debug_str = DebugStr::from(EndianVec::new(LittleEndian));
+        let offsets = strings.write(&mut debug_str).unwrap();
+
+        let read_debug_str = read::DebugStr::new(debug_str.slice(), LittleEndian);
+        let str1 = read_debug_str.get_str(offsets.get(id1)).unwrap();
+        let str2 = read_debug_str.get_str(offsets.get(id2)).unwrap();
+        assert_eq!(str1.slice(), &b"one"[..]);
+        assert_eq!(str2.slice(), &b"two"[..]);
+    }
+}
diff --git a/vendor/gimli/src/write/unit.rs b/vendor/gimli/src/write/unit.rs
new file mode 100644
index 0000000..dd8ba67
--- /dev/null
+++ b/vendor/gimli/src/write/unit.rs
@@ -0,0 +1,3152 @@
+use alloc::vec::Vec;
+use std::ops::{Deref, DerefMut};
+use std::{slice, usize};
+
+use crate::common::{
+    DebugAbbrevOffset, DebugInfoOffset, DebugLineOffset, DebugMacinfoOffset, DebugMacroOffset,
+    DebugStrOffset, DebugTypeSignature, Encoding, Format, SectionId,
+};
+use crate::constants;
+use crate::leb128::write::{sleb128_size, uleb128_size};
+use crate::write::{
+    Abbreviation, AbbreviationTable, Address, AttributeSpecification, BaseId, DebugLineStrOffsets,
+    DebugStrOffsets, Error, Expression, FileId, LineProgram, LineStringId, LocationListId,
+    LocationListOffsets, LocationListTable, RangeListId, RangeListOffsets, RangeListTable,
+    Reference, Result, Section, Sections, StringId, Writer,
+};
+
+define_id!(UnitId, "An identifier for a unit in a `UnitTable`.");
+
+define_id!(UnitEntryId, "An identifier for an entry in a `Unit`.");
+
+/// A table of units that will be stored in the `.debug_info` section.
+#[derive(Debug, Default)]
+pub struct UnitTable {
+    base_id: BaseId,
+    units: Vec<Unit>,
+}
+
+impl UnitTable {
+    /// Create a new unit and add it to the table.
+    ///
+    /// `address_size` must be in bytes.
+    ///
+    /// Returns the `UnitId` of the new unit.
+    #[inline]
+    pub fn add(&mut self, unit: Unit) -> UnitId {
+        let id = UnitId::new(self.base_id, self.units.len());
+        self.units.push(unit);
+        id
+    }
+
+    /// Return the number of units.
+    #[inline]
+    pub fn count(&self) -> usize {
+        self.units.len()
+    }
+
+    /// Return the id of a unit.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `index >= self.count()`.
+    #[inline]
+    pub fn id(&self, index: usize) -> UnitId {
+        assert!(index < self.count());
+        UnitId::new(self.base_id, index)
+    }
+
+    /// Get a reference to a unit.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `id` is invalid.
+    #[inline]
+    pub fn get(&self, id: UnitId) -> &Unit {
+        debug_assert_eq!(self.base_id, id.base_id);
+        &self.units[id.index]
+    }
+
+    /// Get a mutable reference to a unit.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `id` is invalid.
+    #[inline]
+    pub fn get_mut(&mut self, id: UnitId) -> &mut Unit {
+        debug_assert_eq!(self.base_id, id.base_id);
+        &mut self.units[id.index]
+    }
+
+    /// Write the units to the given sections.
+    ///
+    /// `strings` must contain the `.debug_str` offsets of the corresponding
+    /// `StringTable`.
+    pub fn write<W: Writer>(
+        &mut self,
+        sections: &mut Sections<W>,
+        line_strings: &DebugLineStrOffsets,
+        strings: &DebugStrOffsets,
+    ) -> Result<DebugInfoOffsets> {
+        let mut offsets = DebugInfoOffsets {
+            base_id: self.base_id,
+            units: Vec::new(),
+        };
+        for unit in &mut self.units {
+            // TODO: maybe share abbreviation tables
+            let abbrev_offset = sections.debug_abbrev.offset();
+            let mut abbrevs = AbbreviationTable::default();
+
+            offsets.units.push(unit.write(
+                sections,
+                abbrev_offset,
+                &mut abbrevs,
+                line_strings,
+                strings,
+            )?);
+
+            abbrevs.write(&mut sections.debug_abbrev)?;
+        }
+
+        write_section_refs(
+            &mut sections.debug_info_refs,
+            &mut sections.debug_info.0,
+            &offsets,
+        )?;
+        write_section_refs(
+            &mut sections.debug_loc_refs,
+            &mut sections.debug_loc.0,
+            &offsets,
+        )?;
+        write_section_refs(
+            &mut sections.debug_loclists_refs,
+            &mut sections.debug_loclists.0,
+            &offsets,
+        )?;
+
+        Ok(offsets)
+    }
+}
+
+fn write_section_refs<W: Writer>(
+    references: &mut Vec<DebugInfoReference>,
+    w: &mut W,
+    offsets: &DebugInfoOffsets,
+) -> Result<()> {
+    for r in references.drain(..) {
+        let entry_offset = offsets.entry(r.unit, r.entry).0;
+        debug_assert_ne!(entry_offset, 0);
+        w.write_offset_at(r.offset, entry_offset, SectionId::DebugInfo, r.size)?;
+    }
+    Ok(())
+}
+
+/// A unit's debugging information.
+#[derive(Debug)]
+pub struct Unit {
+    base_id: BaseId,
+    /// The encoding parameters for this unit.
+    encoding: Encoding,
+    /// The line number program for this unit.
+    pub line_program: LineProgram,
+    /// A table of range lists used by this unit.
+    pub ranges: RangeListTable,
+    /// A table of location lists used by this unit.
+    pub locations: LocationListTable,
+    /// All entries in this unit. The order is unrelated to the tree order.
+    // Requirements:
+    // - entries form a tree
+    // - entries can be added in any order
+    // - entries have a fixed id
+    // - able to quickly lookup an entry from its id
+    // Limitations of current implementation:
+    // - mutable iteration of children is messy due to borrow checker
+    entries: Vec<DebuggingInformationEntry>,
+    /// The index of the root entry in entries.
+    root: UnitEntryId,
+}
+
+impl Unit {
+    /// Create a new `Unit`.
+    pub fn new(encoding: Encoding, line_program: LineProgram) -> Self {
+        let base_id = BaseId::default();
+        let ranges = RangeListTable::default();
+        let locations = LocationListTable::default();
+        let mut entries = Vec::new();
+        let root = DebuggingInformationEntry::new(
+            base_id,
+            &mut entries,
+            None,
+            constants::DW_TAG_compile_unit,
+        );
+        Unit {
+            base_id,
+            encoding,
+            line_program,
+            ranges,
+            locations,
+            entries,
+            root,
+        }
+    }
+
+    /// Return the encoding parameters for this unit.
+    #[inline]
+    pub fn encoding(&self) -> Encoding {
+        self.encoding
+    }
+
+    /// Return the DWARF version for this unit.
+    #[inline]
+    pub fn version(&self) -> u16 {
+        self.encoding.version
+    }
+
+    /// Return the address size in bytes for this unit.
+    #[inline]
+    pub fn address_size(&self) -> u8 {
+        self.encoding.address_size
+    }
+
+    /// Return the DWARF format for this unit.
+    #[inline]
+    pub fn format(&self) -> Format {
+        self.encoding.format
+    }
+
+    /// Return the number of `DebuggingInformationEntry`s created for this unit.
+    ///
+    /// This includes entries that no longer have a parent.
+    #[inline]
+    pub fn count(&self) -> usize {
+        self.entries.len()
+    }
+
+    /// Return the id of the root entry.
+    #[inline]
+    pub fn root(&self) -> UnitEntryId {
+        self.root
+    }
+
+    /// Add a new `DebuggingInformationEntry` to this unit and return its id.
+    ///
+    /// The `parent` must be within the same unit.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `parent` is invalid.
+    #[inline]
+    pub fn add(&mut self, parent: UnitEntryId, tag: constants::DwTag) -> UnitEntryId {
+        debug_assert_eq!(self.base_id, parent.base_id);
+        DebuggingInformationEntry::new(self.base_id, &mut self.entries, Some(parent), tag)
+    }
+
+    /// Get a reference to an entry.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `id` is invalid.
+    #[inline]
+    pub fn get(&self, id: UnitEntryId) -> &DebuggingInformationEntry {
+        debug_assert_eq!(self.base_id, id.base_id);
+        &self.entries[id.index]
+    }
+
+    /// Get a mutable reference to an entry.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `id` is invalid.
+    #[inline]
+    pub fn get_mut(&mut self, id: UnitEntryId) -> &mut DebuggingInformationEntry {
+        debug_assert_eq!(self.base_id, id.base_id);
+        &mut self.entries[id.index]
+    }
+
+    /// Return true if `self.line_program` is used by a DIE.
+    fn line_program_in_use(&self) -> bool {
+        if self.line_program.is_none() {
+            return false;
+        }
+        if !self.line_program.is_empty() {
+            return true;
+        }
+
+        for entry in &self.entries {
+            for attr in &entry.attrs {
+                if let AttributeValue::FileIndex(Some(_)) = attr.value {
+                    return true;
+                }
+            }
+        }
+
+        false
+    }
+
+    /// Write the unit to the given sections.
+    pub(crate) fn write<W: Writer>(
+        &mut self,
+        sections: &mut Sections<W>,
+        abbrev_offset: DebugAbbrevOffset,
+        abbrevs: &mut AbbreviationTable,
+        line_strings: &DebugLineStrOffsets,
+        strings: &DebugStrOffsets,
+    ) -> Result<UnitOffsets> {
+        let line_program = if self.line_program_in_use() {
+            self.entries[self.root.index]
+                .set(constants::DW_AT_stmt_list, AttributeValue::LineProgramRef);
+            Some(self.line_program.write(
+                &mut sections.debug_line,
+                self.encoding,
+                line_strings,
+                strings,
+            )?)
+        } else {
+            self.entries[self.root.index].delete(constants::DW_AT_stmt_list);
+            None
+        };
+
+        // TODO: use .debug_types for type units in DWARF v4.
+        let w = &mut sections.debug_info;
+
+        let mut offsets = UnitOffsets {
+            base_id: self.base_id,
+            unit: w.offset(),
+            // Entries can be written in any order, so create the complete vec now.
+            entries: vec![EntryOffset::none(); self.entries.len()],
+        };
+
+        let length_offset = w.write_initial_length(self.format())?;
+        let length_base = w.len();
+
+        w.write_u16(self.version())?;
+        if 2 <= self.version() && self.version() <= 4 {
+            w.write_offset(
+                abbrev_offset.0,
+                SectionId::DebugAbbrev,
+                self.format().word_size(),
+            )?;
+            w.write_u8(self.address_size())?;
+        } else if self.version() == 5 {
+            w.write_u8(constants::DW_UT_compile.0)?;
+            w.write_u8(self.address_size())?;
+            w.write_offset(
+                abbrev_offset.0,
+                SectionId::DebugAbbrev,
+                self.format().word_size(),
+            )?;
+        } else {
+            return Err(Error::UnsupportedVersion(self.version()));
+        }
+
+        // Calculate all DIE offsets, so that we are able to output references to them.
+        // However, references to base types in expressions use ULEB128, so base types
+        // must be moved to the front before we can calculate offsets.
+        self.reorder_base_types();
+        let mut offset = w.len();
+        self.entries[self.root.index].calculate_offsets(
+            self,
+            &mut offset,
+            &mut offsets,
+            abbrevs,
+        )?;
+
+        let range_lists = self.ranges.write(sections, self.encoding)?;
+        // Location lists can't be written until we have DIE offsets.
+        let loc_lists = self
+            .locations
+            .write(sections, self.encoding, Some(&offsets))?;
+
+        let w = &mut sections.debug_info;
+        let mut unit_refs = Vec::new();
+        self.entries[self.root.index].write(
+            w,
+            &mut sections.debug_info_refs,
+            &mut unit_refs,
+            self,
+            &mut offsets,
+            line_program,
+            line_strings,
+            strings,
+            &range_lists,
+            &loc_lists,
+        )?;
+
+        let length = (w.len() - length_base) as u64;
+        w.write_initial_length_at(length_offset, length, self.format())?;
+
+        for (offset, entry) in unit_refs {
+            // This does not need relocation.
+            w.write_udata_at(
+                offset.0,
+                offsets.unit_offset(entry),
+                self.format().word_size(),
+            )?;
+        }
+
+        Ok(offsets)
+    }
+
+    /// Reorder base types to come first so that typed stack operations
+    /// can get their offset.
+    fn reorder_base_types(&mut self) {
+        let root = &self.entries[self.root.index];
+        let mut root_children = Vec::with_capacity(root.children.len());
+        for entry in &root.children {
+            if self.entries[entry.index].tag == constants::DW_TAG_base_type {
+                root_children.push(*entry);
+            }
+        }
+        for entry in &root.children {
+            if self.entries[entry.index].tag != constants::DW_TAG_base_type {
+                root_children.push(*entry);
+            }
+        }
+        self.entries[self.root.index].children = root_children;
+    }
+}
+
+/// A Debugging Information Entry (DIE).
+///
+/// DIEs have a set of attributes and optionally have children DIEs as well.
+///
+/// DIEs form a tree without any cycles. This is enforced by specifying the
+/// parent when creating a DIE, and disallowing changes of parent.
+#[derive(Debug)]
+pub struct DebuggingInformationEntry {
+    id: UnitEntryId,
+    parent: Option<UnitEntryId>,
+    tag: constants::DwTag,
+    /// Whether to emit `DW_AT_sibling`.
+    sibling: bool,
+    attrs: Vec<Attribute>,
+    children: Vec<UnitEntryId>,
+}
+
+impl DebuggingInformationEntry {
+    /// Create a new `DebuggingInformationEntry`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `parent` is invalid.
+    #[allow(clippy::new_ret_no_self)]
+    fn new(
+        base_id: BaseId,
+        entries: &mut Vec<DebuggingInformationEntry>,
+        parent: Option<UnitEntryId>,
+        tag: constants::DwTag,
+    ) -> UnitEntryId {
+        let id = UnitEntryId::new(base_id, entries.len());
+        entries.push(DebuggingInformationEntry {
+            id,
+            parent,
+            tag,
+            sibling: false,
+            attrs: Vec::new(),
+            children: Vec::new(),
+        });
+        if let Some(parent) = parent {
+            debug_assert_eq!(base_id, parent.base_id);
+            assert_ne!(parent, id);
+            entries[parent.index].children.push(id);
+        }
+        id
+    }
+
+    /// Return the id of this entry.
+    #[inline]
+    pub fn id(&self) -> UnitEntryId {
+        self.id
+    }
+
+    /// Return the parent of this entry.
+    #[inline]
+    pub fn parent(&self) -> Option<UnitEntryId> {
+        self.parent
+    }
+
+    /// Return the tag of this entry.
+    #[inline]
+    pub fn tag(&self) -> constants::DwTag {
+        self.tag
+    }
+
+    /// Return `true` if a `DW_AT_sibling` attribute will be emitted.
+    #[inline]
+    pub fn sibling(&self) -> bool {
+        self.sibling
+    }
+
+    /// Set whether a `DW_AT_sibling` attribute will be emitted.
+    ///
+    /// The attribute will only be emitted if the DIE has children.
+    #[inline]
+    pub fn set_sibling(&mut self, sibling: bool) {
+        self.sibling = sibling;
+    }
+
+    /// Iterate over the attributes of this entry.
+    #[inline]
+    pub fn attrs(&self) -> slice::Iter<Attribute> {
+        self.attrs.iter()
+    }
+
+    /// Iterate over the attributes of this entry for modification.
+    #[inline]
+    pub fn attrs_mut(&mut self) -> slice::IterMut<Attribute> {
+        self.attrs.iter_mut()
+    }
+
+    /// Get an attribute.
+    pub fn get(&self, name: constants::DwAt) -> Option<&AttributeValue> {
+        self.attrs
+            .iter()
+            .find(|attr| attr.name == name)
+            .map(|attr| &attr.value)
+    }
+
+    /// Get an attribute for modification.
+    pub fn get_mut(&mut self, name: constants::DwAt) -> Option<&mut AttributeValue> {
+        self.attrs
+            .iter_mut()
+            .find(|attr| attr.name == name)
+            .map(|attr| &mut attr.value)
+    }
+
+    /// Set an attribute.
+    ///
+    /// Replaces any existing attribute with the same name.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `name` is `DW_AT_sibling`. Use `set_sibling` instead.
+    pub fn set(&mut self, name: constants::DwAt, value: AttributeValue) {
+        assert_ne!(name, constants::DW_AT_sibling);
+        if let Some(attr) = self.attrs.iter_mut().find(|attr| attr.name == name) {
+            attr.value = value;
+            return;
+        }
+        self.attrs.push(Attribute { name, value });
+    }
+
+    /// Delete an attribute.
+    ///
+    /// Replaces any existing attribute with the same name.
+    pub fn delete(&mut self, name: constants::DwAt) {
+        self.attrs.retain(|x| x.name != name);
+    }
+
+    /// Iterate over the children of this entry.
+    ///
+    /// Note: use `Unit::add` to add a new child to this entry.
+    #[inline]
+    pub fn children(&self) -> slice::Iter<UnitEntryId> {
+        self.children.iter()
+    }
+
+    /// Delete a child entry and all of its children.
+    pub fn delete_child(&mut self, id: UnitEntryId) {
+        self.children.retain(|&child| child != id);
+    }
+
+    /// Return the type abbreviation for this DIE.
+    fn abbreviation(&self, encoding: Encoding) -> Result<Abbreviation> {
+        let mut attrs = Vec::new();
+
+        if self.sibling && !self.children.is_empty() {
+            let form = match encoding.format {
+                Format::Dwarf32 => constants::DW_FORM_ref4,
+                Format::Dwarf64 => constants::DW_FORM_ref8,
+            };
+            attrs.push(AttributeSpecification::new(constants::DW_AT_sibling, form));
+        }
+
+        for attr in &self.attrs {
+            attrs.push(attr.specification(encoding)?);
+        }
+
+        Ok(Abbreviation::new(
+            self.tag,
+            !self.children.is_empty(),
+            attrs,
+        ))
+    }
+
+    fn calculate_offsets(
+        &self,
+        unit: &Unit,
+        offset: &mut usize,
+        offsets: &mut UnitOffsets,
+        abbrevs: &mut AbbreviationTable,
+    ) -> Result<()> {
+        offsets.entries[self.id.index].offset = DebugInfoOffset(*offset);
+        offsets.entries[self.id.index].abbrev = abbrevs.add(self.abbreviation(unit.encoding())?);
+        *offset += self.size(unit, offsets);
+        if !self.children.is_empty() {
+            for child in &self.children {
+                unit.entries[child.index].calculate_offsets(unit, offset, offsets, abbrevs)?;
+            }
+            // Null child
+            *offset += 1;
+        }
+        Ok(())
+    }
+
+    fn size(&self, unit: &Unit, offsets: &UnitOffsets) -> usize {
+        let mut size = uleb128_size(offsets.abbrev(self.id));
+        if self.sibling && !self.children.is_empty() {
+            size += unit.format().word_size() as usize;
+        }
+        for attr in &self.attrs {
+            size += attr.value.size(unit, offsets);
+        }
+        size
+    }
+
+    /// Write the entry to the given sections.
+    fn write<W: Writer>(
+        &self,
+        w: &mut DebugInfo<W>,
+        debug_info_refs: &mut Vec<DebugInfoReference>,
+        unit_refs: &mut Vec<(DebugInfoOffset, UnitEntryId)>,
+        unit: &Unit,
+        offsets: &mut UnitOffsets,
+        line_program: Option<DebugLineOffset>,
+        line_strings: &DebugLineStrOffsets,
+        strings: &DebugStrOffsets,
+        range_lists: &RangeListOffsets,
+        loc_lists: &LocationListOffsets,
+    ) -> Result<()> {
+        debug_assert_eq!(offsets.debug_info_offset(self.id), w.offset());
+        w.write_uleb128(offsets.abbrev(self.id))?;
+
+        let sibling_offset = if self.sibling && !self.children.is_empty() {
+            let offset = w.offset();
+            w.write_udata(0, unit.format().word_size())?;
+            Some(offset)
+        } else {
+            None
+        };
+
+        for attr in &self.attrs {
+            attr.value.write(
+                w,
+                debug_info_refs,
+                unit_refs,
+                unit,
+                offsets,
+                line_program,
+                line_strings,
+                strings,
+                range_lists,
+                loc_lists,
+            )?;
+        }
+
+        if !self.children.is_empty() {
+            for child in &self.children {
+                unit.entries[child.index].write(
+                    w,
+                    debug_info_refs,
+                    unit_refs,
+                    unit,
+                    offsets,
+                    line_program,
+                    line_strings,
+                    strings,
+                    range_lists,
+                    loc_lists,
+                )?;
+            }
+            // Null child
+            w.write_u8(0)?;
+        }
+
+        if let Some(offset) = sibling_offset {
+            let next_offset = (w.offset().0 - offsets.unit.0) as u64;
+            // This does not need relocation.
+            w.write_udata_at(offset.0, next_offset, unit.format().word_size())?;
+        }
+        Ok(())
+    }
+}
+
+/// An attribute in a `DebuggingInformationEntry`, consisting of a name and
+/// associated value.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Attribute {
+    name: constants::DwAt,
+    value: AttributeValue,
+}
+
+impl Attribute {
+    /// Get the name of this attribute.
+    #[inline]
+    pub fn name(&self) -> constants::DwAt {
+        self.name
+    }
+
+    /// Get the value of this attribute.
+    #[inline]
+    pub fn get(&self) -> &AttributeValue {
+        &self.value
+    }
+
+    /// Set the value of this attribute.
+    #[inline]
+    pub fn set(&mut self, value: AttributeValue) {
+        self.value = value;
+    }
+
+    /// Return the type specification for this attribute.
+    fn specification(&self, encoding: Encoding) -> Result<AttributeSpecification> {
+        Ok(AttributeSpecification::new(
+            self.name,
+            self.value.form(encoding)?,
+        ))
+    }
+}
+
+/// The value of an attribute in a `DebuggingInformationEntry`.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum AttributeValue {
+    /// "Refers to some location in the address space of the described program."
+    Address(Address),
+
+    /// A slice of an arbitrary number of bytes.
+    Block(Vec<u8>),
+
+    /// A one byte constant data value. How to interpret the byte depends on context.
+    ///
+    /// From section 7 of the standard: "Depending on context, it may be a
+    /// signed integer, an unsigned integer, a floating-point constant, or
+    /// anything else."
+    Data1(u8),
+
+    /// A two byte constant data value. How to interpret the bytes depends on context.
+    ///
+    /// This value will be converted to the target endian before writing.
+    ///
+    /// From section 7 of the standard: "Depending on context, it may be a
+    /// signed integer, an unsigned integer, a floating-point constant, or
+    /// anything else."
+    Data2(u16),
+
+    /// A four byte constant data value. How to interpret the bytes depends on context.
+    ///
+    /// This value will be converted to the target endian before writing.
+    ///
+    /// From section 7 of the standard: "Depending on context, it may be a
+    /// signed integer, an unsigned integer, a floating-point constant, or
+    /// anything else."
+    Data4(u32),
+
+    /// An eight byte constant data value. How to interpret the bytes depends on context.
+    ///
+    /// This value will be converted to the target endian before writing.
+    ///
+    /// From section 7 of the standard: "Depending on context, it may be a
+    /// signed integer, an unsigned integer, a floating-point constant, or
+    /// anything else."
+    Data8(u64),
+
+    /// A signed integer constant.
+    Sdata(i64),
+
+    /// An unsigned integer constant.
+    Udata(u64),
+
+    /// "The information bytes contain a DWARF expression (see Section 2.5) or
+    /// location description (see Section 2.6)."
+    Exprloc(Expression),
+
+    /// A boolean that indicates presence or absence of the attribute.
+    Flag(bool),
+
+    /// An attribute that is always present.
+    FlagPresent,
+
+    /// A reference to a `DebuggingInformationEntry` in this unit.
+    UnitRef(UnitEntryId),
+
+    /// A reference to a `DebuggingInformationEntry` in a potentially different unit.
+    DebugInfoRef(Reference),
+
+    /// An offset into the `.debug_info` section of the supplementary object file.
+    ///
+    /// The API does not currently assist with generating this offset.
+    /// This variant will be removed from the API once support for writing
+    /// supplementary object files is implemented.
+    DebugInfoRefSup(DebugInfoOffset),
+
+    /// A reference to a line number program.
+    LineProgramRef,
+
+    /// A reference to a location list.
+    LocationListRef(LocationListId),
+
+    /// An offset into the `.debug_macinfo` section.
+    ///
+    /// The API does not currently assist with generating this offset.
+    /// This variant will be removed from the API once support for writing
+    /// `.debug_macinfo` sections is implemented.
+    DebugMacinfoRef(DebugMacinfoOffset),
+
+    /// An offset into the `.debug_macro` section.
+    ///
+    /// The API does not currently assist with generating this offset.
+    /// This variant will be removed from the API once support for writing
+    /// `.debug_macro` sections is implemented.
+    DebugMacroRef(DebugMacroOffset),
+
+    /// A reference to a range list.
+    RangeListRef(RangeListId),
+
+    /// A type signature.
+    ///
+    /// The API does not currently assist with generating this signature.
+    /// This variant will be removed from the API once support for writing
+    /// `.debug_types` sections is implemented.
+    DebugTypesRef(DebugTypeSignature),
+
+    /// A reference to a string in the `.debug_str` section.
+    StringRef(StringId),
+
+    /// An offset into the `.debug_str` section of the supplementary object file.
+    ///
+    /// The API does not currently assist with generating this offset.
+    /// This variant will be removed from the API once support for writing
+    /// supplementary object files is implemented.
+    DebugStrRefSup(DebugStrOffset),
+
+    /// A reference to a string in the `.debug_line_str` section.
+    LineStringRef(LineStringId),
+
+    /// A slice of bytes representing a string. Must not include null bytes.
+    /// Not guaranteed to be UTF-8 or anything like that.
+    String(Vec<u8>),
+
+    /// The value of a `DW_AT_encoding` attribute.
+    Encoding(constants::DwAte),
+
+    /// The value of a `DW_AT_decimal_sign` attribute.
+    DecimalSign(constants::DwDs),
+
+    /// The value of a `DW_AT_endianity` attribute.
+    Endianity(constants::DwEnd),
+
+    /// The value of a `DW_AT_accessibility` attribute.
+    Accessibility(constants::DwAccess),
+
+    /// The value of a `DW_AT_visibility` attribute.
+    Visibility(constants::DwVis),
+
+    /// The value of a `DW_AT_virtuality` attribute.
+    Virtuality(constants::DwVirtuality),
+
+    /// The value of a `DW_AT_language` attribute.
+    Language(constants::DwLang),
+
+    /// The value of a `DW_AT_address_class` attribute.
+    AddressClass(constants::DwAddr),
+
+    /// The value of a `DW_AT_identifier_case` attribute.
+    IdentifierCase(constants::DwId),
+
+    /// The value of a `DW_AT_calling_convention` attribute.
+    CallingConvention(constants::DwCc),
+
+    /// The value of a `DW_AT_inline` attribute.
+    Inline(constants::DwInl),
+
+    /// The value of a `DW_AT_ordering` attribute.
+    Ordering(constants::DwOrd),
+
+    /// An index into the filename entries from the line number information
+    /// table for the unit containing this value.
+    FileIndex(Option<FileId>),
+}
+
+impl AttributeValue {
+    /// Return the form that will be used to encode this value.
+    pub fn form(&self, encoding: Encoding) -> Result<constants::DwForm> {
+        // TODO: missing forms:
+        // - DW_FORM_indirect
+        // - DW_FORM_implicit_const
+        // - FW_FORM_block1/block2/block4
+        // - DW_FORM_str/strx1/strx2/strx3/strx4
+        // - DW_FORM_addrx/addrx1/addrx2/addrx3/addrx4
+        // - DW_FORM_data16
+        // - DW_FORM_line_strp
+        // - DW_FORM_loclistx
+        // - DW_FORM_rnglistx
+        let form = match *self {
+            AttributeValue::Address(_) => constants::DW_FORM_addr,
+            AttributeValue::Block(_) => constants::DW_FORM_block,
+            AttributeValue::Data1(_) => constants::DW_FORM_data1,
+            AttributeValue::Data2(_) => constants::DW_FORM_data2,
+            AttributeValue::Data4(_) => constants::DW_FORM_data4,
+            AttributeValue::Data8(_) => constants::DW_FORM_data8,
+            AttributeValue::Exprloc(_) => constants::DW_FORM_exprloc,
+            AttributeValue::Flag(_) => constants::DW_FORM_flag,
+            AttributeValue::FlagPresent => constants::DW_FORM_flag_present,
+            AttributeValue::UnitRef(_) => {
+                // Using a fixed size format lets us write a placeholder before we know
+                // the value.
+                match encoding.format {
+                    Format::Dwarf32 => constants::DW_FORM_ref4,
+                    Format::Dwarf64 => constants::DW_FORM_ref8,
+                }
+            }
+            AttributeValue::DebugInfoRef(_) => constants::DW_FORM_ref_addr,
+            AttributeValue::DebugInfoRefSup(_) => {
+                // TODO: should this depend on the size of supplementary section?
+                match encoding.format {
+                    Format::Dwarf32 => constants::DW_FORM_ref_sup4,
+                    Format::Dwarf64 => constants::DW_FORM_ref_sup8,
+                }
+            }
+            AttributeValue::LineProgramRef
+            | AttributeValue::LocationListRef(_)
+            | AttributeValue::DebugMacinfoRef(_)
+            | AttributeValue::DebugMacroRef(_)
+            | AttributeValue::RangeListRef(_) => {
+                if encoding.version == 2 || encoding.version == 3 {
+                    match encoding.format {
+                        Format::Dwarf32 => constants::DW_FORM_data4,
+                        Format::Dwarf64 => constants::DW_FORM_data8,
+                    }
+                } else {
+                    constants::DW_FORM_sec_offset
+                }
+            }
+            AttributeValue::DebugTypesRef(_) => constants::DW_FORM_ref_sig8,
+            AttributeValue::StringRef(_) => constants::DW_FORM_strp,
+            AttributeValue::DebugStrRefSup(_) => constants::DW_FORM_strp_sup,
+            AttributeValue::LineStringRef(_) => constants::DW_FORM_line_strp,
+            AttributeValue::String(_) => constants::DW_FORM_string,
+            AttributeValue::Encoding(_)
+            | AttributeValue::DecimalSign(_)
+            | AttributeValue::Endianity(_)
+            | AttributeValue::Accessibility(_)
+            | AttributeValue::Visibility(_)
+            | AttributeValue::Virtuality(_)
+            | AttributeValue::Language(_)
+            | AttributeValue::AddressClass(_)
+            | AttributeValue::IdentifierCase(_)
+            | AttributeValue::CallingConvention(_)
+            | AttributeValue::Inline(_)
+            | AttributeValue::Ordering(_)
+            | AttributeValue::FileIndex(_)
+            | AttributeValue::Udata(_) => constants::DW_FORM_udata,
+            AttributeValue::Sdata(_) => constants::DW_FORM_sdata,
+        };
+        Ok(form)
+    }
+
+    fn size(&self, unit: &Unit, offsets: &UnitOffsets) -> usize {
+        macro_rules! debug_assert_form {
+            ($form:expr) => {
+                debug_assert_eq!(self.form(unit.encoding()).unwrap(), $form)
+            };
+        }
+        match *self {
+            AttributeValue::Address(_) => {
+                debug_assert_form!(constants::DW_FORM_addr);
+                unit.address_size() as usize
+            }
+            AttributeValue::Block(ref val) => {
+                debug_assert_form!(constants::DW_FORM_block);
+                uleb128_size(val.len() as u64) + val.len()
+            }
+            AttributeValue::Data1(_) => {
+                debug_assert_form!(constants::DW_FORM_data1);
+                1
+            }
+            AttributeValue::Data2(_) => {
+                debug_assert_form!(constants::DW_FORM_data2);
+                2
+            }
+            AttributeValue::Data4(_) => {
+                debug_assert_form!(constants::DW_FORM_data4);
+                4
+            }
+            AttributeValue::Data8(_) => {
+                debug_assert_form!(constants::DW_FORM_data8);
+                8
+            }
+            AttributeValue::Sdata(val) => {
+                debug_assert_form!(constants::DW_FORM_sdata);
+                sleb128_size(val)
+            }
+            AttributeValue::Udata(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val)
+            }
+            AttributeValue::Exprloc(ref val) => {
+                debug_assert_form!(constants::DW_FORM_exprloc);
+                let size = val.size(unit.encoding(), Some(offsets));
+                uleb128_size(size as u64) + size
+            }
+            AttributeValue::Flag(_) => {
+                debug_assert_form!(constants::DW_FORM_flag);
+                1
+            }
+            AttributeValue::FlagPresent => {
+                debug_assert_form!(constants::DW_FORM_flag_present);
+                0
+            }
+            AttributeValue::UnitRef(_) => {
+                match unit.format() {
+                    Format::Dwarf32 => debug_assert_form!(constants::DW_FORM_ref4),
+                    Format::Dwarf64 => debug_assert_form!(constants::DW_FORM_ref8),
+                }
+                unit.format().word_size() as usize
+            }
+            AttributeValue::DebugInfoRef(_) => {
+                debug_assert_form!(constants::DW_FORM_ref_addr);
+                if unit.version() == 2 {
+                    unit.address_size() as usize
+                } else {
+                    unit.format().word_size() as usize
+                }
+            }
+            AttributeValue::DebugInfoRefSup(_) => {
+                match unit.format() {
+                    Format::Dwarf32 => debug_assert_form!(constants::DW_FORM_ref_sup4),
+                    Format::Dwarf64 => debug_assert_form!(constants::DW_FORM_ref_sup8),
+                }
+                unit.format().word_size() as usize
+            }
+            AttributeValue::LineProgramRef => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                unit.format().word_size() as usize
+            }
+            AttributeValue::LocationListRef(_) => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                unit.format().word_size() as usize
+            }
+            AttributeValue::DebugMacinfoRef(_) => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                unit.format().word_size() as usize
+            }
+            AttributeValue::DebugMacroRef(_) => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                unit.format().word_size() as usize
+            }
+            AttributeValue::RangeListRef(_) => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                unit.format().word_size() as usize
+            }
+            AttributeValue::DebugTypesRef(_) => {
+                debug_assert_form!(constants::DW_FORM_ref_sig8);
+                8
+            }
+            AttributeValue::StringRef(_) => {
+                debug_assert_form!(constants::DW_FORM_strp);
+                unit.format().word_size() as usize
+            }
+            AttributeValue::DebugStrRefSup(_) => {
+                debug_assert_form!(constants::DW_FORM_strp_sup);
+                unit.format().word_size() as usize
+            }
+            AttributeValue::LineStringRef(_) => {
+                debug_assert_form!(constants::DW_FORM_line_strp);
+                unit.format().word_size() as usize
+            }
+            AttributeValue::String(ref val) => {
+                debug_assert_form!(constants::DW_FORM_string);
+                val.len() + 1
+            }
+            AttributeValue::Encoding(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::DecimalSign(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::Endianity(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::Accessibility(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::Visibility(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::Virtuality(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::Language(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::AddressClass(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::IdentifierCase(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::CallingConvention(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::Inline(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::Ordering(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.0 as u64)
+            }
+            AttributeValue::FileIndex(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                uleb128_size(val.map(FileId::raw).unwrap_or(0))
+            }
+        }
+    }
+
+    /// Write the attribute value to the given sections.
+    fn write<W: Writer>(
+        &self,
+        w: &mut DebugInfo<W>,
+        debug_info_refs: &mut Vec<DebugInfoReference>,
+        unit_refs: &mut Vec<(DebugInfoOffset, UnitEntryId)>,
+        unit: &Unit,
+        offsets: &UnitOffsets,
+        line_program: Option<DebugLineOffset>,
+        line_strings: &DebugLineStrOffsets,
+        strings: &DebugStrOffsets,
+        range_lists: &RangeListOffsets,
+        loc_lists: &LocationListOffsets,
+    ) -> Result<()> {
+        macro_rules! debug_assert_form {
+            ($form:expr) => {
+                debug_assert_eq!(self.form(unit.encoding()).unwrap(), $form)
+            };
+        }
+        match *self {
+            AttributeValue::Address(val) => {
+                debug_assert_form!(constants::DW_FORM_addr);
+                w.write_address(val, unit.address_size())?;
+            }
+            AttributeValue::Block(ref val) => {
+                debug_assert_form!(constants::DW_FORM_block);
+                w.write_uleb128(val.len() as u64)?;
+                w.write(val)?;
+            }
+            AttributeValue::Data1(val) => {
+                debug_assert_form!(constants::DW_FORM_data1);
+                w.write_u8(val)?;
+            }
+            AttributeValue::Data2(val) => {
+                debug_assert_form!(constants::DW_FORM_data2);
+                w.write_u16(val)?;
+            }
+            AttributeValue::Data4(val) => {
+                debug_assert_form!(constants::DW_FORM_data4);
+                w.write_u32(val)?;
+            }
+            AttributeValue::Data8(val) => {
+                debug_assert_form!(constants::DW_FORM_data8);
+                w.write_u64(val)?;
+            }
+            AttributeValue::Sdata(val) => {
+                debug_assert_form!(constants::DW_FORM_sdata);
+                w.write_sleb128(val)?;
+            }
+            AttributeValue::Udata(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(val)?;
+            }
+            AttributeValue::Exprloc(ref val) => {
+                debug_assert_form!(constants::DW_FORM_exprloc);
+                w.write_uleb128(val.size(unit.encoding(), Some(offsets)) as u64)?;
+                val.write(
+                    &mut w.0,
+                    Some(debug_info_refs),
+                    unit.encoding(),
+                    Some(offsets),
+                )?;
+            }
+            AttributeValue::Flag(val) => {
+                debug_assert_form!(constants::DW_FORM_flag);
+                w.write_u8(val as u8)?;
+            }
+            AttributeValue::FlagPresent => {
+                debug_assert_form!(constants::DW_FORM_flag_present);
+            }
+            AttributeValue::UnitRef(id) => {
+                match unit.format() {
+                    Format::Dwarf32 => debug_assert_form!(constants::DW_FORM_ref4),
+                    Format::Dwarf64 => debug_assert_form!(constants::DW_FORM_ref8),
+                }
+                unit_refs.push((w.offset(), id));
+                w.write_udata(0, unit.format().word_size())?;
+            }
+            AttributeValue::DebugInfoRef(reference) => {
+                debug_assert_form!(constants::DW_FORM_ref_addr);
+                let size = if unit.version() == 2 {
+                    unit.address_size()
+                } else {
+                    unit.format().word_size()
+                };
+                match reference {
+                    Reference::Symbol(symbol) => w.write_reference(symbol, size)?,
+                    Reference::Entry(unit, entry) => {
+                        debug_info_refs.push(DebugInfoReference {
+                            offset: w.len(),
+                            unit,
+                            entry,
+                            size,
+                        });
+                        w.write_udata(0, size)?;
+                    }
+                }
+            }
+            AttributeValue::DebugInfoRefSup(val) => {
+                match unit.format() {
+                    Format::Dwarf32 => debug_assert_form!(constants::DW_FORM_ref_sup4),
+                    Format::Dwarf64 => debug_assert_form!(constants::DW_FORM_ref_sup8),
+                }
+                w.write_udata(val.0 as u64, unit.format().word_size())?;
+            }
+            AttributeValue::LineProgramRef => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                match line_program {
+                    Some(line_program) => {
+                        w.write_offset(
+                            line_program.0,
+                            SectionId::DebugLine,
+                            unit.format().word_size(),
+                        )?;
+                    }
+                    None => return Err(Error::InvalidAttributeValue),
+                }
+            }
+            AttributeValue::LocationListRef(val) => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                let section = if unit.version() <= 4 {
+                    SectionId::DebugLoc
+                } else {
+                    SectionId::DebugLocLists
+                };
+                w.write_offset(loc_lists.get(val).0, section, unit.format().word_size())?;
+            }
+            AttributeValue::DebugMacinfoRef(val) => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                w.write_offset(val.0, SectionId::DebugMacinfo, unit.format().word_size())?;
+            }
+            AttributeValue::DebugMacroRef(val) => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                w.write_offset(val.0, SectionId::DebugMacro, unit.format().word_size())?;
+            }
+            AttributeValue::RangeListRef(val) => {
+                if unit.version() >= 4 {
+                    debug_assert_form!(constants::DW_FORM_sec_offset);
+                }
+                let section = if unit.version() <= 4 {
+                    SectionId::DebugRanges
+                } else {
+                    SectionId::DebugRngLists
+                };
+                w.write_offset(range_lists.get(val).0, section, unit.format().word_size())?;
+            }
+            AttributeValue::DebugTypesRef(val) => {
+                debug_assert_form!(constants::DW_FORM_ref_sig8);
+                w.write_u64(val.0)?;
+            }
+            AttributeValue::StringRef(val) => {
+                debug_assert_form!(constants::DW_FORM_strp);
+                w.write_offset(
+                    strings.get(val).0,
+                    SectionId::DebugStr,
+                    unit.format().word_size(),
+                )?;
+            }
+            AttributeValue::DebugStrRefSup(val) => {
+                debug_assert_form!(constants::DW_FORM_strp_sup);
+                w.write_udata(val.0 as u64, unit.format().word_size())?;
+            }
+            AttributeValue::LineStringRef(val) => {
+                debug_assert_form!(constants::DW_FORM_line_strp);
+                w.write_offset(
+                    line_strings.get(val).0,
+                    SectionId::DebugLineStr,
+                    unit.format().word_size(),
+                )?;
+            }
+            AttributeValue::String(ref val) => {
+                debug_assert_form!(constants::DW_FORM_string);
+                w.write(val)?;
+                w.write_u8(0)?;
+            }
+            AttributeValue::Encoding(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::DecimalSign(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::Endianity(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::Accessibility(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::Visibility(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::Virtuality(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::Language(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::AddressClass(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(val.0)?;
+            }
+            AttributeValue::IdentifierCase(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::CallingConvention(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::Inline(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::Ordering(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(u64::from(val.0))?;
+            }
+            AttributeValue::FileIndex(val) => {
+                debug_assert_form!(constants::DW_FORM_udata);
+                w.write_uleb128(val.map(FileId::raw).unwrap_or(0))?;
+            }
+        }
+        Ok(())
+    }
+}
+
+define_section!(
+    DebugInfo,
+    DebugInfoOffset,
+    "A writable `.debug_info` section."
+);
+
+/// The section offsets of all elements within a `.debug_info` section.
+#[derive(Debug, Default)]
+pub struct DebugInfoOffsets {
+    base_id: BaseId,
+    units: Vec<UnitOffsets>,
+}
+
+impl DebugInfoOffsets {
+    #[cfg(test)]
+    #[cfg(feature = "read")]
+    pub(crate) fn unit_offsets(&self, unit: UnitId) -> &UnitOffsets {
+        debug_assert_eq!(self.base_id, unit.base_id);
+        &self.units[unit.index]
+    }
+
+    /// Get the `.debug_info` section offset for the given unit.
+    #[inline]
+    pub fn unit(&self, unit: UnitId) -> DebugInfoOffset {
+        debug_assert_eq!(self.base_id, unit.base_id);
+        self.units[unit.index].unit
+    }
+
+    /// Get the `.debug_info` section offset for the given entry.
+    #[inline]
+    pub fn entry(&self, unit: UnitId, entry: UnitEntryId) -> DebugInfoOffset {
+        debug_assert_eq!(self.base_id, unit.base_id);
+        self.units[unit.index].debug_info_offset(entry)
+    }
+}
+
+/// The section offsets of all elements of a unit within a `.debug_info` section.
+#[derive(Debug)]
+pub(crate) struct UnitOffsets {
+    base_id: BaseId,
+    unit: DebugInfoOffset,
+    entries: Vec<EntryOffset>,
+}
+
+impl UnitOffsets {
+    #[cfg(test)]
+    #[cfg(feature = "read")]
+    fn none() -> Self {
+        UnitOffsets {
+            base_id: BaseId::default(),
+            unit: DebugInfoOffset(0),
+            entries: Vec::new(),
+        }
+    }
+
+    /// Get the .debug_info offset for the given entry.
+    #[inline]
+    pub(crate) fn debug_info_offset(&self, entry: UnitEntryId) -> DebugInfoOffset {
+        debug_assert_eq!(self.base_id, entry.base_id);
+        let offset = self.entries[entry.index].offset;
+        debug_assert_ne!(offset.0, 0);
+        offset
+    }
+
+    /// Get the unit offset for the given entry.
+    #[inline]
+    pub(crate) fn unit_offset(&self, entry: UnitEntryId) -> u64 {
+        let offset = self.debug_info_offset(entry);
+        (offset.0 - self.unit.0) as u64
+    }
+
+    /// Get the abbreviation code for the given entry.
+    #[inline]
+    pub(crate) fn abbrev(&self, entry: UnitEntryId) -> u64 {
+        debug_assert_eq!(self.base_id, entry.base_id);
+        self.entries[entry.index].abbrev
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub(crate) struct EntryOffset {
+    offset: DebugInfoOffset,
+    abbrev: u64,
+}
+
+impl EntryOffset {
+    fn none() -> Self {
+        EntryOffset {
+            offset: DebugInfoOffset(0),
+            abbrev: 0,
+        }
+    }
+}
+
+/// A reference to a `.debug_info` entry that has yet to be resolved.
+#[derive(Debug, Clone, Copy)]
+pub(crate) struct DebugInfoReference {
+    /// The offset within the section of the reference.
+    pub offset: usize,
+    /// The size of the reference.
+    pub size: u8,
+    /// The unit containing the entry.
+    pub unit: UnitId,
+    /// The entry being referenced.
+    pub entry: UnitEntryId,
+}
+
+#[cfg(feature = "read")]
+pub(crate) mod convert {
+    use super::*;
+    use crate::common::{DwoId, UnitSectionOffset};
+    use crate::read::{self, Reader};
+    use crate::write::{self, ConvertError, ConvertResult, LocationList, RangeList};
+    use std::collections::HashMap;
+
+    pub(crate) struct ConvertUnit<R: Reader<Offset = usize>> {
+        from_unit: read::Unit<R>,
+        base_id: BaseId,
+        encoding: Encoding,
+        entries: Vec<DebuggingInformationEntry>,
+        entry_offsets: Vec<read::UnitOffset>,
+        root: UnitEntryId,
+    }
+
+    pub(crate) struct ConvertUnitContext<'a, R: Reader<Offset = usize>> {
+        pub dwarf: &'a read::Dwarf<R>,
+        pub unit: &'a read::Unit<R>,
+        pub line_strings: &'a mut write::LineStringTable,
+        pub strings: &'a mut write::StringTable,
+        pub ranges: &'a mut write::RangeListTable,
+        pub locations: &'a mut write::LocationListTable,
+        pub convert_address: &'a dyn Fn(u64) -> Option<Address>,
+        pub base_address: Address,
+        pub line_program_offset: Option<DebugLineOffset>,
+        pub line_program_files: Vec<FileId>,
+        pub entry_ids: &'a HashMap<UnitSectionOffset, (UnitId, UnitEntryId)>,
+    }
+
+    impl UnitTable {
+        /// Create a unit table by reading the data in the given sections.
+        ///
+        /// This also updates the given tables with the values that are referenced from
+        /// attributes in this section.
+        ///
+        /// `convert_address` is a function to convert read addresses into the `Address`
+        /// type. For non-relocatable addresses, this function may simply return
+        /// `Address::Constant(address)`. For relocatable addresses, it is the caller's
+        /// responsibility to determine the symbol and addend corresponding to the address
+        /// and return `Address::Symbol { symbol, addend }`.
+        pub fn from<R: Reader<Offset = usize>>(
+            dwarf: &read::Dwarf<R>,
+            line_strings: &mut write::LineStringTable,
+            strings: &mut write::StringTable,
+            convert_address: &dyn Fn(u64) -> Option<Address>,
+        ) -> ConvertResult<UnitTable> {
+            let base_id = BaseId::default();
+            let mut unit_entries = Vec::new();
+            let mut entry_ids = HashMap::new();
+
+            let mut from_units = dwarf.units();
+            while let Some(from_unit) = from_units.next()? {
+                let unit_id = UnitId::new(base_id, unit_entries.len());
+                unit_entries.push(Unit::convert_entries(
+                    from_unit,
+                    unit_id,
+                    &mut entry_ids,
+                    dwarf,
+                )?);
+            }
+
+            // Attributes must be converted in a separate pass so that we can handle
+            // references to other compilation units.
+            let mut units = Vec::new();
+            for unit_entries in unit_entries.drain(..) {
+                units.push(Unit::convert_attributes(
+                    unit_entries,
+                    &entry_ids,
+                    dwarf,
+                    line_strings,
+                    strings,
+                    convert_address,
+                )?);
+            }
+
+            Ok(UnitTable { base_id, units })
+        }
+    }
+
+    impl Unit {
+        /// Create a unit by reading the data in the input sections.
+        ///
+        /// Does not add entry attributes.
+        pub(crate) fn convert_entries<R: Reader<Offset = usize>>(
+            from_header: read::UnitHeader<R>,
+            unit_id: UnitId,
+            entry_ids: &mut HashMap<UnitSectionOffset, (UnitId, UnitEntryId)>,
+            dwarf: &read::Dwarf<R>,
+        ) -> ConvertResult<ConvertUnit<R>> {
+            match from_header.type_() {
+                read::UnitType::Compilation => (),
+                _ => return Err(ConvertError::UnsupportedUnitType),
+            }
+            let base_id = BaseId::default();
+
+            let from_unit = dwarf.unit(from_header)?;
+            let encoding = from_unit.encoding();
+
+            let mut entries = Vec::new();
+            let mut entry_offsets = Vec::new();
+
+            let mut from_tree = from_unit.entries_tree(None)?;
+            let from_root = from_tree.root()?;
+            let root = DebuggingInformationEntry::convert_entry(
+                from_root,
+                &from_unit,
+                base_id,
+                &mut entries,
+                &mut entry_offsets,
+                entry_ids,
+                None,
+                unit_id,
+            )?;
+
+            Ok(ConvertUnit {
+                from_unit,
+                base_id,
+                encoding,
+                entries,
+                entry_offsets,
+                root,
+            })
+        }
+
+        /// Create entry attributes by reading the data in the input sections.
+        fn convert_attributes<R: Reader<Offset = usize>>(
+            unit: ConvertUnit<R>,
+            entry_ids: &HashMap<UnitSectionOffset, (UnitId, UnitEntryId)>,
+            dwarf: &read::Dwarf<R>,
+            line_strings: &mut write::LineStringTable,
+            strings: &mut write::StringTable,
+            convert_address: &dyn Fn(u64) -> Option<Address>,
+        ) -> ConvertResult<Unit> {
+            let from_unit = unit.from_unit;
+            let base_address =
+                convert_address(from_unit.low_pc).ok_or(ConvertError::InvalidAddress)?;
+
+            let (line_program_offset, line_program, line_program_files) =
+                match from_unit.line_program {
+                    Some(ref from_program) => {
+                        let from_program = from_program.clone();
+                        let line_program_offset = from_program.header().offset();
+                        let (line_program, line_program_files) = LineProgram::from(
+                            from_program,
+                            dwarf,
+                            line_strings,
+                            strings,
+                            convert_address,
+                        )?;
+                        (Some(line_program_offset), line_program, line_program_files)
+                    }
+                    None => (None, LineProgram::none(), Vec::new()),
+                };
+
+            let mut ranges = RangeListTable::default();
+            let mut locations = LocationListTable::default();
+
+            let mut context = ConvertUnitContext {
+                entry_ids,
+                dwarf,
+                unit: &from_unit,
+                line_strings,
+                strings,
+                ranges: &mut ranges,
+                locations: &mut locations,
+                convert_address,
+                base_address,
+                line_program_offset,
+                line_program_files,
+            };
+
+            let mut entries = unit.entries;
+            for entry in &mut entries {
+                entry.convert_attributes(&mut context, &unit.entry_offsets)?;
+            }
+
+            Ok(Unit {
+                base_id: unit.base_id,
+                encoding: unit.encoding,
+                line_program,
+                ranges,
+                locations,
+                entries,
+                root: unit.root,
+            })
+        }
+    }
+
+    impl DebuggingInformationEntry {
+        /// Create an entry by reading the data in the input sections.
+        ///
+        /// Does not add the entry attributes.
+        fn convert_entry<R: Reader<Offset = usize>>(
+            from: read::EntriesTreeNode<R>,
+            from_unit: &read::Unit<R>,
+            base_id: BaseId,
+            entries: &mut Vec<DebuggingInformationEntry>,
+            entry_offsets: &mut Vec<read::UnitOffset>,
+            entry_ids: &mut HashMap<UnitSectionOffset, (UnitId, UnitEntryId)>,
+            parent: Option<UnitEntryId>,
+            unit_id: UnitId,
+        ) -> ConvertResult<UnitEntryId> {
+            let from_entry = from.entry();
+            let id = DebuggingInformationEntry::new(base_id, entries, parent, from_entry.tag());
+            let offset = from_entry.offset();
+            entry_offsets.push(offset);
+            entry_ids.insert(offset.to_unit_section_offset(from_unit), (unit_id, id));
+
+            let mut from_children = from.children();
+            while let Some(from_child) = from_children.next()? {
+                DebuggingInformationEntry::convert_entry(
+                    from_child,
+                    from_unit,
+                    base_id,
+                    entries,
+                    entry_offsets,
+                    entry_ids,
+                    Some(id),
+                    unit_id,
+                )?;
+            }
+            Ok(id)
+        }
+
+        /// Create an entry's attributes by reading the data in the input sections.
+        fn convert_attributes<R: Reader<Offset = usize>>(
+            &mut self,
+            context: &mut ConvertUnitContext<R>,
+            entry_offsets: &[read::UnitOffset],
+        ) -> ConvertResult<()> {
+            let offset = entry_offsets[self.id.index];
+            let from = context.unit.entry(offset)?;
+            let mut from_attrs = from.attrs();
+            while let Some(from_attr) = from_attrs.next()? {
+                if from_attr.name() == constants::DW_AT_sibling {
+                    // This may point to a null entry, so we have to treat it differently.
+                    self.set_sibling(true);
+                } else if let Some(attr) = Attribute::from(context, &from_attr)? {
+                    self.set(attr.name, attr.value);
+                }
+            }
+            Ok(())
+        }
+    }
+
+    impl Attribute {
+        /// Create an attribute by reading the data in the given sections.
+        pub(crate) fn from<R: Reader<Offset = usize>>(
+            context: &mut ConvertUnitContext<R>,
+            from: &read::Attribute<R>,
+        ) -> ConvertResult<Option<Attribute>> {
+            let value = AttributeValue::from(context, from.value())?;
+            Ok(value.map(|value| Attribute {
+                name: from.name(),
+                value,
+            }))
+        }
+    }
+
+    impl AttributeValue {
+        /// Create an attribute value by reading the data in the given sections.
+        pub(crate) fn from<R: Reader<Offset = usize>>(
+            context: &mut ConvertUnitContext<R>,
+            from: read::AttributeValue<R>,
+        ) -> ConvertResult<Option<AttributeValue>> {
+            let to = match from {
+                read::AttributeValue::Addr(val) => match (context.convert_address)(val) {
+                    Some(val) => AttributeValue::Address(val),
+                    None => return Err(ConvertError::InvalidAddress),
+                },
+                read::AttributeValue::Block(r) => AttributeValue::Block(r.to_slice()?.into()),
+                read::AttributeValue::Data1(val) => AttributeValue::Data1(val),
+                read::AttributeValue::Data2(val) => AttributeValue::Data2(val),
+                read::AttributeValue::Data4(val) => AttributeValue::Data4(val),
+                read::AttributeValue::Data8(val) => AttributeValue::Data8(val),
+                read::AttributeValue::Sdata(val) => AttributeValue::Sdata(val),
+                read::AttributeValue::Udata(val) => AttributeValue::Udata(val),
+                read::AttributeValue::Exprloc(expression) => {
+                    let expression = Expression::from(
+                        expression,
+                        context.unit.encoding(),
+                        Some(context.dwarf),
+                        Some(context.unit),
+                        Some(context.entry_ids),
+                        context.convert_address,
+                    )?;
+                    AttributeValue::Exprloc(expression)
+                }
+                // TODO: it would be nice to preserve the flag form.
+                read::AttributeValue::Flag(val) => AttributeValue::Flag(val),
+                read::AttributeValue::DebugAddrBase(_base) => {
+                    // We convert all address indices to addresses,
+                    // so this is unneeded.
+                    return Ok(None);
+                }
+                read::AttributeValue::DebugAddrIndex(index) => {
+                    let val = context.dwarf.address(context.unit, index)?;
+                    match (context.convert_address)(val) {
+                        Some(val) => AttributeValue::Address(val),
+                        None => return Err(ConvertError::InvalidAddress),
+                    }
+                }
+                read::AttributeValue::UnitRef(val) => {
+                    if !context.unit.header.is_valid_offset(val) {
+                        return Err(ConvertError::InvalidUnitRef);
+                    }
+                    let id = context
+                        .entry_ids
+                        .get(&val.to_unit_section_offset(context.unit))
+                        .ok_or(ConvertError::InvalidUnitRef)?;
+                    AttributeValue::UnitRef(id.1)
+                }
+                read::AttributeValue::DebugInfoRef(val) => {
+                    // TODO: support relocation of this value
+                    let id = context
+                        .entry_ids
+                        .get(&UnitSectionOffset::DebugInfoOffset(val))
+                        .ok_or(ConvertError::InvalidDebugInfoRef)?;
+                    AttributeValue::DebugInfoRef(Reference::Entry(id.0, id.1))
+                }
+                read::AttributeValue::DebugInfoRefSup(val) => AttributeValue::DebugInfoRefSup(val),
+                read::AttributeValue::DebugLineRef(val) => {
+                    // There should only be the line program in the CU DIE which we've already
+                    // converted, so check if it matches that.
+                    if Some(val) == context.line_program_offset {
+                        AttributeValue::LineProgramRef
+                    } else {
+                        return Err(ConvertError::InvalidLineRef);
+                    }
+                }
+                read::AttributeValue::DebugMacinfoRef(val) => AttributeValue::DebugMacinfoRef(val),
+                read::AttributeValue::DebugMacroRef(val) => AttributeValue::DebugMacroRef(val),
+                read::AttributeValue::LocationListsRef(val) => {
+                    let iter = context
+                        .dwarf
+                        .locations
+                        .raw_locations(val, context.unit.encoding())?;
+                    let loc_list = LocationList::from(iter, context)?;
+                    let loc_id = context.locations.add(loc_list);
+                    AttributeValue::LocationListRef(loc_id)
+                }
+                read::AttributeValue::DebugLocListsBase(_base) => {
+                    // We convert all location list indices to offsets,
+                    // so this is unneeded.
+                    return Ok(None);
+                }
+                read::AttributeValue::DebugLocListsIndex(index) => {
+                    let offset = context.dwarf.locations_offset(context.unit, index)?;
+                    let iter = context
+                        .dwarf
+                        .locations
+                        .raw_locations(offset, context.unit.encoding())?;
+                    let loc_list = LocationList::from(iter, context)?;
+                    let loc_id = context.locations.add(loc_list);
+                    AttributeValue::LocationListRef(loc_id)
+                }
+                read::AttributeValue::RangeListsRef(offset) => {
+                    let offset = context.dwarf.ranges_offset_from_raw(context.unit, offset);
+                    let iter = context.dwarf.raw_ranges(context.unit, offset)?;
+                    let range_list = RangeList::from(iter, context)?;
+                    let range_id = context.ranges.add(range_list);
+                    AttributeValue::RangeListRef(range_id)
+                }
+                read::AttributeValue::DebugRngListsBase(_base) => {
+                    // We convert all range list indices to offsets,
+                    // so this is unneeded.
+                    return Ok(None);
+                }
+                read::AttributeValue::DebugRngListsIndex(index) => {
+                    let offset = context.dwarf.ranges_offset(context.unit, index)?;
+                    let iter = context
+                        .dwarf
+                        .ranges
+                        .raw_ranges(offset, context.unit.encoding())?;
+                    let range_list = RangeList::from(iter, context)?;
+                    let range_id = context.ranges.add(range_list);
+                    AttributeValue::RangeListRef(range_id)
+                }
+                read::AttributeValue::DebugTypesRef(val) => AttributeValue::DebugTypesRef(val),
+                read::AttributeValue::DebugStrRef(offset) => {
+                    let r = context.dwarf.string(offset)?;
+                    let id = context.strings.add(r.to_slice()?);
+                    AttributeValue::StringRef(id)
+                }
+                read::AttributeValue::DebugStrRefSup(val) => AttributeValue::DebugStrRefSup(val),
+                read::AttributeValue::DebugStrOffsetsBase(_base) => {
+                    // We convert all string offsets to `.debug_str` references,
+                    // so this is unneeded.
+                    return Ok(None);
+                }
+                read::AttributeValue::DebugStrOffsetsIndex(index) => {
+                    let offset = context.dwarf.string_offset(context.unit, index)?;
+                    let r = context.dwarf.string(offset)?;
+                    let id = context.strings.add(r.to_slice()?);
+                    AttributeValue::StringRef(id)
+                }
+                read::AttributeValue::DebugLineStrRef(offset) => {
+                    let r = context.dwarf.line_string(offset)?;
+                    let id = context.line_strings.add(r.to_slice()?);
+                    AttributeValue::LineStringRef(id)
+                }
+                read::AttributeValue::String(r) => AttributeValue::String(r.to_slice()?.into()),
+                read::AttributeValue::Encoding(val) => AttributeValue::Encoding(val),
+                read::AttributeValue::DecimalSign(val) => AttributeValue::DecimalSign(val),
+                read::AttributeValue::Endianity(val) => AttributeValue::Endianity(val),
+                read::AttributeValue::Accessibility(val) => AttributeValue::Accessibility(val),
+                read::AttributeValue::Visibility(val) => AttributeValue::Visibility(val),
+                read::AttributeValue::Virtuality(val) => AttributeValue::Virtuality(val),
+                read::AttributeValue::Language(val) => AttributeValue::Language(val),
+                read::AttributeValue::AddressClass(val) => AttributeValue::AddressClass(val),
+                read::AttributeValue::IdentifierCase(val) => AttributeValue::IdentifierCase(val),
+                read::AttributeValue::CallingConvention(val) => {
+                    AttributeValue::CallingConvention(val)
+                }
+                read::AttributeValue::Inline(val) => AttributeValue::Inline(val),
+                read::AttributeValue::Ordering(val) => AttributeValue::Ordering(val),
+                read::AttributeValue::FileIndex(val) => {
+                    if val == 0 {
+                        // 0 means not specified, even for version 5.
+                        AttributeValue::FileIndex(None)
+                    } else {
+                        match context.line_program_files.get(val as usize) {
+                            Some(id) => AttributeValue::FileIndex(Some(*id)),
+                            None => return Err(ConvertError::InvalidFileIndex),
+                        }
+                    }
+                }
+                // Should always be a more specific section reference.
+                read::AttributeValue::SecOffset(_) => {
+                    return Err(ConvertError::InvalidAttributeValue);
+                }
+                read::AttributeValue::DwoId(DwoId(val)) => AttributeValue::Udata(val),
+            };
+            Ok(Some(to))
+        }
+    }
+}
+
+#[cfg(test)]
+#[cfg(feature = "read")]
+mod tests {
+    use super::*;
+    use crate::common::{
+        DebugAddrBase, DebugLocListsBase, DebugRngListsBase, DebugStrOffsetsBase, LineEncoding,
+    };
+    use crate::constants;
+    use crate::read;
+    use crate::write::{
+        DebugLine, DebugLineStr, DebugStr, DwarfUnit, EndianVec, LineString, LineStringTable,
+        Location, LocationList, LocationListTable, Range, RangeList, RangeListOffsets,
+        RangeListTable, StringTable,
+    };
+    use crate::LittleEndian;
+    use std::collections::HashMap;
+    use std::mem;
+    use std::sync::Arc;
+
+    #[test]
+    fn test_unit_table() {
+        let mut strings = StringTable::default();
+
+        let mut units = UnitTable::default();
+        let unit_id1 = units.add(Unit::new(
+            Encoding {
+                version: 4,
+                address_size: 8,
+                format: Format::Dwarf32,
+            },
+            LineProgram::none(),
+        ));
+        let unit2 = units.add(Unit::new(
+            Encoding {
+                version: 2,
+                address_size: 4,
+                format: Format::Dwarf64,
+            },
+            LineProgram::none(),
+        ));
+        let unit3 = units.add(Unit::new(
+            Encoding {
+                version: 5,
+                address_size: 4,
+                format: Format::Dwarf32,
+            },
+            LineProgram::none(),
+        ));
+        assert_eq!(units.count(), 3);
+        {
+            let unit1 = units.get_mut(unit_id1);
+            assert_eq!(unit1.version(), 4);
+            assert_eq!(unit1.address_size(), 8);
+            assert_eq!(unit1.format(), Format::Dwarf32);
+            assert_eq!(unit1.count(), 1);
+
+            let root_id = unit1.root();
+            assert_eq!(root_id, UnitEntryId::new(unit1.base_id, 0));
+            {
+                let root = unit1.get_mut(root_id);
+                assert_eq!(root.id(), root_id);
+                assert!(root.parent().is_none());
+                assert_eq!(root.tag(), constants::DW_TAG_compile_unit);
+
+                // Test get/get_mut
+                assert!(root.get(constants::DW_AT_producer).is_none());
+                assert!(root.get_mut(constants::DW_AT_producer).is_none());
+                let mut producer = AttributeValue::String(b"root"[..].into());
+                root.set(constants::DW_AT_producer, producer.clone());
+                assert_eq!(root.get(constants::DW_AT_producer), Some(&producer));
+                assert_eq!(root.get_mut(constants::DW_AT_producer), Some(&mut producer));
+
+                // Test attrs
+                let mut attrs = root.attrs();
+                let attr = attrs.next().unwrap();
+                assert_eq!(attr.name(), constants::DW_AT_producer);
+                assert_eq!(attr.get(), &producer);
+                assert!(attrs.next().is_none());
+            }
+
+            let child1 = unit1.add(root_id, constants::DW_TAG_subprogram);
+            assert_eq!(child1, UnitEntryId::new(unit1.base_id, 1));
+            {
+                let child1 = unit1.get_mut(child1);
+                assert_eq!(child1.parent(), Some(root_id));
+
+                let tmp = AttributeValue::String(b"tmp"[..].into());
+                child1.set(constants::DW_AT_name, tmp.clone());
+                assert_eq!(child1.get(constants::DW_AT_name), Some(&tmp));
+
+                // Test attrs_mut
+                let name = AttributeValue::StringRef(strings.add(&b"child1"[..]));
+                {
+                    let attr = child1.attrs_mut().next().unwrap();
+                    assert_eq!(attr.name(), constants::DW_AT_name);
+                    attr.set(name.clone());
+                }
+                assert_eq!(child1.get(constants::DW_AT_name), Some(&name));
+            }
+
+            let child2 = unit1.add(root_id, constants::DW_TAG_subprogram);
+            assert_eq!(child2, UnitEntryId::new(unit1.base_id, 2));
+            {
+                let child2 = unit1.get_mut(child2);
+                assert_eq!(child2.parent(), Some(root_id));
+
+                let tmp = AttributeValue::String(b"tmp"[..].into());
+                child2.set(constants::DW_AT_name, tmp.clone());
+                assert_eq!(child2.get(constants::DW_AT_name), Some(&tmp));
+
+                // Test replace
+                let name = AttributeValue::StringRef(strings.add(&b"child2"[..]));
+                child2.set(constants::DW_AT_name, name.clone());
+                assert_eq!(child2.get(constants::DW_AT_name), Some(&name));
+            }
+
+            {
+                let root = unit1.get(root_id);
+                assert_eq!(
+                    root.children().cloned().collect::<Vec<_>>(),
+                    vec![child1, child2]
+                );
+            }
+        }
+        {
+            let unit2 = units.get(unit2);
+            assert_eq!(unit2.version(), 2);
+            assert_eq!(unit2.address_size(), 4);
+            assert_eq!(unit2.format(), Format::Dwarf64);
+            assert_eq!(unit2.count(), 1);
+
+            let root = unit2.root();
+            assert_eq!(root, UnitEntryId::new(unit2.base_id, 0));
+            let root = unit2.get(root);
+            assert_eq!(root.id(), UnitEntryId::new(unit2.base_id, 0));
+            assert!(root.parent().is_none());
+            assert_eq!(root.tag(), constants::DW_TAG_compile_unit);
+        }
+
+        let mut sections = Sections::new(EndianVec::new(LittleEndian));
+        let debug_line_str_offsets = DebugLineStrOffsets::none();
+        let debug_str_offsets = strings.write(&mut sections.debug_str).unwrap();
+        units
+            .write(&mut sections, &debug_line_str_offsets, &debug_str_offsets)
+            .unwrap();
+
+        println!("{:?}", sections.debug_str);
+        println!("{:?}", sections.debug_info);
+        println!("{:?}", sections.debug_abbrev);
+
+        let dwarf = read::Dwarf {
+            debug_abbrev: read::DebugAbbrev::new(sections.debug_abbrev.slice(), LittleEndian),
+            debug_info: read::DebugInfo::new(sections.debug_info.slice(), LittleEndian),
+            debug_str: read::DebugStr::new(sections.debug_str.slice(), LittleEndian),
+            ..Default::default()
+        };
+        let mut read_units = dwarf.units();
+
+        {
+            let read_unit1 = read_units.next().unwrap().unwrap();
+            let unit1 = units.get(unit_id1);
+            assert_eq!(unit1.version(), read_unit1.version());
+            assert_eq!(unit1.address_size(), read_unit1.address_size());
+            assert_eq!(unit1.format(), read_unit1.format());
+
+            let read_unit1 = dwarf.unit(read_unit1).unwrap();
+            let mut read_entries = read_unit1.entries();
+
+            let root = unit1.get(unit1.root());
+            {
+                let (depth, read_root) = read_entries.next_dfs().unwrap().unwrap();
+                assert_eq!(depth, 0);
+                assert_eq!(root.tag(), read_root.tag());
+                assert!(read_root.has_children());
+
+                let producer = match root.get(constants::DW_AT_producer).unwrap() {
+                    AttributeValue::String(ref producer) => &**producer,
+                    otherwise => panic!("unexpected {:?}", otherwise),
+                };
+                assert_eq!(producer, b"root");
+                let read_producer = read_root
+                    .attr_value(constants::DW_AT_producer)
+                    .unwrap()
+                    .unwrap();
+                assert_eq!(
+                    dwarf
+                        .attr_string(&read_unit1, read_producer)
+                        .unwrap()
+                        .slice(),
+                    producer
+                );
+            }
+
+            let mut children = root.children().cloned();
+
+            {
+                let child = children.next().unwrap();
+                assert_eq!(child, UnitEntryId::new(unit1.base_id, 1));
+                let child = unit1.get(child);
+                let (depth, read_child) = read_entries.next_dfs().unwrap().unwrap();
+                assert_eq!(depth, 1);
+                assert_eq!(child.tag(), read_child.tag());
+                assert!(!read_child.has_children());
+
+                let name = match child.get(constants::DW_AT_name).unwrap() {
+                    AttributeValue::StringRef(name) => *name,
+                    otherwise => panic!("unexpected {:?}", otherwise),
+                };
+                let name = strings.get(name);
+                assert_eq!(name, b"child1");
+                let read_name = read_child
+                    .attr_value(constants::DW_AT_name)
+                    .unwrap()
+                    .unwrap();
+                assert_eq!(
+                    dwarf.attr_string(&read_unit1, read_name).unwrap().slice(),
+                    name
+                );
+            }
+
+            {
+                let child = children.next().unwrap();
+                assert_eq!(child, UnitEntryId::new(unit1.base_id, 2));
+                let child = unit1.get(child);
+                let (depth, read_child) = read_entries.next_dfs().unwrap().unwrap();
+                assert_eq!(depth, 0);
+                assert_eq!(child.tag(), read_child.tag());
+                assert!(!read_child.has_children());
+
+                let name = match child.get(constants::DW_AT_name).unwrap() {
+                    AttributeValue::StringRef(name) => *name,
+                    otherwise => panic!("unexpected {:?}", otherwise),
+                };
+                let name = strings.get(name);
+                assert_eq!(name, b"child2");
+                let read_name = read_child
+                    .attr_value(constants::DW_AT_name)
+                    .unwrap()
+                    .unwrap();
+                assert_eq!(
+                    dwarf.attr_string(&read_unit1, read_name).unwrap().slice(),
+                    name
+                );
+            }
+
+            assert!(read_entries.next_dfs().unwrap().is_none());
+        }
+
+        {
+            let read_unit2 = read_units.next().unwrap().unwrap();
+            let unit2 = units.get(unit2);
+            assert_eq!(unit2.version(), read_unit2.version());
+            assert_eq!(unit2.address_size(), read_unit2.address_size());
+            assert_eq!(unit2.format(), read_unit2.format());
+
+            let abbrevs = dwarf.abbreviations(&read_unit2).unwrap();
+            let mut read_entries = read_unit2.entries(&abbrevs);
+
+            {
+                let root = unit2.get(unit2.root());
+                let (depth, read_root) = read_entries.next_dfs().unwrap().unwrap();
+                assert_eq!(depth, 0);
+                assert_eq!(root.tag(), read_root.tag());
+                assert!(!read_root.has_children());
+            }
+
+            assert!(read_entries.next_dfs().unwrap().is_none());
+        }
+
+        {
+            let read_unit3 = read_units.next().unwrap().unwrap();
+            let unit3 = units.get(unit3);
+            assert_eq!(unit3.version(), read_unit3.version());
+            assert_eq!(unit3.address_size(), read_unit3.address_size());
+            assert_eq!(unit3.format(), read_unit3.format());
+
+            let abbrevs = dwarf.abbreviations(&read_unit3).unwrap();
+            let mut read_entries = read_unit3.entries(&abbrevs);
+
+            {
+                let root = unit3.get(unit3.root());
+                let (depth, read_root) = read_entries.next_dfs().unwrap().unwrap();
+                assert_eq!(depth, 0);
+                assert_eq!(root.tag(), read_root.tag());
+                assert!(!read_root.has_children());
+            }
+
+            assert!(read_entries.next_dfs().unwrap().is_none());
+        }
+
+        assert!(read_units.next().unwrap().is_none());
+
+        let mut convert_line_strings = LineStringTable::default();
+        let mut convert_strings = StringTable::default();
+        let convert_units = UnitTable::from(
+            &dwarf,
+            &mut convert_line_strings,
+            &mut convert_strings,
+            &|address| Some(Address::Constant(address)),
+        )
+        .unwrap();
+        assert_eq!(convert_units.count(), units.count());
+
+        for i in 0..convert_units.count() {
+            let unit_id = units.id(i);
+            let unit = units.get(unit_id);
+            let convert_unit_id = convert_units.id(i);
+            let convert_unit = convert_units.get(convert_unit_id);
+            assert_eq!(convert_unit.version(), unit.version());
+            assert_eq!(convert_unit.address_size(), unit.address_size());
+            assert_eq!(convert_unit.format(), unit.format());
+            assert_eq!(convert_unit.count(), unit.count());
+
+            let root = unit.get(unit.root());
+            let convert_root = convert_unit.get(convert_unit.root());
+            assert_eq!(convert_root.tag(), root.tag());
+            for (convert_attr, attr) in convert_root.attrs().zip(root.attrs()) {
+                assert_eq!(convert_attr, attr);
+            }
+        }
+    }
+
+    #[test]
+    fn test_attribute_value() {
+        // Create a string table and a string with a non-zero id/offset.
+        let mut strings = StringTable::default();
+        strings.add("string one");
+        let string_id = strings.add("string two");
+        let mut debug_str = DebugStr::from(EndianVec::new(LittleEndian));
+        let debug_str_offsets = strings.write(&mut debug_str).unwrap();
+        let read_debug_str = read::DebugStr::new(debug_str.slice(), LittleEndian);
+
+        let mut line_strings = LineStringTable::default();
+        line_strings.add("line string one");
+        let line_string_id = line_strings.add("line string two");
+        let mut debug_line_str = DebugLineStr::from(EndianVec::new(LittleEndian));
+        let debug_line_str_offsets = line_strings.write(&mut debug_line_str).unwrap();
+        let read_debug_line_str =
+            read::DebugLineStr::from(read::EndianSlice::new(debug_line_str.slice(), LittleEndian));
+
+        let data = vec![1, 2, 3, 4];
+        let read_data = read::EndianSlice::new(&[1, 2, 3, 4], LittleEndian);
+
+        let mut expression = Expression::new();
+        expression.op_constu(57);
+        let read_expression = read::Expression(read::EndianSlice::new(
+            &[constants::DW_OP_constu.0, 57],
+            LittleEndian,
+        ));
+
+        let mut ranges = RangeListTable::default();
+        let range_id = ranges.add(RangeList(vec![Range::StartEnd {
+            begin: Address::Constant(0x1234),
+            end: Address::Constant(0x2345),
+        }]));
+
+        let mut locations = LocationListTable::default();
+        let loc_id = locations.add(LocationList(vec![Location::StartEnd {
+            begin: Address::Constant(0x1234),
+            end: Address::Constant(0x2345),
+            data: expression.clone(),
+        }]));
+
+        for &version in &[2, 3, 4, 5] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+
+                    let mut sections = Sections::new(EndianVec::new(LittleEndian));
+                    let range_list_offsets = ranges.write(&mut sections, encoding).unwrap();
+                    let loc_list_offsets = locations.write(&mut sections, encoding, None).unwrap();
+
+                    let read_debug_ranges =
+                        read::DebugRanges::new(sections.debug_ranges.slice(), LittleEndian);
+                    let read_debug_rnglists =
+                        read::DebugRngLists::new(sections.debug_rnglists.slice(), LittleEndian);
+
+                    let read_debug_loc =
+                        read::DebugLoc::new(sections.debug_loc.slice(), LittleEndian);
+                    let read_debug_loclists =
+                        read::DebugLocLists::new(sections.debug_loclists.slice(), LittleEndian);
+
+                    let mut units = UnitTable::default();
+                    let unit = units.add(Unit::new(encoding, LineProgram::none()));
+                    let unit = units.get(unit);
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+                    let from_unit = read::UnitHeader::new(
+                        encoding,
+                        0,
+                        read::UnitType::Compilation,
+                        DebugAbbrevOffset(0),
+                        DebugInfoOffset(0).into(),
+                        read::EndianSlice::new(&[], LittleEndian),
+                    );
+
+                    for &(ref name, ref value, ref expect_value) in &[
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Address(Address::Constant(0x1234)),
+                            read::AttributeValue::Addr(0x1234),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Block(data.clone()),
+                            read::AttributeValue::Block(read_data),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Data1(0x12),
+                            read::AttributeValue::Data1(0x12),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Data2(0x1234),
+                            read::AttributeValue::Data2(0x1234),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Data4(0x1234),
+                            read::AttributeValue::Data4(0x1234),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Data8(0x1234),
+                            read::AttributeValue::Data8(0x1234),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Sdata(0x1234),
+                            read::AttributeValue::Sdata(0x1234),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Udata(0x1234),
+                            read::AttributeValue::Udata(0x1234),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Exprloc(expression.clone()),
+                            read::AttributeValue::Exprloc(read_expression),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::Flag(false),
+                            read::AttributeValue::Flag(false),
+                        ),
+                        /*
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::FlagPresent,
+                            read::AttributeValue::Flag(true),
+                        ),
+                        */
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::DebugInfoRefSup(DebugInfoOffset(0x1234)),
+                            read::AttributeValue::DebugInfoRefSup(DebugInfoOffset(0x1234)),
+                        ),
+                        (
+                            constants::DW_AT_location,
+                            AttributeValue::LocationListRef(loc_id),
+                            read::AttributeValue::SecOffset(loc_list_offsets.get(loc_id).0),
+                        ),
+                        (
+                            constants::DW_AT_macro_info,
+                            AttributeValue::DebugMacinfoRef(DebugMacinfoOffset(0x1234)),
+                            read::AttributeValue::SecOffset(0x1234),
+                        ),
+                        (
+                            constants::DW_AT_macros,
+                            AttributeValue::DebugMacroRef(DebugMacroOffset(0x1234)),
+                            read::AttributeValue::SecOffset(0x1234),
+                        ),
+                        (
+                            constants::DW_AT_ranges,
+                            AttributeValue::RangeListRef(range_id),
+                            read::AttributeValue::SecOffset(range_list_offsets.get(range_id).0),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::DebugTypesRef(DebugTypeSignature(0x1234)),
+                            read::AttributeValue::DebugTypesRef(DebugTypeSignature(0x1234)),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::StringRef(string_id),
+                            read::AttributeValue::DebugStrRef(debug_str_offsets.get(string_id)),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::DebugStrRefSup(DebugStrOffset(0x1234)),
+                            read::AttributeValue::DebugStrRefSup(DebugStrOffset(0x1234)),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::LineStringRef(line_string_id),
+                            read::AttributeValue::DebugLineStrRef(
+                                debug_line_str_offsets.get(line_string_id),
+                            ),
+                        ),
+                        (
+                            constants::DW_AT_name,
+                            AttributeValue::String(data.clone()),
+                            read::AttributeValue::String(read_data),
+                        ),
+                        (
+                            constants::DW_AT_encoding,
+                            AttributeValue::Encoding(constants::DwAte(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_decimal_sign,
+                            AttributeValue::DecimalSign(constants::DwDs(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_endianity,
+                            AttributeValue::Endianity(constants::DwEnd(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_accessibility,
+                            AttributeValue::Accessibility(constants::DwAccess(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_visibility,
+                            AttributeValue::Visibility(constants::DwVis(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_virtuality,
+                            AttributeValue::Virtuality(constants::DwVirtuality(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_language,
+                            AttributeValue::Language(constants::DwLang(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_address_class,
+                            AttributeValue::AddressClass(constants::DwAddr(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_identifier_case,
+                            AttributeValue::IdentifierCase(constants::DwId(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_calling_convention,
+                            AttributeValue::CallingConvention(constants::DwCc(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_ordering,
+                            AttributeValue::Ordering(constants::DwOrd(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                        (
+                            constants::DW_AT_inline,
+                            AttributeValue::Inline(constants::DwInl(0x12)),
+                            read::AttributeValue::Udata(0x12),
+                        ),
+                    ][..]
+                    {
+                        let form = value.form(encoding).unwrap();
+                        let attr = Attribute {
+                            name: *name,
+                            value: value.clone(),
+                        };
+
+                        let offsets = UnitOffsets::none();
+                        let line_program_offset = None;
+                        let mut debug_info_refs = Vec::new();
+                        let mut unit_refs = Vec::new();
+                        let mut debug_info = DebugInfo::from(EndianVec::new(LittleEndian));
+                        attr.value
+                            .write(
+                                &mut debug_info,
+                                &mut debug_info_refs,
+                                &mut unit_refs,
+                                &unit,
+                                &offsets,
+                                line_program_offset,
+                                &debug_line_str_offsets,
+                                &debug_str_offsets,
+                                &range_list_offsets,
+                                &loc_list_offsets,
+                            )
+                            .unwrap();
+
+                        let spec = read::AttributeSpecification::new(*name, form, None);
+                        let mut r = read::EndianSlice::new(debug_info.slice(), LittleEndian);
+                        let read_attr = read::parse_attribute(&mut r, encoding, spec).unwrap();
+                        let read_value = &read_attr.raw_value();
+                        // read::AttributeValue is invariant in the lifetime of R.
+                        // The lifetimes here are all okay, so transmute it.
+                        let read_value = unsafe {
+                            mem::transmute::<
+                                &read::AttributeValue<read::EndianSlice<LittleEndian>>,
+                                &read::AttributeValue<read::EndianSlice<LittleEndian>>,
+                            >(read_value)
+                        };
+                        assert_eq!(read_value, expect_value);
+
+                        let dwarf = read::Dwarf {
+                            debug_str: read_debug_str.clone(),
+                            debug_line_str: read_debug_line_str.clone(),
+                            ranges: read::RangeLists::new(read_debug_ranges, read_debug_rnglists),
+                            locations: read::LocationLists::new(
+                                read_debug_loc,
+                                read_debug_loclists,
+                            ),
+                            ..Default::default()
+                        };
+
+                        let unit = read::Unit {
+                            header: from_unit,
+                            abbreviations: Arc::new(read::Abbreviations::default()),
+                            name: None,
+                            comp_dir: None,
+                            low_pc: 0,
+                            str_offsets_base: DebugStrOffsetsBase(0),
+                            addr_base: DebugAddrBase(0),
+                            loclists_base: DebugLocListsBase(0),
+                            rnglists_base: DebugRngListsBase(0),
+                            line_program: None,
+                            dwo_id: None,
+                        };
+
+                        let mut context = convert::ConvertUnitContext {
+                            dwarf: &dwarf,
+                            unit: &unit,
+                            line_strings: &mut line_strings,
+                            strings: &mut strings,
+                            ranges: &mut ranges,
+                            locations: &mut locations,
+                            convert_address: &|address| Some(Address::Constant(address)),
+                            base_address: Address::Constant(0),
+                            line_program_offset: None,
+                            line_program_files: Vec::new(),
+                            entry_ids: &HashMap::new(),
+                        };
+
+                        let convert_attr =
+                            Attribute::from(&mut context, &read_attr).unwrap().unwrap();
+                        assert_eq!(convert_attr, attr);
+                    }
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn test_unit_ref() {
+        let mut units = UnitTable::default();
+        let unit_id1 = units.add(Unit::new(
+            Encoding {
+                version: 4,
+                address_size: 8,
+                format: Format::Dwarf32,
+            },
+            LineProgram::none(),
+        ));
+        assert_eq!(unit_id1, units.id(0));
+        let unit_id2 = units.add(Unit::new(
+            Encoding {
+                version: 2,
+                address_size: 4,
+                format: Format::Dwarf64,
+            },
+            LineProgram::none(),
+        ));
+        assert_eq!(unit_id2, units.id(1));
+        let unit1_child1 = UnitEntryId::new(units.get(unit_id1).base_id, 1);
+        let unit1_child2 = UnitEntryId::new(units.get(unit_id1).base_id, 2);
+        let unit2_child1 = UnitEntryId::new(units.get(unit_id2).base_id, 1);
+        let unit2_child2 = UnitEntryId::new(units.get(unit_id2).base_id, 2);
+        {
+            let unit1 = units.get_mut(unit_id1);
+            let root = unit1.root();
+            let child_id1 = unit1.add(root, constants::DW_TAG_subprogram);
+            assert_eq!(child_id1, unit1_child1);
+            let child_id2 = unit1.add(root, constants::DW_TAG_subprogram);
+            assert_eq!(child_id2, unit1_child2);
+            {
+                let child1 = unit1.get_mut(child_id1);
+                child1.set(constants::DW_AT_type, AttributeValue::UnitRef(child_id2));
+            }
+            {
+                let child2 = unit1.get_mut(child_id2);
+                child2.set(
+                    constants::DW_AT_type,
+                    AttributeValue::DebugInfoRef(Reference::Entry(unit_id2, unit2_child1)),
+                );
+            }
+        }
+        {
+            let unit2 = units.get_mut(unit_id2);
+            let root = unit2.root();
+            let child_id1 = unit2.add(root, constants::DW_TAG_subprogram);
+            assert_eq!(child_id1, unit2_child1);
+            let child_id2 = unit2.add(root, constants::DW_TAG_subprogram);
+            assert_eq!(child_id2, unit2_child2);
+            {
+                let child1 = unit2.get_mut(child_id1);
+                child1.set(constants::DW_AT_type, AttributeValue::UnitRef(child_id2));
+            }
+            {
+                let child2 = unit2.get_mut(child_id2);
+                child2.set(
+                    constants::DW_AT_type,
+                    AttributeValue::DebugInfoRef(Reference::Entry(unit_id1, unit1_child1)),
+                );
+            }
+        }
+
+        let debug_line_str_offsets = DebugLineStrOffsets::none();
+        let debug_str_offsets = DebugStrOffsets::none();
+        let mut sections = Sections::new(EndianVec::new(LittleEndian));
+        let debug_info_offsets = units
+            .write(&mut sections, &debug_line_str_offsets, &debug_str_offsets)
+            .unwrap();
+
+        println!("{:?}", sections.debug_info);
+        println!("{:?}", sections.debug_abbrev);
+
+        let dwarf = read::Dwarf {
+            debug_abbrev: read::DebugAbbrev::new(sections.debug_abbrev.slice(), LittleEndian),
+            debug_info: read::DebugInfo::new(sections.debug_info.slice(), LittleEndian),
+            ..Default::default()
+        };
+
+        let mut read_units = dwarf.units();
+        {
+            let read_unit1 = read_units.next().unwrap().unwrap();
+            assert_eq!(
+                read_unit1.offset(),
+                debug_info_offsets.unit(unit_id1).into()
+            );
+
+            let abbrevs = dwarf.abbreviations(&read_unit1).unwrap();
+            let mut read_entries = read_unit1.entries(&abbrevs);
+            {
+                let (_, _read_root) = read_entries.next_dfs().unwrap().unwrap();
+            }
+            {
+                let (_, read_child1) = read_entries.next_dfs().unwrap().unwrap();
+                let offset = debug_info_offsets
+                    .entry(unit_id1, unit1_child2)
+                    .to_unit_offset(&read_unit1)
+                    .unwrap();
+                assert_eq!(
+                    read_child1.attr_value(constants::DW_AT_type).unwrap(),
+                    Some(read::AttributeValue::UnitRef(offset))
+                );
+            }
+            {
+                let (_, read_child2) = read_entries.next_dfs().unwrap().unwrap();
+                let offset = debug_info_offsets.entry(unit_id2, unit2_child1);
+                assert_eq!(
+                    read_child2.attr_value(constants::DW_AT_type).unwrap(),
+                    Some(read::AttributeValue::DebugInfoRef(offset))
+                );
+            }
+        }
+        {
+            let read_unit2 = read_units.next().unwrap().unwrap();
+            assert_eq!(
+                read_unit2.offset(),
+                debug_info_offsets.unit(unit_id2).into()
+            );
+
+            let abbrevs = dwarf.abbreviations(&read_unit2).unwrap();
+            let mut read_entries = read_unit2.entries(&abbrevs);
+            {
+                let (_, _read_root) = read_entries.next_dfs().unwrap().unwrap();
+            }
+            {
+                let (_, read_child1) = read_entries.next_dfs().unwrap().unwrap();
+                let offset = debug_info_offsets
+                    .entry(unit_id2, unit2_child2)
+                    .to_unit_offset(&read_unit2)
+                    .unwrap();
+                assert_eq!(
+                    read_child1.attr_value(constants::DW_AT_type).unwrap(),
+                    Some(read::AttributeValue::UnitRef(offset))
+                );
+            }
+            {
+                let (_, read_child2) = read_entries.next_dfs().unwrap().unwrap();
+                let offset = debug_info_offsets.entry(unit_id1, unit1_child1);
+                assert_eq!(
+                    read_child2.attr_value(constants::DW_AT_type).unwrap(),
+                    Some(read::AttributeValue::DebugInfoRef(offset))
+                );
+            }
+        }
+
+        let mut convert_line_strings = LineStringTable::default();
+        let mut convert_strings = StringTable::default();
+        let convert_units = UnitTable::from(
+            &dwarf,
+            &mut convert_line_strings,
+            &mut convert_strings,
+            &|address| Some(Address::Constant(address)),
+        )
+        .unwrap();
+        assert_eq!(convert_units.count(), units.count());
+
+        for i in 0..convert_units.count() {
+            let unit = units.get(units.id(i));
+            let convert_unit = convert_units.get(convert_units.id(i));
+            assert_eq!(convert_unit.version(), unit.version());
+            assert_eq!(convert_unit.address_size(), unit.address_size());
+            assert_eq!(convert_unit.format(), unit.format());
+            assert_eq!(convert_unit.count(), unit.count());
+
+            let root = unit.get(unit.root());
+            let convert_root = convert_unit.get(convert_unit.root());
+            assert_eq!(convert_root.tag(), root.tag());
+            for (convert_attr, attr) in convert_root.attrs().zip(root.attrs()) {
+                assert_eq!(convert_attr, attr);
+            }
+
+            let child1 = unit.get(UnitEntryId::new(unit.base_id, 1));
+            let convert_child1 = convert_unit.get(UnitEntryId::new(convert_unit.base_id, 1));
+            assert_eq!(convert_child1.tag(), child1.tag());
+            for (convert_attr, attr) in convert_child1.attrs().zip(child1.attrs()) {
+                assert_eq!(convert_attr.name, attr.name);
+                match (convert_attr.value.clone(), attr.value.clone()) {
+                    (
+                        AttributeValue::DebugInfoRef(Reference::Entry(convert_unit, convert_entry)),
+                        AttributeValue::DebugInfoRef(Reference::Entry(unit, entry)),
+                    ) => {
+                        assert_eq!(convert_unit.index, unit.index);
+                        assert_eq!(convert_entry.index, entry.index);
+                    }
+                    (AttributeValue::UnitRef(convert_id), AttributeValue::UnitRef(id)) => {
+                        assert_eq!(convert_id.index, id.index);
+                    }
+                    (convert_value, value) => assert_eq!(convert_value, value),
+                }
+            }
+
+            let child2 = unit.get(UnitEntryId::new(unit.base_id, 2));
+            let convert_child2 = convert_unit.get(UnitEntryId::new(convert_unit.base_id, 2));
+            assert_eq!(convert_child2.tag(), child2.tag());
+            for (convert_attr, attr) in convert_child2.attrs().zip(child2.attrs()) {
+                assert_eq!(convert_attr.name, attr.name);
+                match (convert_attr.value.clone(), attr.value.clone()) {
+                    (
+                        AttributeValue::DebugInfoRef(Reference::Entry(convert_unit, convert_entry)),
+                        AttributeValue::DebugInfoRef(Reference::Entry(unit, entry)),
+                    ) => {
+                        assert_eq!(convert_unit.index, unit.index);
+                        assert_eq!(convert_entry.index, entry.index);
+                    }
+                    (AttributeValue::UnitRef(convert_id), AttributeValue::UnitRef(id)) => {
+                        assert_eq!(convert_id.index, id.index);
+                    }
+                    (convert_value, value) => assert_eq!(convert_value, value),
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn test_sibling() {
+        fn add_child(
+            unit: &mut Unit,
+            parent: UnitEntryId,
+            tag: constants::DwTag,
+            name: &str,
+        ) -> UnitEntryId {
+            let id = unit.add(parent, tag);
+            let child = unit.get_mut(id);
+            child.set(constants::DW_AT_name, AttributeValue::String(name.into()));
+            child.set_sibling(true);
+            id
+        }
+
+        fn add_children(units: &mut UnitTable, unit_id: UnitId) {
+            let unit = units.get_mut(unit_id);
+            let root = unit.root();
+            let child1 = add_child(unit, root, constants::DW_TAG_subprogram, "child1");
+            add_child(unit, child1, constants::DW_TAG_variable, "grandchild1");
+            add_child(unit, root, constants::DW_TAG_subprogram, "child2");
+            add_child(unit, root, constants::DW_TAG_subprogram, "child3");
+        }
+
+        fn next_child<R: read::Reader<Offset = usize>>(
+            entries: &mut read::EntriesCursor<R>,
+        ) -> (read::UnitOffset, Option<read::UnitOffset>) {
+            let (_, entry) = entries.next_dfs().unwrap().unwrap();
+            let offset = entry.offset();
+            let sibling =
+                entry
+                    .attr_value(constants::DW_AT_sibling)
+                    .unwrap()
+                    .map(|attr| match attr {
+                        read::AttributeValue::UnitRef(offset) => offset,
+                        _ => panic!("bad sibling value"),
+                    });
+            (offset, sibling)
+        }
+
+        fn check_sibling<R: read::Reader<Offset = usize>>(
+            unit: &read::UnitHeader<R>,
+            debug_abbrev: &read::DebugAbbrev<R>,
+        ) {
+            let abbrevs = unit.abbreviations(debug_abbrev).unwrap();
+            let mut entries = unit.entries(&abbrevs);
+            // root
+            entries.next_dfs().unwrap().unwrap();
+            // child1
+            let (_, sibling1) = next_child(&mut entries);
+            // grandchild1
+            entries.next_dfs().unwrap().unwrap();
+            // child2
+            let (offset2, sibling2) = next_child(&mut entries);
+            // child3
+            let (_, _) = next_child(&mut entries);
+            assert_eq!(sibling1, Some(offset2));
+            assert_eq!(sibling2, None);
+        }
+
+        let encoding = Encoding {
+            format: Format::Dwarf32,
+            version: 4,
+            address_size: 8,
+        };
+        let mut units = UnitTable::default();
+        let unit_id1 = units.add(Unit::new(encoding, LineProgram::none()));
+        add_children(&mut units, unit_id1);
+        let unit_id2 = units.add(Unit::new(encoding, LineProgram::none()));
+        add_children(&mut units, unit_id2);
+
+        let debug_line_str_offsets = DebugLineStrOffsets::none();
+        let debug_str_offsets = DebugStrOffsets::none();
+        let mut sections = Sections::new(EndianVec::new(LittleEndian));
+        units
+            .write(&mut sections, &debug_line_str_offsets, &debug_str_offsets)
+            .unwrap();
+
+        println!("{:?}", sections.debug_info);
+        println!("{:?}", sections.debug_abbrev);
+
+        let read_debug_info = read::DebugInfo::new(sections.debug_info.slice(), LittleEndian);
+        let read_debug_abbrev = read::DebugAbbrev::new(sections.debug_abbrev.slice(), LittleEndian);
+        let mut read_units = read_debug_info.units();
+        check_sibling(&read_units.next().unwrap().unwrap(), &read_debug_abbrev);
+        check_sibling(&read_units.next().unwrap().unwrap(), &read_debug_abbrev);
+    }
+
+    #[test]
+    fn test_line_ref() {
+        for &version in &[2, 3, 4, 5] {
+            for &address_size in &[4, 8] {
+                for &format in &[Format::Dwarf32, Format::Dwarf64] {
+                    let encoding = Encoding {
+                        format,
+                        version,
+                        address_size,
+                    };
+
+                    // The line program we'll be referencing.
+                    let mut line_program = LineProgram::new(
+                        encoding,
+                        LineEncoding::default(),
+                        LineString::String(b"comp_dir".to_vec()),
+                        LineString::String(b"comp_name".to_vec()),
+                        None,
+                    );
+                    let dir = line_program.default_directory();
+                    let file1 =
+                        line_program.add_file(LineString::String(b"file1".to_vec()), dir, None);
+                    let file2 =
+                        line_program.add_file(LineString::String(b"file2".to_vec()), dir, None);
+
+                    // Write, read, and convert the line program, so that we have the info
+                    // required to convert the attributes.
+                    let line_strings = DebugLineStrOffsets::none();
+                    let strings = DebugStrOffsets::none();
+                    let mut debug_line = DebugLine::from(EndianVec::new(LittleEndian));
+                    let line_program_offset = line_program
+                        .write(&mut debug_line, encoding, &line_strings, &strings)
+                        .unwrap();
+                    let read_debug_line = read::DebugLine::new(debug_line.slice(), LittleEndian);
+                    let read_line_program = read_debug_line
+                        .program(
+                            line_program_offset,
+                            address_size,
+                            Some(read::EndianSlice::new(b"comp_dir", LittleEndian)),
+                            Some(read::EndianSlice::new(b"comp_name", LittleEndian)),
+                        )
+                        .unwrap();
+                    let dwarf = read::Dwarf::default();
+                    let mut convert_line_strings = LineStringTable::default();
+                    let mut convert_strings = StringTable::default();
+                    let (_, line_program_files) = LineProgram::from(
+                        read_line_program,
+                        &dwarf,
+                        &mut convert_line_strings,
+                        &mut convert_strings,
+                        &|address| Some(Address::Constant(address)),
+                    )
+                    .unwrap();
+
+                    // Fake the unit.
+                    let mut units = UnitTable::default();
+                    let unit = units.add(Unit::new(encoding, LineProgram::none()));
+                    let unit = units.get(unit);
+                    let from_unit = read::UnitHeader::new(
+                        encoding,
+                        0,
+                        read::UnitType::Compilation,
+                        DebugAbbrevOffset(0),
+                        DebugInfoOffset(0).into(),
+                        read::EndianSlice::new(&[], LittleEndian),
+                    );
+
+                    for &(ref name, ref value, ref expect_value) in &[
+                        (
+                            constants::DW_AT_stmt_list,
+                            AttributeValue::LineProgramRef,
+                            read::AttributeValue::SecOffset(line_program_offset.0),
+                        ),
+                        (
+                            constants::DW_AT_decl_file,
+                            AttributeValue::FileIndex(Some(file1)),
+                            read::AttributeValue::Udata(file1.raw()),
+                        ),
+                        (
+                            constants::DW_AT_decl_file,
+                            AttributeValue::FileIndex(Some(file2)),
+                            read::AttributeValue::Udata(file2.raw()),
+                        ),
+                    ][..]
+                    {
+                        let mut ranges = RangeListTable::default();
+                        let mut locations = LocationListTable::default();
+                        let mut strings = StringTable::default();
+                        let mut line_strings = LineStringTable::default();
+
+                        let form = value.form(encoding).unwrap();
+                        let attr = Attribute {
+                            name: *name,
+                            value: value.clone(),
+                        };
+
+                        let mut debug_info_refs = Vec::new();
+                        let mut unit_refs = Vec::new();
+                        let mut debug_info = DebugInfo::from(EndianVec::new(LittleEndian));
+                        let offsets = UnitOffsets::none();
+                        let debug_line_str_offsets = DebugLineStrOffsets::none();
+                        let debug_str_offsets = DebugStrOffsets::none();
+                        let range_list_offsets = RangeListOffsets::none();
+                        let loc_list_offsets = LocationListOffsets::none();
+                        attr.value
+                            .write(
+                                &mut debug_info,
+                                &mut debug_info_refs,
+                                &mut unit_refs,
+                                &unit,
+                                &offsets,
+                                Some(line_program_offset),
+                                &debug_line_str_offsets,
+                                &debug_str_offsets,
+                                &range_list_offsets,
+                                &loc_list_offsets,
+                            )
+                            .unwrap();
+
+                        let spec = read::AttributeSpecification::new(*name, form, None);
+                        let mut r = read::EndianSlice::new(debug_info.slice(), LittleEndian);
+                        let read_attr = read::parse_attribute(&mut r, encoding, spec).unwrap();
+                        let read_value = &read_attr.raw_value();
+                        // read::AttributeValue is invariant in the lifetime of R.
+                        // The lifetimes here are all okay, so transmute it.
+                        let read_value = unsafe {
+                            mem::transmute::<
+                                &read::AttributeValue<read::EndianSlice<LittleEndian>>,
+                                &read::AttributeValue<read::EndianSlice<LittleEndian>>,
+                            >(read_value)
+                        };
+                        assert_eq!(read_value, expect_value);
+
+                        let unit = read::Unit {
+                            header: from_unit,
+                            abbreviations: Arc::new(read::Abbreviations::default()),
+                            name: None,
+                            comp_dir: None,
+                            low_pc: 0,
+                            str_offsets_base: DebugStrOffsetsBase(0),
+                            addr_base: DebugAddrBase(0),
+                            loclists_base: DebugLocListsBase(0),
+                            rnglists_base: DebugRngListsBase(0),
+                            line_program: None,
+                            dwo_id: None,
+                        };
+
+                        let mut context = convert::ConvertUnitContext {
+                            dwarf: &dwarf,
+                            unit: &unit,
+                            line_strings: &mut line_strings,
+                            strings: &mut strings,
+                            ranges: &mut ranges,
+                            locations: &mut locations,
+                            convert_address: &|address| Some(Address::Constant(address)),
+                            base_address: Address::Constant(0),
+                            line_program_offset: Some(line_program_offset),
+                            line_program_files: line_program_files.clone(),
+                            entry_ids: &HashMap::new(),
+                        };
+
+                        let convert_attr =
+                            Attribute::from(&mut context, &read_attr).unwrap().unwrap();
+                        assert_eq!(convert_attr, attr);
+                    }
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn test_line_program_used() {
+        for used in vec![false, true] {
+            let encoding = Encoding {
+                format: Format::Dwarf32,
+                version: 5,
+                address_size: 8,
+            };
+
+            let line_program = LineProgram::new(
+                encoding,
+                LineEncoding::default(),
+                LineString::String(b"comp_dir".to_vec()),
+                LineString::String(b"comp_name".to_vec()),
+                None,
+            );
+
+            let mut unit = Unit::new(encoding, line_program);
+            let file_id = if used { Some(FileId::new(0)) } else { None };
+            let root = unit.root();
+            unit.get_mut(root).set(
+                constants::DW_AT_decl_file,
+                AttributeValue::FileIndex(file_id),
+            );
+
+            let mut units = UnitTable::default();
+            units.add(unit);
+
+            let debug_line_str_offsets = DebugLineStrOffsets::none();
+            let debug_str_offsets = DebugStrOffsets::none();
+            let mut sections = Sections::new(EndianVec::new(LittleEndian));
+            units
+                .write(&mut sections, &debug_line_str_offsets, &debug_str_offsets)
+                .unwrap();
+            assert_eq!(!used, sections.debug_line.slice().is_empty());
+        }
+    }
+
+    #[test]
+    fn test_delete_child() {
+        fn set_name(unit: &mut Unit, id: UnitEntryId, name: &str) {
+            let entry = unit.get_mut(id);
+            entry.set(constants::DW_AT_name, AttributeValue::String(name.into()));
+        }
+        fn check_name<R: read::Reader>(
+            entry: &read::DebuggingInformationEntry<R>,
+            debug_str: &read::DebugStr<R>,
+            name: &str,
+        ) {
+            let name_attr = entry.attr(constants::DW_AT_name).unwrap().unwrap();
+            let entry_name = name_attr.string_value(debug_str).unwrap();
+            let entry_name_str = entry_name.to_string().unwrap();
+            assert_eq!(entry_name_str, name);
+        }
+        let encoding = Encoding {
+            format: Format::Dwarf32,
+            version: 4,
+            address_size: 8,
+        };
+        let mut dwarf = DwarfUnit::new(encoding);
+        let root = dwarf.unit.root();
+
+        // Add and delete entries in the root unit
+        let child1 = dwarf.unit.add(root, constants::DW_TAG_subprogram);
+        set_name(&mut dwarf.unit, child1, "child1");
+        let grandchild1 = dwarf.unit.add(child1, constants::DW_TAG_variable);
+        set_name(&mut dwarf.unit, grandchild1, "grandchild1");
+        let child2 = dwarf.unit.add(root, constants::DW_TAG_subprogram);
+        set_name(&mut dwarf.unit, child2, "child2");
+        // This deletes both `child1` and its child `grandchild1`
+        dwarf.unit.get_mut(root).delete_child(child1);
+        let child3 = dwarf.unit.add(root, constants::DW_TAG_subprogram);
+        set_name(&mut dwarf.unit, child3, "child3");
+        let child4 = dwarf.unit.add(root, constants::DW_TAG_subprogram);
+        set_name(&mut dwarf.unit, child4, "child4");
+        let grandchild4 = dwarf.unit.add(child4, constants::DW_TAG_variable);
+        set_name(&mut dwarf.unit, grandchild4, "grandchild4");
+        dwarf.unit.get_mut(child4).delete_child(grandchild4);
+
+        let mut sections = Sections::new(EndianVec::new(LittleEndian));
+
+        // Write DWARF data which should only include `child2`, `child3` and `child4`
+        dwarf.write(&mut sections).unwrap();
+
+        let read_debug_info = read::DebugInfo::new(sections.debug_info.slice(), LittleEndian);
+        let read_debug_abbrev = read::DebugAbbrev::new(sections.debug_abbrev.slice(), LittleEndian);
+        let read_debug_str = read::DebugStr::new(sections.debug_str.slice(), LittleEndian);
+        let read_unit = read_debug_info.units().next().unwrap().unwrap();
+        let abbrevs = read_unit.abbreviations(&read_debug_abbrev).unwrap();
+        let mut entries = read_unit.entries(&abbrevs);
+        // root
+        entries.next_dfs().unwrap().unwrap();
+        // child2
+        let (_, read_child2) = entries.next_dfs().unwrap().unwrap();
+        check_name(read_child2, &read_debug_str, "child2");
+        // child3
+        let (_, read_child3) = entries.next_dfs().unwrap().unwrap();
+        check_name(read_child3, &read_debug_str, "child3");
+        // child4
+        let (_, read_child4) = entries.next_dfs().unwrap().unwrap();
+        check_name(read_child4, &read_debug_str, "child4");
+        // There should be no more entries
+        assert!(entries.next_dfs().unwrap().is_none());
+    }
+}
diff --git a/vendor/gimli/src/write/writer.rs b/vendor/gimli/src/write/writer.rs
new file mode 100644
index 0000000..1ce3641
--- /dev/null
+++ b/vendor/gimli/src/write/writer.rs
@@ -0,0 +1,494 @@
+use crate::common::{Format, SectionId};
+use crate::constants;
+use crate::endianity::Endianity;
+use crate::leb128;
+use crate::write::{Address, Error, Result};
+
+/// A trait for writing the data to a DWARF section.
+///
+/// All write operations append to the section unless otherwise specified.
+#[allow(clippy::len_without_is_empty)]
+pub trait Writer {
+    /// The endianity of bytes that are written.
+    type Endian: Endianity;
+
+    /// Return the endianity of bytes that are written.
+    fn endian(&self) -> Self::Endian;
+
+    /// Return the current section length.
+    ///
+    /// This may be used as an offset for future `write_at` calls.
+    fn len(&self) -> usize;
+
+    /// Write a slice.
+    fn write(&mut self, bytes: &[u8]) -> Result<()>;
+
+    /// Write a slice at a given offset.
+    ///
+    /// The write must not extend past the current section length.
+    fn write_at(&mut self, offset: usize, bytes: &[u8]) -> Result<()>;
+
+    /// Write an address.
+    ///
+    /// If the writer supports relocations, then it must provide its own implementation
+    /// of this method.
+    // TODO: use write_reference instead?
+    fn write_address(&mut self, address: Address, size: u8) -> Result<()> {
+        match address {
+            Address::Constant(val) => self.write_udata(val, size),
+            Address::Symbol { .. } => Err(Error::InvalidAddress),
+        }
+    }
+
+    /// Write an address with a `.eh_frame` pointer encoding.
+    ///
+    /// The given size is only used for `DW_EH_PE_absptr` formats.
+    ///
+    /// If the writer supports relocations, then it must provide its own implementation
+    /// of this method.
+    fn write_eh_pointer(
+        &mut self,
+        address: Address,
+        eh_pe: constants::DwEhPe,
+        size: u8,
+    ) -> Result<()> {
+        match address {
+            Address::Constant(val) => {
+                // Indirect doesn't matter here.
+                let val = match eh_pe.application() {
+                    constants::DW_EH_PE_absptr => val,
+                    constants::DW_EH_PE_pcrel => {
+                        // TODO: better handling of sign
+                        let offset = self.len() as u64;
+                        val.wrapping_sub(offset)
+                    }
+                    _ => {
+                        return Err(Error::UnsupportedPointerEncoding(eh_pe));
+                    }
+                };
+                self.write_eh_pointer_data(val, eh_pe.format(), size)
+            }
+            Address::Symbol { .. } => Err(Error::InvalidAddress),
+        }
+    }
+
+    /// Write a value with a `.eh_frame` pointer format.
+    ///
+    /// The given size is only used for `DW_EH_PE_absptr` formats.
+    ///
+    /// This must not be used directly for values that may require relocation.
+    fn write_eh_pointer_data(
+        &mut self,
+        val: u64,
+        format: constants::DwEhPe,
+        size: u8,
+    ) -> Result<()> {
+        match format {
+            constants::DW_EH_PE_absptr => self.write_udata(val, size),
+            constants::DW_EH_PE_uleb128 => self.write_uleb128(val),
+            constants::DW_EH_PE_udata2 => self.write_udata(val, 2),
+            constants::DW_EH_PE_udata4 => self.write_udata(val, 4),
+            constants::DW_EH_PE_udata8 => self.write_udata(val, 8),
+            constants::DW_EH_PE_sleb128 => self.write_sleb128(val as i64),
+            constants::DW_EH_PE_sdata2 => self.write_sdata(val as i64, 2),
+            constants::DW_EH_PE_sdata4 => self.write_sdata(val as i64, 4),
+            constants::DW_EH_PE_sdata8 => self.write_sdata(val as i64, 8),
+            _ => Err(Error::UnsupportedPointerEncoding(format)),
+        }
+    }
+
+    /// Write an offset that is relative to the start of the given section.
+    ///
+    /// If the writer supports relocations, then it must provide its own implementation
+    /// of this method.
+    fn write_offset(&mut self, val: usize, _section: SectionId, size: u8) -> Result<()> {
+        self.write_udata(val as u64, size)
+    }
+
+    /// Write an offset that is relative to the start of the given section.
+    ///
+    /// If the writer supports relocations, then it must provide its own implementation
+    /// of this method.
+    fn write_offset_at(
+        &mut self,
+        offset: usize,
+        val: usize,
+        _section: SectionId,
+        size: u8,
+    ) -> Result<()> {
+        self.write_udata_at(offset, val as u64, size)
+    }
+
+    /// Write a reference to a symbol.
+    ///
+    /// If the writer supports symbols, then it must provide its own implementation
+    /// of this method.
+    fn write_reference(&mut self, _symbol: usize, _size: u8) -> Result<()> {
+        Err(Error::InvalidReference)
+    }
+
+    /// Write a u8.
+    fn write_u8(&mut self, val: u8) -> Result<()> {
+        let bytes = [val];
+        self.write(&bytes)
+    }
+
+    /// Write a u16.
+    fn write_u16(&mut self, val: u16) -> Result<()> {
+        let mut bytes = [0; 2];
+        self.endian().write_u16(&mut bytes, val);
+        self.write(&bytes)
+    }
+
+    /// Write a u32.
+    fn write_u32(&mut self, val: u32) -> Result<()> {
+        let mut bytes = [0; 4];
+        self.endian().write_u32(&mut bytes, val);
+        self.write(&bytes)
+    }
+
+    /// Write a u64.
+    fn write_u64(&mut self, val: u64) -> Result<()> {
+        let mut bytes = [0; 8];
+        self.endian().write_u64(&mut bytes, val);
+        self.write(&bytes)
+    }
+
+    /// Write a u8 at the given offset.
+    fn write_u8_at(&mut self, offset: usize, val: u8) -> Result<()> {
+        let bytes = [val];
+        self.write_at(offset, &bytes)
+    }
+
+    /// Write a u16 at the given offset.
+    fn write_u16_at(&mut self, offset: usize, val: u16) -> Result<()> {
+        let mut bytes = [0; 2];
+        self.endian().write_u16(&mut bytes, val);
+        self.write_at(offset, &bytes)
+    }
+
+    /// Write a u32 at the given offset.
+    fn write_u32_at(&mut self, offset: usize, val: u32) -> Result<()> {
+        let mut bytes = [0; 4];
+        self.endian().write_u32(&mut bytes, val);
+        self.write_at(offset, &bytes)
+    }
+
+    /// Write a u64 at the given offset.
+    fn write_u64_at(&mut self, offset: usize, val: u64) -> Result<()> {
+        let mut bytes = [0; 8];
+        self.endian().write_u64(&mut bytes, val);
+        self.write_at(offset, &bytes)
+    }
+
+    /// Write unsigned data of the given size.
+    ///
+    /// Returns an error if the value is too large for the size.
+    /// This must not be used directly for values that may require relocation.
+    fn write_udata(&mut self, val: u64, size: u8) -> Result<()> {
+        match size {
+            1 => {
+                let write_val = val as u8;
+                if val != u64::from(write_val) {
+                    return Err(Error::ValueTooLarge);
+                }
+                self.write_u8(write_val)
+            }
+            2 => {
+                let write_val = val as u16;
+                if val != u64::from(write_val) {
+                    return Err(Error::ValueTooLarge);
+                }
+                self.write_u16(write_val)
+            }
+            4 => {
+                let write_val = val as u32;
+                if val != u64::from(write_val) {
+                    return Err(Error::ValueTooLarge);
+                }
+                self.write_u32(write_val)
+            }
+            8 => self.write_u64(val),
+            otherwise => Err(Error::UnsupportedWordSize(otherwise)),
+        }
+    }
+
+    /// Write signed data of the given size.
+    ///
+    /// Returns an error if the value is too large for the size.
+    /// This must not be used directly for values that may require relocation.
+    fn write_sdata(&mut self, val: i64, size: u8) -> Result<()> {
+        match size {
+            1 => {
+                let write_val = val as i8;
+                if val != i64::from(write_val) {
+                    return Err(Error::ValueTooLarge);
+                }
+                self.write_u8(write_val as u8)
+            }
+            2 => {
+                let write_val = val as i16;
+                if val != i64::from(write_val) {
+                    return Err(Error::ValueTooLarge);
+                }
+                self.write_u16(write_val as u16)
+            }
+            4 => {
+                let write_val = val as i32;
+                if val != i64::from(write_val) {
+                    return Err(Error::ValueTooLarge);
+                }
+                self.write_u32(write_val as u32)
+            }
+            8 => self.write_u64(val as u64),
+            otherwise => Err(Error::UnsupportedWordSize(otherwise)),
+        }
+    }
+
+    /// Write a word of the given size at the given offset.
+    ///
+    /// Returns an error if the value is too large for the size.
+    /// This must not be used directly for values that may require relocation.
+    fn write_udata_at(&mut self, offset: usize, val: u64, size: u8) -> Result<()> {
+        match size {
+            1 => {
+                let write_val = val as u8;
+                if val != u64::from(write_val) {
+                    return Err(Error::ValueTooLarge);
+                }
+                self.write_u8_at(offset, write_val)
+            }
+            2 => {
+                let write_val = val as u16;
+                if val != u64::from(write_val) {
+                    return Err(Error::ValueTooLarge);
+                }
+                self.write_u16_at(offset, write_val)
+            }
+            4 => {
+                let write_val = val as u32;
+                if val != u64::from(write_val) {
+                    return Err(Error::ValueTooLarge);
+                }
+                self.write_u32_at(offset, write_val)
+            }
+            8 => self.write_u64_at(offset, val),
+            otherwise => Err(Error::UnsupportedWordSize(otherwise)),
+        }
+    }
+
+    /// Write an unsigned LEB128 encoded integer.
+    fn write_uleb128(&mut self, val: u64) -> Result<()> {
+        let mut bytes = [0u8; 10];
+        // bytes is long enough so this will never fail.
+        let len = leb128::write::unsigned(&mut { &mut bytes[..] }, val).unwrap();
+        self.write(&bytes[..len])
+    }
+
+    /// Read an unsigned LEB128 encoded integer.
+    fn write_sleb128(&mut self, val: i64) -> Result<()> {
+        let mut bytes = [0u8; 10];
+        // bytes is long enough so this will never fail.
+        let len = leb128::write::signed(&mut { &mut bytes[..] }, val).unwrap();
+        self.write(&bytes[..len])
+    }
+
+    /// Write an initial length according to the given DWARF format.
+    ///
+    /// This will only write a length of zero, since the length isn't
+    /// known yet, and a subsequent call to `write_initial_length_at`
+    /// will write the actual length.
+    fn write_initial_length(&mut self, format: Format) -> Result<InitialLengthOffset> {
+        if format == Format::Dwarf64 {
+            self.write_u32(0xffff_ffff)?;
+        }
+        let offset = InitialLengthOffset(self.len());
+        self.write_udata(0, format.word_size())?;
+        Ok(offset)
+    }
+
+    /// Write an initial length at the given offset according to the given DWARF format.
+    ///
+    /// `write_initial_length` must have previously returned the offset.
+    fn write_initial_length_at(
+        &mut self,
+        offset: InitialLengthOffset,
+        length: u64,
+        format: Format,
+    ) -> Result<()> {
+        self.write_udata_at(offset.0, length, format.word_size())
+    }
+}
+
+/// The offset at which an initial length should be written.
+#[derive(Debug, Clone, Copy)]
+pub struct InitialLengthOffset(usize);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::write;
+    use crate::{BigEndian, LittleEndian};
+    use std::{i64, u64};
+
+    #[test]
+    fn test_writer() {
+        let mut w = write::EndianVec::new(LittleEndian);
+        w.write_address(Address::Constant(0x1122_3344), 4).unwrap();
+        assert_eq!(w.slice(), &[0x44, 0x33, 0x22, 0x11]);
+        assert_eq!(
+            w.write_address(
+                Address::Symbol {
+                    symbol: 0,
+                    addend: 0
+                },
+                4
+            ),
+            Err(Error::InvalidAddress)
+        );
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        w.write_offset(0x1122_3344, SectionId::DebugInfo, 4)
+            .unwrap();
+        assert_eq!(w.slice(), &[0x44, 0x33, 0x22, 0x11]);
+        w.write_offset_at(1, 0x5566, SectionId::DebugInfo, 2)
+            .unwrap();
+        assert_eq!(w.slice(), &[0x44, 0x66, 0x55, 0x11]);
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        w.write_u8(0x11).unwrap();
+        w.write_u16(0x2233).unwrap();
+        w.write_u32(0x4455_6677).unwrap();
+        w.write_u64(0x8081_8283_8485_8687).unwrap();
+        #[rustfmt::skip]
+        assert_eq!(w.slice(), &[
+            0x11,
+            0x33, 0x22,
+            0x77, 0x66, 0x55, 0x44,
+            0x87, 0x86, 0x85, 0x84, 0x83, 0x82, 0x81, 0x80,
+        ]);
+        w.write_u8_at(14, 0x11).unwrap();
+        w.write_u16_at(12, 0x2233).unwrap();
+        w.write_u32_at(8, 0x4455_6677).unwrap();
+        w.write_u64_at(0, 0x8081_8283_8485_8687).unwrap();
+        #[rustfmt::skip]
+        assert_eq!(w.slice(), &[
+            0x87, 0x86, 0x85, 0x84, 0x83, 0x82, 0x81, 0x80,
+            0x77, 0x66, 0x55, 0x44,
+            0x33, 0x22,
+            0x11,
+        ]);
+
+        let mut w = write::EndianVec::new(BigEndian);
+        w.write_u8(0x11).unwrap();
+        w.write_u16(0x2233).unwrap();
+        w.write_u32(0x4455_6677).unwrap();
+        w.write_u64(0x8081_8283_8485_8687).unwrap();
+        #[rustfmt::skip]
+        assert_eq!(w.slice(), &[
+            0x11,
+            0x22, 0x33,
+            0x44, 0x55, 0x66, 0x77,
+            0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
+        ]);
+        w.write_u8_at(14, 0x11).unwrap();
+        w.write_u16_at(12, 0x2233).unwrap();
+        w.write_u32_at(8, 0x4455_6677).unwrap();
+        w.write_u64_at(0, 0x8081_8283_8485_8687).unwrap();
+        #[rustfmt::skip]
+        assert_eq!(w.slice(), &[
+            0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
+            0x44, 0x55, 0x66, 0x77,
+            0x22, 0x33,
+            0x11,
+        ]);
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        w.write_udata(0x11, 1).unwrap();
+        w.write_udata(0x2233, 2).unwrap();
+        w.write_udata(0x4455_6677, 4).unwrap();
+        w.write_udata(0x8081_8283_8485_8687, 8).unwrap();
+        #[rustfmt::skip]
+        assert_eq!(w.slice(), &[
+            0x11,
+            0x33, 0x22,
+            0x77, 0x66, 0x55, 0x44,
+            0x87, 0x86, 0x85, 0x84, 0x83, 0x82, 0x81, 0x80,
+        ]);
+        assert_eq!(w.write_udata(0x100, 1), Err(Error::ValueTooLarge));
+        assert_eq!(w.write_udata(0x1_0000, 2), Err(Error::ValueTooLarge));
+        assert_eq!(w.write_udata(0x1_0000_0000, 4), Err(Error::ValueTooLarge));
+        assert_eq!(w.write_udata(0x00, 3), Err(Error::UnsupportedWordSize(3)));
+        w.write_udata_at(14, 0x11, 1).unwrap();
+        w.write_udata_at(12, 0x2233, 2).unwrap();
+        w.write_udata_at(8, 0x4455_6677, 4).unwrap();
+        w.write_udata_at(0, 0x8081_8283_8485_8687, 8).unwrap();
+        #[rustfmt::skip]
+        assert_eq!(w.slice(), &[
+            0x87, 0x86, 0x85, 0x84, 0x83, 0x82, 0x81, 0x80,
+            0x77, 0x66, 0x55, 0x44,
+            0x33, 0x22,
+            0x11,
+        ]);
+        assert_eq!(w.write_udata_at(0, 0x100, 1), Err(Error::ValueTooLarge));
+        assert_eq!(w.write_udata_at(0, 0x1_0000, 2), Err(Error::ValueTooLarge));
+        assert_eq!(
+            w.write_udata_at(0, 0x1_0000_0000, 4),
+            Err(Error::ValueTooLarge)
+        );
+        assert_eq!(
+            w.write_udata_at(0, 0x00, 3),
+            Err(Error::UnsupportedWordSize(3))
+        );
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        w.write_uleb128(0).unwrap();
+        assert_eq!(w.slice(), &[0]);
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        w.write_uleb128(u64::MAX).unwrap();
+        assert_eq!(
+            w.slice(),
+            &[0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 1]
+        );
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        w.write_sleb128(0).unwrap();
+        assert_eq!(w.slice(), &[0]);
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        w.write_sleb128(i64::MAX).unwrap();
+        assert_eq!(
+            w.slice(),
+            &[0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0]
+        );
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        w.write_sleb128(i64::MIN).unwrap();
+        assert_eq!(
+            w.slice(),
+            &[0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x7f]
+        );
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        let offset = w.write_initial_length(Format::Dwarf32).unwrap();
+        assert_eq!(w.slice(), &[0, 0, 0, 0]);
+        w.write_initial_length_at(offset, 0x1122_3344, Format::Dwarf32)
+            .unwrap();
+        assert_eq!(w.slice(), &[0x44, 0x33, 0x22, 0x11]);
+        assert_eq!(
+            w.write_initial_length_at(offset, 0x1_0000_0000, Format::Dwarf32),
+            Err(Error::ValueTooLarge)
+        );
+
+        let mut w = write::EndianVec::new(LittleEndian);
+        let offset = w.write_initial_length(Format::Dwarf64).unwrap();
+        assert_eq!(w.slice(), &[0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0]);
+        w.write_initial_length_at(offset, 0x1122_3344_5566_7788, Format::Dwarf64)
+            .unwrap();
+        assert_eq!(
+            w.slice(),
+            &[0xff, 0xff, 0xff, 0xff, 0x88, 0x77, 0x66, 0x55, 0x44, 0x33, 0x22, 0x11]
+        );
+    }
+}