1 files changed, 172 insertions, 0 deletions
diff --git a/vendor/portable-atomic/src/imp/fallback/outline_atomics.rs b/vendor/portable-atomic/src/imp/fallback/outline_atomics.rs
new file mode 100644
index 0000000..895b60c
--- /dev/null
+++ b/vendor/portable-atomic/src/imp/fallback/outline_atomics.rs
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+// Helper for outline-atomics.
+//
+// On architectures where DW atomics are not supported on older CPUs, we use
+// fallback implementation when DW atomic instructions are not supported and
+// outline-atomics is enabled.
+//
+// This module provides helpers to implement them.
+
+use core::sync::atomic::Ordering;
+
+#[cfg(any(target_arch = "x86_64", target_arch = "powerpc64"))]
+pub(crate) type Udw = u128;
+#[cfg(any(target_arch = "x86_64", target_arch = "powerpc64"))]
+pub(crate) type AtomicUdw = super::super::fallback::AtomicU128;
+#[cfg(any(target_arch = "x86_64", target_arch = "powerpc64"))]
+pub(crate) type AtomicIdw = super::super::fallback::AtomicI128;
+
+#[cfg(target_arch = "arm")]
+pub(crate) type Udw = u64;
+#[cfg(target_arch = "arm")]
+pub(crate) type AtomicUdw = super::super::fallback::AtomicU64;
+#[cfg(target_arch = "arm")]
+pub(crate) type AtomicIdw = super::super::fallback::AtomicI64;
+
+// Asserts that the function is called in the correct context.
+macro_rules! debug_assert_outline_atomics {
+    () => {
+        #[cfg(target_arch = "x86_64")]
+        {
+            debug_assert!(!super::detect::detect().has_cmpxchg16b());
+        }
+        #[cfg(target_arch = "powerpc64")]
+        {
+            debug_assert!(!super::detect::detect().has_quadword_atomics());
+        }
+        #[cfg(target_arch = "arm")]
+        {
+            debug_assert!(!super::has_kuser_cmpxchg64());
+        }
+    };
+}
+
+#[cold]
+pub(crate) unsafe fn atomic_load(src: *mut Udw, order: Ordering) -> Udw {
+    debug_assert_outline_atomics!();
+    #[allow(clippy::cast_ptr_alignment)]
+    // SAFETY: the caller must uphold the safety contract.
+    unsafe {
+        (*(src as *const AtomicUdw)).load(order)
+    }
+}
+fn_alias! {
+    #[cold]
+    pub(crate) unsafe fn(src: *mut Udw) -> Udw;
+    // fallback's atomic load has at least acquire semantics.
+    #[cfg(not(any(target_arch = "arm", target_arch = "x86_64")))]
+    atomic_load_non_seqcst = atomic_load(Ordering::Acquire);
+    atomic_load_seqcst = atomic_load(Ordering::SeqCst);
+}
+
+#[cold]
+pub(crate) unsafe fn atomic_store(dst: *mut Udw, val: Udw, order: Ordering) {
+    debug_assert_outline_atomics!();
+    #[allow(clippy::cast_ptr_alignment)]
+    // SAFETY: the caller must uphold the safety contract.
+    unsafe {
+        (*(dst as *const AtomicUdw)).store(val, order);
+    }
+}
+fn_alias! {
+    #[cold]
+    pub(crate) unsafe fn(dst: *mut Udw, val: Udw);
+    // fallback's atomic store has at least release semantics.
+    #[cfg(not(target_arch = "arm"))]
+    atomic_store_non_seqcst = atomic_store(Ordering::Release);
+    atomic_store_seqcst = atomic_store(Ordering::SeqCst);
+}
+
+#[cold]
+pub(crate) unsafe fn atomic_compare_exchange(
+    dst: *mut Udw,
+    old: Udw,
+    new: Udw,
+    success: Ordering,
+    failure: Ordering,
+) -> (Udw, bool) {
+    debug_assert_outline_atomics!();
+    #[allow(clippy::cast_ptr_alignment)]
+    // SAFETY: the caller must uphold the safety contract.
+    unsafe {
+        match (*(dst as *const AtomicUdw)).compare_exchange(old, new, success, failure) {
+            Ok(v) => (v, true),
+            Err(v) => (v, false),
+        }
+    }
+}
+fn_alias! {
+    #[cold]
+    pub(crate) unsafe fn(dst: *mut Udw, old: Udw, new: Udw) -> (Udw, bool);
+    // fallback's atomic CAS has at least AcqRel semantics.
+    #[cfg(not(any(target_arch = "arm", target_arch = "x86_64")))]
+    atomic_compare_exchange_non_seqcst
+        = atomic_compare_exchange(Ordering::AcqRel, Ordering::Acquire);
+    atomic_compare_exchange_seqcst
+        = atomic_compare_exchange(Ordering::SeqCst, Ordering::SeqCst);
+}
+
+macro_rules! atomic_rmw_3 {
+    (
+        $name:ident($atomic_type:ident::$method_name:ident),
+        $non_seqcst_alias:ident, $seqcst_alias:ident
+    ) => {
+        #[cold]
+        pub(crate) unsafe fn $name(dst: *mut Udw, val: Udw, order: Ordering) -> Udw {
+            debug_assert_outline_atomics!();
+            #[allow(clippy::cast_ptr_alignment)]
+            // SAFETY: the caller must uphold the safety contract.
+            unsafe {
+                (*(dst as *const $atomic_type)).$method_name(val as _, order) as Udw
+            }
+        }
+        fn_alias! {
+            #[cold]
+            pub(crate) unsafe fn(dst: *mut Udw, val: Udw) -> Udw;
+            // fallback's atomic RMW has at least AcqRel semantics.
+            #[cfg(not(any(target_arch = "arm", target_arch = "x86_64")))]
+            $non_seqcst_alias = $name(Ordering::AcqRel);
+            $seqcst_alias = $name(Ordering::SeqCst);
+        }
+    };
+}
+macro_rules! atomic_rmw_2 {
+    (
+        $name:ident($atomic_type:ident::$method_name:ident),
+        $non_seqcst_alias:ident, $seqcst_alias:ident
+    ) => {
+        #[cold]
+        pub(crate) unsafe fn $name(dst: *mut Udw, order: Ordering) -> Udw {
+            debug_assert_outline_atomics!();
+            #[allow(clippy::cast_ptr_alignment)]
+            // SAFETY: the caller must uphold the safety contract.
+            unsafe {
+                (*(dst as *const $atomic_type)).$method_name(order) as Udw
+            }
+        }
+        fn_alias! {
+            #[cold]
+            pub(crate) unsafe fn(dst: *mut Udw) -> Udw;
+            // fallback's atomic RMW has at least AcqRel semantics.
+            #[cfg(not(any(target_arch = "arm", target_arch = "x86_64")))]
+            $non_seqcst_alias = $name(Ordering::AcqRel);
+            $seqcst_alias = $name(Ordering::SeqCst);
+        }
+    };
+}
+
+atomic_rmw_3!(atomic_swap(AtomicUdw::swap), atomic_swap_non_seqcst, atomic_swap_seqcst);
+atomic_rmw_3!(atomic_add(AtomicUdw::fetch_add), atomic_add_non_seqcst, atomic_add_seqcst);
+atomic_rmw_3!(atomic_sub(AtomicUdw::fetch_sub), atomic_sub_non_seqcst, atomic_sub_seqcst);
+atomic_rmw_3!(atomic_and(AtomicUdw::fetch_and), atomic_and_non_seqcst, atomic_and_seqcst);
+atomic_rmw_3!(atomic_nand(AtomicUdw::fetch_nand), atomic_nand_non_seqcst, atomic_nand_seqcst);
+atomic_rmw_3!(atomic_or(AtomicUdw::fetch_or), atomic_or_non_seqcst, atomic_or_seqcst);
+atomic_rmw_3!(atomic_xor(AtomicUdw::fetch_xor), atomic_xor_non_seqcst, atomic_xor_seqcst);
+atomic_rmw_3!(atomic_max(AtomicIdw::fetch_max), atomic_max_non_seqcst, atomic_max_seqcst);
+atomic_rmw_3!(atomic_umax(AtomicUdw::fetch_max), atomic_umax_non_seqcst, atomic_umax_seqcst);
+atomic_rmw_3!(atomic_min(AtomicIdw::fetch_min), atomic_min_non_seqcst, atomic_min_seqcst);
+atomic_rmw_3!(atomic_umin(AtomicUdw::fetch_min), atomic_umin_non_seqcst, atomic_umin_seqcst);
+
+atomic_rmw_2!(atomic_not(AtomicUdw::fetch_not), atomic_not_non_seqcst, atomic_not_seqcst);
+atomic_rmw_2!(atomic_neg(AtomicUdw::fetch_neg), atomic_neg_non_seqcst, atomic_neg_seqcst);