From 4cc5ab95e0a2d4d12d03502bf848b9642c550f3c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomasz=20Mi=C4=85sko?= <tomasz.miasko@gmail.com>
Date: Mon, 18 Jul 2022 00:00:00 +0000
Subject: [PATCH] Remove restrictions on compare-exchange memory ordering.
Update cmpxchg16b to match changes from rust-lang/rust#98383.
---
crates/core_arch/src/x86_64/cmpxchg16b.rs | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/crates/core_arch/src/x86_64/cmpxchg16b.rs b/crates/core_arch/src/x86_64/cmpxchg16b.rs
index 1a8a5de754..e1e9262e54 100644
--- a/crates/core_arch/src/x86_64/cmpxchg16b.rs
+++ b/crates/core_arch/src/x86_64/cmpxchg16b.rs
@@ -34,7 +34,7 @@ use stdarch_test::assert_instr;
/// support `cmpxchg16b` and the program enters an execution path that
/// eventually would reach this function the behavior is undefined.
///
-/// The `success` ordering must also be stronger or equal to `failure`, or this
+/// The failure ordering must be [`SeqCst`], [`Acquire`] or [`Relaxed`], or this
/// function call is undefined. See the `Atomic*` documentation's
/// `compare_exchange` function for more information. When `compare_exchange`
/// panics, this is undefined behavior. Currently this function aborts the
@@ -54,15 +54,21 @@ pub unsafe fn cmpxchg16b(
debug_assert!(dst as usize % 16 == 0);
let (val, _ok) = match (success, failure) {
- (Acquire, Acquire) => intrinsics::atomic_cxchg_acquire_acquire(dst, old, new),
- (Release, Relaxed) => intrinsics::atomic_cxchg_release_relaxed(dst, old, new),
- (AcqRel, Acquire) => intrinsics::atomic_cxchg_acqrel_acquire(dst, old, new),
(Relaxed, Relaxed) => intrinsics::atomic_cxchg_relaxed_relaxed(dst, old, new),
- (SeqCst, SeqCst) => intrinsics::atomic_cxchg_seqcst_seqcst(dst, old, new),
+ (Relaxed, Acquire) => intrinsics::atomic_cxchg_relaxed_acquire(dst, old, new),
+ (Relaxed, SeqCst) => intrinsics::atomic_cxchg_relaxed_seqcst(dst, old, new),
(Acquire, Relaxed) => intrinsics::atomic_cxchg_acquire_relaxed(dst, old, new),
+ (Acquire, Acquire) => intrinsics::atomic_cxchg_acquire_acquire(dst, old, new),
+ (Acquire, SeqCst) => intrinsics::atomic_cxchg_acquire_seqcst(dst, old, new),
+ (Release, Relaxed) => intrinsics::atomic_cxchg_release_relaxed(dst, old, new),
+ (Release, Acquire) => intrinsics::atomic_cxchg_release_acquire(dst, old, new),
+ (Release, SeqCst) => intrinsics::atomic_cxchg_release_seqcst(dst, old, new),
(AcqRel, Relaxed) => intrinsics::atomic_cxchg_acqrel_relaxed(dst, old, new),
+ (AcqRel, Acquire) => intrinsics::atomic_cxchg_acqrel_acquire(dst, old, new),
+ (AcqRel, SeqCst) => intrinsics::atomic_cxchg_acqrel_seqcst(dst, old, new),
(SeqCst, Relaxed) => intrinsics::atomic_cxchg_seqcst_relaxed(dst, old, new),
(SeqCst, Acquire) => intrinsics::atomic_cxchg_seqcst_acquire(dst, old, new),
+ (SeqCst, SeqCst) => intrinsics::atomic_cxchg_seqcst_seqcst(dst, old, new),
// The above block is all copied from libcore, and this statement is
// also copied from libcore except that it's a panic in libcore and we