[llvm-branch-commits] [clang] 98f06b1 - [AArch64][Docs] Release notes 12.x on outline atomics

[Pavel Iliin via llvm-branch-commits]

Author: Pavel Iliin
Date: 2021-03-01T17:36:24Z
New Revision: 98f06b16a313ece593f5711778d7da9037f3a2ef

URL: https://github.com/llvm/llvm-project/commit/98f06b16a313ece593f5711778d7da9037f3a2ef
DIFF: https://github.com/llvm/llvm-project/commit/98f06b16a313ece593f5711778d7da9037f3a2ef.diff

LOG: [AArch64][Docs] Release notes 12.x on outline atomics

Description for AArch64 -moutline-atomics, -mno-outline-atomics
options added to release notes.

Differential Revision: https://reviews.llvm.org/D97510

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst

Removed: 
    


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diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index a43cc33988ab..64f737ff488f 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -73,6 +73,15 @@ New Compiler Flags
 
 - ...
 
+- AArch64 options ``-moutline-atomics``, ``-mno-outline-atomics`` to enable
+  and disable calls to helper functions implementing atomic operations. These
+  out-of-line helpers like '__aarch64_cas8_relax' will detect at runtime
+  AArch64 Large System Extensions (LSE) availability and either use their
+  atomic instructions, or falls back to LL/SC loop. These options do not apply
+  if the compilation target supports LSE. Atomic instructions are used directly
+  in that case. The option's behaviour mirrors GCC, the helpers are implemented
+  both in compiler-rt and libgcc.
+
 - -fpch-codegen and -fpch-debuginfo generate shared code and/or debuginfo
   for contents of a precompiled header in a separate object file. This object
   file needs to be linked in, but its contents do not need to be generated