[all-commits] [llvm/llvm-project] 83582c: [clang][CodeGen] Do not use atomicrmw in compound ...

[Antonio Frighetto via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 83582cfcdb4973a337195c1f59d6a3468d135434
      https://github.com/llvm/llvm-project/commit/83582cfcdb4973a337195c1f59d6a3468d135434
  Author: Antonio Frighetto <me at antoniofrighetto.com>
  Date:   2026-07-16 (Thu, 16 Jul 2026)

  Changed paths:
    M clang/lib/CodeGen/CGExprScalar.cpp
    M clang/test/CodeGen/c11atomics.c

  Log Message:
  -----------
  [clang][CodeGen] Do not use atomicrmw in compound assignments with FP conversions (#209114)

Per C11 6.5.16.2p1, when the left operand of operator `+=` has atomic
type, the right shall have arithmetic type. Do not try the `atomicrmw`
fast-path when FP conversion, arithmetic and truncation are required, as
a single atomic operation may not correctly capture the combined
semantics.

Fixes: https://github.com/llvm/llvm-project/issues/208997.



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