[all-commits] [llvm/llvm-project] 5e158f: [Clang][AMDGPU] Add ``amdgpu_av("none")`` attribut...

[Sameer Sahasrabuddhe via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 5e158f2fdb4ae1caf76278d991b2a83deb541506
      https://github.com/llvm/llvm-project/commit/5e158f2fdb4ae1caf76278d991b2a83deb541506
  Author: Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>
  Date:   2026-08-05 (Wed, 05 Aug 2026)

  Changed paths:
    M clang/include/clang/Basic/Attr.td
    M clang/include/clang/Basic/AttrDocs.td
    M clang/include/clang/Basic/DiagnosticGroups.td
    M clang/include/clang/Basic/DiagnosticSemaKinds.td
    M clang/lib/CodeGen/CGAtomic.cpp
    M clang/lib/CodeGen/CGBuiltin.cpp
    M clang/lib/CodeGen/CGStmt.cpp
    M clang/lib/CodeGen/CodeGenFunction.h
    M clang/lib/CodeGen/TargetBuiltins/AMDGPU.cpp
    M clang/lib/CodeGen/Targets/AMDGPU.cpp
    M clang/lib/Sema/SemaStmtAttr.cpp
    A clang/test/CodeGen/AMDGPU/amdgcn-av-non-atomic.cpp
    A clang/test/CodeGen/AMDGPU/amdgcn-av-none-amdgpu-atomic.cpp
    A clang/test/CodeGen/AMDGPU/amdgcn-av-none-attr-c-atomic.c
    A clang/test/CodeGen/AMDGPU/amdgcn-av-none-attr.cpp

  Log Message:
  -----------
  [Clang][AMDGPU] Add ``amdgpu_av("none")`` attribute for atomic expressions (#199622)

Add a statement attribute that suppresses MakeAvailable/MakeVisible
cache operations on AMDGPU atomic instructions while preserving memory
ordering (waits). The attribute takes a string argument specifying the
mode. Currently "none" is the only supported mode. The resulting atomic
or fence instruction carries !mmra !{!"amdgcn-av", !"none"} metadata.

This only works with builtins that get lowered to intrinsics or
instructions. The attribute does not survive inlining. For example, a
C++ std atomic is typically a wrapper around a Clang builtin, and
applying this attribute on the std atomic does not remove the
MakeAvailableMakeVisible semantics built into it.

Part of a stack:

- #199486
- #199621
- #199489 
- #208395 
- #199622

Fixes: LCOMPILER-2214

Assisted-By: Claude Opus 4.6



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