[all-commits] [llvm/llvm-project] 2ed7fa: [DirectX] Support `cmpxchg` on buffer resources in...

[Joshua Batista via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2ed7fafcb06c8c314fc5d88580a93a50e9054d1a
      https://github.com/llvm/llvm-project/commit/2ed7fafcb06c8c314fc5d88580a93a50e9054d1a
  Author: Joshua Batista <jbatista at microsoft.com>
  Date:   2026-09-24 (Thu, 24 Sep 2026)

  Changed paths:
    M llvm/include/llvm/IR/IntrinsicsDirectX.td
    M llvm/lib/Target/DirectX/DXIL.td
    M llvm/lib/Target/DirectX/DXILOpLowering.cpp
    M llvm/lib/Target/DirectX/DXILResourceAccess.cpp
    A llvm/test/CodeGen/DirectX/ResourceAtomicCompareExchange-i64-sm65.ll
    A llvm/test/CodeGen/DirectX/ResourceAtomicCompareExchange-texture-nonscalar.ll
    A llvm/test/CodeGen/DirectX/ResourceAtomicCompareExchange-texture-unsupported-kind.ll
    A llvm/test/CodeGen/DirectX/ResourceAtomicCompareExchange-texture.ll
    A llvm/test/CodeGen/DirectX/ResourceAtomicCompareExchange-unsupported-result.ll
    A llvm/test/CodeGen/DirectX/ResourceAtomicCompareExchange.ll

  Log Message:
  -----------
  [DirectX] Support `cmpxchg` on buffer resources in DXIL lowering (#222162)

This PR is a backend change alone. It teaches DXIL lowering to handle a
`cmpxchg` on a buffer resource pointer, which the
`InterlockedCompareStore`
and `InterlockedCompareExchange` PRs above it in this stack need.

The PR adds:

- the `llvm.dx.resource.atomic.compare.exchange` intrinsic,
- its DXIL operation and op lowering,
- the `DXILResourceAccess` handling that turns a `cmpxchg` on a value
  returned by `llvm.dx.resource.getpointer` into that intrinsic.

DXIL has no atomic compare exchange for texture resources, so the pass
reports an error for them. A test covers that path.

There is no Clang change here, and no HLSL function becomes available.

Assisted by: Github Copilot



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