[all-commits] [llvm/llvm-project] 594cce: [AMDGPU] Change static NOP last terminator SI_DEMO...

[Domenic Nutile via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 594cce3cbcdbe46d6f9ac3c6a53f86ae63c5bc42
      https://github.com/llvm/llvm-project/commit/594cce3cbcdbe46d6f9ac3c6a53f86ae63c5bc42
  Author: Domenic Nutile <domenic.nutile at gmail.com>
  Date:   2026-06-23 (Tue, 23 Jun 2026)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp
    A llvm/test/CodeGen/AMDGPU/uniform-intrin-combine-wqm-demote.ll

  Log Message:
  -----------
  [AMDGPU] Change static NOP last terminator SI_DEMOTE_I1 to be replaced by S_BRANCH instead of assert (#204649)

This issue was first discovered in some testing downstream. A specific
chain of transformations on a ballot instruction with a constant
argument followed by an llvm.amgcn.wqm.demote call leads to an
instruction of `SI_DEMOTE_I1 -1, 0` being the last terminator of a block
with a single successor. This instruction is a NOP and can safely be
replaced with an S_BRANCH to the block's successor instead of asserting
failure.

The test added in this change is a very simplified recreation of the
pattern seen in the shader compilation in the downstream that lead to
assertion failure



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