[all-commits] [llvm/llvm-project] 23cc19: AMDGPU: Invalidate VCC live ranges when lowering k...

[Matt Arsenault via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 23cc19ae2dc9fa7db608fc748cbcf04c186b64f0
      https://github.com/llvm/llvm-project/commit/23cc19ae2dc9fa7db608fc748cbcf04c186b64f0
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2026-09-24 (Thu, 24 Sep 2026)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp
    M llvm/test/CodeGen/AMDGPU/wqm.mir

  Log Message:
  -----------
  AMDGPU: Invalidate VCC live ranges when lowering kill instructions (#226040)

lowerKillInstr replaces the kill pseudo with a v_cmp defining VCC plus
two instructions reading it, but left any previously computed VCC
regunit ranges alone. If something had already materialized them, the
new uses have no live segment:

  *** Bad machine code: No live segment at use ***
  - instruction: $exec = S_ANDN2_B64_term $exec, $vcc, implicit-def $scc

Drop the ranges so they are recomputed on demand, as is already done for
EXEC and SCC.

Co-Authored-By: Claude Opus 5 <noreply at anthropic.com>



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