[all-commits] [llvm/llvm-project] db7d61: CodeGen: Mark dead PHI destination copies dead in ...

[Matt Arsenault via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: db7d6187d470e93f89d142831182ae928472fce7
      https://github.com/llvm/llvm-project/commit/db7d6187d470e93f89d142831182ae928472fce7
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2026-09-23 (Wed, 23 Sep 2026)

  Changed paths:
    M llvm/lib/CodeGen/PHIElimination.cpp
    A llvm/test/CodeGen/X86/phi-elimination-dead-def.mir

  Log Message:
  -----------
  CodeGen: Mark dead PHI destination copies dead in the LiveIntervals path (#225760)

When PHIElimination lowers a PHI whose destination is dead, it records a
dead def in LiveIntervals but did not set the dead flag on the lowered
copy's def operand. The LiveVariables path set this via addVirtualRegisterDead.

Avoids "Instruction ending live segment on dead slot has no dead flag"
verifier errors once LiveVariables is removed.

Co-authored-by: Claude (Opus 4.8) <noreply at anthropic.com>



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