[all-commits] [llvm/llvm-project] 99492a: CodeGen: Mark dead PHI destination copies dead in ...

[Matt Arsenault via All-commits]

  Branch: refs/heads/users/arsenm/phi-elimination-mark-dead-live-intervals
  Home:   https://github.com/llvm/llvm-project
  Commit: 99492a29f1243b2af4449031d42224b499994194
      https://github.com/llvm/llvm-project/commit/99492a29f1243b2af4449031d42224b499994194
  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

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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