[all-commits] [llvm/llvm-project] 5a11b1: 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: 5a11b16842ae5ddb4412fdf4a61ca75d342764b9
      https://github.com/llvm/llvm-project/commit/5a11b16842ae5ddb4412fdf4a61ca75d342764b9
  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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