[all-commits] [llvm/llvm-project] 94b410: RISCV: Maintain VL/VTYPE liveness when clearing de...

[Matt Arsenault via All-commits]

  Branch: refs/heads/users/arsenm/riscv/vsetvli-dead-flag-liveness
  Home:   https://github.com/llvm/llvm-project
  Commit: 94b410e866600f971ef0dfa9852dca77d347f8b8
      https://github.com/llvm/llvm-project/commit/94b410e866600f971ef0dfa9852dca77d347f8b8
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2026-09-11 (Fri, 11 Sep 2026)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
    A llvm/test/CodeGen/RISCV/rvv/vsetvli-dead-vl-vtype-liveness.mir

  Log Message:
  -----------
  RISCV: Maintain VL/VTYPE liveness when clearing dead flags in InsertVSETVLI

Drop the stale VL/VTYPE ranges when a dead flag is cleared.

RISCVInsertVSETVLI marks the VL and VTYPE defs of an explicit VSETVLI as live by
clearing their dead flags, but did not update LiveIntervals. When a def was
previously a dead def, its live range is a zero-length dead-def segment
ending at the def slot; clearing the flag extends the def past that slot without
extending the range leaving a segment that references no instruction.

Co-authored-by: Claude claude-opus-4.8 <noreply at anthropic.com>



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