[all-commits] [llvm/llvm-project] 989ef9: [DAG] isGuaranteedNotToBeUndefOrPoison - add ISD::...

[Krzysztof Drewniak via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 989ef9ccdf6eb327f7b358485509774f11eadbce
      https://github.com/llvm/llvm-project/commit/989ef9ccdf6eb327f7b358485509774f11eadbce
  Author: Krzysztof Drewniak <Krzysztof.Drewniak at amd.com>
  Date:   2026-06-05 (Fri, 05 Jun 2026)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    M llvm/test/CodeGen/X86/freeze-vector.ll

  Log Message:
  -----------
  [DAG] isGuaranteedNotToBeUndefOrPoison - add ISD::BITCAST demanded elements handling (#200933)

Bitcasts preserve undef/poison status, but vector bitcasts can change
which source lanes cover a demanded result lane. Map the demanded
element mask through fixed-length vector bitcasts before checking the
source where possible.

AI note: an LLM generated the code and the test, I've read them

Fixes #161512

Co-Authored-By: OpenAI Codex <codex at openai.com>

---------

Co-authored-by: OpenAI Codex <codex at openai.com>



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