[all-commits] [llvm/llvm-project] 04f693: [DAG] Handle build_vector with all undefs in reduc...

[Pierre van Houtryve via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 04f69345894dc6f750b25e7cfb1d4240817203a7
      https://github.com/llvm/llvm-project/commit/04f69345894dc6f750b25e7cfb1d4240817203a7
  Author: pvanhout <pierre.vanhoutryve at amd.com>
  Date:   2023-02-14 (Tue, 14 Feb 2023)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    A llvm/test/CodeGen/AMDGPU/undef-build-vector.ll

  Log Message:
  -----------
  [DAG] Handle build_vector with all undefs in reduceBuildVecTruncToBitCast

While working on D143731 I hit a case where a build_vector with 2 undef operands could be generated (with one undef hidden behind a bitcast).
That made `reduceBuildVecTruncToBitCast` crash because it seems to assume there is at least one good operand.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D143886