[all-commits] [llvm/llvm-project] c83698: [VPlan] Remove unused first mask op from VPBlendRe...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c83698367125703827f1b739393f006c399cb213
      https://github.com/llvm/llvm-project/commit/c83698367125703827f1b739393f006c399cb213
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2024-04-09 (Tue, 09 Apr 2024)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/lib/Transforms/Vectorize/VPlan.h
    M llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
    M llvm/test/Transforms/LoopVectorize/AArch64/sve-tail-folding-reductions.ll
    M llvm/test/Transforms/LoopVectorize/RISCV/divrem.ll
    M llvm/test/Transforms/LoopVectorize/RISCV/select-cmp-reduction.ll
    M llvm/test/Transforms/LoopVectorize/RISCV/uniform-load-store.ll
    M llvm/test/Transforms/LoopVectorize/X86/drop-poison-generating-flags.ll
    M llvm/test/Transforms/LoopVectorize/X86/imprecise-through-phis.ll
    M llvm/test/Transforms/LoopVectorize/X86/load-deref-pred.ll
    M llvm/test/Transforms/LoopVectorize/X86/x86-predication.ll
    M llvm/test/Transforms/LoopVectorize/if-pred-non-void.ll
    M llvm/test/Transforms/LoopVectorize/if-reduction.ll
    M llvm/test/Transforms/LoopVectorize/load-deref-pred-align.ll
    M llvm/test/Transforms/LoopVectorize/reduction-small-size.ll
    M llvm/test/Transforms/LoopVectorize/select-cmp-predicated.ll
    M llvm/test/Transforms/LoopVectorize/single-value-blend-phis.ll
    M llvm/test/Transforms/LoopVectorize/uniform-blend.ll
    A llvm/test/Transforms/LoopVectorize/unused-blend-mask-for-first-operand.ll
    M llvm/test/Transforms/LoopVectorize/vplan-printing.ll
    M llvm/test/Transforms/LoopVectorize/vplan-sink-scalars-and-merge.ll
    M llvm/unittests/Transforms/Vectorize/VPlanTest.cpp

  Log Message:
  -----------
  [VPlan] Remove unused first mask op from VPBlendRecipe. (#87770)

VPBlendRecipe does not use the first mask operand. Removing it allows
VPlan-based DCE to remove unused mask computations.

This also fixes #87410, where unused Not VPInstructions are considered
having only their first lane demanded, but some of their operands
providing a vector value due to other users.

Fixes https://github.com/llvm/llvm-project/issues/87410

PR: https://github.com/llvm/llvm-project/pull/87770



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