[PATCH] D155218: [InstCombine] Optimize addition/subtraction operations of splats of vscale multiplied by a constant

[Igor Kirillov via Phabricator via llvm-commits]

igor.kirillov created this revision.
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This patch enhances the InstCombine pass to optimize addition and
subtraction operations involving splat values optionally multiplied
by a constant or shifted by a constant. The transformation combines
the operations as follows:

  (A +/- splat(B)) +/- splat(C) -> A +/- splat(B +/- C)

This optimization improves the performance of vectorized code with
interleave factor > 1, where indices are part of an expression.
For example, in cases such as the following loop:

  for (int i = A; i < B; ++i)
    out[i + offset] = (i + X) * Y;


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D155218

Files:
  llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
  llvm/test/Transforms/InstCombine/vscale.ll
  llvm/test/Transforms/LoopVectorize/AArch64/sve-gather-scatter.ll
  llvm/test/Transforms/LoopVectorize/scalable-inductions.ll

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