[PATCH] D45834: [TTI] Add a hook to TTI for choosing scalarized shuffle-reduction sequence for reduction idiom

[Farhana Aleen via Phabricator via llvm-commits]

FarhanaAleen created this revision.
FarhanaAleen added a reviewer: RKSimon.

This patch adds a hook to TTI for choosing scalarized shuffle-reduction as opposed to vectorized shuffle-reduction sequence for reduction idiom.

Allows generation:

  %0 = extractelement <4 x float> %bin.rdx, i32 0
  %1 = extractelement <4 x float> %bin.rdx, i32 1
  %res = fadd fast float %0, %1

Instead of

  %rdx.shuf1 = shufflevector <4 x float> %bin.rdx, <4 x float> undef, <4 x i32> <i32 1, i32 undef, i32 undef, i32 undef>
  %bin.rdx2 = fadd fast <4 x float> %bin.rdx, %rdx.shuf1
  %res = extractelement <4 x float> %bin.rdx2, i32 0

Hi Simon,

This patch reflects your suggestion on https://reviews.llvm.org/D45393


https://reviews.llvm.org/D45834

Files:
  include/llvm/Analysis/TargetTransformInfo.h
  include/llvm/Analysis/TargetTransformInfoImpl.h
  include/llvm/Transforms/Utils/LoopUtils.h
  lib/Analysis/TargetTransformInfo.cpp
  lib/Transforms/Utils/LoopUtils.cpp

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