[PATCH] D54585: [TTI] Reduction costs only need to include a single extract element cost

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: ABataev, spatel, fhahn, craig.topper, javed.absar.
Herald added a subscriber: zzheng.

We were adding the entire scalarization extraction cost for reductions, which returns the total cost of extracting every element of a vector type.

For reductions we don't need to do this - we just need to extract the 0'th element after the reduction pattern has completed.

Fixes PR37731


Repository:
  rL LLVM

https://reviews.llvm.org/D54585

Files:
  include/llvm/CodeGen/BasicTTIImpl.h
  test/Analysis/CostModel/AArch64/vector-reduce.ll
  test/Analysis/CostModel/X86/reduce-add.ll
  test/Analysis/CostModel/X86/reduce-and.ll
  test/Analysis/CostModel/X86/reduce-mul.ll
  test/Analysis/CostModel/X86/reduce-or.ll
  test/Analysis/CostModel/X86/reduce-smax.ll
  test/Analysis/CostModel/X86/reduce-smin.ll
  test/Analysis/CostModel/X86/reduce-umax.ll
  test/Analysis/CostModel/X86/reduce-umin.ll
  test/Analysis/CostModel/X86/reduce-xor.ll
  test/Analysis/CostModel/X86/reduction.ll
  test/Transforms/SLPVectorizer/X86/horizontal-minmax.ll
  test/Transforms/SLPVectorizer/X86/reduction_unrolled.ll
  test/Transforms/SLPVectorizer/X86/remark_horcost.ll

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