[PATCH] D25910: [VectorLegalizer] Expansion of CTLZ using CTPOP when possible

[Simon Pilgrim via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: echristo, craig.topper, ab, spatel, andreadb.
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This patch avoids scalarization of CTLZ by instead expanding to use CTPOP (from "Hacker's Delight") when the necessary operations are available.

This also adds the necessary cost models for X86 SSE2 targets (the main beneficiary) to ensure vectorization only happens when its useful.


Repository:
  rL LLVM

https://reviews.llvm.org/D25910

Files:
  lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
  lib/Target/X86/X86TargetTransformInfo.cpp
  test/Analysis/CostModel/X86/ctbits-cost.ll
  test/CodeGen/X86/vec_ctbits.ll
  test/CodeGen/X86/vector-lzcnt-128.ll
  test/Transforms/SLPVectorizer/X86/ctlz.ll

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