[all-commits] [llvm/llvm-project] 167848: [LV] FoldTail w/o Primary Induction

[azaks via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 16784892347b213da1d53bc05f59984d66dd014d
      https://github.com/llvm/llvm-project/commit/16784892347b213da1d53bc05f59984d66dd014d
  Author: Ayal Zaks <ayal.zaks at intel.com>
  Date:   2020-04-09 (Thu, 09 Apr 2020)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/lib/Transforms/Vectorize/VPlan.cpp
    M llvm/lib/Transforms/Vectorize/VPlan.h
    M llvm/test/Transforms/LoopVectorize/X86/small-size.ll
    M llvm/test/Transforms/LoopVectorize/tail-folding-counting-down.ll

  Log Message:
  -----------
  [LV] FoldTail w/o Primary Induction

Introduce a new VPWidenCanonicalIVRecipe to generate a canonical vector
induction for use in fold-tail-with-masking, if a primary induction is absent.

The canonical scalar IV having start = 0 and step = VF*UF, created during code
-gen to control the vector loop, is widened into a canonical vector IV having
start = {<Part*VF, Part*VF+1, ..., Part*VF+VF-1> for 0 <= Part < UF} and
step = <VF*UF, VF*UF, ..., VF*UF>.

Differential Revision: https://reviews.llvm.org/D77635