[all-commits] [llvm/llvm-project] bda8fb: [LV] Fallback strategies if tail-folding fails

[sjoerdmeijer via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: bda8fbe2d2af208181efcf029b0c0bc0606da39b
      https://github.com/llvm/llvm-project/commit/bda8fbe2d2af208181efcf029b0c0bc0606da39b
  Author: Sjoerd Meijer <sjoerd.meijer at arm.com>
  Date:   2020-08-26 (Wed, 26 Aug 2020)

  Changed paths:
    M llvm/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h
    M llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/test/Transforms/LoopVectorize/ARM/prefer-tail-loop-folding.ll
    M llvm/test/Transforms/LoopVectorize/ARM/tail-folding-counting-down.ll
    M llvm/test/Transforms/LoopVectorize/ARM/tail-folding-prefer-flag.ll
    M llvm/test/Transforms/LoopVectorize/ARM/tail-folding-reduces-vf.ll
    A llvm/test/Transforms/LoopVectorize/ARM/tail-folding-scalar-epilogue-fallback.ll
    M llvm/test/Transforms/LoopVectorize/Hexagon/invalidate-cm-after-invalidating-interleavegroups.ll
    M llvm/test/Transforms/LoopVectorize/X86/tail_loop_folding.ll
    M llvm/test/Transforms/LoopVectorize/memdep-fold-tail.ll
    M llvm/test/Transforms/LoopVectorize/pr46525-expander-insertpoint.ll
    M llvm/test/Transforms/LoopVectorize/reduction-predselect.ll
    M llvm/test/Transforms/LoopVectorize/tail-folding-counting-down.ll
    A llvm/test/Transforms/LoopVectorize/use-scalar-epilogue-if-tp-fails.ll

  Log Message:
  -----------
  [LV] Fallback strategies if tail-folding fails

This implements 2 different vectorisation fallback strategies if tail-folding
fails: 1) don't vectorise at all, or 2) vectorise using a scalar epilogue. This
can be controlled with option -prefer-predicate-over-epilogue, that has been
changed to take a numeric value corresponding to the tail-folding preference
and preferred fallback.

Patch by: Pierre van Houtryve, Sjoerd Meijer.

Differential Revision: https://reviews.llvm.org/D79783