[all-commits] [llvm/llvm-project] 8e0c5f: [LV] Mark first-order recurrences as allowed exits

[azaks via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 8e0c5f72005855377197d0f8eb851d7cb889c834
      https://github.com/llvm/llvm-project/commit/8e0c5f72005855377197d0f8eb851d7cb889c834
  Author: Ayal Zaks <ayal.zaks at intel.com>
  Date:   2020-04-18 (Sat, 18 Apr 2020)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
    M llvm/test/Transforms/LoopVectorize/optsize.ll

  Log Message:
  -----------
  [LV] Mark first-order recurrences as allowed exits

First-order recurrences require special treatment when they are live-out;
such treatment is provided by fixFirstOrderRecurrence(), so they should be
included in AllowedExit set.

(Should probably have been included originally in D16197.)

Fixes PR45526: AllowedExit set is used by prepareToFoldTailByMasking() to
check whether the treatment for live-outs also holds when folding the tail,
which is not (yet) the case for first-order recurrences.

Differential Revision: https://reviews.llvm.org/D78210