[all-commits] [llvm/llvm-project] 32d9a3: [LV] Keep Primary Induction alive when folding tai...

[azaks via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 32d9a386bf8f447dbbfaf55f6fef4fea4463205b
      https://github.com/llvm/llvm-project/commit/32d9a386bf8f447dbbfaf55f6fef4fea4463205b
  Author: Ayal Zaks <ayal.zaks at intel.com>
  Date:   2020-11-24 (Tue, 24 Nov 2020)

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

  Log Message:
  -----------
  [LV] Keep Primary Induction alive when folding tail by masking

Fix PR47390.

The primary induction should be considered alive when folding tail by masking,
because it will be used by said masking; even when it may otherwise appear
useless: feeding only its own 'bump', which is correctly considered dead, and
as the 'bump' of another induction variable, which may wrongfully want to
consider its bump = the primary induction, dead.

Differential Revision: https://reviews.llvm.org/D92017