[PATCH] D149404: [ValueTracking][InstCombine] Add a new API to allow to ignore poison generating flags or metadatas when implying poison

[luxufan via Phabricator via llvm-commits]

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This patch add a new API `impliesPoisonIgnoreFlagsOrMetadatas` which is
the same as `impliesPoison` but ignoring poison generating flags or
metadatas in the process of implying poison and recording these ignored
instructions.

In InstCombineSelect, replacing `impliesPoison` with
`impliesPoisonIgnoreFlagsOrMetadatas` to allow more patterns like
`select i1 %a, i1 %b, i1 false` to be optimized to and/or instructions
by droping the poison generating flags or metadatas.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D149404

Files:
  llvm/include/llvm/Analysis/ValueTracking.h
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
  llvm/test/Transforms/InstCombine/ispow2.ll
  llvm/test/Transforms/InstCombine/prevent-cmp-merge.ll

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