[PATCH] D77890: [ValueTracking] Implement isPoisonIf and canPushFreezeIntoOperands

[Juneyoung Lee via Phabricator via llvm-commits]

aqjune created this revision.
aqjune added reviewers: spatel, nikic, lebedev.ri.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

This PR implements two functions:

(1) isPoisonIf(V, ValAssumedPoison) is a function that returns true if V is poison under the assumption that
ValAssumedPoison is poison.

isPoisonIf can be used for sound optimization of select, as discussed in D77868 <https://reviews.llvm.org/D77868>.

(2) canPushFreezeIntoOperands(Instruction *I) returns true if I does not generate poison from non-poison
values, making freeze(op x y) -> (freeze x) (freeze y) valid.

canPushFreezeIntoOperands is used by isPoisonIf for more precise analysis.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77890

Files:
  llvm/include/llvm/Analysis/ValueTracking.h
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/unittests/Analysis/ValueTrackingTest.cpp

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