[PATCH] D157807: [ValueTracking] Strengthen analysis in `computeKnownBits` of phi

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n created this revision.
goldstein.w.n added reviewers: nikic, RKSimon, foad.
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The changes are twofold.

1. Base the recursion limit on how many incoming edges there actually are. If there are only a few we don't need to worry so much about the exponential explosion.
2. Use the comparison based analysis to strengthen the standard knownbits analysis rather than choosing either/or.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D157807

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Analysis/ScalarEvolution/outer_phi.ll
  llvm/test/Transforms/InstCombine/catchswitch-phi.ll
  llvm/test/Transforms/InstCombine/known-phi-recurse.ll
  llvm/test/Transforms/LoopUnroll/AArch64/runtime-unroll-generic.ll
  llvm/test/Transforms/LoopUnroll/runtime-unroll-remainder.ll
  llvm/test/Transforms/PhaseOrdering/X86/pr38280.ll

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