[PATCH] D67411: [InstSimplify] simplifyUnsignedRangeCheck(): handle more cases (PR43251)

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri created this revision.
lebedev.ri added reviewers: spatel, nikic, xbolva00.
lebedev.ri added a project: LLVM.
Herald added a subscriber: hiraditya.

I don't have a direct motivational case for this,
but it would be good to have this for completeness/symmetry.

This pattern is basically the motivational pattern from
https://bugs.llvm.org/show_bug.cgi?id=43251
but with different predicate that requires that the offset is non-zero.

The completeness bit comes from the fact that a similar pattern (offset != zero)
will be needed for https://bugs.llvm.org/show_bug.cgi?id=43259,
so it'd seem to be good to not overlook very similar patterns..

Also, there is something odd with `isKnownNonZero()`, if the non-zero
knowledge was specified as an assumption, it didn't pick it up (PR43267)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D67411

Files:
  llvm/lib/Analysis/InstructionSimplify.cpp
  llvm/test/Transforms/InstSimplify/result-of-usub-by-nonzero-is-non-zero-and-no-overflow.ll

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