[PATCH] D74066: [ValueTracking] usub(a, b) cannot overflow if a >= b.

[Florian Hahn via Phabricator via llvm-commits]

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

If we know that a >= b (unsigned), usub.with.overflow(a, b) cannot
overflow. Similarly, if b > a, the same expression overflows.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74066

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Transforms/InstCombine/usub-overflow-known-by-implied-cond.ll

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