[PATCH] D42835: [SCEV] Make isLoopEntryGuardedByCond a bit smarter

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.
mkazantsev added reviewers: sanjoy, jbhateja, reames.

Sometimes `isLoopEntryGuardedByCond` cannot prove predicate `a > b` directly.
But it is a common situation when `a >= b` is known from ranges and `a != b` is
known from a dominating condition. Thia patch teaches SCEV to sum these facts
together and prove strict comparison via non-strict one.


https://reviews.llvm.org/D42835

Files:
  lib/Analysis/ScalarEvolution.cpp
  test/Transforms/IRCE/decrementing-loop.ll

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