[PATCH] D13042: [SCEV] Try to prove predicates by splitting them.

[Sanjoy Das via llvm-commits]

sanjoy created this revision.
sanjoy added reviewers: reames, atrick, hfinkel, nlewycky.
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This change teaches SCEV that to prove `A u< B` it is sufficient to
prove each of these facts individually:

 - B >= 0
 - A s< B
 - A >= 0

In practice, SCEV sometimes it is easier to prove these facts
individually than to prove `A u< B` as one atomic step.

http://reviews.llvm.org/D13042

Files:
  include/llvm/Analysis/ScalarEvolution.h
  lib/Analysis/ScalarEvolution.cpp
  test/Transforms/IndVarSimplify/eliminate-comparison.ll

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