[PATCH] D32686: [InstCombine][KnownBits] Use KnownBits better to detect nsw adds

[Yoav Ben-Shalom via Phabricator via llvm-commits]

yabash created this revision.

Change checkRippleForAdd from a heuristic to a full check -
if it is provable that the add does not overflow return true, otherwise false.


https://reviews.llvm.org/D32686

Files:
  lib/Transforms/InstCombine/InstCombineAddSub.cpp
  test/Transforms/InstCombine/AddOverFlow.ll
  test/Transforms/InstCombine/demand_shrink_nsw.ll

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