Recommit r333226 "[ValueTracking] Teach computeKnownBits that the result of an absolute value pattern that uses nsw flag is always positive."
Libfuzzer tests have been fixed to prevent being optimized.
Original commit message:
If the nsw flag is used in the absolute value then it is undefined for INT_MIN. For all other value it will produce a positive number. So we can assume the result is positive.
This breaks some InstCombine abs/nabs combining tests because we simplify the second compare from known bits rather than as the whole pattern. Looks like we can probably fix it by adding a neg+abs/nabs combine to just swap the select operands. N
Differential Revision: https://reviews.llvm.org/D47041
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333300 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed