Nikita Popov b1b7a2f7b6 [InstCombine] Fold uadd.sat(a, b) == 0 and usub.sat(a, b) == 0 ...

This adds folds for comparing uadd.sat/usub.sat with zero:

 * uadd.sat(a, b) == 0 => a == 0 && b == 0 => (a | b) == 0
 * usub.sat(a, b) == 0 => a <= b

And inverted forms for !=.

Differential Revision: https://reviews.llvm.org/D69224

llvm-svn: 375374

2019-10-20 20:19:42 +00:00

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