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1 Commits

Author SHA1 Message Date
James Molloy 1d88d6f289 [ValueTracking] Add a new predicate: isKnownNonEqual()
isKnownNonEqual(A, B) returns true if it can be determined that A != B.

At the moment it only knows two facts, that a non-wrapping add of nonzero to a value cannot be that value:

A + B != A [where B != 0, addition is nsw or nuw]

and that contradictory known bits imply two values are not equal.

This patch also hooks this up to InstSimplify; InstSimplify had a peephole for the first fact but not the second so this teaches InstSimplify a new trick too (alas no measured performance impact!)

llvm-svn: 251012
2015-10-22 13:18:42 +00:00