[PATCH] Added InstCombine transform for pattern " ( ( A ^ B ) ^ ( ( ~A ) | B ) -> ( A | ( ~ B ) ) ".

[David Majnemer]

Looking at it some more, the generalized from can be simplified.

`(A ^ B) ^ ((A ^ C) | B)` -> `C ^ (B & (A ^ C))`

This takes us from four binops to three binops.

http://reviews.llvm.org/D5001