6b6c553bb8
Summary: Finally fixes [[ https://bugs.llvm.org/show_bug.cgi?id=6773 | PR6773 ]]. Now that the backend is all done, we can finally fold it! The canonical unfolded masked merge pattern is ```(x & m) | (y & ~m)``` There is a second, equivalent variant: ```(x | ~m) & (y | m)``` Only one of them (the or-of-and's i think) is canonical. And if the mask is not a constant, we should fold it to: ```((x ^ y) & M) ^ y``` https://rise4fun.com/Alive/ndQw Reviewers: spatel, craig.topper Reviewed By: spatel Subscribers: nicholas, RKSimon, llvm-commits Differential Revision: https://reviews.llvm.org/D46814 llvm-svn: 333106