[PATCH] D44911: [MachineCopyPropagation] Handle COPY with overlapping source/dest.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

COPY in registers is sort of like memmove in memory; the value in the destination is equivalent to the value that was in the source.

If you try copyprop5 on trunk, you'll find it eliminates the second COPY, but not the first, so q28 and q29 contain the wrong value at the point of the call.


Repository:
  rL LLVM

https://reviews.llvm.org/D44911