[PATCH] Correctly handle range metadata when hoisting instructions out of then/else into if blocks

[Rafael Ávila de Espíndola]

LGTM.

This patch is correct and can be committed, but there are other related bugs:

* We also need to merge TBAA for example.
* We need to delete unknown metadata.

GVN has code in patchReplacementInstruction that should probably be refactored to an utility function that is also used here. Do you want to try to implement that? If not, please at least open a bug to track it.

Thanks

http://reviews.llvm.org/D4595