[PATCH] D20907: [IfConversion] Bugfix: don't add Undef flag on use if reg is live.

[Krzysztof Parzyszek via llvm-commits]

kparzysz added a subscriber: kparzysz.
kparzysz added a comment.

In http://reviews.llvm.org/D20907#451165, @jonpa wrote:

> A follow-up question here is if it is really such a good idea to just throw on extra implicit use-ops on the predicated MI? Wouldn't it generally make more sense in the case where a register is conditionally defined to model this as a tied use-operand?


The register does not actually have to be defined prior to the predicated definition.  If you have the tied use, you will need to mark it as <undef> in such cases.


http://reviews.llvm.org/D20907