[PATCH] D20531: MachineCopyPropagation: remove some more copys when they are not needed

[Jonas Paulsson via llvm-commits]

jonpa added a comment.

> > If a register use is defined by a COPY, and the COPY source reg could be used directly, use it instead if it seems that the COPY may be removable then.

> 




> That is not generally safe. In particular, if the definition is required by the ABI, you cannot eliminate that copy.


What are the exact checks that need to be done? The only one I know of is the involvement of a reserved register.


http://reviews.llvm.org/D20531