[PATCH] D22011: [SystemZ] Generate fewer instructions for (sub <constant>, x)

[Ulrich Weigand via llvm-commits]

uweigand added a comment.

In https://reviews.llvm.org/D22011#510210, @assem wrote:

> Thanks Ulrich. I have tried to implement what you have suggested in the two-address pass. However, it seems that checking for reg1026 and reg1025 being mapped to the same physical register is very broad and can catch a lot of cases that we don't want to convert to 3-address form.


Huh.  Do you have an example where this happens (i.e. the two are mapped to the same physical register but we do *not* want to convert to 3-address form)?


https://reviews.llvm.org/D22011