[PATCH] D18508: Replace at most one dead register with zero register on aarch64

[Tim Northover via llvm-commits]

t.p.northover added a comment.

I think it would be better to check `MI->definesRegister(AArch64::XZR) || MI->definesRegister(AArch64::WZR)` and continue. It seems to be a general principle that you can't write to even XZR twice in the same instruction, so that ought to be more robust.

We should also add a test to test/CodeGen/AArch64.

Cheers.

Tim.


http://reviews.llvm.org/D18508