[PATCH] D41908: [X86][MMX] Add support for MMX zero vector creation

[Philip Reames via Phabricator via llvm-commits]

reames added a comment.

Reading along for my own education, feel free to ignore if I'm way off base.

I think I'm missing something here.  If we have a bitcast of a zero element, why don't we have a generic combine to convert that to a zeroinitializer of the target type?  Wouldn't we already need/have handling for a zeroinitializer constant of x86_mmx type?

More generally, why doesn't that generic combine exist for *any* constant?


Repository:
  rL LLVM

https://reviews.llvm.org/D41908