[PATCH] D48877: [X86][BtVer2][MCA] Recognize CMPEQ zero-idioms too

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri planned changes to this revision.
lebedev.ri added a comment.

In https://reviews.llvm.org/D48877#1150824, @RKSimon wrote:

> I think you're confusing zero-idioms with dependency breaking instructions.


Yes, indeed.

> Zero idioms break dependencies, don't use any resources (the frontend just sets the PRF value to zero) and then retires.
> 
> PCMPEQ 'ones' patterns can break dependencies but still use resources to set the bits to all ones before retiring.

Would it be valuable to salvage those into `one-idioms.s` with a comment that these are dep-breaking?
I'm not sure any special handling is needed in the sched model.


Repository:
  rL LLVM

https://reviews.llvm.org/D48877