[PATCH] D23446: [X86] Enable setcc to srl(ctlz) transformation on btver2 architectures.

[pierre gousseau via llvm-commits]

pgousseau added inline comments.


> RKSimon wrote in X86ISelLowering.cpp:29016
> Should we return early if !Subtarget.isCtlzFast()?

Yes that makes sense.

> RKSimon wrote in X86ISelLowering.cpp:29022
> Are we letting vector types through here?

Yes it seems that way, will have to restrict to 32-bit and 64-bit integers, thanks for spotting this.

> RKSimon wrote in X86ISelLowering.cpp:31797
> Comment this. Should this be part of a separate patch with its own tests? Its fine if its only exposed by this patch to leave it here, but it should have a comment either way.

Yes would make sense to have a separate patch, will try to find an associated test case.

> RKSimon wrote in lzcnt-zext-cmp.ll:7
> Test single input version to make sure it isn't being used.

Makes sense.

https://reviews.llvm.org/D23446