X86 backend code ownership


I’d like to continue the discussion on the X86 backend ownership that started here [1]. I think that Craig Topper would be a great code owner. Several people replied to the email with +1s. Quentin had some concerns. Let’s continue the discussion.


[1] - http://lists.llvm.org/pipermail/llvm-dev/2016-November/106931.html.

Copy/pasting my concerns here to ease the reading:
Craig is indeed one of the main contributor of the X86 backend (in terms of commits). My concern though is that Craig’s focus is on the assembly (TableGen classes clean-up and such) and not so much on CodeGen (ISel and various X86-specific passes) as far as I can tell.

Thanks for the support Nadav, Zvi, Chandler, Renato, and anyone else I missed.

Quetin, to maybe address your concerns. My focus lately has been fixing inconsistency in instruction selection behavior between the older AVX instruction encodings and the new AVX512 encodings. I’ve also been trying to fix cases where concepts haven’t been extended to wider vectors yet. For instance, the instcombine handling of x86 shift intrinsics. I’ve also been trying to remove AVX512 intrinsics for things that can be represented with native IR or where we can use a legacy instrinsic and only need a masking IR select instruction to support AVX512.


Fwiw, I also think that Craig would be a good code owner. So, my +1 goes to him :slight_smile:

@Nadav, thanks again for all your kind help and contributions to the x86 backend!


+1 - especially since I think Craig convinced Intel that LLVM isn’t just a hobby project for him. :slight_smile:


Alright, works for me then!


As a final point, I think there are very few (if any) people who have deep knowledge of all of the x86 backend at this point. Being a code owner shouldn’t be predicated on that. Whomever it is can always reach out to the other major contributors to other parts of the backend as necessary.

I agree. Craig, if you’re willing to carry the burden of code review and delegate to others who are more experienced in areas that you’re not familiar with, then I have absolutely no concerns. Assuming no other strong objections show up in the next 24 hours, please update CODE_OWNERS.txt - congrats!