[PATCH] D57504: RFC: Prototype & Roadmap for vector predication in LLVM

Simon Moll via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Mon Nov 4 04:33:09 PST 2019


simoll added a comment.

In D57504#1729839 <https://reviews.llvm.org/D57504#1729839>, @SjoerdMeijer wrote:

> In D57504#1726715 <https://reviews.llvm.org/D57504#1726715>, @simoll wrote:
>
> > In D57504#1726007 <https://reviews.llvm.org/D57504#1726007>, @SjoerdMeijer wrote:
> >
> > > Hi Simon, I went through the code for the first time, and this is a first round of proper nitpicks from my side. Please ignore if you want to focus on the bigger picture at this point in the discussion, but these are just some things I noticed. General nitpick is that you should run clang-format as there are quite a few coding style issues: indentation, indentation of arguments, exceeding 80 columns, placement of `*` and `&` in arguments and return values, etc.  And find some more nitpicks inlined.
> >
> >
> > Hi Sjoerd, thanks for you comments! i've fixed the inline nitpicks right away. I'll do a style pass for the actual commits.
>
>
> Cheers. Just curious, what are your next steps? People can correct me if I'm wrong, but my impression is that with the RFC, this prototype, the discussion at the US LLVM dev conference, there is consensus and people are on-board with the general idea and direction. There are still some discussions on e.g. the (constrained) FP part, but would it now be the time split this for example up in an separate commits, like an INT and FP part (if that makes sense), so that they can be (separately) progressed?


Yes, i hope that's where things are right now ;-) I am planning to go by functional slices. Each slice comes with IR-level intrinsics, TTI support, basic lowering to standard IR, Selection DAG support and tests.

I am preparing the first patchset for integer support atm.

Slices:

- Integer slice.
- Memory slice.
- Reduction slice.
- FP (with unconstrained metadata args) slice.

Standalone patch:

- Mask, VectorLength and Passthru attributes (in preparation of vector function calls).

Pending discussion/separate RFC:

- Constrained FP (being able to fully optimize constrained fp intrinsics in the default fp env).
- Generalized pattern match (aka optimizing VP).


Repository:
  rG LLVM Github Monorepo

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