[PATCH] D115244: [LICM] Promote conditional, loop-invariant memory accesses to scalars

[Dimitrije Milošević via Phabricator via llvm-commits]

dmilosevic141 updated this revision to Diff 428010.
dmilosevic141 edited the summary of this revision.
dmilosevic141 set the repository for this revision to rG LLVM Github Monorepo.
dmilosevic141 added a comment.

Thanks @reames!
I took some time to dive deeper into the predicated instructions. So far, two things stand out to me:

- The //ScalarizeMaskedMemIntrin// pass, which is a standard part of the //CodeGen// pipeline. This pass translates the masked memory intrinsics into chains of basic blocks, by loading/storing elements one-by-one. For single-value vectors, handling looks pretty much identical to the initial version of the patch. Scalarization of the masked memory intrinsics is, however, target-dependent (e.g. for //x86//, the scalarization of calls with single-value vectors passed in as arguments does occur; for //RISC-V//, it does not).
- The Vector Predication Roadmap (Vector Predication Roadmap <https://llvm.org/docs/Proposals/VectorPredication.html>).

Having said that, I'm a little bit stuck in regards to the next steps towards better handling of single-value vectors, as I'm not sure that the //ScalarieMaskedMemIntrin// pass is //*the*// place for that. The Vector Predication Roadmap is a little bit overwhelming - i.e. I'm not sure which part of it is related to the better handling of single-value vectors. If you (or anyone else) have something concrete to point me to, I'd be really thankful. :)
I've updated the patch to use the //llvm.masked.store// intrinsic, instead of the complicated //CFG// manipulation.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115244/new/

https://reviews.llvm.org/D115244

Files:
  llvm/lib/Transforms/Scalar/LICM.cpp
  llvm/test/Transforms/LICM/conditional-access-promotion.ll

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