[PATCH] D85364: [SVE][WIP] Implement lowering for fixed width select

[Cameron McInally via Phabricator via llvm-commits]

cameron.mcinally updated this revision to Diff 290496.
cameron.mcinally added a comment.

Turns out that ReconstructShuffle(...) needs a lot of work to be updated. The EXTRACT_SUBVECTOR index assumes we're extracting a 1/2 width vector. I missed that.

I added a function that lowers specific BUILD_VECTORs to EXTRACT_SUBVECTORs, hoping that it would short-circuit the ReconstructShuffle(...) problem. That was a dead end, since small EXTRACT_SUBVECTORs aren't legal. And we'd still run into the ReconstructShuffle(...) problem with those small BUILD_VECTORs..

But when the EXTRACT_SUBVECTORs are large enough to be legal, the new function could be a win with some tuning. It replaces the scalar loads with a vector load. I've included that function in this Diff for review, but will break it out into a separate Diff if it seems interesting enough to pursue. Thoughts?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D85364/new/

https://reviews.llvm.org/D85364

Files:
  llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
  llvm/lib/Target/AArch64/AArch64ISelLowering.h
  llvm/test/CodeGen/AArch64/sve-fixed-length-fp-select.ll
  llvm/test/CodeGen/AArch64/sve-fixed-length-int-select.ll

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