[PATCH] D141902: [GlobalISel] Detect splats built with G_CONCAT_VECTORS

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

> This should make it easier to match complex immediates for certain
> instructions on AMDGPU, where for instance a <8 x s16> will be split
> before instruction selection into a G_CONCAT_VECTORS of <2 x s16>
> splats.

I don't quite understand when this would be useful. If <8 x s16> is split up into <2 x s16> pieces during legalization, because only the latter is legal, then why would we still have a G_CONCAT_VECTORS with result type <8 x s16>? What operations would use that result? Do you have an example in mind?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D141902/new/

https://reviews.llvm.org/D141902