[PATCH] D135145: [AMDGPU][GISel] Combine G_INSERT_VECTOR_ELT to G_SHUFFLE_VECTOR

[Pierre van Houtryve via Phabricator via llvm-commits]

Pierre-vh added a comment.

In D135145#3861774 <https://reviews.llvm.org/D135145#3861774>, @foad wrote:

> What is the motivation for this?
>
> Can you add a comment somewhere explaining what the combine does?

We want to use SHUFFLE_VECTOR (which is always lowered during legalization anyway) as the canonical form for this kind of operation (INSERT_VECTOR_ELT w/ a constant index on small vectors). It benefits mad_mix codegen.


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  https://reviews.llvm.org/D135145/new/

https://reviews.llvm.org/D135145