[PATCH] D74661: AMDGPU/GlobalISel: Insert readfirstlane on SGPR returns

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In D74661#1878110 <https://reviews.llvm.org/D74661#1878110>, @nhaehnle wrote:

> Please remove the changes in the bswap test. It is critically important that we do not insert unnecessary v_readfirstlane insructions. Mesa performance leans on this quite heavily.


This is just noise for the purpose of the bswap test. We already fold out unneeded. readfirstlanes in 3 different places which already have tests. I’m also planning on adding another in the regbank aware combiner


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