[PATCH] D139852: [amdgpu] Lower CopyToReg into SGPR explicitly to avoid illegal vgpr to sgpr copy

[Jon Chesterfield via Phabricator via llvm-commits]

JonChesterfield added a comment.

In D139852#3989251 <https://reviews.llvm.org/D139852#3989251>, @alex-t wrote:

> Since we ensure all the VGPR to SGPR copies are uniform, we just need to V_READFIRSTLANE_B32 here.

What ensures this copy is uniform?

Even if it is uniform, is there a reason to expect readfirstlane to be better than a mov immediate?


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https://reviews.llvm.org/D139852