[PATCH] D109243: AMDGPU/GlobalISel: Add build_vector_trunc post-legalizer combine

[Petar Avramovic via Phabricator via llvm-commits]

Petar.Avramovic planned changes to this revision.
Petar.Avramovic added a comment.

As mentioned before there are some regressions here. I think that it would be best to:
not lower vgpr v2s16 build_vector_trunc in regbank select, and deal with all cases in instruction select
second element is undef -> first elemenent (this patch)
default case -> bit shift packing like in regbankselect


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  https://reviews.llvm.org/D109243/new/

https://reviews.llvm.org/D109243