[PATCH] D20839: AMDGPU: Add amdgpu-ps-wqm-outputs function attributes

[Marek Olšák via llvm-commits]

mareko added a comment.

I don't understand the comment.

If a pixel shader doesn't use DDX/DDY and sample/gather, WQM can be disabled in the prolog. tgsi_scan can get that information.

If a pixel shader uses those, WQM can be enabled at the beginning of the prolog and disabled at the end, so that the main part starts with the original EXEC mask. This adds 2 unnecessary SALU (s_mov_b64, s_wqm_b64) at the prolog->main boundary, but I don't think that matters much. Prologs are usually empty with the GL core profile anyway.


http://reviews.llvm.org/D20839