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AMDGPU: llvm.SI.fs.constant is a source of divergence
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Authored by nhaehnle on Apr 29 2016, 2:37 PM.

Details

Summary

This intrinsic is used to get flat-shaded fragment shader inputs. Those are
uniform across a primitive, but a fragment shader wave may process pixels from
multiple primitives (as indicated by the prim_mask), and so that's where
divergence can arise.

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nhaehnle updated this revision to Diff 55673.Apr 29 2016, 2:37 PM
nhaehnle retitled this revision from to AMDGPU: llvm.SI.fs.constant is a source of divergence.
nhaehnle updated this object.
nhaehnle added reviewers: arsenm, tstellarAMD.
nhaehnle added a subscriber: llvm-commits.
arsenm accepted this revision.Apr 29 2016, 2:43 PM
arsenm edited edge metadata.

LGTM

This revision is now accepted and ready to land.Apr 29 2016, 2:43 PM
This revision was automatically updated to reflect the committed changes.