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AMDGPU: Raise the priority of MAD24 in instruction selection.

Authored by cfang on Jan 15 2019, 2:46 PM.



We have seen performance regression when v_add3 is generated. The major reason is that the v_mad pattern
is broken when v_add3 is generated. We also see the register pressure increased. While we could not properly
estimate register pressure during instruction selection, we can give mad a higher priority.

In this work, we raise the priority for mad24 in selection and resolve the performance regression.

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Event Timeline

cfang created this revision.Jan 15 2019, 2:46 PM
rampitec added inline comments.Jan 15 2019, 2:50 PM
33 ↗(On Diff #181889)

There should be no unnamed variables left.

cfang updated this revision to Diff 181896.Jan 15 2019, 3:05 PM

update the test based on the following suggestion:

There should be no unnamed variables left.

cfang marked an inline comment as done.Jan 15 2019, 3:06 PM
This revision is now accepted and ready to land.Jan 15 2019, 3:07 PM
This revision was automatically updated to reflect the committed changes.