[PATCH] D159452: [AMDGPU] Machine scheduler should take care of the 'amdgpu-num-vgp' function attribute

Tue Sep 5 13:37:53 PDT 2023

alex-t added a comment.

One more case that we may want to consider: with "amdgpu-num-vgpr"=8 the difference between 2 RPs of 2 is significant.
The schedule that spends 7 VGPRs does not spill but another one, which spends 9 will.
Currently, we have a "less" operator defined for the GCNRegPressure which only compares the occupancy based on the default target number of available registers and the number of VGPRs from the RP.  To this method, RPs in my case are equal as they both have occupancy 10. This is yet another reason why we cannot use the excess RP set to decide if we need to keep or revert the current schedule.

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https://reviews.llvm.org/D159452