[PATCH] D87585: [AMDGPU] Dynamically clear renamable to avoid constant bus errors

Carl Ritson via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Sep 16 01:34:43 PDT 2020


critson added a comment.

In D87585#2276097 <https://reviews.llvm.org/D87585#2276097>, @foad wrote:

> Are there any other significant changes? I'm thinking of things like this that would help with dependency stalls on gfx10:
>
>   v_mov v0, 0
>   v_mov v1, v0
>
> ->
>
>   v_mov v0, 0
>   v_mov v1, 0
>
>
>
>>> I started this change as I am looking at moving WQM after MI scheduling, and this potentially leaves some additional copies around.
>>> But I could addressed these with very limited special case copy elimination in the WQM pass itself.
>>>
>>> Does anyone have an opinion on whether I should continue pushing this?
>>
>> Honestly it does not sound like a good justification for a new pass.
>
> Agreed, but maybe it's worth revisiting after the WQM pass has been moved.

I will review shader changes; however, I do not think Machine Copy Propagation propagates constants.


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