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

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

In D87585#2274305 <https://reviews.llvm.org/D87585#2274305>, @rampitec wrote:

> In D87585#2274280 <https://reviews.llvm.org/D87585#2274280>, @critson wrote:
>
>> The numbers for this change are not vastly compelling.
>> I looked at 11598 game shaders and compiled these for GFX7, GFX9 and GFX10.
>> On GFX7, 1 shader lost 1 instruction.
>> On GFX9, 1 shader lost 1 instruction, but 64 shaders gained 1 instruction.
>> On GFX10, 1 shader lost 1 instruction, but 2 shaders gained 1 instruction.

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.


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