[PATCH] D112644: [AMDGPU] Fix global isel for kernels using agprs on gfx90a

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In D112644#3091224 <https://reviews.llvm.org/D112644#3091224>, @rampitec wrote:

> In D112644#3091209 <https://reviews.llvm.org/D112644#3091209>, @arsenm wrote:
>
>> In D112644#3091088 <https://reviews.llvm.org/D112644#3091088>, @rampitec wrote:
>>
>>> In D112644#3091054 <https://reviews.llvm.org/D112644#3091054>, @arsenm wrote:
>>>
>>>> How was this breaking?
>>>
>>> LLVM ERROR: no registers from class available to allocate
>>>
>>> What happens `usesAGPRs()` does not see any agprs used and then the whole register budget is allocated to vgprs.
>>
>> Wouldn't it work correctly after later getReservedRegs calls? I don't think we should be calling this before finalizeIsel?
>
> It does work correctly with a later call from `freezeReservedRegs()`. The first call though comes from `MachineVerifier::visitMachineFunctionBefore()`.

But if the later call fixes it up, how is it able to break in allocation later?


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