[PATCH] D102107: [OpenMP] Codegen aggregate for outlined function captures

[Alexey Bataev via Phabricator via cfe-commits]

ABataev added a comment.

In D102107#2832286 <https://reviews.llvm.org/D102107#2832286>, @jdoerfert wrote:

> In D102107#2824581 <https://reviews.llvm.org/D102107#2824581>, @ABataev wrote:
>
>> In D102107#2823706 <https://reviews.llvm.org/D102107#2823706>, @jdoerfert wrote:
>>
>>> In D102107#2821976 <https://reviews.llvm.org/D102107#2821976>, @ABataev wrote:
>>>
>>>> We used this kind of codegen initially but later found out that it causes a large overhead when gathering pointers into a record. What about hybrid scheme where the first args are passed as arguments and others (if any) are gathered into a record?
>>>
>>> I'm confused, maybe I misunderstand the problem. The parallel function arguments need to go from the main thread to the workers somehow, I don't see how this is done w/o a record. This patch makes it explicit though.
>>
>> Pass it in a record for workers only? And use a hybrid scheme for all other parallel regions.
>
> I still do not follow. What does it mean for workers only? What is a hybrid scheme? And, probably most importantly, how would we not eventually put everything into a record anyway?

On the host you don’t need to put everything into a record, especially for small parallel regions. Pass some first args in registers and only the remaining args gather into the record. For workers just pass all args in the record.


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