[PATCH] D120353: [OpenMP] Add option to make offloading mandatory

Tue Feb 22 14:30:53 PST 2022

ABataev added a comment.

In D120353#3338647 <https://reviews.llvm.org/D120353#3338647>, @jhuber6 wrote:

> In D120353#3338589 <https://reviews.llvm.org/D120353#3338589>, @ABataev wrote:
>
>>> This is necessary for implementing features like conditional offloading and ensuring that unhandled pragmas don't result in missing symbols.
>>
>> This behavior is part of the standard.
>
> I believe it's reasonable to have this as an option flag to defy the standard, we have other flags that do this already (e.g. -fopenmp-cuda-mode).

I mean it is not the implementation feature.

>>> For offloading tests we can silently fail to the host without realizing that offloading failed.
>>
>> It is controlled by the OMP_TARGET_OFFLOAD env variable, no? You can set this env var to mandatory to avoid this problem.
>
> Yes, I don't think we set it in the tests right now for some reason.

I thought it is the default behavior. But we need to set it for offloading tests to be sure in their behavior.

> But the main reason I made this patch is for interoperability. Without this if you want to call a CUDA function from the OpenMP device you'd need a variant and a dummy implementation. If you don't write a dummy implementation you'll get a linker error, if you don't use a variant you'll override the CUDA version.

Ah, ok, I see. How is supposed to be used? In Cuda code or in plain C/C++ code?

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https://reviews.llvm.org/D120353