[PATCH] D145591: [clang][HIP][OpenMP] Add warning if mixed HIP / OpenMP offloading

Thu Mar 9 10:07:10 PST 2023

tra added a subscriber: jhuber6.
tra added a comment.

In D145591#4180908 <https://reviews.llvm.org/D145591#4180908>, @mhalk wrote:

> For example: when using `-x hip -fopenmp --offload-arch=...` (+ other reasonable parameters) a HIP program with OpenMP target directives will compile without warning / error.
> But only host-related OpenMP code will be executed properly.
>
> Another hint that HIP and OpenMP target offloading do not work concurrently ATM is that when compiling with `-x hip -fopenmp -fopenmp-targets=...` clang will throw an error.

It sounds like what we want is to make `-x hip` and `-fopenmp` mutually exclusive, with a hard error when both are used. If you look at the problem as "-fopenmp completely breaks HIP compilation", a warning is a bit too weak of a measure, IMO.

We can restate it all as "mixing offloading modes is not supported" and generalize it to both CUDA and HIP.

@jhuber6 - WDYT?

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https://reviews.llvm.org/D145591