[Openmp-commits] [PATCH] D106310: [Libomptarget] Remove volatile from NVPTX work function

[Jon Chesterfield via Phabricator via Openmp-commits]

JonChesterfield added a comment.

This seems hazardous.

The value is written from one warp and then read from another. It should be atomic qualified, but isn't, because cuda doesn't do that.

Previously it was volatile, which happens to get treated in broadly similar fashion to atomic.

So before it was a data race, but one that the compiler was unlikely to miscompile. Now it's a non-volatile data race. That is indeed more likely to be transformed.

I don't think we can reasonably assume this change is safe. Making it a relaxed atomic instead would be better.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D106310/new/

https://reviews.llvm.org/D106310