[Openmp-commits] [openmp] [libomptarget][nextgen-plugin] Use SCRELEASE/SCACQUIRE in packet headers (PR #85678)

[Joseph Huber via Openmp-commits]

jhuber6 wrote:

I don't think we need to worry about the header moving honestly, that would be an incredibly ABI breaking change and it's called header for a reason. We already rely implicitly on this storing the two 16-byte values that are right next to eachother.

Right now we have "store 32-bytes at the beginning of the struct" and this turns that into "Store 32-bytes at a 16-byte pointer assuming that the out of bounds access is correct." We also do not want to make this two-16 byte stores because this should happen in a single operation. So I think it's fine the way it is.

We should probably change the name though, the documentation says it's depcreated and just makes them the same value anyway so it's NFC. From the HSA headers:

```
HSA_PACKET_HEADER_SCACQUIRE_FENCE_SCOPE = 9,
HSA_PACKET_HEADER_ACQUIRE_FENCE_SCOPE = 9,
```

https://github.com/llvm/llvm-project/pull/85678