[Openmp-commits] [openmp] [Libomptarget] Remove requires information from plugin (PR #80345)

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carlobertolli wrote:

Current upstream implementation of auto zero-copy does not support global variables. They need to be handled differently from unified_shared_memory. Thinking about it, we should have all the information in libomptarget as we surfaced it as a requires flag. That is, in libomptarget we know that we are in auto zero-copy and not usm, and that should be sufficient to decide on how to handle global variables. 

I am attending the OpenMP face-2-face this week and I didn't have time to work on the patch to support global variables, but will do next week.

What we have downstream is support to prepopulate GPU page tables from the CPU without using XNACK. I haven't yet figured out if we need to exclude the usm case (prepopulating could apply to usm as well, as a potential optimization), so I don't yet know if we need the info in the plugin.

I *think* we can go on with this and still be able to support global variables for automatic zero-copy.

https://github.com/llvm/llvm-project/pull/80345