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The HAS_DEVICE_ADDR indicates that the object(s) listed exists at an address that is a valid device address. Specifically, `has_device_addr(x)` means that (in C/C++ terms) `&x` is a device address. When entering a target region, `x` does not need to be allocated on the device, or have its contents copied over (in the absence of additional mapping clauses). Passing its address verbatim to the region for use is sufficient, and is the intended goal of the clause. Some Fortran objects use descriptors in their in-memory representation. If `x` had a descriptor, both the descriptor and the contents of `x` would be located in the device memory. However, the descriptors are managed by the compiler, and can be regenerated at various points as needed. The address of the effective descriptor may change, hence it's not safe to pass the address of the descriptor to the target region. Instead, the descriptor itself is always copied, but for objects like `x`, no further mapping takes place (as this keeps the storage pointer in the descriptor unchanged). --------- Co-authored-by: Sergio Afonso <safonsof@amd.com>
The LLVM/Offload Subproject
The Offload subproject aims at providing tooling, runtimes, and APIs that allow users to execute code on accelerators or other "co-processors" that may or may not match the architecture of their "host". In the long run, all kinds of targets are in scope of this effort, including but not limited to: CPUs, GPUs, FPGAs, AI/ML accelerators, distributed resources, etc.
For OpenMP offload users, the project is ready and fully usable. The final API design is still under development. More content will show up here and on our webpage soon. In the meantime, people are encouraged to participate in our meetings (see below) and check our development board as well as the discussions on Discourse.
Meetings
Every second Wednesday, 7:00 - 8:00am PT, starting Jan 24, 2024. Alternates with the OpenMP in LLVM meeting. invite.ics Meeting Minutes and Agenda