[Bug libgomp/110813] [OpenMP] omp_target_memcpy_rect (+ strided 'target update'): Improve GCN performance and contiguous subranges

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110813

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> ---
Consider also to use a library function for *inter*-device copy if the device
type or the function pointer is the same.

(If unsupported, the function can still return "-1" to skip to the fallback
code.)

For CUDA, that's cuMemcpyPeer + cuMemcpy3DPeer - the latter must then be used
for 2D and 3D as a 2D version is missing.