The 'RPCHandleTy' was intended to capture the intention that a specific
device owns its slot in the RPC server. However, this required creating
a temporary store to hold these pointers. This was causing really weird
spurious failure due to undefined behaviour in the order of library
teardown. For example, the x64 plugin would be torn down, set this to
some invalid memory, and then the CUDA plugin would crash. Rather than
spend the time to fully diagnose this problem I found it pertinent to
simply remove the failure mode.
This patch removes this indirection so now the usage of the RPC server
must always be done with the intended device. This just requires some
extra handling for the AMDGPU indirection where we need to store a
reference to the device.
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D154971
This patch adds the intial support for running an RPC server in
libomptarget to handle host services. We interface with the library
provided by the `libc` project to stand up a basic server. We introduce
a new type that is controlled by the plugin and has each device
intialize its interface. We then run a basic server to check the RPC
buffer.
This patch does not fully implement the interface. In the future each
plugin will want to define special handlers via the interface to support
things like malloc or H2D copies coming from RPC. We will also want to
allow the plugin to specify t he number of ports. This is currently
capped in the implementation but will be adjusted soon.
Right now running the server is handled by whatever thread ends up doing
the waiting. This is probably not a completely sound solution but I am
not overly familiar with the behaviour of OpenMP tasks and what would be
required here. This works okay with synchrnous regions, and somewhat
fine with `nowait` regions, but I've observed some weird behavior when
one of those regions calls `exit`.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D154312
