[Bug libgomp/81177] New: Dump cubin module to file before offloading in nvptx libgomp plugin

["vries at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81177

            Bug ID: 81177
           Summary: Dump cubin module to file before offloading in nvptx
                    libgomp plugin
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: libgomp
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vries at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org
  Target Milestone: ---

The nvptx libgomp plugin adds a number of ptx sources to a CUlinkState object
using cuLinkAddData, and then links them together using the cuLinkComplete
call: 
...
static bool
link_ptx (CUmodule *module, const struct targ_ptx_obj *ptx_objs,
          unsigned num_objs)
{
  ...
  GOMP_PLUGIN_debug (0, "Linking\n");
  r = CUDA_CALL_NOCHECK (cuLinkComplete, linkstate, &linkout, &linkoutsize);

  GOMP_PLUGIN_debug (0, "Link complete: %fms\n", elapsed);
  GOMP_PLUGIN_debug (0, "Link log %s\n", &ilog[0]);

  if (r != CUDA_SUCCESS)
    {
      GOMP_PLUGIN_error ("cuLinkComplete error: %s", cuda_error (r));
      return false;
    }

  CUDA_CALL (cuModuleLoadData, module, linkout);
  CUDA_CALL (cuLinkDestroy, linkstate);
  return true;
}
...

After that, the module is loaded using cuModuleLoadData.

For debugging purposes, it would be good to be able to inspect the module.