[llvm-branch-commits] [OpenMP] Support 'taskgraph' semantics via new libomp API entry points (PR #194051)

[Julian Brown via llvm-branch-commits]

https://github.com/jtb20 created https://github.com/llvm/llvm-project/pull/194051

This patch supports the OpenMP 6.0 'taskgraph' directive via several
new API entry points for libomp.

New entry points are used for several reasons.  The first reason
is to pass extra information from the compiler relevant to the
taskgraph-recording case -- e.g. the __kmpc_taskgraph_task entry point
has extra arguments relating to shared data.  The second reason is to
reduce the potential overhead of the taskgraph implementation on the
rest of the runtime.  A third intention is to capture OpenMP semantics
at a slightly higher level: in particular when we come to add offload
target tasks to this implementation, those will also use new API entry
points to hopefully allow dependencies to be handled entirely on the GPU,
rather than by being wrapped in a host task.

commit-id:87387b9b