OpenMP patch review and work in progress

[Tobias Burnus]

Hi Jakub, hello all,

let's start with a list of smaller patches, which are pending review
but each of them should be relatively quickly approvable. Some are really
tiny and obvious bug fixes - others are a bit larger but still smallish:

* [Patch] OpenMP: Fix use_device_{addr,ptr} with in-data-sharing arg
  https://gcc.gnu.org/pipermail/gcc-patches/2022-April/593419.html
* [Patch] OpenMP, libgomp, gimple: omp_get_max_teams, omp_set_num_teams, and 
omp_{gs}et_teams_thread_limit on offload devices
  https://gcc.gnu.org/pipermail/gcc-patches/2022-April/593260.html
* [Patch] OpenMP, libgomp: Add new runtime routine omp_target_is_accessible.
  https://gcc.gnu.org/pipermail/gcc-patches/2022-March/591601.html
* [PATCH, OpenMP, C++] Allow classes with static members to be mappable
  https://gcc.gnu.org/pipermail/gcc-patches/2022-March/591449.html
* [PATCH] OpenMP, C++: Add template support for the has_device_addr clause.
  https://gcc.gnu.org/pipermail/gcc-patches/2022-February/590813.html
* [PATCH, OpenMP, C/C++] Handle array reference base-pointers in array sections
  https://gcc.gnu.org/pipermail/gcc-patches/2022-February/590658.html
* OpenMP, libgomp: Add new runtime routines omp_target_memcpy_async and 
omp_target_memcpy_rect_async
  https://gcc.gnu.org/pipermail/gcc-patches/2022-February/590651.html
* [PATCH] Add a restriction on allocate clause (OpenMP 5.0)
  https://gcc.gnu.org/pipermail/gcc-patches/2022-February/590597.html
* OpenMP, libgomp: Environment variable syntax extension
  https://gcc.gnu.org/pipermail/gcc-patches/2022-January/588728.html

I think it makes sense to reduce this list before starting on the larger list.
On the larger side, I collected the following ones.

* Memory Management
- OpenMP: allow requires dynamic_allocators
  https://gcc.gnu.org/pipermail/gcc-patches/2021-December/587201.html
- libgomp, nvptx: low-latency memory allocator
  https://gcc.gnu.org/pipermail/gcc-patches/2021-December/587207.html
- Pinned Memory thread
  https://gcc.gnu.org/pipermail/gcc-patches/2022-January/587612.html
- Support for allocate directive (OpenMP 5.0)
  https://gcc.gnu.org/pipermail/gcc-patches/2022-January/588367.html

* declare mapper
  https://gcc.gnu.org/pipermail/gcc-patches/2022-March/591973.html

* Metadirectives
  https://gcc.gnu.org/pipermail/gcc-patches/2021-December/586600.html

* [PATCH 0/5] openmp: Handle pinned and unified shared memory.
  https://gcc.gnu.org/pipermail/gcc-patches/2022-March/591349.html

* [PATCH 00/16] OpenMP: lvalues in "map" clauses and struct handling rework
  https://gcc.gnu.org/pipermail/gcc-patches/2021-November/584994.html

Plus:

* Fortran deep-mapping patch
  I intent to submit it in pieces.
  Lastest email in the thread:
  https://gcc.gnu.org/pipermail/gcc-patches/2022-April/593562.html

* OpenACC Kernels/Graphite: That's not OpenMP but rather generic, but I
  want to mention it for completeness:
   https://gcc.gnu.org/pipermail/gcc-patches/2021-December/586901.html

Tobias