[clang][OpenMP] Fix/enforce order-concurrent-nestable rules (#135463)

OpenMP has restrictions on directives allowed to be strictly nested
inside a
construct with the order(concurrent) clause specified.
 - OpenMP 5.0, 5.1, and 5.2 allows: 'loop', 'parallel', 'simd', and
     combined directives starting with 'parallel'.
 - OpenMP 6.0 allows: the above directives plus 'atomic' and
     all loop-transformation directives.

Furthermore, a region that corresponds to a construct with
order(concurrent)
specified may not contain calls to the OpenMP runtime API.

This PR fixes the following issues in the current implementation:

With -fopenmp-version=50: none of the nesting restrictions above were
enforced
 With -fopenmp-version=60:
1. Clang did not reject OpenMP runtime APIs encountered in the region.
2. Clang erroneously rejected combined directives starting with
parallel.

---------

Co-authored-by: Zahira Ammarguellat <zahira.ammarguellat@intel.com>

0 files changed, 0 insertions, 0 deletions