openmp: Parsing and some semantic analysis of OpenMP allocate clause

openmp: Parsing and some semantic analysis of OpenMP allocate clause

This patch adds parsing of OpenMP allocate clause, but still ignores
it during OpenMP lowering where we should for privatized variables
with allocate clause use the corresponding allocators rather than
allocating them on the stack.

2020-10-28  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* tree-core.h (enum omp_clause_code): Add OMP_CLAUSE_ALLOCATE.
	* tree.h (OMP_CLAUSE_ALLOCATE_ALLOCATOR,
	OMP_CLAUSE_ALLOCATE_COMBINED): Define.
	* tree.c (omp_clause_num_ops, omp_clause_code_name): Add allocate
	clause.
	(walk_tree_1): Handle OMP_CLAUSE_ALLOCATE.
	* tree-pretty-print.c (dump_omp_clause): Likewise.
	* gimplify.c (gimplify_scan_omp_clauses, gimplify_adjust_omp_clauses,
	gimplify_omp_for): Likewise.
	* tree-nested.c (convert_nonlocal_omp_clauses,
	convert_local_omp_clauses): Likewise.
	* omp-low.c (scan_sharing_clauses): Likewise.
gcc/c-family/
	* c-pragma.h (enum pragma_omp_clause): Add PRAGMA_OMP_CLAUSE_ALLOCATE.
	* c-omp.c: Include bitmap.h.
	(c_omp_split_clauses): Handle OMP_CLAUSE_ALLOCATE.
gcc/c/
	* c-parser.c (c_parser_omp_clause_name): Handle allocate.
	(c_parser_omp_clause_allocate): New function.
	(c_parser_omp_all_clauses): Handle PRAGMA_OMP_CLAUSE_ALLOCATE.
	(OMP_FOR_CLAUSE_MASK, OMP_SECTIONS_CLAUSE_MASK,
	OMP_PARALLEL_CLAUSE_MASK, OMP_SINGLE_CLAUSE_MASK,
	OMP_TASK_CLAUSE_MASK, OMP_TASKGROUP_CLAUSE_MASK,
	OMP_DISTRIBUTE_CLAUSE_MASK, OMP_TEAMS_CLAUSE_MASK,
	OMP_TARGET_CLAUSE_MASK, OMP_TASKLOOP_CLAUSE_MASK): Add
	PRAGMA_OMP_CLAUSE_ALLOCATE.
	* c-typeck.c (c_finish_omp_clauses): Handle OMP_CLAUSE_ALLOCATE.
gcc/cp/
	* parser.c (cp_parser_omp_clause_name): Handle allocate.
	(cp_parser_omp_clause_allocate): New function.
	(cp_parser_omp_all_clauses): Handle PRAGMA_OMP_CLAUSE_ALLOCATE.
	(OMP_FOR_CLAUSE_MASK, OMP_SECTIONS_CLAUSE_MASK,
	OMP_PARALLEL_CLAUSE_MASK, OMP_SINGLE_CLAUSE_MASK,
	OMP_TASK_CLAUSE_MASK, OMP_TASKGROUP_CLAUSE_MASK,
	OMP_DISTRIBUTE_CLAUSE_MASK, OMP_TEAMS_CLAUSE_MASK,
	OMP_TARGET_CLAUSE_MASK, OMP_TASKLOOP_CLAUSE_MASK): Add
	PRAGMA_OMP_CLAUSE_ALLOCATE.
	* semantics.c (finish_omp_clauses): Handle OMP_CLAUSE_ALLOCATE.
	* pt.c (tsubst_omp_clauses): Likewise.
gcc/testsuite/
	* c-c++-common/gomp/allocate-1.c: New test.
	* c-c++-common/gomp/allocate-2.c: New test.
	* c-c++-common/gomp/clauses-1.c (omp_allocator_handle_t): New typedef.
	(foo, bar, baz): Add allocate clauses where allowed.