openmp: Add support for OpenMP 5.1 atomics for C++

Besides the C++ FE changes, I've noticed that the C FE didn't reject
  #pragma omp atomic capture compare
  { v = x; x = y; }
and other forms of atomic swap, this patch fixes that too.  And the
c-family/ routine needed quite a few changes so that the new code
in it works fine with both FEs.

2021-09-17  Jakub Jelinek  <jakub@redhat.com>

gcc/c-family/
	* c-omp.c (c_finish_omp_atomic): Avoid creating
	TARGET_EXPR if test is true, use create_tmp_var_raw instead of
	create_tmp_var and add a zero initializer to TARGET_EXPRs that
	had NULL initializer.  When omitting operands after v = x,
	use type of v rather than type of x.  Fix type of vtmp
	TARGET_EXPR.
gcc/c/
	* c-parser.c (c_parser_omp_atomic): Reject atomic swap if capture
	is true.
gcc/cp/
	* cp-tree.h (finish_omp_atomic): Add r and weak arguments.
	* parser.c (cp_parser_omp_atomic): Update function comment for
	OpenMP 5.1 atomics, parse OpenMP 5.1 atomics and fail, compare and
	weak clauses.
	* semantics.c (finish_omp_atomic): Add r and weak arguments, handle
	them, handle COND_EXPRs.
	* pt.c (tsubst_expr): Adjust for COND_EXPR forms that
	finish_omp_atomic can now produce.
gcc/testsuite/
	* c-c++-common/gomp/atomic-18.c: Expect same diagnostics in C++ as in
	C.
	* c-c++-common/gomp/atomic-25.c: Drop c effective target.
	* c-c++-common/gomp/atomic-26.c: Likewise.
	* c-c++-common/gomp/atomic-27.c: Likewise.
	* c-c++-common/gomp/atomic-28.c: Likewise.
	* c-c++-common/gomp/atomic-29.c: Likewise.
	* c-c++-common/gomp/atomic-30.c: Likewise.  Adjust expected diagnostics
	for C++ when it differs from C.
	(foo): Change return type from double to void.
	* g++.dg/gomp/atomic-5.C: Adjust expected diagnostics wording.
	* g++.dg/gomp/atomic-20.C: New test.
libgomp/
	* testsuite/libgomp.c-c++-common/atomic-19.c: Drop c effective target.
	Use /* */ comments instead of //.
	* testsuite/libgomp.c-c++-common/atomic-20.c: Likewise.
	* testsuite/libgomp.c-c++-common/atomic-21.c: Likewise.
	* testsuite/libgomp.c++/atomic-16.C: New test.
	* testsuite/libgomp.c++/atomic-17.C: New test.

1 files changed, 1 insertions, 1 deletions

diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index d82c042..eba9bbf 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -18500,7 +18500,7 @@ restart:
 		  c_parser_consume_token (parser);
 		  goto restart;
 		}
-	      if (structured_block)
+	      if (structured_block && !compare)
 		{
 		  opcode = NOP_EXPR;
 		  expr = default_function_array_read_conversion (eloc, expr);