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, 14 insertions, 14 deletions

diff --git a/gcc/c-family/c-omp.c b/gcc/c-family/c-omp.c
index 75184a3..476abc1 100644
--- a/gcc/c-family/c-omp.c
+++ b/gcc/c-family/c-omp.c
@@ -376,7 +376,7 @@ c_finish_omp_atomic (location_t loc, enum tree_code code,
 	return error_mark_node;
       gcc_assert (TREE_CODE (rhs1) == EQ_EXPR);
       tree cmptype = TREE_TYPE (TREE_OPERAND (rhs1, 0));
-      if (SCALAR_FLOAT_TYPE_P (cmptype))
+      if (SCALAR_FLOAT_TYPE_P (cmptype) && !test)
 	{
 	  bool clear_padding = false;
 	  if (BITS_PER_UNIT == 8 && CHAR_BIT == 8)
@@ -443,12 +443,14 @@ c_finish_omp_atomic (location_t loc, enum tree_code code,
 		}
 	    }
 	}
-      if (r)
+      if (r && test)
+	rtmp = rhs1;
+      else if (r)
 	{
-	  tree var = create_tmp_var (boolean_type_node);
+	  tree var = create_tmp_var_raw (boolean_type_node);
 	  DECL_CONTEXT (var) = current_function_decl;
 	  rtmp = build4 (TARGET_EXPR, boolean_type_node, var,
-			 NULL, NULL, NULL);
+			 boolean_false_node, NULL, NULL);
 	  save = in_late_binary_op;
 	  in_late_binary_op = true;
 	  x = build_modify_expr (loc, var, NULL_TREE, NOP_EXPR,
@@ -529,14 +531,11 @@ c_finish_omp_atomic (location_t loc, enum tree_code code,
 	    }
 	}
       if (blhs)
+	x = build3_loc (loc, BIT_FIELD_REF, TREE_TYPE (blhs), x,
+			bitsize_int (bitsize), bitsize_int (bitpos));
+      if (r && !test)
 	{
-	  x = build3_loc (loc, BIT_FIELD_REF, TREE_TYPE (blhs), x,
-			  bitsize_int (bitsize), bitsize_int (bitpos));
-	  type = TREE_TYPE (blhs);
-	}
-      if (r)
-	{
-	  vtmp = create_tmp_var (TREE_TYPE (x));
+	  vtmp = create_tmp_var_raw (TREE_TYPE (x));
 	  DECL_CONTEXT (vtmp) = current_function_decl;
 	}
       else
@@ -545,10 +544,11 @@ c_finish_omp_atomic (location_t loc, enum tree_code code,
 			     loc, x, NULL_TREE);
       if (x == error_mark_node)
 	return error_mark_node;
-      if (r)
+      type = TREE_TYPE (x);
+      if (r && !test)
 	{
-	  vtmp = build4 (TARGET_EXPR, boolean_type_node, vtmp,
-			 NULL, NULL, NULL);
+	  vtmp = build4 (TARGET_EXPR, TREE_TYPE (vtmp), vtmp,
+			 build_zero_cst (TREE_TYPE (vtmp)), NULL, NULL);
 	  gcc_assert (TREE_CODE (x) == MODIFY_EXPR
 		      && TREE_OPERAND (x, 0) == TARGET_EXPR_SLOT (vtmp));
 	  TREE_OPERAND (x, 0) = vtmp;