openmp: Map holds clause to IFN_ASSUME for C/C++

Now that [[assume (cond)]] support is in, this simple patch makes
  #pragma omp assume holds(cond)
use it.

2022-10-06  Jakub Jelinek  <jakub@redhat.com>

	* c-parser.cc (c_parser_omp_assumption_clauses): Emit IFN_ASSUME
	call for holds clause on assume construct.

	* parser.cc (cp_parser_omp_assumption_clauses): Emit IFN_ASSUME
	call for holds clause on assume construct.

	* c-c++-common/gomp/assume-4.c: New test.

3 files changed, 33 insertions, 6 deletions

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 9b76637..67b919c 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -23571,10 +23571,12 @@ c_parser_omp_assumption_clauses (c_parser *parser, bool is_assume)
 	      tree t = convert_lvalue_to_rvalue (eloc, expr, true, true).value;
 	      t = c_objc_common_truthvalue_conversion (eloc, t);
 	      t = c_fully_fold (t, false, NULL);
-	      if (is_assume)
+	      if (is_assume && t != error_mark_node)
 		{
-		  /* FIXME: Emit .ASSUME (t) call here.  */
-		  (void) t;
+		  tree fn = build_call_expr_internal_loc (eloc, IFN_ASSUME,
+							  void_type_node, 1,
+							  t);
+		  add_stmt (fn);
 		}
 	      parens.skip_until_found_close (parser);
 	    }
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index baa808a..90e06f9 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -46023,13 +46023,15 @@ cp_parser_omp_assumption_clauses (cp_parser *parser, cp_token *pragma_tok,
 	  matching_parens parens;
 	  if (parens.require_open (parser))
 	    {
+	      location_t eloc = cp_lexer_peek_token (parser->lexer)->location;
 	      tree t = cp_parser_assignment_expression (parser);
 	      if (!type_dependent_expression_p (t))
 		t = contextual_conv_bool (t, tf_warning_or_error);
-	      if (is_assume)
+	      if (is_assume && !error_operand_p (t))
 		{
-		  /* FIXME: Emit .ASSUME (t) call here.  */
-		  (void) t;
+		  t = build_call_expr_internal_loc (eloc, IFN_ASSUME,
+						    void_type_node, 1, t);
+		  finish_expr_stmt (t);
 		}
 	      if (!parens.require_close (parser))
 		cp_parser_skip_to_closing_parenthesis (parser,
diff --git a/gcc/testsuite/c-c++-common/gomp/assume-4.c b/gcc/testsuite/c-c++-common/gomp/assume-4.c
new file mode 100644
index 0000000..9da2296
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/assume-4.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-fopenmp -O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-times "return 42;" 2 "optimized" } } */
+/* { dg-final { scan-tree-dump-not "return -1;" "optimized" } } */
+
+int
+foo (int x)
+{
+  int y;
+  #pragma omp assume holds (x == 42)
+  y = x;
+  return y;
+}
+
+int
+bar (int x)
+{
+  #pragma omp assume holds (x < 42)
+  ;
+  if (x == 42)
+    return -1;
+  return 42;
+}