openmp: Allow private or firstprivate arguments to default clause even for C/C++

OpenMP 5.1 allows default(private) or default(firstprivate) even in C/C++,
but it behaves the same way as in Fortran only for variables not declared at
namespace or file scope.  For the namespace/file scope variables it instead
behaves as default(none).

2021-09-18  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* gimplify.c (omp_default_clause): For C/C++ default({,first}private),
	if file/namespace scope variable doesn't have predetermined sharing,
	treat it as if there was default(none).
gcc/c/
	* c-parser.c (c_parser_omp_clause_default): Handle private and
	firstprivate arguments, adjust diagnostics on unknown argument.
gcc/cp/
	* parser.c (cp_parser_omp_clause_default): Handle private and
	firstprivate arguments, adjust diagnostics on unknown argument.
	* cp-gimplify.c (cxx_omp_finish_clause): Handle OMP_CLAUSE_PRIVATE.
gcc/testsuite/
	* c-c++-common/gomp/default-2.c: New test.
	* c-c++-common/gomp/default-3.c: New test.
	* g++.dg/gomp/default-1.C: New test.
libgomp/
	* testsuite/libgomp.c++/default-1.C: New test.
	* testsuite/libgomp.c-c++-common/default-1.c: New test.
	* libgomp.texi (OpenMP 5.1): Mark "private and firstprivate argument
	to default clause in C and C++" as implemented.

1 files changed, 22 insertions, 3 deletions

diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index eba9bbf..c5e222b 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -13420,6 +13420,9 @@ c_parser_omp_clause_copyprivate (c_parser *parser, tree list)
 /* OpenMP 2.5:
    default ( none | shared )
 
+   OpenMP 5.1:
+   default ( private | firstprivate )
+
    OpenACC:
    default ( none | present ) */
 
@@ -13446,9 +13449,24 @@ c_parser_omp_clause_default (c_parser *parser, tree list, bool is_oacc)
 	  break;
 
 	case 'p':
-	  if (strcmp ("present", p) != 0 || !is_oacc)
+	  if (is_oacc)
+	    {
+	      if (strcmp ("present", p) != 0)
+		goto invalid_kind;
+	      kind = OMP_CLAUSE_DEFAULT_PRESENT;
+	    }
+	  else
+	    {
+	      if (strcmp ("private", p) != 0)
+		goto invalid_kind;
+	      kind = OMP_CLAUSE_DEFAULT_PRIVATE;
+	    }
+	  break;
+
+	case 'f':
+	  if (strcmp ("firstprivate", p) != 0 || is_oacc)
 	    goto invalid_kind;
-	  kind = OMP_CLAUSE_DEFAULT_PRESENT;
+	  kind = OMP_CLAUSE_DEFAULT_FIRSTPRIVATE;
 	  break;
 
 	case 's':
@@ -13469,7 +13487,8 @@ c_parser_omp_clause_default (c_parser *parser, tree list, bool is_oacc)
       if (is_oacc)
 	c_parser_error (parser, "expected %<none%> or %<present%>");
       else
-	c_parser_error (parser, "expected %<none%> or %<shared%>");
+	c_parser_error (parser, "expected %<none%>, %<shared%>, "
+				"%<private%> or %<firstprivate%>");
     }
   parens.skip_until_found_close (parser);