c-family: Add __builtin_assoc_barrier

New builtin to enable explicit use of PAREN_EXPR in C & C++ code.

Signed-off-by: Matthias Kretz <m.kretz@gsi.de>

gcc/testsuite/ChangeLog:

	* c-c++-common/builtin-assoc-barrier-1.c: New test.

gcc/cp/ChangeLog:

	* constexpr.c (cxx_eval_constant_expression): Handle PAREN_EXPR
	via cxx_eval_constant_expression.
	* cp-objcp-common.c (names_builtin_p): Handle
	RID_BUILTIN_ASSOC_BARRIER.
	* cp-tree.h: Adjust TREE_LANG_FLAG documentation to include
	PAREN_EXPR in REF_PARENTHESIZED_P.
	(REF_PARENTHESIZED_P): Add PAREN_EXPR.
	* parser.c (cp_parser_postfix_expression): Handle
	RID_BUILTIN_ASSOC_BARRIER.
	* pt.c (tsubst_copy_and_build): If the PAREN_EXPR is not a
	parenthesized initializer, build a new PAREN_EXPR.
	* semantics.c (force_paren_expr): Simplify conditionals. Set
	REF_PARENTHESIZED_P on PAREN_EXPR.
	(maybe_undo_parenthesized_ref): Test PAREN_EXPR for
	REF_PARENTHESIZED_P.

gcc/c-family/ChangeLog:

	* c-common.c (c_common_reswords): Add __builtin_assoc_barrier.
	* c-common.h (enum rid): Add RID_BUILTIN_ASSOC_BARRIER.

gcc/c/ChangeLog:

	* c-decl.c (names_builtin_p): Handle RID_BUILTIN_ASSOC_BARRIER.
	* c-parser.c (c_parser_postfix_expression): Likewise.

gcc/ChangeLog:

	* doc/extend.texi: Document __builtin_assoc_barrier.

1 files changed, 7 insertions, 16 deletions

diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 1540442..8f79f04 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -2048,24 +2048,17 @@ force_paren_expr (tree expr, bool even_uneval)
   if (cp_unevaluated_operand && !even_uneval)
     return expr;
 
-  if (!DECL_P (tree_strip_any_location_wrapper (expr))
-      && TREE_CODE (expr) != COMPONENT_REF
-      && TREE_CODE (expr) != SCOPE_REF)
-    return expr;
-
-  location_t loc = cp_expr_location (expr);
-
   if (TREE_CODE (expr) == COMPONENT_REF
       || TREE_CODE (expr) == SCOPE_REF)
     REF_PARENTHESIZED_P (expr) = true;
-  else if (processing_template_decl)
-    expr = build1_loc (loc, PAREN_EXPR, TREE_TYPE (expr), expr);
-  else
+  else if (DECL_P (tree_strip_any_location_wrapper (expr)))
     {
-      expr = build1_loc (loc, VIEW_CONVERT_EXPR, TREE_TYPE (expr), expr);
+      location_t loc = cp_expr_location (expr);
+      const tree_code code = processing_template_decl ? PAREN_EXPR
+						      : VIEW_CONVERT_EXPR;
+      expr = build1_loc (loc, code, TREE_TYPE (expr), expr);
       REF_PARENTHESIZED_P (expr) = true;
     }
-
   return expr;
 }
 
@@ -2090,10 +2083,8 @@ maybe_undo_parenthesized_ref (tree t)
 		  || TREE_CODE (t) == STATIC_CAST_EXPR);
       t = TREE_OPERAND (t, 0);
     }
-  else if (TREE_CODE (t) == PAREN_EXPR)
-    t = TREE_OPERAND (t, 0);
-  else if (TREE_CODE (t) == VIEW_CONVERT_EXPR
-	   && REF_PARENTHESIZED_P (t))
+  else if ((TREE_CODE (t) == PAREN_EXPR || TREE_CODE (t) == VIEW_CONVERT_EXPR)
+	     && REF_PARENTHESIZED_P (t))
     t = TREE_OPERAND (t, 0);
 
   return t;