From: Jason Merrill <jason@redhat.com>
Date: Tue, 17 Nov 2015 21:44:08 +0000 (-0500)
Subject: Don't fold -(constant) or -0.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8c2bebddd224cddee49a9e436aac395a1f7716f5;p=gcc.git

Don't fold -(constant) or -0.

	* parser.c (cp_parser_unary_expression): Fold -constant here.
	* typeck.c (cp_build_unary_op): Not here.

From-SVN: r230506
---

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index e4103004286..536fee0b1ba 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,8 @@
 2015-11-17  Jason Merrill  <jason@redhat.com>
 
+	* parser.c (cp_parser_unary_expression): Fold -constant here.
+	* typeck.c (cp_build_unary_op): Not here.
+
 	PR bootstrap/68361
 	* cvt.c (cp_convert_and_check): Use warning_sentinel to suppress
 	-Wparentheses.
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 286c8db54c9..c5f95301e34 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -7662,6 +7662,8 @@ cp_parser_unary_expression (cp_parser *parser, cp_id_kind * pidk,
 
       /* Consume the operator token.  */
       token = cp_lexer_consume_token (parser->lexer);
+      enum cpp_ttype op_ttype = cp_lexer_peek_token (parser->lexer)->type;
+
       /* Parse the cast-expression.  */
       cast_expression
 	= cp_parser_cast_expression (parser,
@@ -7693,8 +7695,25 @@ cp_parser_unary_expression (cp_parser *parser, cp_id_kind * pidk,
 	  non_constant_p = unary_operator == PREINCREMENT_EXPR
 			   ? NIC_PREINCREMENT : NIC_PREDECREMENT;
 	  /* Fall through.  */
-	case UNARY_PLUS_EXPR:
 	case NEGATE_EXPR:
+	  /* Immediately fold negation of a constant, unless the constant is 0
+	     (since -0 == 0) or it would overflow.  */
+	  if (unary_operator == NEGATE_EXPR && op_ttype == CPP_NUMBER
+	      && CONSTANT_CLASS_P (cast_expression)
+	      && !integer_zerop (cast_expression)
+	      && !TREE_OVERFLOW (cast_expression))
+	    {
+	      tree folded = fold_build1 (unary_operator,
+					 TREE_TYPE (cast_expression),
+					 cast_expression);
+	      if (CONSTANT_CLASS_P (folded) && !TREE_OVERFLOW (folded))
+		{
+		  expression = folded;
+		  break;
+		}
+	    }
+	  /* Fall through.  */
+	case UNARY_PLUS_EXPR:
 	case TRUTH_NOT_EXPR:
 	  expression = finish_unary_op_expr (loc, unary_operator,
 					     cast_expression, complain);
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 6541e97cca5..b7395cf072a 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -5768,10 +5768,6 @@ cp_build_unary_op (enum tree_code code, tree xarg, int noconvert,
 	    /* Make sure the result is not an lvalue: a unary plus or minus
 	       expression is always a rvalue.  */
 	    arg = rvalue (arg);
-
-	    if (code == NEGATE_EXPR && CONSTANT_CLASS_P (arg))
-	      /* Immediately fold negation of a constant.  */
-	      return fold_build1 (code, TREE_TYPE (arg), arg);
 	  }
       }
       break;