re PR middle-end/56956 (ftrapv traps on valid abs-like code)

2015-10-29  Richard Biener  <rguenther@suse.de>

	PR middle-end/56956
	* fold-const.c (fold_cond_expr_with_comparison): Do not fold
	unsigned conditonal negation to ABS_EXPR.

	* c-c++-common/ubsan/pr56956.c: New testcase.

From-SVN: r229517

gcc/ChangeLog

 2015-10-29  Richard Biener  <rguenther@suse.de>
 
+	PR middle-end/56956
+	* fold-const.c (fold_cond_expr_with_comparison): Do not fold
+	unsigned conditonal negation to ABS_EXPR.
+
+2015-10-29  Richard Biener  <rguenther@suse.de>
+
 	* gimple-match-head.c (gimple_simplify): Remove premature checking
 	of builtin_decl_implicit of function calls we simplify.
 

gcc/fold-const.c

@@ -4963,8 +4963,7 @@ fold_cond_expr_with_comparison (location_t loc, tree type,
       case GE_EXPR:
       case GT_EXPR:
 	if (TYPE_UNSIGNED (TREE_TYPE (arg1)))
-	  arg1 = fold_convert_loc (loc, signed_type_for
-			       (TREE_TYPE (arg1)), arg1);
+	  break;
 	tem = fold_build1_loc (loc, ABS_EXPR, TREE_TYPE (arg1), arg1);
 	return pedantic_non_lvalue_loc (loc, fold_convert_loc (loc, type, tem));
       case UNLE_EXPR:
@@ -4974,8 +4973,7 @@ fold_cond_expr_with_comparison (location_t loc, tree type,
       case LE_EXPR:
       case LT_EXPR:
 	if (TYPE_UNSIGNED (TREE_TYPE (arg1)))
-	  arg1 = fold_convert_loc (loc, signed_type_for
-			       (TREE_TYPE (arg1)), arg1);
+	  break;
 	tem = fold_build1_loc (loc, ABS_EXPR, TREE_TYPE (arg1), arg1);
 	return negate_expr (fold_convert_loc (loc, type, tem));
       default:

gcc/testsuite/ChangeLog

+2015-10-29  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/56956
+	* c-c++-common/ubsan/pr56956.c: New testcase.
+
 2015-10-28  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/discr44.adb: New test.

gcc/testsuite/c-c++-common/ubsan/pr56956.c

+/* { dg-do run } */
+/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
+
+unsigned int __attribute__((noinline,noclone))
+foo (unsigned int x)
+{
+  return x <= __INT_MAX__ ? x : -x;
+}
+
+int
+main ()
+{
+  volatile unsigned int tem = foo (-__INT_MAX__ - 1);
+  return 0;
+}