fold-const.c (fold_negate_expr): Don't fold INTEGER_CST if that overflows when…

fold-const.c (fold_negate_expr): Don't fold INTEGER_CST if that overflows when SANITIZE_SI_OVERFLOW is on.

	* fold-const.c (fold_negate_expr): Don't fold INTEGER_CST if
	that overflows when SANITIZE_SI_OVERFLOW is on.  Guard -(-A)
	folding with TYPE_OVERFLOW_SANITIZED.

	* c-c++-common/ubsan/overflow-negate-3.c: New test.

From-SVN: r217556

gcc/ChangeLog

 2014-11-14  Marek Polacek  <polacek@redhat.com>
 
+	* fold-const.c (fold_negate_expr): Don't fold INTEGER_CST if
+	that overflows when SANITIZE_SI_OVERFLOW is on.  Guard -(-A)
+	folding with TYPE_OVERFLOW_SANITIZED.
+
+2014-11-14  Marek Polacek  <polacek@redhat.com>
+
 	PR sanitizer/63839
 	* asan.c (ATTR_CONST_NORETURN_NOTHROW_LEAF_LIST,
 	ATTR_COLD_CONST_NORETURN_NOTHROW_LEAF_LIST): Define.

gcc/fold-const.c

@@ -554,7 +554,8 @@ fold_negate_expr (location_t loc, tree t)
     case INTEGER_CST:
       tem = fold_negate_const (t, type);
       if (TREE_OVERFLOW (tem) == TREE_OVERFLOW (t)
-	  || !TYPE_OVERFLOW_TRAPS (type))
+	  || (!TYPE_OVERFLOW_TRAPS (type)
+	      && (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0))
 	return tem;
       break;
 
@@ -611,7 +612,9 @@ fold_negate_expr (location_t loc, tree t)
       break;
 
     case NEGATE_EXPR:
-      return TREE_OPERAND (t, 0);
+      if (!TYPE_OVERFLOW_SANITIZED (type))
+	return TREE_OPERAND (t, 0);
+      break;
 
     case PLUS_EXPR:
       if (!HONOR_SIGN_DEPENDENT_ROUNDING (TYPE_MODE (type))

gcc/testsuite/ChangeLog

 2014-11-14  Marek Polacek  <polacek@redhat.com>
 
+	* c-c++-common/ubsan/overflow-negate-3.c: New test.
+
+2014-11-14  Marek Polacek  <polacek@redhat.com>
+
 	PR sanitizer/63839
 	* c-c++-common/ubsan/pr63839.c: New test.
 	* c-c++-common/ubsan/unreachable-2.c: New test.

gcc/testsuite/c-c++-common/ubsan/overflow-negate-3.c

+/* { dg-do run } */
+/* { dg-options "-fsanitize=signed-integer-overflow" } */
+
+#define INT_MIN (-__INT_MAX__ - 1)
+
+int
+main ()
+{
+  int x = INT_MIN;
+  int y;
+  asm ("" : "+g" (x));
+  y = -(-x);
+  asm ("" : "+g" (y));
+  y = -(-INT_MIN);
+  asm ("" : "+g" (y));
+}
+
+/* { dg-output "negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */