re PR middle-end/34130 (the builtin abs() gives wrong result when used in some expression)

2007-11-17  Richard Guenther  <rguenther@suse.de>

	PR middle-end/34130
	* fold-const.c (extract_muldiv_1): Do not move negative
	constants inside ABS_EXPR.

	* gcc.c-torture/execute/pr34130.c: New testcase.

From-SVN: r130258

gcc/ChangeLog

+2007-11-17  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/34130
+	* fold-const.c (extract_muldiv_1): Do not move negative
+	constants inside ABS_EXPR.
+
 2007-11-16  Ian Lance Taylor  <iant@google.com>
 
 	* collect2.c (dump_file): If a demangled symbol is followed by a

gcc/fold-const.c

@@ -6095,6 +6095,9 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
             }
           break;
         }
+      /* If the constant is negative, we cannot simplify this.  */
+      if (tree_int_cst_sgn (c) == -1)
+        break;
       /* FALLTHROUGH */
     case NEGATE_EXPR:
       if ((t1 = extract_muldiv (op0, c, code, wide_type, strict_overflow_p))

gcc/testsuite/ChangeLog

+2007-11-17  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/34130
+	* gcc.c-torture/execute/pr34130.c: New testcase.
+
 2007-11-17  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>
 
 	PR fortran/34108

gcc/testsuite/gcc.c-torture/execute/pr34130.c

+extern void abort (void);
+int foo (int i)
+{
+  return -2 * __builtin_abs(i - 2);
+}
+int main()
+{
+  if (foo(1) != -2
+      || foo(3) != -2)
+    abort ();
+  return 0;
+}