match.pd: When combining divisions exclude the degenerate case involving INT_MIN from...

2014-12-02  Richard Biener  <rguenther@suse.de>

	* match.pd: When combining divisions exclude the degenerate
	case involving INT_MIN from overflow handling.

	* gcc.dg/torture/20141202-1.c: New testcase.

From-SVN: r218269

gcc/ChangeLog

+2014-12-02  Richard Biener  <rguenther@suse.de>
+
+	* match.pd: When combining divisions exclude the degenerate
+	case involving INT_MIN from overflow handling.
+
 2014-12-02  Wilco Dijkstra  <wilco.dijkstra@arm.com>
 
 	* ira-costs.c (scan_one_insn): Improve spill cost adjustment.

gcc/match.pd

@@ -140,7 +140,9 @@ along with GCC; see the file COPYING3.  If not see
    }
    (if (!overflow_p)
     (div @0 { wide_int_to_tree (type, mul); }))
-   (if (overflow_p)
+   (if (overflow_p
+        && (TYPE_UNSIGNED (type)
+	    || mul != wi::min_value (TYPE_PRECISION (type), SIGNED)))
     { build_zero_cst (type); }))))
 
 /* Optimize A / A to 1.0 if we don't care about

gcc/testsuite/ChangeLog

+2014-12-02  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/torture/20141202-1.c: New testcase.
+
 2014-12-02  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ipa/63814

gcc/testsuite/gcc.dg/torture/20141202-1.c

+/* { dg-do run } */
+
+extern void abort (void);
+
+int foo (int x)
+{
+  return (x / 2) / ((-__INT_MAX__ - 1) / -2);
+}
+
+int main()
+{
+  if (foo (- __INT_MAX__ - 1) != -1)
+    abort ();
+  return 0;
+}