revert: tree-ssa-loop-ch.c (copy_loop_headers): Decrement nb_iterations_upper_bound by one.

2013-11-22  Richard Biener  <rguenther@suse.de>

	Revert
	2013-11-21  Richard Biener  <rguenther@suse.de>

	* tree-ssa-loop-ch.c (copy_loop_headers): Decrement
	nb_iterations_upper_bound by one.

        * gcc.dg/torture/20131122-0.c: New testcase.

From-SVN: r205256

gcc/ChangeLog

+2013-11-22  Richard Biener  <rguenther@suse.de>
+
+	Revert
+	2013-11-21  Richard Biener  <rguenther@suse.de>
+
+	* tree-ssa-loop-ch.c (copy_loop_headers): Decrement
+	nb_iterations_upper_bound by one.
+
 2013-11-22  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config/i386/i386.c (processor_alias_table): Enable PTA_POPCNT

gcc/testsuite/ChangeLog

+2013-11-22  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/torture/20131122-0.c: New testcase.
+
 2013-11-22  Jakub Jelinek  <jakub@redhat.com>
 
 	* gcc.dg/vect/vect-124.c: New test.

gcc/testsuite/gcc.dg/torture/20131122-0.c

+/* { dg-do run } */
+
+extern int memcmp (const void *, const void *, __SIZE_TYPE__);
+extern void abort (void);
+
+void __attribute__ ((noinline))
+f (long *s, long *t, int len1, int len2)
+{
+  int i, j;
+
+  j = 2;
+  for (i = len1 - 1; i >= 0; i--)
+    {
+      s[j--] = (i < len2 ? t[i] : t[len2 - 1] < 0 ? -1 : 0);
+      if (j < 0)
+	break;
+    }
+}
+
+long s[3];
+long t[3];
+
+int
+main (void)
+{
+  t[0] = 1;
+  t[1] = 2;
+  t[2] = 3;
+  f (s, t, 3, 3);
+  if (memcmp (s, t, sizeof (s)) != 0)
+    abort ();
+  return 0;
+}
+

gcc/tree-ssa-loop-ch.c

@@ -243,16 +243,6 @@ copy_loop_headers (void)
 	 are not now, since there was the loop exit condition.  */
       split_edge (loop_preheader_edge (loop));
       split_edge (loop_latch_edge (loop));
-
-      /* We peeled off one iteration of the loop thus we can lower
-	 the maximum number of iterations if we have a previously
-	 recorded value for that.  */
-      double_int max;
-      if (get_max_loop_iterations (loop, &max))
-	{
-	  max -= double_int_one;
-	  loop->nb_iterations_upper_bound = max;
-	}
     }
 
   update_ssa (TODO_update_ssa);