[backport gcc-4.8/trunk r195046 <mikpe@it.uu.se>]

gcc/

2013-01-09  Steven Bosscher  <steven@gcc.gnu.org>
	    Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/48189
	* predict.c (predict_loops): If max is 0, don't call compare_tree_int.
	If nitercst is 0, don't predict the exit edge.

gcc/testsuite/

2013-01-09  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/48189
	* gcc.dg/pr48189.c: New test.

--- gcc-4.6.3/gcc/predict.c.~1~	2011-01-22 22:47:40.000000000 +0100
+++ gcc-4.6.3/gcc/predict.c	2013-03-03 14:15:58.245660910 +0100
@@ -966,7 +966,8 @@ predict_loops (void)
 	  if (TREE_CODE (niter) == INTEGER_CST)
 	    {
 	      if (host_integerp (niter, 1)
-		  && compare_tree_int (niter, max-1) == -1)
+		  && max
+		  && compare_tree_int (niter, max - 1) == -1)
 		nitercst = tree_low_cst (niter, 1) + 1;
 	      else
 		nitercst = max;
@@ -988,6 +989,11 @@ predict_loops (void)
 	  else
 	    continue;
 
+	  /* If the prediction for number of iterations is zero, do not
+	     predict the exit edges.  */
+	  if (nitercst == 0)
+	    continue;
+
 	  probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst);
 	  predict_edge (ex, predictor, probability);
 	}
--- gcc-4.6.3/gcc/testsuite/gcc.dg/pr48189.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.6.3/gcc/testsuite/gcc.dg/pr48189.c	2013-03-03 14:15:58.245660910 +0100
@@ -0,0 +1,13 @@
+/* PR tree-optimization/48189 */
+/* { dg-do compile } */
+/* { dg-options "-O --param max-predicted-iterations=0" } */
+
+struct S { int s[8]; };
+  
+void
+foo (int *x, struct S *y)
+{
+  int i;
+  for (i = 0; y[i].s[i]; i++)
+    *x++ = y[i].s[i];
+}