I'd like to backport the fox for PR48189 to 4.7 branch, so we can
close the PR. Ok?
2013-04-16 Marek Polacek <pola...@redhat.com>
Backport from mainline
2013-01-08 Steven Bosscher <ste...@gcc.gnu.org>
Jakub Jelinek <ja...@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.dg/pr48189.c: New test.
--- gcc/predict.c.mp 2013-04-16 08:57:31.922977475 +0200
+++ gcc/predict.c 2013-04-16 08:57:34.978987175 +0200
@@ -983,7 +983,8 @@ 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;
@@ -1005,6 +1006,11 @@ 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/testsuite/gcc.dg/pr48189.c.mp 2013-04-16 09:00:08.141473343 +0200
+++ gcc/testsuite/gcc.dg/pr48189.c 2013-04-16 08:59:59.443445251 +0200
@@ -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];
+}
Marek
