cap frequency in make_forwarder_block

In the testcase the block with problematic frequency has to incoming
edges.  Each edge has probability 1.  The first edge's source bb has
frequency 873/10000, and the second has a frequency of 9409/10000.  So
at least one of those is slightly high probably from some sort of rounding
issue related to fixed point, but in any case make_forwarder_block
should not create basic blocks with frequency greater than BB_FREQ_MAX.

gcc/

	PR tree-optimization/64326
	* cfghooks.c (make_forwarder_block): Cap frequency of created
	basic block.

From-SVN: r220585

gcc/ChangeLog

+2015-02-10  Trevor Saunders  <tsaunders@mozilla.com>
+
+	PR tree-optimization/64326
+	* cfghooks.c (make_forwarder_block): Cap frequency of created block.
+
 2015-02-10  Rainer Emrich  <rainer@emrich-ebersheim.de>
 
 	PR gcov-profile/61889

gcc/cfghooks.c

@@ -863,6 +863,9 @@ make_forwarder_block (basic_block bb, bool (*redirect_edge_p) (edge),
       if (redirect_edge_p (e))
 	{
 	  dummy->frequency += EDGE_FREQUENCY (e);
+	  if (dummy->frequency > BB_FREQ_MAX)
+	    dummy->frequency = BB_FREQ_MAX;
+
 	  dummy->count += e->count;
 	  fallthru->count += e->count;
 	  ei_next (&ei);

gcc/testsuite/gcc.dg/torture/pr64326.c

+/* { dg-do compile } */
+
+int a, b, c, d, e, f[5][2];
+char g;
+
+int
+fn1 ()
+{
+	  return d && c ? 0 : 1;
+}
+
+int
+fn2 ()
+{
+	  int h;
+	    for (;;)
+		        for (; e;)
+				      {
+					              int i, j;
+						              h = a ? 1 : b;
+							              if (h || fn1 () ^ g - 682)
+									                {
+												            for (i = 0; i < 5; i++)
+														                  for (j = 0; j < 2; j++)
+																	                  f[i][j] = 0;
+													                return 0;
+															          }
+								            }
+}
+