Add iteration count to DOM stats

[Diego Novillo]

Used it to evaluate the upcoming fix to PR 22550.



	* tree-ssa-dom.c (struct opt_stats_d): Add field num_iterations.
	(tree_ssa_dominator_optimize): Increment it.
	(dump_dominator_optimization_stats): Print it.

Index: tree-ssa-dom.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-ssa-dom.c,v
retrieving revision 2.125
diff -d -u -p -r2.125 tree-ssa-dom.c
--- tree-ssa-dom.c	28 Jul 2005 16:29:55 -0000	2.125
+++ tree-ssa-dom.c	29 Jul 2005 04:30:40 -0000
@@ -166,6 +166,7 @@ struct opt_stats_d
   long num_re;
   long num_const_prop;
   long num_copy_prop;
+  long num_iterations;
 };
 
 static struct opt_stats_d opt_stats;
@@ -524,6 +525,8 @@ tree_ssa_dominator_optimize (void)
 	  if (value && !is_gimple_min_invariant (value))
 	    SSA_NAME_VALUE (name) = NULL;
 	}
+
+      opt_stats.num_iterations++;
     }
   while (optimize > 1 && cfg_altered);
 
@@ -1356,6 +1359,9 @@ dump_dominator_optimization_stats (FILE 
   fprintf (file, "    Copies propagated:                        %6ld\n",
 	   opt_stats.num_copy_prop);
 
+  fprintf (file, "\nTotal number of DOM iterations:             %6ld\n",
+	   opt_stats.num_iterations);
+
   fprintf (file, "\nHash table statistics:\n");
 
   fprintf (file, "    avail_exprs: ");