2013-01-29 Richard Biener <rguenther@suse.de>

	PR tree-optimization/56113
	* tree-ssa-structalias.c (equiv_class_lookup): Also return
	the bitmap leader.
	(label_visit): Free duplicate bitmaps and record the leader instead.
	(perform_var_substitution): Adjust.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@195541 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 22 insertions, 6 deletions

diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index 4ad956f6649..cacfdab3732 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -1907,10 +1907,10 @@ equiv_class_label_eq (const void *p1, const void *p2)
 }
 
 /* Lookup a equivalence class in TABLE by the bitmap of LABELS it
-   contains.  */
+   contains.  Sets *REF_LABELS to the bitmap LABELS is equivalent to.  */
 
 static unsigned int
-equiv_class_lookup (htab_t table, bitmap labels)
+equiv_class_lookup (htab_t table, bitmap labels, bitmap *ref_labels)
 {
   void **slot;
   struct equiv_class_label ecl;
@@ -1921,9 +1921,18 @@ equiv_class_lookup (htab_t table, bitmap labels)
   slot = htab_find_slot_with_hash (table, &ecl,
 				   ecl.hashcode, NO_INSERT);
   if (!slot)
-    return 0;
+    {
+      if (ref_labels)
+	*ref_labels = NULL;
+      return 0;
+    }
   else
-    return ((equiv_class_label_t) *slot)->equivalence_class;
+    {
+      equiv_class_label_t ec = (equiv_class_label_t) *slot;
+      if (ref_labels)
+	*ref_labels = ec->labels;
+      return ec->equivalence_class;
+    }
 }
 
 
@@ -2123,14 +2132,21 @@ label_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
 
   if (!bitmap_empty_p (graph->points_to[n]))
     {
+      bitmap ref_points_to;
       unsigned int label = equiv_class_lookup (pointer_equiv_class_table,
-					       graph->points_to[n]);
+					       graph->points_to[n],
+					       &ref_points_to);
       if (!label)
 	{
 	  label = pointer_equiv_class++;
 	  equiv_class_add (pointer_equiv_class_table,
 			   label, graph->points_to[n]);
 	}
+      else
+	{
+	  BITMAP_FREE (graph->points_to[n]);
+	  graph->points_to[n] = ref_points_to;
+	}
       graph->pointer_label[n] = label;
     }
 }
@@ -2190,7 +2206,7 @@ perform_var_substitution (constraint_graph_t graph)
       /* Look up the location equivalence label if one exists, or make
 	 one otherwise.  */
       label = equiv_class_lookup (location_equiv_class_table,
-				  pointed_by);
+				  pointed_by, NULL);
       if (label == 0)
 	{
 	  label = location_equiv_class++;