tree-ssa.c (walk_use_def_chains_1): Make the visited map a pointer set instead of a bitmap.

	* tree-ssa.c (walk_use_def_chains_1): Make the visited map a
	pointer set instead of a bitmap.
	(walk_use_def_chains): Create, pass and clean up that pointer_set.

	* tree-ssa-alias.c (struct alias_info): Make the ssa_names_visited
	field an sbitmap.
	(init_alias_info): Allocate and zero it here.
	(delete_alias_info): Delete it here.
	(collect_points_to_info_for): Use it.

From-SVN: r90508

gcc/ChangeLog

+2004-11-12  Steven Bosscher  <stevenb@suse.de>
+
+	* tree-ssa.c (walk_use_def_chains_1): Make the visited map a
+	pointer set instead of a bitmap.
+	(walk_use_def_chains): Create, pass and clean up that pointer_set.
+
+	* tree-ssa-alias.c (struct alias_info): Make the ssa_names_visited
+	field an sbitmap.
+	(init_alias_info): Allocate and zero it here.
+	(delete_alias_info): Delete it here.
+	(collect_points_to_info_for): Use it.
+
 2004-11-11  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* alias.c (record_alias_subset, addr_side_effect_eval):

gcc/tree-ssa-alias.c

@@ -73,7 +73,7 @@ struct alias_info
   /* SSA names visited while collecting points-to information.  If bit I
      is set, it means that SSA variable with version I has already been
      visited.  */
-  bitmap ssa_names_visited;
+  sbitmap ssa_names_visited;
 
   /* Array of SSA_NAME pointers processed by the points-to collector.  */
   varray_type processed_ptrs;
@@ -368,7 +368,8 @@ init_alias_info (void)
   static bool aliases_computed_p = false;
 
   ai = xcalloc (1, sizeof (struct alias_info));
-  ai->ssa_names_visited = BITMAP_XMALLOC ();
+  ai->ssa_names_visited = sbitmap_alloc (num_ssa_names);
+  sbitmap_zero (ai->ssa_names_visited);
   VARRAY_TREE_INIT (ai->processed_ptrs, 50, "processed_ptrs");
   ai->addresses_needed = BITMAP_XMALLOC ();
   VARRAY_UINT_INIT (ai->num_references, num_referenced_vars, "num_references");
@@ -449,7 +450,7 @@ delete_alias_info (struct alias_info *ai)
 {
   size_t i;
 
-  BITMAP_XFREE (ai->ssa_names_visited);
+  sbitmap_free (ai->ssa_names_visited);
   ai->processed_ptrs = NULL;
   BITMAP_XFREE (ai->addresses_needed);
 
@@ -484,9 +485,9 @@ collect_points_to_info_for (struct alias_info *ai, tree ptr)
 {
   gcc_assert (POINTER_TYPE_P (TREE_TYPE (ptr)));
 
-  if (!bitmap_bit_p (ai->ssa_names_visited, SSA_NAME_VERSION (ptr)))
+  if (!TEST_BIT (ai->ssa_names_visited, SSA_NAME_VERSION (ptr)))
     {
-      bitmap_set_bit (ai->ssa_names_visited, SSA_NAME_VERSION (ptr));
+      SET_BIT (ai->ssa_names_visited, SSA_NAME_VERSION (ptr));
       walk_use_def_chains (ptr, collect_points_to_info_r, ai, true);
       VARRAY_PUSH_TREE (ai->processed_ptrs, ptr);
     }

gcc/tree-ssa.c

@@ -36,6 +36,7 @@ Boston, MA 02111-1307, USA.  */
 #include "function.h"
 #include "diagnostic.h"
 #include "bitmap.h"
+#include "pointer-set.h"
 #include "tree-flow.h"
 #include "tree-gimple.h"
 #include "tree-inline.h"
@@ -905,8 +906,10 @@ tree_ssa_useless_type_conversion (tree expr)
 /* Internal helper for walk_use_def_chains.  VAR, FN and DATA are as
    described in walk_use_def_chains.
    
-   VISITED is a bitmap used to mark visited SSA_NAMEs to avoid
-      infinite loops.
+   VISITED is a pointer set used to mark visited SSA_NAMEs to avoid
+      infinite loops.  We used to have a bitmap for this to just mark
+      SSA versions we had visited.  But non-sparse bitmaps are way too
+      expensive, while sparse bitmaps may cause quadratic behavior.
 
    IS_DFS is true if the caller wants to perform a depth-first search
       when visiting PHI nodes.  A DFS will visit each PHI argument and
@@ -916,15 +919,13 @@ tree_ssa_useless_type_conversion (tree expr)
 
 static bool
 walk_use_def_chains_1 (tree var, walk_use_def_chains_fn fn, void *data,
-		       bitmap visited, bool is_dfs)
+		       struct pointer_set_t *visited, bool is_dfs)
 {
   tree def_stmt;
 
-  if (bitmap_bit_p (visited, SSA_NAME_VERSION (var)))
+  if (pointer_set_insert (visited, var))
     return false;
 
-  bitmap_set_bit (visited, SSA_NAME_VERSION (var));
-
   def_stmt = SSA_NAME_DEF_STMT (var);
 
   if (TREE_CODE (def_stmt) != PHI_NODE)
@@ -1002,9 +1003,9 @@ walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data,
     (*fn) (var, def_stmt, data);
   else
     {
-      bitmap visited = BITMAP_XMALLOC ();
+      struct pointer_set_t *visited = pointer_set_create ();
       walk_use_def_chains_1 (var, fn, data, visited, is_dfs);
-      BITMAP_XFREE (visited);
+      pointer_set_destroy (visited);
     }
 }