bitmap.h (bitmap_set_bit): Return bool.

2008-07-02  Richard Guenther  <rguenther@suse.de>

	* bitmap.h (bitmap_set_bit): Return bool.
	(bitmap_clear_bit): Likewise.
	* bitmap.c (bitmap_set_bit): Return if the bit changed.  Only
	write to the bitmap if it would.
	(bitmap_clear_bit): Likewise.
	* tree-ssa-structalias.c (add_implicit_graph_edge): Use
	bitmap_set_bit return value.
	(add_pred_graph_edge): Likewise.
	(add_graph_edge): Likewise.
	(do_sd_constraint): Likewise.
	(do_ds_constraint): Likewise.

From-SVN: r137345

4 files changed, 53 insertions, 40 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fe4267560fd..3f1a21e40eb 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,17 @@
+2008-07-02  Richard Guenther  <rguenther@suse.de>
+
+	* bitmap.h (bitmap_set_bit): Return bool.
+	(bitmap_clear_bit): Likewise.
+	* bitmap.c (bitmap_set_bit): Return if the bit changed.  Only
+	write to the bitmap if it would.
+	(bitmap_clear_bit): Likewise.
+	* tree-ssa-structalias.c (add_implicit_graph_edge): Use
+	bitmap_set_bit return value.
+	(add_pred_graph_edge): Likewise.
+	(add_graph_edge): Likewise.
+	(do_sd_constraint): Likewise.
+	(do_ds_constraint): Likewise.
+
 2008-07-02  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* config/alpha/alpha.c (alpha_need_linkage, alpha_use_linkage):
diff --git a/gcc/bitmap.c b/gcc/bitmap.c
index 97e60de6b3c..4fabdc915d2 100644
--- a/gcc/bitmap.c
+++ b/gcc/bitmap.c
@@ -595,9 +595,9 @@ bitmap_find_bit (bitmap head, unsigned int bit)
   return element;
 }
 
-/* Clear a single bit in a bitmap.  */
+/* Clear a single bit in a bitmap.  Return true if the bit changed.  */
 
-void
+bool
 bitmap_clear_bit (bitmap head, int bit)
 {
   bitmap_element *const ptr = bitmap_find_bit (head, bit);
@@ -606,17 +606,24 @@ bitmap_clear_bit (bitmap head, int bit)
     {
       unsigned bit_num  = bit % BITMAP_WORD_BITS;
       unsigned word_num = bit / BITMAP_WORD_BITS % BITMAP_ELEMENT_WORDS;
-      ptr->bits[word_num] &= ~ (((BITMAP_WORD) 1) << bit_num);
+      BITMAP_WORD bit_val = ((BITMAP_WORD) 1) << bit_num;
+      bool res = (ptr->bits[word_num] & bit_val) != 0;
+      if (res)
+	ptr->bits[word_num] &= ~bit_val;
 
       /* If we cleared the entire word, free up the element.  */
       if (bitmap_element_zerop (ptr))
 	bitmap_element_free (head, ptr);
+
+      return res;
     }
+
+  return false;
 }
 
-/* Set a single bit in a bitmap.  */
+/* Set a single bit in a bitmap.  Return true if the bit changed.  */
 
-void
+bool
 bitmap_set_bit (bitmap head, int bit)
 {
   bitmap_element *ptr = bitmap_find_bit (head, bit);
@@ -630,9 +637,15 @@ bitmap_set_bit (bitmap head, int bit)
       ptr->indx = bit / BITMAP_ELEMENT_ALL_BITS;
       ptr->bits[word_num] = bit_val;
       bitmap_element_link (head, ptr);
+      return true;
     }
   else
-    ptr->bits[word_num] |= bit_val;
+    {
+      bool res = (ptr->bits[word_num] & bit_val) == 0;
+      if (res)
+	ptr->bits[word_num] |= bit_val;
+      return res;
+    }
 }
 
 /* Return whether a bit is set within a bitmap.  */
diff --git a/gcc/bitmap.h b/gcc/bitmap.h
index 2a3b0b4baf8..7f17dc1d361 100644
--- a/gcc/bitmap.h
+++ b/gcc/bitmap.h
@@ -136,11 +136,11 @@ extern bool bitmap_ior_and_compl (bitmap DST, const_bitmap A, const_bitmap B, co
 /* A |= (B & ~C).  Return true if A changes.  */
 extern bool bitmap_ior_and_compl_into (bitmap DST, const_bitmap B, const_bitmap C);
 
-/* Clear a single register in a register set.  */
-extern void bitmap_clear_bit (bitmap, int);
+/* Clear a single bit in a bitmap.  Return true if the bit changed.  */
+extern bool bitmap_clear_bit (bitmap, int);
 
-/* Set a single register in a register set.  */
-extern void bitmap_set_bit (bitmap, int);
+/* Set a single bit in a bitmap.  Return true if the bit changed.  */
+extern bool bitmap_set_bit (bitmap, int);
 
 /* Return true if a register is set in a register set.  */
 extern int bitmap_bit_p (bitmap, int);
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index 57a02a4c754..e2b90c86b2e 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -904,11 +904,8 @@ add_implicit_graph_edge (constraint_graph_t graph, unsigned int to,
   if (!graph->implicit_preds[to])
     graph->implicit_preds[to] = BITMAP_ALLOC (&predbitmap_obstack);
 
-  if (!bitmap_bit_p (graph->implicit_preds[to], from))
-    {
-      stats.num_implicit_edges++;
-      bitmap_set_bit (graph->implicit_preds[to], from);
-    }
+  if (bitmap_set_bit (graph->implicit_preds[to], from))
+    stats.num_implicit_edges++;
 }
 
 /* Add a predecessor graph edge to GRAPH, going from TO to FROM if
@@ -921,8 +918,7 @@ add_pred_graph_edge (constraint_graph_t graph, unsigned int to,
 {
   if (!graph->preds[to])
     graph->preds[to] = BITMAP_ALLOC (&predbitmap_obstack);
-  if (!bitmap_bit_p (graph->preds[to], from))
-    bitmap_set_bit (graph->preds[to], from);
+  bitmap_set_bit (graph->preds[to], from);
 }
 
 /* Add a graph edge to GRAPH, going from FROM to TO if
@@ -943,12 +939,11 @@ add_graph_edge (constraint_graph_t graph, unsigned int to,
 
       if (!graph->succs[from])
 	graph->succs[from] = BITMAP_ALLOC (&pta_obstack);
-      if (!bitmap_bit_p (graph->succs[from], to))
+      if (bitmap_set_bit (graph->succs[from], to))
 	{
 	  r = true;
 	  if (to < FIRST_REF_NODE && from < FIRST_REF_NODE)
 	    stats.num_edges++;
-	  bitmap_set_bit (graph->succs[from], to);
 	}
       return r;
     }
@@ -1405,13 +1400,11 @@ do_sd_constraint (constraint_graph_t graph, constraint_t c,
   unsigned int j;
   bitmap_iterator bi;
 
- if (bitmap_bit_p (delta, anything_id))
-   {
-     flag = !bitmap_bit_p (sol, anything_id);
-     if (flag)
-       bitmap_set_bit (sol, anything_id);
-     goto done;
-   }
+  if (bitmap_bit_p (delta, anything_id))
+    {
+      flag |= bitmap_set_bit (sol, anything_id);
+      goto done;
+    }
 
   /* For each variable j in delta (Sol(y)), add
      an edge in the graph from j to x, and union Sol(j) into Sol(x).  */
@@ -1436,13 +1429,9 @@ do_sd_constraint (constraint_graph_t graph, constraint_t c,
 	  /* Merging the solution from ESCAPED needlessly increases
 	     the set.  Use ESCAPED as representative instead.
 	     Same for CALLUSED.  */
-	  else if ((get_varinfo (t)->id == escaped_id
-		    || get_varinfo (t)->id == callused_id)
-		   && !bitmap_bit_p (sol, get_varinfo (t)->id))
-	    {
-	      bitmap_set_bit (sol, get_varinfo (t)->id);
-	      flag = true;
-	    }
+	  else if (get_varinfo (t)->id == escaped_id
+		   || get_varinfo (t)->id == callused_id)
+	    flag |= bitmap_set_bit (sol, get_varinfo (t)->id);
 	  else if (add_graph_edge (graph, lhs, t))
 	    flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
 	}
@@ -1486,14 +1475,11 @@ do_ds_constraint (constraint_t c, bitmap delta)
 	   continue;
 	 t = find (v->id);
 
-	 if (!bitmap_bit_p (get_varinfo (t)->solution, anything_id))
+	 if (bitmap_set_bit (get_varinfo (t)->solution, anything_id)
+	     && !TEST_BIT (changed, t))
 	   {
-	     bitmap_set_bit (get_varinfo (t)->solution, anything_id);
-	     if (!TEST_BIT (changed, t))
-	       {
-		 SET_BIT (changed, t);
-		 changed_count++;
-	       }
+	     SET_BIT (changed, t);
+	     changed_count++;
 	   }
        }
      return;