ggc-page.c (compute_inverse): Short circuit calculation for object sizes larger than half a page.

	* ggc-page.c (compute_inverse): Short circuit calculation for
	object sizes larger than half a page.

From-SVN: r56548

gcc/ChangeLog

+2002-08-23  Zack Weinberg  <zack@codesourcery.com>
+
+	* ggc-page.c (compute_inverse): Short circuit calculation for
+	object sizes larger than half a page.
+
 2002-08-23  David Edelsohn  <edelsohn@gnu.org>
 
 	* config/rs6000/rs6000.c (rs6000_elf_select_section): Treat

gcc/ggc-page.c

@@ -1080,6 +1080,18 @@ compute_inverse (order)
 {
   unsigned size, inv, e;
 
+  /* There can be only one object per "page" in a bucket for sizes
+     larger than half a machine page; it will always have offset zero.  */
+  if (OBJECT_SIZE (order) > G.pagesize/2)
+    {
+      if (OBJECTS_PER_PAGE (order) != 1)
+	abort ();
+
+      DIV_MULT (order) = 1;
+      DIV_SHIFT (order) = 0;
+      return;
+    }
+
   size = OBJECT_SIZE (order);
   e = 0;
   while (size % 2 == 0)