diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9a266369b93..a00e858faeb 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2009-11-23  Richard Guenther  <rguenther@suse.de>
+
+	* tree-dfa.c (get_ref_base_and_extent): Adjust maximum access
+	size for DECL bases.
+
 2009-11-22  Richard Henderson  <rth@redhat.com>
 
 	* i386.c (avx_vpermilp_parallel): New function.
diff --git a/gcc/tree-dfa.c b/gcc/tree-dfa.c
index d1f84a2ebaa..20bdad2cbdd 100644
--- a/gcc/tree-dfa.c
+++ b/gcc/tree-dfa.c
@@ -914,13 +914,23 @@ get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
      the array.  The simplest way to conservatively deal with this
      is to punt in the case that offset + maxsize reaches the
      base type boundary.  This needs to include possible trailing padding
-     that is there for alignment purposes.  */
+     that is there for alignment purposes.
 
-  if (seen_variable_array_ref
-      && maxsize != -1
-      && (!host_integerp (TYPE_SIZE (TREE_TYPE (exp)), 1)
-	  || (bit_offset + maxsize
-	      == (signed) TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (exp))))))
+     That is of course only true if the base object is not a decl.  */
+
+  if (DECL_P (exp))
+    {
+      /* If maxsize is unknown adjust it according to the size of the
+         base decl.  */
+      if (maxsize == -1
+	  && host_integerp (DECL_SIZE (exp), 1))
+	maxsize = TREE_INT_CST_LOW (DECL_SIZE (exp)) - bit_offset;
+    }
+  else if (seen_variable_array_ref
+	   && maxsize != -1
+	   && (!host_integerp (TYPE_SIZE (TREE_TYPE (exp)), 1)
+	       || (bit_offset + maxsize
+		   == (signed) TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (exp))))))
     maxsize = -1;
 
   /* ???  Due to negative offsets in ARRAY_REF we can end up with