diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f1e815e3f0b..b9eb340befd 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2012-10-08  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/54825
+	* tree-ssa-sccvn.c (vn_nary_length_from_stmt): Handle BIT_FIELD_REF.
+	(init_vn_nary_op_from_stmt): Likewise.
+	* tree-ssa-pre.c (compute_avail): Use vn_nary_op_lookup_stmt.
+	* tree-ssa-sccvn.h (sizeof_vn_nary_op): Avoid overflow.
+
 2012-10-08  Richard Guenther  <rguenther@suse.de>
 
 	* tree-ssa-pre.c (postorder_num): New global.
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 5feed3b5153..fe9186cefa9 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -3849,11 +3849,7 @@ compute_avail (void)
 			  || code == VEC_COND_EXPR)
 			continue;
 
-		      vn_nary_op_lookup_pieces (gimple_num_ops (stmt) - 1,
-						code,
-						gimple_expr_type (stmt),
-						gimple_assign_rhs1_ptr (stmt),
-						&nary);
+		      vn_nary_op_lookup_stmt (stmt, &nary);
 		      if (!nary)
 			continue;
 
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 832328d328a..2391632364d 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -2194,6 +2194,9 @@ vn_nary_length_from_stmt (gimple stmt)
     case VIEW_CONVERT_EXPR:
       return 1;
 
+    case BIT_FIELD_REF:
+      return 3;
+
     case CONSTRUCTOR:
       return CONSTRUCTOR_NELTS (gimple_assign_rhs1 (stmt));
 
@@ -2220,6 +2223,13 @@ init_vn_nary_op_from_stmt (vn_nary_op_t vno, gimple stmt)
       vno->op[0] = TREE_OPERAND (gimple_assign_rhs1 (stmt), 0);
       break;
 
+    case BIT_FIELD_REF:
+      vno->length = 3;
+      vno->op[0] = TREE_OPERAND (gimple_assign_rhs1 (stmt), 0);
+      vno->op[1] = TREE_OPERAND (gimple_assign_rhs1 (stmt), 1);
+      vno->op[2] = TREE_OPERAND (gimple_assign_rhs1 (stmt), 2);
+      break;
+
     case CONSTRUCTOR:
       vno->length = CONSTRUCTOR_NELTS (gimple_assign_rhs1 (stmt));
       for (i = 0; i < vno->length; ++i)
@@ -2227,6 +2237,7 @@ init_vn_nary_op_from_stmt (vn_nary_op_t vno, gimple stmt)
       break;
 
     default:
+      gcc_checking_assert (!gimple_assign_single_p (stmt));
       vno->length = gimple_num_ops (stmt) - 1;
       for (i = 0; i < vno->length; ++i)
 	vno->op[i] = gimple_op (stmt, i + 1);
diff --git a/gcc/tree-ssa-sccvn.h b/gcc/tree-ssa-sccvn.h
index 956bde22da1..cd418da8704 100644
--- a/gcc/tree-ssa-sccvn.h
+++ b/gcc/tree-ssa-sccvn.h
@@ -51,7 +51,7 @@ typedef const struct vn_nary_op_s *const_vn_nary_op_t;
 static inline size_t
 sizeof_vn_nary_op (unsigned int length)
 {
-  return sizeof (struct vn_nary_op_s) + sizeof (tree) * (length - 1);
+  return sizeof (struct vn_nary_op_s) + sizeof (tree) * length - sizeof (tree);
 }
 
 /* Phi nodes in the hashtable consist of their non-VN_TOP phi