diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 373ed3f2172..8339ab413ad 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2007-01-18  Ben Elliston  <bje@au.ibm.com>
+
+	* genpreds.c (write_insn_preds_c): Only write out the function
+	body for regclass_for_constraint if we have register constraints.
+
 2007-01-17  Tom Tromey  <tromey@redhat.com>
 
 	* doc/sourcebuild.texi (libgcj Tests): Use sourceware.org.
diff --git a/gcc/genpreds.c b/gcc/genpreds.c
index 535c9ddde77..93ce942e50a 100644
--- a/gcc/genpreds.c
+++ b/gcc/genpreds.c
@@ -2,7 +2,8 @@
    - prototype declarations for operand predicates (tm-preds.h)
    - function definitions of operand predicates, if defined new-style
      (insn-preds.c)
-   Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007
+   Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -1336,7 +1337,8 @@ write_insn_preds_c (void)
   if (constraint_max_namelen > 0)
     {
       write_lookup_constraint ();
-      write_regclass_for_constraint ();
+      if (have_register_constraints)
+	write_regclass_for_constraint ();
       write_constraint_satisfied_p ();
       
       if (constraint_max_namelen > 1)