Patch: FYI: clean up uses_jv_markobj_p a little

[Tom Tromey <tromey at redhat dot com>]

I'm checking this in on the trunk.

uses_jv_markobj_p has been bothering me a little bit.  It uses 2
unnamed constants, which is kind of lame.  This patch removes one of
them and documents a couple scenarios where the code is incorrect at
the moment (this isn't severe as it is only used with
flag_reduced_reflection).

Tom

Index: ChangeLog
from  Tom Tromey  <tromey@redhat.com>
	* java-tree.h (uses_jv_markobj_p): Declare.
	* class.c (uses_jv_markobj_p): Removed.
	* boehm.c (PROCEDURE_OBJECT_DESCRIPTOR): New define.
	(get_boehm_type_descriptor): Use it.
	(uses_jv_markobj_p): Moved from class.c.  Return bool.

Index: class.c
===================================================================
--- class.c	(revision 113541)
+++ class.c	(working copy)
@@ -1611,16 +1611,6 @@
   return 1;
 }
 
-/* The forth (index of 3) element in the vtable is the GC descriptor.
-   A value of 2 indicates that the class uses _Jv_MarkObj. */
-static int
-uses_jv_markobj_p(tree dtable)
-{
-  tree v;
-  v = VEC_index (constructor_elt, CONSTRUCTOR_ELTS (dtable), 3)->value;
-  return (2 == TREE_INT_CST_LOW (v));
-}
-
 void
 make_class_data (tree type)
 {
@@ -1659,7 +1649,7 @@
       && !flag_indirect_dispatch)
     {
       tree dtable = get_dispatch_table (type, this_class_addr);
-      uses_jv_markobj = uses_jv_markobj_p(dtable);
+      uses_jv_markobj = uses_jv_markobj_p (dtable);
       dtable_decl = build_dtable_decl (type);
       DECL_INITIAL (dtable_decl) = dtable;
       TREE_STATIC (dtable_decl) = 1;
Index: java-tree.h
===================================================================
--- java-tree.h	(revision 113541)
+++ java-tree.h	(working copy)
@@ -1,6 +1,6 @@
 /* Definitions for parsing and type checking for the GNU compiler for
    the Java(TM) language.
-   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
+   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -1358,6 +1358,7 @@
 extern void safe_layout_class (tree);
 
 extern tree get_boehm_type_descriptor (tree);
+extern bool uses_jv_markobj_p (tree);
 extern bool class_has_finalize_method (tree);
 extern void java_check_methods (tree);
 extern void init_jcf_parse (void);
Index: boehm.c
===================================================================
--- boehm.c	(revision 113541)
+++ boehm.c	(working copy)
@@ -40,6 +40,14 @@
 static void set_bit (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *,
 		     unsigned int);
 
+/* A procedure-based object descriptor.  We know that our
+   `kind' is 0, and `env' is likewise 0, so we have a simple
+   computation.  From the GC sources:
+   (((((env) << LOG_MAX_MARK_PROCS) | (proc_index)) << DS_TAG_BITS)	\
+   | DS_PROC)
+   Here DS_PROC == 2.  */
+#define PROCEDURE_OBJECT_DESCRIPTOR 2
+
 /* Treat two HOST_WIDE_INT's as a contiguous bitmap, with bit 0 being
    the least significant.  This function sets bit N in the bitmap.  */
 static void
@@ -220,15 +228,25 @@
     }
   else
     {
-      /* Compute a procedure-based object descriptor.  We know that our
-	 `kind' is 0, and `env' is likewise 0, so we have a simple
-	 computation.  From the GC sources:
-	    (((((env) << LOG_MAX_MARK_PROCS) | (proc_index)) << DS_TAG_BITS) \
-	    | DS_PROC)
-	 Here DS_PROC == 2.  */
     procedure_object_descriptor:
-      value = build_int_cst (value_type, 2);
+      value = build_int_cst (value_type, PROCEDURE_OBJECT_DESCRIPTOR);
     }
 
   return value;
 }
+
+/* The fourth (index of 3) element in the vtable is the GC descriptor.
+   A value of 2 indicates that the class uses _Jv_MarkObj. */
+bool
+uses_jv_markobj_p (tree dtable)
+{
+  tree v;
+  /* FIXME: what do we return if !flag_use_boehm_gc ? */
+  gcc_assert (flag_use_boehm_gc);
+  /* FIXME: this is wrong if TARGET_VTABLE_USES_DESCRIPTORS.  However,
+     this function is only used with flag_reduced_reflection.  No
+     point in asserting unless we hit the bad case.  */
+  gcc_assert (!flag_reduced_reflection || TARGET_VTABLE_USES_DESCRIPTORS == 0);
+  v = VEC_index (constructor_elt, CONSTRUCTOR_ELTS (dtable), 3)->value;
+  return (PROCEDURE_OBJECT_DESCRIPTOR == TREE_INT_CST_LOW (v));
+}