cp-tree.def (THUNK_DECL): Discuss vcall indices.

	* cp-tree.def (THUNK_DECL): Discuss vcall indices.
	* cp-tree.h (BINFO_VIRTUALS): Update documentation.
	(BF_DELTA): New macro.
	(BF_VCALL_INDEX): Likewise.
	(BF_FN): Likewise.
	(THUNK_VCALL_OFFSET): Likewise.
	(make_thunk): Change prototype.
	* class.c (build_vtable_entry): Integrate
	build_vtable_entry_for_fn.  Handle vcall indices.
	(build_vtable_entry_for_fn): Remove.
	(set_rtti_entry): Handle vcall indices.  Use BF_DELTA,
	BF_VCALL_INDEX, BF_FN.
	(modify_vtable_entry): Integrate common code from
	modify_one_vtable and dfs_fixup_vtable_deltas.
	(add_virtual_function): Set BF_VCALL_INDEX.
	(build_vtbl_initializer): Simplify.  Use BF_DELTA, BF_VCALL_INDEX,
	and BF_FN.
	(modify_one_vtable): Simplify.
	(dfs_fixup_vtable_deltas): Likewise.
	(override_one_vtable): Use BF_DELTA, BF_VCALL_INDEX, BF_FN.
	* method.c (make_thunk): Handle vcall indices.

From-SVN: r31684

gcc/cp/ChangeLog

+2000-01-27  Mark Mitchell  <mark@codesourcery.com>
+
+	* cp-tree.def (THUNK_DECL): Discuss vcall indices.
+	* cp-tree.h (BINFO_VIRTUALS): Update documentation.
+	(BF_DELTA): New macro.
+	(BF_VCALL_INDEX): Likewise.
+	(BF_FN): Likewise.
+	(THUNK_VCALL_OFFSET): Likewise.
+	(make_thunk): Change prototype.
+	* class.c (build_vtable_entry): Integrate
+	build_vtable_entry_for_fn.  Handle vcall indices.
+	(build_vtable_entry_for_fn): Remove.
+	(set_rtti_entry): Handle vcall indices.  Use BF_DELTA,
+	BF_VCALL_INDEX, BF_FN.
+	(modify_vtable_entry): Integrate common code from
+	modify_one_vtable and dfs_fixup_vtable_deltas.
+	(add_virtual_function): Set BF_VCALL_INDEX.
+	(build_vtbl_initializer): Simplify.  Use BF_DELTA, BF_VCALL_INDEX,
+	and BF_FN.
+	(modify_one_vtable): Simplify.
+	(dfs_fixup_vtable_deltas): Likewise.
+	(override_one_vtable): Use BF_DELTA, BF_VCALL_INDEX, BF_FN. 
+	* method.c (make_thunk): Handle vcall indices.
+	
 2000-01-28  Nathan Sidwell  <sidwell@codesourcery.com>
 
 	Compiler side new abi rtti (not enabled).

gcc/cp/cp-tree.def

 /* This file contains the definitions and documentation for the
    additional tree codes used in the GNU C++ compiler (see tree.def
    for the standard codes).
-   Copyright (C) 1987,88,90,93,97-8,1999 Free Software Foundation, Inc.
+   Copyright (C) 1987,88,90,93,97-8,1999, 2000 Free Software Foundation, Inc.
    Hacked by Michael Tiemann (tiemann@cygnus.com)
 
 This file is part of GNU CC.
@@ -159,12 +159,22 @@ DEFTREECODE (TYPEOF_TYPE, "typeof_type", 't', 0)
 
 /* A thunk is a stub function.
 
-   Thunks are used to implement multiple inheritance:
-   At run-time, such a thunk subtracts THUNK_DELTA (an int, not a tree)
-   from the this pointer, and then jumps to DECL_INITIAL
-   (which is an ADDR_EXPR whose operand is a FUNCTION_DECL).
+   A THUNK_DECL is an alternate entry point for an ordinary
+   FUNCTION_DECL.  It's job is to adjust the `this' poitner before
+   transferring control to the FUNCTION_DECL.
 
-   Other kinds of thunks may be defined later. */
+   A thunk may perform either, or both, of the following operations:
+
+   o Adjust the `this' pointer by a constant offset.
+   o Adjust the `this' pointer by looking up a vcall-offset
+     in the vtable.
+
+   If both operations are performed, then the constant adjument to
+   `this' is performed first.
+
+   The constant adjustment is given by THUNK_DELTA.  If the
+   vcall-offset is required, the index into the vtable is given by
+   THUNK_VCALL_OFFSET.  */
 DEFTREECODE (THUNK_DECL, "thunk_decl", 'd', 0)
 
 /* A using declaration.  DECL_INITIAL contains the specified scope.  

gcc/cp/cp-tree.h

@@ -115,15 +115,18 @@ Boston, MA 02111-1307, USA.  */
      For a static VAR_DECL, this is DECL_INIT_PRIORITY.
 
    BINFO_VIRTUALS
-     For a binfo, this is a TREE_LIST.  The TREE_PURPOSE of each node
+     For a binfo, this is a TREE_LIST.  The BF_DELTA of each node
      gives the amount by which to adjust the `this' pointer when
      calling the function.  If the method is an overriden version of a
      base class method, then it is assumed that, prior to adjustment,
      the this pointer points to an object of the base class.
 
-     The TREE_VALUE is the declaration for the virtual function
-     itself.  When CLASSTYPE_COM_INTERFACE_P does not hold, the first
-     entry does not have a TREE_VALUE; it is just an offset.
+     The BF_VCALL_INDEX of each node, if non-NULL, gives the vtable
+     index of the vcall offset for this entry.
+
+     The BF_FN is the declaration for the virtual function itself.
+     When CLASSTYPE_COM_INTERFACE_P does not hold, the first entry
+     does not have a BF_FN; it is just an offset.
 
    DECL_ARGUMENTS
      For a VAR_DECL this is DECL_ANON_UNION_ELEMS.  
@@ -1720,6 +1723,18 @@ struct lang_type
 
 /* Get the value of the top-most type dominating the non-`normal' vfields.  */
 #define VF_DERIVED_VALUE(NODE) (VF_BINFO_VALUE (NODE) ? BINFO_TYPE (VF_BINFO_VALUE (NODE)) : NULL_TREE)
+
+/* The number of bytes by which to adjust the `this' pointer when
+   calling this virtual function.  */
+#define BF_DELTA(NODE) (TREE_PURPOSE (NODE))
+
+/* If non-NULL, the vtable index at which to find the vcall offset
+   when calling this virtual function.  */
+#define BF_VCALL_INDEX(NODE) (TREE_TYPE (NODE))
+
+/* The function to call.  */
+#define BF_FN(NODE) (TREE_VALUE (NODE))
+
 
 /* Nonzero for TREE_LIST node means that this list of things
    is a list of parameters, as opposed to a list of expressions.  */
@@ -2789,8 +2804,16 @@ extern int flag_new_for_scope;
 #define DECL_REALLY_EXTERN(NODE) \
   (DECL_EXTERNAL (NODE) && ! DECL_NOT_REALLY_EXTERN (NODE))
 
+/* An integer indicating how many bytes should be subtracted from the
+   `this' pointer when this function is called.  */
 #define THUNK_DELTA(DECL) ((DECL)->decl.frame_size.i)
 
+/* An integer indicating how many bytes should be subtracted from the
+   vtable for the `this' pointer to find the vcall offset.  (The vptr
+   is always located at offset zero from the `this' pointer.)  If
+   zero, then there is no vcall offset.  */
+#define THUNK_VCALL_OFFSET(DECL) (DECL_FIELD_SIZE (DECL))
+
 /* DECL_NEEDED_P holds of a declaration when we need to emit its
    definition.  This is true when the back-end tells us that
    the symbol has been referenced in the generated code.  If, however,
@@ -3918,7 +3941,7 @@ extern tree build_overload_with_type		PARAMS ((tree, tree));
 extern tree build_destructor_name		PARAMS ((tree));
 extern tree build_opfncall			PARAMS ((enum tree_code, int, tree, tree, tree));
 extern tree hack_identifier			PARAMS ((tree, tree));
-extern tree make_thunk				PARAMS ((tree, int));
+extern tree make_thunk				PROTO((tree, int, int));
 extern void emit_thunk				PARAMS ((tree));
 extern void synthesize_method			PARAMS ((tree));
 extern tree get_id_2				PARAMS ((const char *, tree));

gcc/cp/method.c

@@ -2008,9 +2008,10 @@ hack_identifier (value, name)
 
 
 tree
-make_thunk (function, delta)
+make_thunk (function, delta, vcall_index)
      tree function;
      int delta;
+     int vcall_index;
 {
   tree thunk_id;
   tree thunk;
@@ -2033,6 +2034,11 @@ make_thunk (function, delta)
     icat (-delta);
   OB_PUTC ('_');
   OB_PUTID (DECL_ASSEMBLER_NAME (func_decl));
+  if (vcall_index)
+    {
+      OB_PUTC ('_');
+      icat (vcall_index);
+    }
   OB_FINISH ();
   thunk_id = get_identifier (obstack_base (&scratch_obstack));
 
@@ -2052,6 +2058,8 @@ make_thunk (function, delta)
       TREE_SET_CODE (thunk, THUNK_DECL);
       DECL_INITIAL (thunk) = function;
       THUNK_DELTA (thunk) = delta;
+      THUNK_VCALL_OFFSET (thunk) 
+	= vcall_index * TREE_INT_CST_LOW (TYPE_SIZE (vtable_entry_type));
       DECL_EXTERNAL (thunk) = 1;
       DECL_ARTIFICIAL (thunk) = 1;
       /* So that finish_file can write out any thunks that need to be: */