1 /* src/vm/linker.h - class linker header
3 Copyright (C) 1996-2005 R. Grafl, A. Krall, C. Kruegel, C. Oates,
4 R. Obermaisser, M. Platter, M. Probst, S. Ring, E. Steiner,
5 C. Thalinger, D. Thuernbeck, P. Tomsich, C. Ullrich, J. Wenninger,
6 Institut f. Computersprachen - TU Wien
8 This file is part of CACAO.
10 This program is free software; you can redistribute it and/or
11 modify it under the terms of the GNU General Public License as
12 published by the Free Software Foundation; either version 2, or (at
13 your option) any later version.
15 This program is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with this program; if not, write to the Free Software
22 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
25 Contact: cacao@complang.tuwien.ac.at
27 Authors: Christian Thalinger
31 $Id: linker.h 3266 2005-09-21 20:20:48Z twisti $
38 /* forward typedefs ***********************************************************/
40 typedef struct _vftbl vftbl_t;
41 typedef struct arraydescriptor arraydescriptor;
42 typedef struct primitivetypeinfo primitivetypeinfo;
46 #include "vm/references.h"
49 /* virtual function table ******************************************************
51 The vtbl has a bidirectional layout with open ends at both sides.
52 interfacetablelength gives the number of entries of the interface
53 table at the start of the vftbl. The vftbl pointer points to
54 &interfacetable[0]. vftbllength gives the number of entries of
55 table at the end of the vftbl.
57 runtime type check (checkcast):
59 Different methods are used for runtime type check depending on the
60 argument of checkcast/instanceof.
62 A check against a class is implemented via relative numbering on
63 the class hierachy tree. The tree is numbered in a depth first
64 traversal setting the base field and the diff field. The diff field
65 gets the result of (high - base) so that a range check can be
66 implemented by an unsigned compare. A sub type test is done by
67 checking the inclusion of base of the sub class in the range of the
70 A check against an interface is implemented via the
71 interfacevftbl. If the interfacevftbl contains a nonnull value a
72 class is a subclass of this interface.
76 Like standard virtual methods interface methods are called using
77 virtual function tables. All interfaces are numbered sequentially
78 (starting with zero). For each class there exist an interface table
79 of virtual function tables for each implemented interface. The
80 length of the interface table is determined by the highest number
81 of an implemented interface.
83 The following example assumes a class which implements interface 0 and 3:
85 interfacetablelength = 4
88 +-----------+ | method 2 |---> method z
89 | class | | method 1 |---> method y
90 +-----------+ | method 0 |---> method x
91 | ivftbl 0 |----------> +----------+
92 vftblptr ---> +-----------+
93 | ivftbl -1 |--> NULL +----------+
94 | ivftbl -2 |--> NULL | method 1 |---> method x
95 | ivftbl -3 |-----+ | method 0 |---> method a
96 +-----------+ +----> +----------+
103 interfacevftbllength ---> +---------------+
105 *******************************************************************************/
108 methodptr *interfacetable[1]; /* interface table (access via macro) */
109 classinfo *class; /* class, the vtbl belongs to */
110 arraydescriptor *arraydesc; /* for array classes, otherwise NULL */
111 s4 vftbllength; /* virtual function table length */
112 s4 interfacetablelength; /* interface table length */
113 s4 baseval; /* base for runtime type check */
114 /* (-index for interfaces) */
115 s4 diffval; /* high - base for runtime type check */
116 s4 *interfacevftbllength; /* length of interface vftbls */
117 methodptr table[1]; /* class vftbl */
121 /* arraydescriptor *************************************************************
123 For every array class an arraydescriptor is allocated which
124 describes the array class. The arraydescriptor is referenced from
125 the vftbl of the array class.
127 *******************************************************************************/
129 struct arraydescriptor {
130 vftbl_t *componentvftbl; /* vftbl of the component type, NULL for primit. */
131 vftbl_t *elementvftbl; /* vftbl of the element type, NULL for primitive */
132 s2 arraytype; /* ARRAYTYPE_* constant */
133 s2 dimension; /* dimension of the array (always >= 1) */
134 s4 dataoffset; /* offset of the array data from object pointer */
135 s4 componentsize; /* size of a component in bytes */
136 s2 elementtype; /* ARRAYTYPE_* constant */
140 /* primitivetypeinfo **********************************************************/
142 struct primitivetypeinfo {
143 classinfo *class_wrap; /* class for wrapping primitive type */
144 classinfo *class_primitive; /* primitive class */
145 char *wrapname; /* name of class for wrapping */
146 char typesig; /* one character type signature */
147 char *name; /* name of primitive class */
148 char *arrayname; /* name of primitive array class */
149 classinfo *arrayclass; /* primitive array class */
150 vftbl_t *arrayvftbl; /* vftbl of primitive array class */
154 /* global variables ***********************************************************/
156 /* This array can be indexed by the PRIMITIVETYPE_ and ARRAYTYPE_ constants */
157 /* (except ARRAYTYPE_OBJECT). */
159 extern primitivetypeinfo primitivetype_table[PRIMITIVETYPE_COUNT];
162 /* function prototypes ********************************************************/
164 /* initialize the linker subsystem */
165 bool linker_init(void);
168 classinfo *link_class(classinfo *c);
170 #endif /* _LINKER_H */
174 * These are local overrides for various environment variables in Emacs.
175 * Please do not remove this and leave it at the end of the file, where
176 * Emacs will automagically detect them.
177 * ---------------------------------------------------------------------
180 * indent-tabs-mode: t