1 /*
2 * Copyright 1999-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // ciObject
26 //
27 // This class represents an oop in the HotSpot virtual machine.
28 // Its subclasses are structured in a hierarchy which mirrors
29 // an aggregate of the VM's oop and klass hierarchies (see
30 // oopHierarchy.hpp). Each instance of ciObject holds a handle
31 // to a corresponding oop on the VM side and provides routines
32 // for accessing the information in its oop. By using the ciObject
33 // hierarchy for accessing oops in the VM, the compiler ensures
34 // that it is safe with respect to garbage collection; that is,
35 // GC and compilation can proceed independently without
36 // interference.
37 //
38 // Within the VM, the oop and klass hierarchies are separate.
39 // The compiler interface does not preserve this separation --
40 // the distinction between `klassOop' and `Klass' are not
41 // reflected in the interface and instead the Klass hierarchy
42 // is directly modeled as the subclasses of ciKlass.
43 class ciObject : public ResourceObj {
44 CI_PACKAGE_ACCESS
45 friend class ciEnv;
46
47 private:
48 // A JNI handle referring to an oop in the VM. This
49 // handle may, in a small set of cases, correctly be NULL.
50 jobject _handle;
51 ciKlass* _klass;
52 uint _ident;
53
54 enum { FLAG_BITS = 2 };
55 enum {
56 PERM_FLAG = 1,
57 SCAVENGABLE_FLAG = 2
58 };
59 protected:
60 ciObject();
61 ciObject(oop o);
62 ciObject(Handle h);
63 ciObject(ciKlass* klass);
64
65 jobject handle() const { return _handle; }
66 // Get the VM oop that this object holds.
67 oop get_oop() const {
68 assert(_handle != NULL, "null oop");
69 return JNIHandles::resolve_non_null(_handle);
70 }
71
72 void init_flags_from(oop x) {
73 int flags = 0;
74 if (x != NULL) {
75 if (x->is_perm())
76 flags |= PERM_FLAG;
77 if (x->is_scavengable())
78 flags |= SCAVENGABLE_FLAG;
79 }
80 _ident |= flags;
81 }
82
83 // Virtual behavior of the print() method.
84 virtual void print_impl(outputStream* st) {}
85
86 virtual const char* type_string() { return "ciObject"; }
87
88 void set_ident(uint id);
89 public:
90 // The klass of this ciObject.
91 ciKlass* klass();
92
93 // A number unique to this object.
94 uint ident();
95
96 // Are two ciObjects equal?
97 bool equals(ciObject* obj);
98
99 // A hash value for the convenience of compilers.
100 int hash();
101
102 // Tells if this oop has an encoding as a constant.
103 // True if is_scavengable is false.
104 // Also true if ScavengeRootsInCode is non-zero.
105 // If it does not have an encoding, the compiler is responsible for
106 // making other arrangements for dealing with the oop.
107 // See ciEnv::make_array
108 bool can_be_constant();
109
110 // Tells if this oop should be made a constant.
111 // True if is_scavengable is false or ScavengeRootsInCode > 1.
112 bool should_be_constant();
113
114 // Is this object guaranteed to be in the permanent part of the heap?
115 // If so, CollectedHeap::can_elide_permanent_oop_store_barriers is relevant.
116 // If the answer is false, no guarantees are made.
117 bool is_perm() { return (_ident & PERM_FLAG) != 0; }
118
119 // Might this object possibly move during a scavenge operation?
120 // If the answer is true and ScavengeRootsInCode==0, the oop cannot be embedded in code.
121 bool is_scavengable() { return (_ident & SCAVENGABLE_FLAG) != 0; }
122
123 // The address which the compiler should embed into the
124 // generated code to represent this oop. This address
125 // is not the true address of the oop -- it will get patched
126 // during nmethod creation.
127 //
128 // Usage note: no address arithmetic allowed. Oop must
129 // be registered with the oopRecorder.
130 jobject constant_encoding();
131
132 // What kind of ciObject is this?
133 virtual bool is_null_object() const { return false; }
134 virtual bool is_instance() { return false; }
135 virtual bool is_method() { return false; }
136 virtual bool is_method_data() { return false; }
137 virtual bool is_array() { return false; }
138 virtual bool is_obj_array() { return false; }
139 virtual bool is_type_array() { return false; }
140 virtual bool is_symbol() { return false; }
141 virtual bool is_type() { return false; }
142 virtual bool is_return_address() { return false; }
143 virtual bool is_klass() { return false; }
144 virtual bool is_instance_klass() { return false; }
145 virtual bool is_method_klass() { return false; }
146 virtual bool is_array_klass() { return false; }
147 virtual bool is_obj_array_klass() { return false; }
148 virtual bool is_type_array_klass() { return false; }
149 virtual bool is_symbol_klass() { return false; }
150 virtual bool is_klass_klass() { return false; }
151 virtual bool is_instance_klass_klass() { return false; }
152 virtual bool is_array_klass_klass() { return false; }
153 virtual bool is_obj_array_klass_klass() { return false; }
154 virtual bool is_type_array_klass_klass() { return false; }
155
156 // Is this a type or value which has no associated class?
157 // It is true of primitive types and null objects.
158 virtual bool is_classless() const { return false; }
159
160 // Is this ciObject a Java Language Object? That is,
161 // is the ciObject an instance or an array
162 virtual bool is_java_object() { return false; }
163
164 // Does this ciObject represent a Java Language class?
165 // That is, is the ciObject an instanceKlass or arrayKlass?
166 virtual bool is_java_klass() { return false; }
167
168 // Is this ciObject the ciInstanceKlass representing
169 // java.lang.Object()?
170 virtual bool is_java_lang_Object() { return false; }
171
172 // Does this ciObject refer to a real oop in the VM?
173 //
174 // Note: some ciObjects refer to oops which have yet to be
175 // created. We refer to these as "unloaded". Specifically,
176 // there are unloaded ciMethods, ciObjArrayKlasses, and
177 // ciInstanceKlasses. By convention the ciNullObject is
178 // considered loaded, and primitive types are considered loaded.
179 bool is_loaded() const {
180 return handle() != NULL || is_classless();
181 }
182
183 // Subclass casting with assertions.
184 ciNullObject* as_null_object() {
185 assert(is_null_object(), "bad cast");
186 return (ciNullObject*)this;
187 }
188 ciInstance* as_instance() {
189 assert(is_instance(), "bad cast");
190 return (ciInstance*)this;
191 }
192 ciMethod* as_method() {
193 assert(is_method(), "bad cast");
194 return (ciMethod*)this;
195 }
196 ciMethodData* as_method_data() {
197 assert(is_method_data(), "bad cast");
198 return (ciMethodData*)this;
199 }
200 ciArray* as_array() {
201 assert(is_array(), "bad cast");
202 return (ciArray*)this;
203 }
204 ciObjArray* as_obj_array() {
205 assert(is_obj_array(), "bad cast");
206 return (ciObjArray*)this;
207 }
208 ciTypeArray* as_type_array() {
209 assert(is_type_array(), "bad cast");
210 return (ciTypeArray*)this;
211 }
212 ciSymbol* as_symbol() {
213 assert(is_symbol(), "bad cast");
214 return (ciSymbol*)this;
215 }
216 ciType* as_type() {
217 assert(is_type(), "bad cast");
218 return (ciType*)this;
219 }
220 ciReturnAddress* as_return_address() {
221 assert(is_return_address(), "bad cast");
222 return (ciReturnAddress*)this;
223 }
224 ciKlass* as_klass() {
225 assert(is_klass(), "bad cast");
226 return (ciKlass*)this;
227 }
228 ciInstanceKlass* as_instance_klass() {
229 assert(is_instance_klass(), "bad cast");
230 return (ciInstanceKlass*)this;
231 }
232 ciMethodKlass* as_method_klass() {
233 assert(is_method_klass(), "bad cast");
234 return (ciMethodKlass*)this;
235 }
236 ciArrayKlass* as_array_klass() {
237 assert(is_array_klass(), "bad cast");
238 return (ciArrayKlass*)this;
239 }
240 ciObjArrayKlass* as_obj_array_klass() {
241 assert(is_obj_array_klass(), "bad cast");
242 return (ciObjArrayKlass*)this;
243 }
244 ciTypeArrayKlass* as_type_array_klass() {
245 assert(is_type_array_klass(), "bad cast");
246 return (ciTypeArrayKlass*)this;
247 }
248 ciSymbolKlass* as_symbol_klass() {
249 assert(is_symbol_klass(), "bad cast");
250 return (ciSymbolKlass*)this;
251 }
252 ciKlassKlass* as_klass_klass() {
253 assert(is_klass_klass(), "bad cast");
254 return (ciKlassKlass*)this;
255 }
256 ciInstanceKlassKlass* as_instance_klass_klass() {
257 assert(is_instance_klass_klass(), "bad cast");
258 return (ciInstanceKlassKlass*)this;
259 }
260 ciArrayKlassKlass* as_array_klass_klass() {
261 assert(is_array_klass_klass(), "bad cast");
262 return (ciArrayKlassKlass*)this;
263 }
264 ciObjArrayKlassKlass* as_obj_array_klass_klass() {
265 assert(is_obj_array_klass_klass(), "bad cast");
266 return (ciObjArrayKlassKlass*)this;
267 }
268 ciTypeArrayKlassKlass* as_type_array_klass_klass() {
269 assert(is_type_array_klass_klass(), "bad cast");
270 return (ciTypeArrayKlassKlass*)this;
271 }
272
273 // Print debugging output about this ciObject.
274 void print(outputStream* st = tty);
275
276 // Print debugging output about the oop this ciObject represents.
277 void print_oop(outputStream* st = tty);
278 };