1 /*
2 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciObject.hpp"
27 #include "ci/ciUtilities.hpp"
28 #include "gc_interface/collectedHeap.inline.hpp"
29 #include "oops/oop.inline2.hpp"
30
31 // ciObject
32 //
33 // This class represents an oop in the HotSpot virtual machine.
34 // Its subclasses are structured in a hierarchy which mirrors
35 // an aggregate of the VM's oop and klass hierarchies (see
36 // oopHierarchy.hpp). Each instance of ciObject holds a handle
37 // to a corresponding oop on the VM side and provides routines
38 // for accessing the information in its oop. By using the ciObject
39 // hierarchy for accessing oops in the VM, the compiler ensures
40 // that it is safe with respect to garbage collection; that is,
41 // GC and compilation can proceed independently without
42 // interference.
43 //
44 // Within the VM, the oop and klass hierarchies are separate.
45 // The compiler interface does not preserve this separation --
46 // the distinction between `klassOop' and `Klass' are not
47 // reflected in the interface and instead the Klass hierarchy
48 // is directly modeled as the subclasses of ciKlass.
49
50 // ------------------------------------------------------------------
51 // ciObject::ciObject
52 ciObject::ciObject(oop o) {
53 ASSERT_IN_VM;
54 if (ciObjectFactory::is_initialized()) {
55 _handle = JNIHandles::make_local(o);
56 } else {
57 _handle = JNIHandles::make_global(o);
58 }
59 _klass = NULL;
60 _ident = 0;
61 init_flags_from(o);
62 }
63
64 // ------------------------------------------------------------------
65 // ciObject::ciObject
66 //
67 ciObject::ciObject(Handle h) {
68 ASSERT_IN_VM;
69 if (ciObjectFactory::is_initialized()) {
70 _handle = JNIHandles::make_local(h());
71 } else {
72 _handle = JNIHandles::make_global(h);
73 }
74 _klass = NULL;
75 _ident = 0;
76 init_flags_from(h());
77 }
78
79 // ------------------------------------------------------------------
80 // ciObject::ciObject
81 //
82 // Unloaded klass/method variant. `klass' is the klass of the unloaded
83 // klass/method, if that makes sense.
84 ciObject::ciObject(ciKlass* klass) {
85 ASSERT_IN_VM;
86 assert(klass != NULL, "must supply klass");
87 _handle = NULL;
88 _klass = klass;
89 _ident = 0;
90 }
91
92 // ------------------------------------------------------------------
93 // ciObject::ciObject
94 //
95 // NULL variant. Used only by ciNullObject.
96 ciObject::ciObject() {
97 ASSERT_IN_VM;
98 _handle = NULL;
99 _klass = NULL;
100 _ident = 0;
101 }
102
103 // ------------------------------------------------------------------
104 // ciObject::klass
105 //
106 // Get the ciKlass of this ciObject.
107 ciKlass* ciObject::klass() {
108 if (_klass == NULL) {
109 if (_handle == NULL) {
110 // When both _klass and _handle are NULL, we are dealing
111 // with the distinguished instance of ciNullObject.
112 // No one should ask it for its klass.
113 assert(is_null_object(), "must be null object");
114 ShouldNotReachHere();
115 return NULL;
116 }
117
118 GUARDED_VM_ENTRY(
119 oop o = get_oop();
120 _klass = CURRENT_ENV->get_object(o->klass())->as_klass();
121 );
122 }
123 return _klass;
124 }
125
126 // ------------------------------------------------------------------
127 // ciObject::set_ident
128 //
129 // Set the unique identity number of a ciObject.
130 void ciObject::set_ident(uint id) {
131 assert((_ident >> FLAG_BITS) == 0, "must only initialize once");
132 assert( id < ((uint)1 << (BitsPerInt-FLAG_BITS)), "id too big");
133 _ident = _ident + (id << FLAG_BITS);
134 }
135
136 // ------------------------------------------------------------------
137 // ciObject::ident
138 //
139 // Report the unique identity number of a ciObject.
140 uint ciObject::ident() {
141 uint id = _ident >> FLAG_BITS;
142 assert(id != 0, "must be initialized");
143 return id;
144 }
145
146 // ------------------------------------------------------------------
147 // ciObject::equals
148 //
149 // Are two ciObjects equal?
150 bool ciObject::equals(ciObject* obj) {
151 return (this == obj);
152 }
153
154 // ------------------------------------------------------------------
155 // ciObject::hash
156 //
157 // A hash value for the convenience of compilers.
158 //
159 // Implementation note: we use the address of the ciObject as the
160 // basis for the hash. Use the _ident field, which is well-behaved.
161 int ciObject::hash() {
162 return ident() * 31;
163 }
164
165 // ------------------------------------------------------------------
166 // ciObject::constant_encoding
167 //
168 // The address which the compiler should embed into the
169 // generated code to represent this oop. This address
170 // is not the true address of the oop -- it will get patched
171 // during nmethod creation.
172 //
173 //
174 //
175 // Implementation note: we use the handle as the encoding. The
176 // nmethod constructor resolves the handle and patches in the oop.
177 //
178 // This method should be changed to return an generified address
179 // to discourage use of the JNI handle.
180 jobject ciObject::constant_encoding() {
181 assert(is_null_object() || handle() != NULL, "cannot embed null pointer");
182 assert(can_be_constant(), "oop must be NULL or perm");
183 return handle();
184 }
185
186 // ------------------------------------------------------------------
187 // ciObject::can_be_constant
188 bool ciObject::can_be_constant() {
189 if (ScavengeRootsInCode >= 1) return true; // now everybody can encode as a constant
190 return handle() == NULL || is_perm();
191 }
192
193 // ------------------------------------------------------------------
194 // ciObject::should_be_constant()
195 bool ciObject::should_be_constant() {
196 if (ScavengeRootsInCode >= 2) return true; // force everybody to be a constant
197 ciEnv* env = CURRENT_ENV;
198 if (!JavaObjectsInPerm && !is_null_object()) {
199 // We want Strings and Classes to be embeddable by default since
200 // they used to be in the perm world. Not all Strings used to be
201 // embeddable but there's no easy way to distinguish the interned
202 // from the regulars ones so just treat them all that way.
203 if (klass() == env->String_klass() || klass() == env->Class_klass()) {
204 return true;
205 }
206 }
207 if (EnableInvokeDynamic &&
208 (klass()->is_subclass_of(env->MethodHandle_klass()) ||
209 klass()->is_subclass_of(env->CallSite_klass()))) {
210 assert(ScavengeRootsInCode >= 1, "must be");
211 // We want to treat these aggressively.
212 return true;
213 }
214
215 return handle() == NULL || is_perm();
216 }
217
218
219 // ------------------------------------------------------------------
220 // ciObject::print
221 //
222 // Print debugging output about this ciObject.
223 //
224 // Implementation note: dispatch to the virtual print_impl behavior
225 // for this ciObject.
226 void ciObject::print(outputStream* st) {
227 st->print("<%s", type_string());
228 GUARDED_VM_ENTRY(print_impl(st);)
229 st->print(" ident=%d %s%s address=0x%x>", ident(),
230 is_perm() ? "PERM" : "",
231 is_scavengable() ? "SCAVENGABLE" : "",
232 (address)this);
233 }
234
235 // ------------------------------------------------------------------
236 // ciObject::print_oop
237 //
238 // Print debugging output about the oop this ciObject represents.
239 void ciObject::print_oop(outputStream* st) {
240 if (is_null_object()) {
241 st->print_cr("NULL");
242 } else if (!is_loaded()) {
243 st->print_cr("UNLOADED");
244 } else {
245 GUARDED_VM_ENTRY(get_oop()->print_on(st);)
246 }
247 }