1 /*
2 * Copyright (c) 1999, 2012, 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 #ifndef SHARE_VM_CI_CIOBJECT_HPP
26 #define SHARE_VM_CI_CIOBJECT_HPP
27
28 #include "ci/ciBaseObject.hpp"
29 #include "ci/ciClassList.hpp"
30 #include "gc/shared/barrierSet.hpp"
31 #include "memory/allocation.hpp"
32 #include "runtime/handles.hpp"
33 #include "runtime/jniHandles.hpp"
34
35 // ciObject
36 //
37 // This class represents an oop in the HotSpot virtual machine.
38 // Its subclasses are structured in a hierarchy which mirrors
39 // an aggregate of the VM's oop and klass hierarchies (see
40 // oopHierarchy.hpp). Each instance of ciObject holds a handle
41 // to a corresponding oop on the VM side and provides routines
42 // for accessing the information in its oop. By using the ciObject
43 // hierarchy for accessing oops in the VM, the compiler ensures
44 // that it is safe with respect to garbage collection; that is,
45 // GC and compilation can proceed independently without
46 // interference.
47 //
48 // Within the VM, the oop and klass hierarchies are separate.
49 // The compiler interface does not preserve this separation --
50 // the distinction between `Klass*' and `Klass' are not
51 // reflected in the interface and instead the Klass hierarchy
52 // is directly modeled as the subclasses of ciKlass.
53 class ciObject : public ciBaseObject {
54 CI_PACKAGE_ACCESS
55 friend class ciEnv;
56
57 private:
58 // A JNI handle referring to an oop in the VM. This
59 // handle may, in a small set of cases, correctly be NULL.
60 jobject _handle;
61 ciKlass* _klass;
62
63 protected:
64 ciObject();
65 ciObject(oop o);
66 ciObject(Handle h);
67 ciObject(ciKlass* klass);
68
69 jobject handle() const { return _handle; }
70 // Get the VM oop that this object holds.
71 oop get_oop() const {
72 assert(_handle != NULL, "null oop");
73 oop obj = JNIHandles::resolve_non_null(_handle);
74 assert(obj == oopDesc::bs()->resolve_and_maybe_copy_oop(obj), "expect to-space copy");
75 return obj;
76 }
77
78 void init_flags_from(oop x);
79
80 // Virtual behavior of the print() method.
81 virtual void print_impl(outputStream* st) {}
82
83 virtual const char* type_string() { return "ciObject"; }
84
85 public:
86 // The klass of this ciObject.
87 ciKlass* klass();
88
89 // Are two ciObjects equal?
90 bool equals(ciObject* obj);
91
92 // A hash value for the convenience of compilers.
93 int hash();
94
95 // Tells if this oop has an encoding as a constant.
96 // True if is_perm is true.
97 // Also true if ScavengeRootsInCode is non-zero.
98 // If it does not have an encoding, the compiler is responsible for
99 // making other arrangements for dealing with the oop.
100 // See ciEnv::make_array
101 bool can_be_constant();
102
103 // Tells if this oop should be made a constant.
104 // True if is_perm is true or ScavengeRootsInCode > 1.
105 bool should_be_constant();
106
107 // Might this object possibly move during a scavenge operation?
108 // If the answer is true and ScavengeRootsInCode==0, the oop cannot be embedded in code.
109 bool is_scavengable() { return (_ident & SCAVENGABLE_FLAG) != 0; }
110
111 // The address which the compiler should embed into the
112 // generated code to represent this oop. This address
113 // is not the true address of the oop -- it will get patched
114 // during nmethod creation.
115 //
116 // Usage note: no address arithmetic allowed. Oop must
117 // be registered with the oopRecorder.
118 jobject constant_encoding();
119
120 virtual bool is_object() const { return true; }
121
122 // What kind of ciObject is this?
123 virtual bool is_null_object() const { return false; }
124 virtual bool is_call_site() const { return false; }
125 virtual bool is_cpcache() const { return false; }
126 virtual bool is_instance() { return false; }
127 virtual bool is_member_name() const { return false; }
128 virtual bool is_method_handle() const { return false; }
129 virtual bool is_method_type() const { return false; }
130 virtual bool is_array() { return false; }
131 virtual bool is_obj_array() { return false; }
132 virtual bool is_type_array() { return false; }
133
134 // Is this a type or value which has no associated class?
135 // It is true of primitive types and null objects.
136 virtual bool is_classless() const { return false; }
137 virtual void dump_replay_data(outputStream* st) { /* do nothing */ }
138
139 // Note: some ciObjects refer to oops which have yet to be created.
140 // We refer to these as "unloaded". Specifically, there are
141 // unloaded instances of java.lang.Class,
142 // java.lang.invoke.MethodHandle, and java.lang.invoke.MethodType.
143 // By convention the ciNullObject is considered loaded, and
144 // primitive types are considered loaded.
145 bool is_loaded() const {
146 return handle() != NULL || is_classless();
147 }
148
149 // Subclass casting with assertions.
150 ciNullObject* as_null_object() {
151 assert(is_null_object(), "bad cast");
152 return (ciNullObject*)this;
153 }
154 ciCallSite* as_call_site() {
155 assert(is_call_site(), "bad cast");
156 return (ciCallSite*)this;
157 }
158 ciInstance* as_instance() {
159 assert(is_instance(), "bad cast");
160 return (ciInstance*)this;
161 }
162 ciMemberName* as_member_name() {
163 assert(is_member_name(), "bad cast");
164 return (ciMemberName*)this;
165 }
166 ciMethodHandle* as_method_handle() {
167 assert(is_method_handle(), "bad cast");
168 return (ciMethodHandle*)this;
169 }
170 ciMethodType* as_method_type() {
171 assert(is_method_type(), "bad cast");
172 return (ciMethodType*)this;
173 }
174 ciArray* as_array() {
175 assert(is_array(), "bad cast");
176 return (ciArray*)this;
177 }
178 ciObjArray* as_obj_array() {
179 assert(is_obj_array(), "bad cast");
180 return (ciObjArray*)this;
181 }
182 ciTypeArray* as_type_array() {
183 assert(is_type_array(), "bad cast");
184 return (ciTypeArray*)this;
185 }
186
187 // Print debugging output about this ciObject.
188 void print(outputStream* st);
189 void print() { print(tty); } // GDB cannot handle default arguments
190
191 // Print debugging output about the oop this ciObject represents.
192 void print_oop(outputStream* st = tty);
193 };
194
195 #endif // SHARE_VM_CI_CIOBJECT_HPP