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