1 /*
2 * Copyright (c) 1999, 2019, 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
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23 */
24
25 #ifndef SHARE_CI_CIOBJECT_HPP
26 #define SHARE_CI_CIOBJECT_HPP
27
28 #include "ci/ciBaseObject.hpp"
29 #include "ci/ciClassList.hpp"
30 #include "runtime/handles.hpp"
31 #include "runtime/jniHandles.hpp"
32
33 // ciObject
34 //
35 // This class represents an oop in the HotSpot virtual machine.
36 // Its subclasses are structured in a hierarchy which mirrors
37 // an aggregate of the VM's oop and klass hierarchies (see
38 // oopHierarchy.hpp). Each instance of ciObject holds a handle
39 // to a corresponding oop on the VM side and provides routines
40 // for accessing the information in its oop. By using the ciObject
41 // hierarchy for accessing oops in the VM, the compiler ensures
42 // that it is safe with respect to garbage collection; that is,
43 // GC and compilation can proceed independently without
44 // interference.
45 //
46 // Within the VM, the oop and klass hierarchies are separate.
47 // The compiler interface does not preserve this separation --
48 // the distinction between `Klass*' and `Klass' are not
49 // reflected in the interface and instead the Klass hierarchy
50 // is directly modeled as the subclasses of ciKlass.
51 class ciObject : public ciBaseObject {
52 CI_PACKAGE_ACCESS
53 friend class ciEnv;
54
55 private:
56 // A JNI handle referring to an oop in the VM. This
57 // handle may, in a small set of cases, correctly be NULL.
58 jobject _handle;
59 ciKlass* _klass;
60
61 protected:
62 ciObject();
63 ciObject(oop o);
64 ciObject(Handle h);
65 ciObject(ciKlass* klass);
66
67 jobject handle() const { return _handle; }
68 // Get the VM oop that this object holds.
69 oop get_oop() const;
70
71 void init_flags_from(oop x);
72
73 // Virtual behavior of the print() method.
74 virtual void print_impl(outputStream* st) {}
75
76 virtual const char* type_string() { return "ciObject"; }
77
78 public:
79 // The klass of this ciObject.
80 ciKlass* klass();
81
82 // Are two ciObjects equal?
83 bool equals(ciObject* obj);
84
85 // A hash value for the convenience of compilers.
86 int hash();
87
88 // Tells if this oop has an encoding as a constant.
89 // True if is_perm is true.
90 // Also true if ScavengeRootsInCode is non-zero.
91 // If it does not have an encoding, the compiler is responsible for
92 // making other arrangements for dealing with the oop.
93 // See ciEnv::make_array
94 bool can_be_constant();
95
96 // Tells if this oop should be made a constant.
97 // True if is_perm is true or ScavengeRootsInCode > 1.
98 bool should_be_constant();
99
100 // Might this object possibly move during a scavenge operation?
101 // If the answer is true and ScavengeRootsInCode==0, the oop cannot be embedded in code.
102 bool is_scavengable() { return (_ident & SCAVENGABLE_FLAG) != 0; }
103
104 // The address which the compiler should embed into the
105 // generated code to represent this oop. This address
106 // is not the true address of the oop -- it will get patched
107 // during nmethod creation.
108 //
109 // Usage note: no address arithmetic allowed. Oop must
110 // be registered with the oopRecorder.
111 jobject constant_encoding();
112
113 virtual bool is_object() const { return true; }
114
115 // What kind of ciObject is this?
116 virtual bool is_null_object() const { return false; }
117 virtual bool is_call_site() const { return false; }
118 virtual bool is_instance() { return false; }
119 virtual bool is_member_name() const { return false; }
120 virtual bool is_method_handle() const { return false; }
121 virtual bool is_method_type() const { return false; }
122 virtual bool is_array() { return false; }
123 virtual bool is_obj_array() { return false; }
124 virtual bool is_type_array() { return false; }
125
126 // Is this a type or value which has no associated class?
127 // It is true of primitive types and null objects.
128 virtual bool is_classless() const { return false; }
129 virtual void dump_replay_data(outputStream* st) { /* do nothing */ }
130
131 // Note: some ciObjects refer to oops which have yet to be created.
132 // We refer to these as "unloaded". Specifically, there are
133 // unloaded instances of java.lang.Class,
134 // java.lang.invoke.MethodHandle, and java.lang.invoke.MethodType.
135 // By convention the ciNullObject is considered loaded, and
136 // primitive types are considered loaded.
137 bool is_loaded() const {
138 return handle() != NULL || is_classless();
139 }
140
141 // Subclass casting with assertions.
142 ciNullObject* as_null_object() {
143 assert(is_null_object(), "bad cast");
144 return (ciNullObject*)this;
145 }
146 ciCallSite* as_call_site() {
147 assert(is_call_site(), "bad cast");
148 return (ciCallSite*)this;
149 }
150 ciInstance* as_instance() {
151 assert(is_instance(), "bad cast");
152 return (ciInstance*)this;
153 }
154 ciMemberName* as_member_name() {
155 assert(is_member_name(), "bad cast");
156 return (ciMemberName*)this;
157 }
158 ciMethodHandle* as_method_handle() {
159 assert(is_method_handle(), "bad cast");
160 return (ciMethodHandle*)this;
161 }
162 ciMethodType* as_method_type() {
163 assert(is_method_type(), "bad cast");
164 return (ciMethodType*)this;
165 }
166 ciArray* as_array() {
167 assert(is_array(), "bad cast");
168 return (ciArray*)this;
169 }
170 ciObjArray* as_obj_array() {
171 assert(is_obj_array(), "bad cast");
172 return (ciObjArray*)this;
173 }
174 ciTypeArray* as_type_array() {
175 assert(is_type_array(), "bad cast");
176 return (ciTypeArray*)this;
177 }
178
179 // Print debugging output about this ciObject.
180 void print(outputStream* st);
181 void print() { print(tty); } // GDB cannot handle default arguments
182
183 // Print debugging output about the oop this ciObject represents.
184 void print_oop(outputStream* st = tty);
185 };
186
187 #endif // SHARE_CI_CIOBJECT_HPP