1 /*
2 * Copyright (c) 1997, 2002, 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 // The classes in this file provide a simple framework for the
26 // management of little pieces of machine code - or stubs -
27 // created on the fly and frequently discarded. In this frame-
28 // work stubs are stored in a queue.
29
30
31 // Stub serves as abstract base class. A concrete stub
32 // implementation is a subclass of Stub, implementing
33 // all (non-virtual!) functions required sketched out
34 // in the Stub class.
35 //
36 // A concrete stub layout may look like this (both data
37 // and code sections could be empty as well):
38 //
39 // ________
40 // stub -->| | <--+
41 // | data | |
42 // |________| |
43 // code_begin -->| | |
44 // | | |
45 // | code | | size
46 // | | |
47 // |________| |
48 // code_end -->| | |
49 // | data | |
50 // |________| |
51 // <--+
52
53
54 class Stub VALUE_OBJ_CLASS_SPEC {
55 public:
56 // Initialization/finalization
57 void initialize(int size) { ShouldNotCallThis(); } // called to initialize/specify the stub's size
58 void finalize() { ShouldNotCallThis(); } // called before the stub is deallocated
59
60 // General info/converters
61 int size() const { ShouldNotCallThis(); return 0; } // must return the size provided by initialize
62 static int code_size_to_size(int code_size) { ShouldNotCallThis(); return 0; } // computes the size given the code size
63
64 // Code info
65 address code_begin() const { ShouldNotCallThis(); return NULL; } // points to the first byte of the code
66 address code_end() const { ShouldNotCallThis(); return NULL; } // points to the first byte after the code
67
68 // Debugging
69 void verify() { ShouldNotCallThis(); } // verifies the Stub
70 void print() { ShouldNotCallThis(); } // prints some information about the stub
71 };
72
73
74 // A stub interface defines the interface between a stub queue
75 // and the stubs it queues. In order to avoid a vtable and
76 // (and thus the extra word) in each stub, a concrete stub
77 // interface object is created and associated with a stub
78 // buffer which in turn uses the stub interface to interact
79 // with its stubs.
80 //
81 // StubInterface serves as an abstract base class. A concrete
82 // stub interface implementation is a subclass of StubInterface,
83 // forwarding its virtual function calls to non-virtual calls
84 // of the concrete stub (see also macro below). There's exactly
85 // one stub interface instance required per stub queue.
86
87 class StubInterface: public CHeapObj {
88 public:
89 // Initialization/finalization
90 virtual void initialize(Stub* self, int size) = 0; // called after creation (called twice if allocated via (request, commit))
91 virtual void finalize(Stub* self) = 0; // called before deallocation
92
93 // General info/converters
94 virtual int size(Stub* self) const = 0; // the total size of the stub in bytes (must be a multiple of CodeEntryAlignment)
95 virtual int code_size_to_size(int code_size) const = 0; // computes the total stub size in bytes given the code size in bytes
96
97 // Code info
98 virtual address code_begin(Stub* self) const = 0; // points to the first code byte
99 virtual address code_end(Stub* self) const = 0; // points to the first byte after the code
100
101 // Debugging
102 virtual void verify(Stub* self) = 0; // verifies the stub
103 virtual void print(Stub* self) = 0; // prints information about the stub
104 };
105
106
107 // DEF_STUB_INTERFACE is used to create a concrete stub interface
108 // class, forwarding stub interface calls to the corresponding
109 // stub calls.
110
111 #define DEF_STUB_INTERFACE(stub) \
112 class stub##Interface: public StubInterface { \
113 private: \
114 static stub* cast(Stub* self) { return (stub*)self; } \
115 \
116 public: \
117 /* Initialization/finalization */ \
118 virtual void initialize(Stub* self, int size) { cast(self)->initialize(size); } \
119 virtual void finalize(Stub* self) { cast(self)->finalize(); } \
120 \
121 /* General info */ \
122 virtual int size(Stub* self) const { return cast(self)->size(); } \
123 virtual int code_size_to_size(int code_size) const { return stub::code_size_to_size(code_size); } \
124 \
125 /* Code info */ \
126 virtual address code_begin(Stub* self) const { return cast(self)->code_begin(); } \
127 virtual address code_end(Stub* self) const { return cast(self)->code_end(); } \
128 \
129 /* Debugging */ \
130 virtual void verify(Stub* self) { cast(self)->verify(); } \
131 virtual void print(Stub* self) { cast(self)->print(); } \
132 };
133
134
135 // A StubQueue maintains a queue of stubs.
136 // Note: All sizes (spaces) are given in bytes.
137
138 class StubQueue: public CHeapObj {
139 friend class VMStructs;
140 private:
141 StubInterface* _stub_interface; // the interface prototype
142 address _stub_buffer; // where all stubs are stored
143 int _buffer_size; // the buffer size in bytes
144 int _buffer_limit; // the (byte) index of the actual buffer limit (_buffer_limit <= _buffer_size)
145 int _queue_begin; // the (byte) index of the first queue entry (word-aligned)
146 int _queue_end; // the (byte) index of the first entry after the queue (word-aligned)
147 int _number_of_stubs; // the number of buffered stubs
148 Mutex* const _mutex; // the lock used for a (request, commit) transaction
149
150 void check_index(int i) const { assert(0 <= i && i < _buffer_limit && i % CodeEntryAlignment == 0, "illegal index"); }
151 bool is_contiguous() const { return _queue_begin <= _queue_end; }
152 int index_of(Stub* s) const { int i = (address)s - _stub_buffer; check_index(i); return i; }
153 Stub* stub_at(int i) const { check_index(i); return (Stub*)(_stub_buffer + i); }
154 Stub* current_stub() const { return stub_at(_queue_end); }
155
156 // Stub functionality accessed via interface
157 void stub_initialize(Stub* s, int size) { assert(size % CodeEntryAlignment == 0, "size not aligned"); _stub_interface->initialize(s, size); }
158 void stub_finalize(Stub* s) { _stub_interface->finalize(s); }
159 int stub_size(Stub* s) const { return _stub_interface->size(s); }
160 bool stub_contains(Stub* s, address pc) const { return _stub_interface->code_begin(s) <= pc && pc < _stub_interface->code_end(s); }
161 int stub_code_size_to_size(int code_size) const { return _stub_interface->code_size_to_size(code_size); }
162 void stub_verify(Stub* s) { _stub_interface->verify(s); }
163 void stub_print(Stub* s) { _stub_interface->print(s); }
164
165 static void register_queue(StubQueue*);
166
167 public:
168 StubQueue(StubInterface* stub_interface, int buffer_size, Mutex* lock,
169 const char* name);
170 ~StubQueue();
171
172 // General queue info
173 bool is_empty() const { return _queue_begin == _queue_end; }
174 int total_space() const { return _buffer_size - 1; }
175 int available_space() const { int d = _queue_begin - _queue_end - 1; return d < 0 ? d + _buffer_size : d; }
176 int used_space() const { return total_space() - available_space(); }
177 int number_of_stubs() const { return _number_of_stubs; }
178 bool contains(address pc) const { return _stub_buffer <= pc && pc < _stub_buffer + _buffer_limit; }
179 Stub* stub_containing(address pc) const;
180 address code_start() const { return _stub_buffer; }
181 address code_end() const { return _stub_buffer + _buffer_limit; }
182
183 // Stub allocation (atomic transactions)
184 Stub* request_committed(int code_size); // request a stub that provides exactly code_size space for code
185 Stub* request(int requested_code_size); // request a stub with a (maximum) code space - locks the queue
186 void commit (int committed_code_size); // commit the previously requested stub - unlocks the queue
187
188 // Stub deallocation
189 void remove_first(); // remove the first stub in the queue
190 void remove_first(int n); // remove the first n stubs in the queue
191 void remove_all(); // remove all stubs in the queue
192
193 // Iteration
194 static void queues_do(void f(StubQueue* s)); // call f with each StubQueue
195 void stubs_do(void f(Stub* s)); // call f with all stubs
196 Stub* first() const { return number_of_stubs() > 0 ? stub_at(_queue_begin) : NULL; }
197 Stub* next(Stub* s) const { int i = index_of(s) + stub_size(s);
198 if (i == _buffer_limit) i = 0;
199 return (i == _queue_end) ? NULL : stub_at(i);
200 }
201
202 address stub_code_begin(Stub* s) const { return _stub_interface->code_begin(s); }
203 address stub_code_end(Stub* s) const { return _stub_interface->code_end(s); }
204
205 // Debugging/printing
206 void verify(); // verifies the stub queue
207 void print(); // prints information about the stub queue
208 };