1 /*
2 * Copyright (c) 1997, 2016, 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_VM_CODE_STUBS_HPP
26 #define SHARE_VM_CODE_STUBS_HPP
27
28 #include "asm/codeBuffer.hpp"
29 #include "memory/allocation.hpp"
30
31 // The classes in this file provide a simple framework for the
32 // management of little pieces of machine code - or stubs -
33 // created on the fly and frequently discarded. In this frame-
34 // work stubs are stored in a queue.
35
36
37 // Stub serves as abstract base class. A concrete stub
38 // implementation is a subclass of Stub, implementing
39 // all (non-virtual!) functions required sketched out
40 // in the Stub class.
41 //
42 // A concrete stub layout may look like this (both data
43 // and code sections could be empty as well):
44 //
45 // ________
46 // stub -->| | <--+
47 // | data | |
48 // |________| |
49 // code_begin -->| | |
50 // | | |
51 // | code | | size
52 // | | |
53 // |________| |
54 // code_end -->| | |
55 // | data | |
56 // |________| |
57 // <--+
58
59
60 class Stub VALUE_OBJ_CLASS_SPEC {
61 public:
62 // Initialization/finalization
63 void initialize(int size,
64 CodeStrings& strings) { ShouldNotCallThis(); } // called to initialize/specify the stub's size
65 void finalize() { ShouldNotCallThis(); } // called before the stub is deallocated
66
67 // General info/converters
68 int size() const { ShouldNotCallThis(); return 0; } // must return the size provided by initialize
69 static int code_size_to_size(int code_size) { ShouldNotCallThis(); return 0; } // computes the size given the code size
70
71 // Code info
72 address code_begin() const { ShouldNotCallThis(); return NULL; } // points to the first byte of the code
73 address code_end() const { ShouldNotCallThis(); return NULL; } // points to the first byte after the code
74
75 // Debugging
76 void verify() { ShouldNotCallThis(); } // verifies the Stub
77 void print() { ShouldNotCallThis(); } // prints some information about the stub
78 };
79
80
81 // A stub interface defines the interface between a stub queue
82 // and the stubs it queues. In order to avoid a vtable and
83 // (and thus the extra word) in each stub, a concrete stub
84 // interface object is created and associated with a stub
85 // buffer which in turn uses the stub interface to interact
86 // with its stubs.
87 //
88 // StubInterface serves as an abstract base class. A concrete
89 // stub interface implementation is a subclass of StubInterface,
90 // forwarding its virtual function calls to non-virtual calls
91 // of the concrete stub (see also macro below). There's exactly
92 // one stub interface instance required per stub queue.
93
94 class StubInterface: public CHeapObj<mtCode> {
95 public:
96 // Initialization/finalization
97 virtual void initialize(Stub* self, int size,
98 CodeStrings& strings) = 0; // called after creation (called twice if allocated via (request, commit))
99 virtual void finalize(Stub* self) = 0; // called before deallocation
100
101 // General info/converters
102 virtual int size(Stub* self) const = 0; // the total size of the stub in bytes (must be a multiple of CodeEntryAlignment)
103 virtual int code_size_to_size(int code_size) const = 0; // computes the total stub size in bytes given the code size in bytes
104
105 // Code info
106 virtual address code_begin(Stub* self) const = 0; // points to the first code byte
107 virtual address code_end(Stub* self) const = 0; // points to the first byte after the code
108
109 // Debugging
110 virtual void verify(Stub* self) = 0; // verifies the stub
111 virtual void print(Stub* self) = 0; // prints information about the stub
112 };
113
114
115 // DEF_STUB_INTERFACE is used to create a concrete stub interface
116 // class, forwarding stub interface calls to the corresponding
117 // stub calls.
118
119 #define DEF_STUB_INTERFACE(stub) \
120 class stub##Interface: public StubInterface { \
121 private: \
122 static stub* cast(Stub* self) { return (stub*)self; } \
123 \
124 public: \
125 /* Initialization/finalization */ \
126 virtual void initialize(Stub* self, int size, \
127 CodeStrings& strings) { cast(self)->initialize(size, strings); } \
128 virtual void finalize(Stub* self) { cast(self)->finalize(); } \
129 \
130 /* General info */ \
131 virtual int size(Stub* self) const { return cast(self)->size(); } \
132 virtual int code_size_to_size(int code_size) const { return stub::code_size_to_size(code_size); } \
133 \
134 /* Code info */ \
135 virtual address code_begin(Stub* self) const { return cast(self)->code_begin(); } \
136 virtual address code_end(Stub* self) const { return cast(self)->code_end(); } \
137 \
138 /* Debugging */ \
139 virtual void verify(Stub* self) { cast(self)->verify(); } \
140 virtual void print(Stub* self) { cast(self)->print(); } \
141 };
142
143
144 // A StubQueue maintains a queue of stubs.
145 // Note: All sizes (spaces) are given in bytes.
146
147 class StubQueue: public CHeapObj<mtCode> {
148 friend class VMStructs;
149 private:
150 StubInterface* _stub_interface; // the interface prototype
151 address _stub_buffer; // where all stubs are stored
152 int _buffer_size; // the buffer size in bytes
153 int _buffer_limit; // the (byte) index of the actual buffer limit (_buffer_limit <= _buffer_size)
154 int _queue_begin; // the (byte) index of the first queue entry (word-aligned)
155 int _queue_end; // the (byte) index of the first entry after the queue (word-aligned)
156 int _number_of_stubs; // the number of buffered stubs
157 Mutex* const _mutex; // the lock used for a (request, commit) transaction
158
159 void check_index(int i) const { assert(0 <= i && i < _buffer_limit && i % CodeEntryAlignment == 0, "illegal index"); }
160 bool is_contiguous() const { return _queue_begin <= _queue_end; }
161 int index_of(Stub* s) const { int i = (address)s - _stub_buffer; check_index(i); return i; }
162 Stub* stub_at(int i) const { check_index(i); return (Stub*)(_stub_buffer + i); }
163 Stub* current_stub() const { return stub_at(_queue_end); }
164
165 // Stub functionality accessed via interface
166 void stub_initialize(Stub* s, int size,
167 CodeStrings& strings) { assert(size % CodeEntryAlignment == 0, "size not aligned"); _stub_interface->initialize(s, size, strings); }
168 void stub_finalize(Stub* s) { _stub_interface->finalize(s); }
169 int stub_size(Stub* s) const { return _stub_interface->size(s); }
170 bool stub_contains(Stub* s, address pc) const { return _stub_interface->code_begin(s) <= pc && pc < _stub_interface->code_end(s); }
171 int stub_code_size_to_size(int code_size) const { return _stub_interface->code_size_to_size(code_size); }
172 void stub_verify(Stub* s) { _stub_interface->verify(s); }
173 void stub_print(Stub* s) { _stub_interface->print(s); }
174
175 static void register_queue(StubQueue*);
176
177 public:
178 StubQueue(StubInterface* stub_interface, int buffer_size, Mutex* lock,
179 const char* name);
180 ~StubQueue();
181
182 // General queue info
183 bool is_empty() const { return _queue_begin == _queue_end; }
184 int total_space() const { return _buffer_size - 1; }
185 int available_space() const { int d = _queue_begin - _queue_end - 1; return d < 0 ? d + _buffer_size : d; }
186 int used_space() const { return total_space() - available_space(); }
187 int number_of_stubs() const { return _number_of_stubs; }
188 bool contains(address pc) const { return _stub_buffer <= pc && pc < _stub_buffer + _buffer_limit; }
189 Stub* stub_containing(address pc) const;
190 address code_start() const { return _stub_buffer; }
191 address code_end() const { return _stub_buffer + _buffer_limit; }
192
193 // Stub allocation (atomic transactions)
194 Stub* request_committed(int code_size); // request a stub that provides exactly code_size space for code
195 Stub* request(int requested_code_size); // request a stub with a (maximum) code space - locks the queue
196 void commit (int committed_code_size,
197 CodeStrings& strings); // commit the previously requested stub - unlocks the queue
198
199 // Stub deallocation
200 void remove_first(); // remove the first stub in the queue
201 void remove_first(int n); // remove the first n stubs in the queue
202 void remove_all(); // remove all stubs in the queue
203
204 // Iteration
205 static void queues_do(void f(StubQueue* s)); // call f with each StubQueue
206 void stubs_do(void f(Stub* s)); // call f with all stubs
207 Stub* first() const { return number_of_stubs() > 0 ? stub_at(_queue_begin) : NULL; }
208 Stub* next(Stub* s) const { int i = index_of(s) + stub_size(s);
209 if (i == _buffer_limit) i = 0;
210 return (i == _queue_end) ? NULL : stub_at(i);
211 }
212
213 address stub_code_begin(Stub* s) const { return _stub_interface->code_begin(s); }
214 address stub_code_end(Stub* s) const { return _stub_interface->code_end(s); }
215
216 // Debugging/printing
217 void verify(); // verifies the stub queue
218 void print(); // prints information about the stub queue
219
220 };
221
222 #endif // SHARE_VM_CODE_STUBS_HPP