1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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24
25#ifndef SHARE_CODE_STUBS_HPP
26#define SHARE_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
60class Stub {
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
94class 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
147class 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 public:
176 StubQueue(StubInterface* stub_interface, int buffer_size, Mutex* lock,
177 const char* name);
178 ~StubQueue();
179
180 // General queue info
181 bool is_empty() const { return _queue_begin == _queue_end; }
182 int total_space() const { return _buffer_size - 1; }
183 int available_space() const { int d = _queue_begin - _queue_end - 1; return d < 0 ? d + _buffer_size : d; }
184 int used_space() const { return total_space() - available_space(); }
185 int number_of_stubs() const { return _number_of_stubs; }
186 bool contains(address pc) const { return _stub_buffer <= pc && pc < _stub_buffer + _buffer_limit; }
187 Stub* stub_containing(address pc) const;
188 address code_start() const { return _stub_buffer; }
189 address code_end() const { return _stub_buffer + _buffer_limit; }
190
191 // Stub allocation (atomic transactions)
192 Stub* request_committed(int code_size); // request a stub that provides exactly code_size space for code
193 Stub* request(int requested_code_size); // request a stub with a (maximum) code space - locks the queue
194 void commit (int committed_code_size,
195 CodeStrings& strings); // commit the previously requested stub - unlocks the queue
196
197 // Stub deallocation
198 void remove_first(); // remove the first stub in the queue
199 void remove_first(int n); // remove the first n stubs in the queue
200 void remove_all(); // remove all stubs in the queue
201
202 void deallocate_unused_tail(); // deallocate the unused tail of the underlying CodeBlob
203 // only used from TemplateInterpreter::initialize()
204 // Iteration
205 Stub* first() const { return number_of_stubs() > 0 ? stub_at(_queue_begin) : NULL; }
206 Stub* next(Stub* s) const { int i = index_of(s) + stub_size(s);
207 // Only wrap around in the non-contiguous case (see stubss.cpp)
208 if (i == _buffer_limit && _queue_end < _buffer_limit) i = 0;
209 return (i == _queue_end) ? NULL : stub_at(i);
210 }
211
212 // Debugging/printing
213 void verify(); // verifies the stub queue
214 void print(); // prints information about the stub queue
215
216};
217
218#endif // SHARE_CODE_STUBS_HPP
219