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1 /*
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2 * Copyright 1997-2002 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // The classes in this file provide a simple framework for the
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26 // management of little pieces of machine code - or stubs -
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27 // created on the fly and frequently discarded. In this frame-
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28 // work stubs are stored in a queue.
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29
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30
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31 // Stub serves as abstract base class. A concrete stub
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32 // implementation is a subclass of Stub, implementing
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33 // all (non-virtual!) functions required sketched out
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34 // in the Stub class.
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35 //
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36 // A concrete stub layout may look like this (both data
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37 // and code sections could be empty as well):
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38 //
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39 // ________
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40 // stub -->| | <--+
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41 // | data | |
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42 // |________| |
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43 // code_begin -->| | |
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44 // | | |
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45 // | code | | size
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46 // | | |
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47 // |________| |
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48 // code_end -->| | |
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49 // | data | |
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50 // |________| |
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51 // <--+
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52
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53
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54 class Stub VALUE_OBJ_CLASS_SPEC {
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55 public:
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56 // Initialization/finalization
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57 void initialize(int size) { ShouldNotCallThis(); } // called to initialize/specify the stub's size
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58 void finalize() { ShouldNotCallThis(); } // called before the stub is deallocated
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59
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60 // General info/converters
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61 int size() const { ShouldNotCallThis(); return 0; } // must return the size provided by initialize
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62 static int code_size_to_size(int code_size) { ShouldNotCallThis(); return 0; } // computes the size given the code size
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63
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64 // Code info
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65 address code_begin() const { ShouldNotCallThis(); return NULL; } // points to the first byte of the code
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66 address code_end() const { ShouldNotCallThis(); return NULL; } // points to the first byte after the code
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67
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68 // Debugging
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69 void verify() { ShouldNotCallThis(); } // verifies the Stub
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70 void print() { ShouldNotCallThis(); } // prints some information about the stub
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71 };
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72
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73
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74 // A stub interface defines the interface between a stub queue
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75 // and the stubs it queues. In order to avoid a vtable and
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76 // (and thus the extra word) in each stub, a concrete stub
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77 // interface object is created and associated with a stub
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78 // buffer which in turn uses the stub interface to interact
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79 // with its stubs.
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80 //
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81 // StubInterface serves as an abstract base class. A concrete
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82 // stub interface implementation is a subclass of StubInterface,
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83 // forwarding its virtual function calls to non-virtual calls
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84 // of the concrete stub (see also macro below). There's exactly
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85 // one stub interface instance required per stub queue.
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86
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87 class StubInterface: public CHeapObj {
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88 public:
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89 // Initialization/finalization
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90 virtual void initialize(Stub* self, int size) = 0; // called after creation (called twice if allocated via (request, commit))
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91 virtual void finalize(Stub* self) = 0; // called before deallocation
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92
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93 // General info/converters
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94 virtual int size(Stub* self) const = 0; // the total size of the stub in bytes (must be a multiple of CodeEntryAlignment)
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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
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96
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97 // Code info
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98 virtual address code_begin(Stub* self) const = 0; // points to the first code byte
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99 virtual address code_end(Stub* self) const = 0; // points to the first byte after the code
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100
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101 // Debugging
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102 virtual void verify(Stub* self) = 0; // verifies the stub
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103 virtual void print(Stub* self) = 0; // prints information about the stub
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104 };
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105
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106
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107 // DEF_STUB_INTERFACE is used to create a concrete stub interface
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108 // class, forwarding stub interface calls to the corresponding
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109 // stub calls.
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110
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111 #define DEF_STUB_INTERFACE(stub) \
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112 class stub##Interface: public StubInterface { \
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113 private: \
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114 static stub* cast(Stub* self) { return (stub*)self; } \
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115 \
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116 public: \
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117 /* Initialization/finalization */ \
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118 virtual void initialize(Stub* self, int size) { cast(self)->initialize(size); } \
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119 virtual void finalize(Stub* self) { cast(self)->finalize(); } \
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120 \
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121 /* General info */ \
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122 virtual int size(Stub* self) const { return cast(self)->size(); } \
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123 virtual int code_size_to_size(int code_size) const { return stub::code_size_to_size(code_size); } \
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124 \
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125 /* Code info */ \
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126 virtual address code_begin(Stub* self) const { return cast(self)->code_begin(); } \
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127 virtual address code_end(Stub* self) const { return cast(self)->code_end(); } \
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128 \
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129 /* Debugging */ \
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130 virtual void verify(Stub* self) { cast(self)->verify(); } \
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131 virtual void print(Stub* self) { cast(self)->print(); } \
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132 };
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133
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134
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135 // A StubQueue maintains a queue of stubs.
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136 // Note: All sizes (spaces) are given in bytes.
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137
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138 class StubQueue: public CHeapObj {
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139 friend class VMStructs;
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140 private:
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141 StubInterface* _stub_interface; // the interface prototype
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142 address _stub_buffer; // where all stubs are stored
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143 int _buffer_size; // the buffer size in bytes
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144 int _buffer_limit; // the (byte) index of the actual buffer limit (_buffer_limit <= _buffer_size)
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145 int _queue_begin; // the (byte) index of the first queue entry (word-aligned)
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146 int _queue_end; // the (byte) index of the first entry after the queue (word-aligned)
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147 int _number_of_stubs; // the number of buffered stubs
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148 Mutex* const _mutex; // the lock used for a (request, commit) transaction
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149
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150 void check_index(int i) const { assert(0 <= i && i < _buffer_limit && i % CodeEntryAlignment == 0, "illegal index"); }
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151 bool is_contiguous() const { return _queue_begin <= _queue_end; }
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152 int index_of(Stub* s) const { int i = (address)s - _stub_buffer; check_index(i); return i; }
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153 Stub* stub_at(int i) const { check_index(i); return (Stub*)(_stub_buffer + i); }
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154 Stub* current_stub() const { return stub_at(_queue_end); }
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155
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156 // Stub functionality accessed via interface
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157 void stub_initialize(Stub* s, int size) { assert(size % CodeEntryAlignment == 0, "size not aligned"); _stub_interface->initialize(s, size); }
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158 void stub_finalize(Stub* s) { _stub_interface->finalize(s); }
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159 int stub_size(Stub* s) const { return _stub_interface->size(s); }
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160 bool stub_contains(Stub* s, address pc) const { return _stub_interface->code_begin(s) <= pc && pc < _stub_interface->code_end(s); }
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161 int stub_code_size_to_size(int code_size) const { return _stub_interface->code_size_to_size(code_size); }
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162 void stub_verify(Stub* s) { _stub_interface->verify(s); }
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163 void stub_print(Stub* s) { _stub_interface->print(s); }
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164
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165 static void register_queue(StubQueue*);
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166
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167 public:
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168 StubQueue(StubInterface* stub_interface, int buffer_size, Mutex* lock,
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169 const char* name);
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170 ~StubQueue();
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171
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172 // General queue info
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173 bool is_empty() const { return _queue_begin == _queue_end; }
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174 int total_space() const { return _buffer_size - 1; }
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175 int available_space() const { int d = _queue_begin - _queue_end - 1; return d < 0 ? d + _buffer_size : d; }
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176 int used_space() const { return total_space() - available_space(); }
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177 int number_of_stubs() const { return _number_of_stubs; }
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178 bool contains(address pc) const { return _stub_buffer <= pc && pc < _stub_buffer + _buffer_limit; }
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179 Stub* stub_containing(address pc) const;
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180 address code_start() const { return _stub_buffer; }
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181 address code_end() const { return _stub_buffer + _buffer_limit; }
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182
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183 // Stub allocation (atomic transactions)
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184 Stub* request_committed(int code_size); // request a stub that provides exactly code_size space for code
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185 Stub* request(int requested_code_size); // request a stub with a (maximum) code space - locks the queue
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186 void commit (int committed_code_size); // commit the previously requested stub - unlocks the queue
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187
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188 // Stub deallocation
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189 void remove_first(); // remove the first stub in the queue
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190 void remove_first(int n); // remove the first n stubs in the queue
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191 void remove_all(); // remove all stubs in the queue
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192
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193 // Iteration
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194 static void queues_do(void f(StubQueue* s)); // call f with each StubQueue
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195 void stubs_do(void f(Stub* s)); // call f with all stubs
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196 Stub* first() const { return number_of_stubs() > 0 ? stub_at(_queue_begin) : NULL; }
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197 Stub* next(Stub* s) const { int i = index_of(s) + stub_size(s);
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198 if (i == _buffer_limit) i = 0;
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199 return (i == _queue_end) ? NULL : stub_at(i);
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200 }
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201
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202 address stub_code_begin(Stub* s) const { return _stub_interface->code_begin(s); }
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203 address stub_code_end(Stub* s) const { return _stub_interface->code_end(s); }
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204
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205 // Debugging/printing
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206 void verify(); // verifies the stub queue
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207 void print(); // prints information about the stub queue
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208 };
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