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1 /*
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2 * Copyright 1998-2007 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 // This file provides the basic support for exception handling in the VM.
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26 // Note: We do not use C++ exceptions to avoid compiler dependencies and
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27 // unpredictable performance.
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28 //
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29 // Scheme: Exceptions are stored with the thread. There is never more
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30 // than one pending exception per thread. All functions that can throw
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31 // an exception carry a THREAD argument (usually the last argument and
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32 // declared with the TRAPS macro). Throwing an exception means setting
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33 // a pending exception in the thread. Upon return from a function that
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34 // can throw an exception, we must check if an exception is pending.
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35 // The CHECK macros do this in a convenient way. Carrying around the
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36 // thread provides also convenient access to it (e.g. for Handle
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37 // creation, w/o the need for recomputation).
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38
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39
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40
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41 // Forward declarations to be independent of the include structure.
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42 // This allows us to have exceptions.hpp included in top.hpp.
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43
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44 class Thread;
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45 class Handle;
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46 class symbolHandle;
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47 class symbolOopDesc;
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48 class JavaCallArguments;
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49
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50 // The ThreadShadow class is a helper class to access the _pending_exception
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51 // field of the Thread class w/o having access to the Thread's interface (for
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52 // include hierachy reasons).
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53
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54 class ThreadShadow: public CHeapObj {
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55 protected:
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56 oop _pending_exception; // Thread has gc actions.
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57 const char* _exception_file; // file information for exception (debugging only)
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58 int _exception_line; // line information for exception (debugging only)
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59 friend void check_ThreadShadow(); // checks _pending_exception offset
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60
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61 // The following virtual exists only to force creation of a vtable.
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62 // We need ThreadShadow to have a vtable, even in product builds,
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63 // so that its layout will start at an offset of zero relative to Thread.
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64 // Some C++ compilers are so "clever" that they put the ThreadShadow
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65 // base class at offset 4 in Thread (after Thread's vtable), if they
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66 // notice that Thread has a vtable but ThreadShadow does not.
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67 virtual void unused_initial_virtual() { }
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68
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69 public:
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70 oop pending_exception() const { return _pending_exception; }
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71 bool has_pending_exception() const { return _pending_exception != NULL; }
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72 const char* exception_file() const { return _exception_file; }
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73 int exception_line() const { return _exception_line; }
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74
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75 // Code generation support
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76 static ByteSize pending_exception_offset() { return byte_offset_of(ThreadShadow, _pending_exception); }
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77
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78 // use THROW whenever possible!
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79 void set_pending_exception(oop exception, const char* file, int line);
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80
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81 // use CLEAR_PENDING_EXCEPTION whenever possible!
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82 void clear_pending_exception();
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83
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84 ThreadShadow() : _pending_exception(NULL),
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85 _exception_file(NULL), _exception_line(0) {}
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86 };
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87
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88
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89 // Exceptions is a helper class that encapsulates all operations
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90 // that require access to the thread interface and which are
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91 // relatively rare. The Exceptions operations should only be
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92 // used directly if the macros below are insufficient.
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93
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94 class Exceptions {
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95 static bool special_exception(Thread *thread, const char* file, int line, Handle exception);
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96 static bool special_exception(Thread* thread, const char* file, int line, symbolHandle name, const char* message);
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97 public:
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98 // this enum is defined to indicate whether it is safe to
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99 // ignore the encoding scheme of the original message string.
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100 typedef enum {
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101 safe_to_utf8 = 0,
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102 unsafe_to_utf8 = 1
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103 } ExceptionMsgToUtf8Mode;
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104 // Throw exceptions: w/o message, w/ message & with formatted message.
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105 static void _throw_oop(Thread* thread, const char* file, int line, oop exception);
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106 static void _throw(Thread* thread, const char* file, int line, Handle exception);
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107 static void _throw_msg(Thread* thread, const char* file, int line,
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108 symbolHandle name, const char* message, Handle loader,
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109 Handle protection_domain);
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110 static void _throw_msg(Thread* thread, const char* file, int line,
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111 symbolOop name, const char* message);
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112 static void _throw_msg(Thread* thread, const char* file, int line,
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113 symbolHandle name, const char* message);
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114 static void _throw_args(Thread* thread, const char* file, int line,
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115 symbolHandle name, symbolHandle signature,
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116 JavaCallArguments* args);
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117 static void _throw_msg_cause(Thread* thread, const char* file,
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118 int line, symbolHandle h_name, const char* message,
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119 Handle h_cause, Handle h_loader, Handle h_protection_domain);
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120 static void _throw_msg_cause(Thread* thread, const char* file, int line,
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121 symbolHandle name, const char* message, Handle cause);
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122
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123 // There is no THROW... macro for this method. Caller should remember
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124 // to do a return after calling it.
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125 static void fthrow(Thread* thread, const char* file, int line, symbolHandle name,
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126 const char* format, ...);
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127
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128 // Create and initialize a new exception
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129 static Handle new_exception(Thread* thread, symbolHandle name,
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130 symbolHandle signature, JavaCallArguments* args,
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131 Handle cause, Handle loader,
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132 Handle protection_domain);
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133
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134 static Handle new_exception(Thread* thread, symbolHandle name,
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135 const char* message, Handle cause, Handle loader,
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136 Handle protection_domain,
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137 ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);
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138
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139 static Handle new_exception(Thread* thread, symbolOop name,
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140 const char* message,
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141 ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);
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142
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143 static void throw_stack_overflow_exception(Thread* thread, const char* file, int line);
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144
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145 // for AbortVMOnException flag
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146 NOT_PRODUCT(static void debug_check_abort(Handle exception);)
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147 NOT_PRODUCT(static void debug_check_abort(const char *value_string);)
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148 };
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149
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150
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151 // The THREAD & TRAPS macros facilitate the declaration of functions that throw exceptions.
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152 // Convention: Use the TRAPS macro as the last argument of such a function; e.g.:
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153 //
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154 // int this_function_may_trap(int x, float y, TRAPS)
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155
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156 #define THREAD __the_thread__
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157 #define TRAPS Thread* THREAD
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158
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159
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160 // The CHECK... macros should be used to pass along a THREAD reference and to check for pending
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161 // exceptions. In special situations it is necessary to handle pending exceptions explicitly,
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162 // in these cases the PENDING_EXCEPTION helper macros should be used.
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163 //
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164 // Macro naming conventions: Macros that end with _ require a result value to be returned. They
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165 // are for functions with non-void result type. The result value is usually ignored because of
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166 // the exception and is only needed for syntactic correctness. The _0 ending is a shortcut for
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167 // _(0) since this is a frequent case. Example:
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168 //
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169 // int result = this_function_may_trap(x_arg, y_arg, CHECK_0);
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170 //
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171 // CAUTION: make sure that the function call using a CHECK macro is not the only statement of a
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172 // conditional branch w/o enclosing {} braces, since the CHECK macros expand into several state-
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173 // ments!
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174
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175 #define PENDING_EXCEPTION (((ThreadShadow*)THREAD)->pending_exception())
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176 #define HAS_PENDING_EXCEPTION (((ThreadShadow*)THREAD)->has_pending_exception())
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177 #define CLEAR_PENDING_EXCEPTION (((ThreadShadow*)THREAD)->clear_pending_exception())
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178
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179 #define CHECK THREAD); if (HAS_PENDING_EXCEPTION) return ; (0
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180 #define CHECK_(result) THREAD); if (HAS_PENDING_EXCEPTION) return result; (0
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181 #define CHECK_0 CHECK_(0)
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182 #define CHECK_NH CHECK_(Handle())
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183 #define CHECK_NULL CHECK_(NULL)
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184 #define CHECK_false CHECK_(false)
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185
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186 // The THROW... macros should be used to throw an exception. They require a THREAD variable to be
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187 // visible within the scope containing the THROW. Usually this is achieved by declaring the function
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188 // with a TRAPS argument.
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189
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190 #define THREAD_AND_LOCATION THREAD, __FILE__, __LINE__
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191
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192 #define THROW_OOP(e) \
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193 { Exceptions::_throw_oop(THREAD_AND_LOCATION, e); return; }
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194
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195 #define THROW_HANDLE(e) \
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196 { Exceptions::_throw(THREAD_AND_LOCATION, e); return; }
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197
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198 #define THROW(name) \
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199 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return; }
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200
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201 #define THROW_MSG(name, message) \
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202 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return; }
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203
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204 #define THROW_MSG_LOADER(name, message, loader, protection_domain) \
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205 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return; }
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206
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207 #define THROW_ARG(name, signature, args) \
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208 { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return; }
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209
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210 #define THROW_OOP_(e, result) \
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211 { Exceptions::_throw_oop(THREAD_AND_LOCATION, e); return result; }
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212
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213 #define THROW_HANDLE_(e, result) \
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214 { Exceptions::_throw(THREAD_AND_LOCATION, e); return result; }
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215
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216 #define THROW_(name, result) \
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217 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return result; }
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218
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219 #define THROW_MSG_(name, message, result) \
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220 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return result; }
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221
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222 #define THROW_MSG_LOADER_(name, message, loader, protection_domain, result) \
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223 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return result; }
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224
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225 #define THROW_ARG_(name, signature, args, result) \
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226 { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return result; }
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227
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228 #define THROW_MSG_CAUSE_(name, message, cause, result) \
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229 { Exceptions::_throw_msg_cause(THREAD_AND_LOCATION, name, message, cause); return result; }
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230
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231
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232 #define THROW_OOP_0(e) THROW_OOP_(e, 0)
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233 #define THROW_HANDLE_0(e) THROW_HANDLE_(e, 0)
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234 #define THROW_0(name) THROW_(name, 0)
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235 #define THROW_MSG_0(name, message) THROW_MSG_(name, message, 0)
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236 #define THROW_WRAPPED_0(name, oop_to_wrap) THROW_WRAPPED_(name, oop_to_wrap, 0)
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237 #define THROW_ARG_0(name, signature, arg) THROW_ARG_(name, signature, arg, 0)
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238 #define THROW_MSG_CAUSE_0(name, message, cause) THROW_MSG_CAUSE_(name, message, cause, 0)
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239
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240 // The CATCH macro checks that no exception has been thrown by a function; it is used at
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241 // call sites about which is statically known that the callee cannot throw an exception
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242 // even though it is declared with TRAPS.
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243
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244 #define CATCH \
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245 THREAD); if (HAS_PENDING_EXCEPTION) { \
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246 oop ex = PENDING_EXCEPTION; \
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247 CLEAR_PENDING_EXCEPTION; \
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248 ex->print(); \
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249 ShouldNotReachHere(); \
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250 } (0
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251
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252
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253 // ExceptionMark is a stack-allocated helper class for local exception handling.
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254 // It is used with the EXCEPTION_MARK macro.
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255
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256 class ExceptionMark {
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257 private:
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258 Thread* _thread;
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259
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260 public:
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261 ExceptionMark(Thread*& thread);
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262 ~ExceptionMark();
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263 };
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264
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265
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266
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267 // Use an EXCEPTION_MARK for 'local' exceptions. EXCEPTION_MARK makes sure that no
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268 // pending exception exists upon entering its scope and tests that no pending exception
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269 // exists when leaving the scope.
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270
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271 // See also preserveException.hpp for PRESERVE_EXCEPTION_MARK macro,
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272 // which preserves pre-existing exceptions and does not allow new
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273 // exceptions.
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274
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275 #define EXCEPTION_MARK Thread* THREAD; ExceptionMark __em(THREAD);
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