1 | /* Implements exception handling. |
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2 | Copyright (C) 1989, 92-97, 1998 Free Software Foundation, Inc. |
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3 | Contributed by Mike Stump <mrs@cygnus.com>. |
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4 | |
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5 | This file is part of GNU CC. |
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6 | |
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7 | GNU CC is free software; you can redistribute it and/or modify |
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8 | it under the terms of the GNU General Public License as published by |
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9 | the Free Software Foundation; either version 2, or (at your option) |
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10 | any later version. |
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11 | |
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12 | GNU CC is distributed in the hope that it will be useful, |
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13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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15 | GNU General Public License for more details. |
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16 | |
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17 | You should have received a copy of the GNU General Public License |
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18 | along with GNU CC; see the file COPYING. If not, write to |
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19 | the Free Software Foundation, 59 Temple Place - Suite 330, |
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20 | Boston, MA 02111-1307, USA. */ |
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21 | |
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22 | |
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23 | /* An exception is an event that can be signaled from within a |
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24 | function. This event can then be "caught" or "trapped" by the |
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25 | callers of this function. This potentially allows program flow to |
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26 | be transferred to any arbitrary code associated with a function call |
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27 | several levels up the stack. |
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28 | |
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29 | The intended use for this mechanism is for signaling "exceptional |
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30 | events" in an out-of-band fashion, hence its name. The C++ language |
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31 | (and many other OO-styled or functional languages) practically |
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32 | requires such a mechanism, as otherwise it becomes very difficult |
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33 | or even impossible to signal failure conditions in complex |
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34 | situations. The traditional C++ example is when an error occurs in |
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35 | the process of constructing an object; without such a mechanism, it |
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36 | is impossible to signal that the error occurs without adding global |
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37 | state variables and error checks around every object construction. |
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38 | |
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39 | The act of causing this event to occur is referred to as "throwing |
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40 | an exception". (Alternate terms include "raising an exception" or |
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41 | "signaling an exception".) The term "throw" is used because control |
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42 | is returned to the callers of the function that is signaling the |
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43 | exception, and thus there is the concept of "throwing" the |
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44 | exception up the call stack. |
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45 | |
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46 | There are two major codegen options for exception handling. The |
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47 | flag -fsjlj-exceptions can be used to select the setjmp/longjmp |
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48 | approach, which is the default. -fno-sjlj-exceptions can be used to |
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49 | get the PC range table approach. While this is a compile time |
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50 | flag, an entire application must be compiled with the same codegen |
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51 | option. The first is a PC range table approach, the second is a |
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52 | setjmp/longjmp based scheme. We will first discuss the PC range |
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53 | table approach, after that, we will discuss the setjmp/longjmp |
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54 | based approach. |
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55 | |
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56 | It is appropriate to speak of the "context of a throw". This |
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57 | context refers to the address where the exception is thrown from, |
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58 | and is used to determine which exception region will handle the |
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59 | exception. |
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60 | |
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61 | Regions of code within a function can be marked such that if it |
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62 | contains the context of a throw, control will be passed to a |
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63 | designated "exception handler". These areas are known as "exception |
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64 | regions". Exception regions cannot overlap, but they can be nested |
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65 | to any arbitrary depth. Also, exception regions cannot cross |
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66 | function boundaries. |
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67 | |
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68 | Exception handlers can either be specified by the user (which we |
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69 | will call a "user-defined handler") or generated by the compiler |
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70 | (which we will designate as a "cleanup"). Cleanups are used to |
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71 | perform tasks such as destruction of objects allocated on the |
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72 | stack. |
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73 | |
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74 | In the current implementation, cleanups are handled by allocating an |
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75 | exception region for the area that the cleanup is designated for, |
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76 | and the handler for the region performs the cleanup and then |
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77 | rethrows the exception to the outer exception region. From the |
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78 | standpoint of the current implementation, there is little |
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79 | distinction made between a cleanup and a user-defined handler, and |
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80 | the phrase "exception handler" can be used to refer to either one |
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81 | equally well. (The section "Future Directions" below discusses how |
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82 | this will change). |
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83 | |
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84 | Each object file that is compiled with exception handling contains |
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85 | a static array of exception handlers named __EXCEPTION_TABLE__. |
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86 | Each entry contains the starting and ending addresses of the |
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87 | exception region, and the address of the handler designated for |
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88 | that region. |
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89 | |
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90 | If the target does not use the DWARF 2 frame unwind information, at |
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91 | program startup each object file invokes a function named |
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92 | __register_exceptions with the address of its local |
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93 | __EXCEPTION_TABLE__. __register_exceptions is defined in libgcc2.c, and |
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94 | is responsible for recording all of the exception regions into one list |
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95 | (which is kept in a static variable named exception_table_list). |
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96 | |
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97 | On targets that support crtstuff.c, the unwind information |
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98 | is stored in a section named .eh_frame and the information for the |
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99 | entire shared object or program is registered with a call to |
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100 | __register_frame_info. On other targets, the information for each |
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101 | translation unit is registered from the file generated by collect2. |
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102 | __register_frame_info is defined in frame.c, and is responsible for |
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103 | recording all of the unwind regions into one list (which is kept in a |
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104 | static variable named unwind_table_list). |
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105 | |
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106 | The function __throw is actually responsible for doing the |
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107 | throw. On machines that have unwind info support, __throw is generated |
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108 | by code in libgcc2.c, otherwise __throw is generated on a |
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109 | per-object-file basis for each source file compiled with |
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110 | -fexceptions by the the C++ frontend. Before __throw is invoked, |
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111 | the current context of the throw needs to be placed in the global |
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112 | variable __eh_pc. |
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113 | |
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114 | __throw attempts to find the appropriate exception handler for the |
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115 | PC value stored in __eh_pc by calling __find_first_exception_table_match |
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116 | (which is defined in libgcc2.c). If __find_first_exception_table_match |
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117 | finds a relevant handler, __throw transfers control directly to it. |
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118 | |
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119 | If a handler for the context being thrown from can't be found, __throw |
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120 | walks (see Walking the stack below) the stack up the dynamic call chain to |
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121 | continue searching for an appropriate exception handler based upon the |
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122 | caller of the function it last sought a exception handler for. It stops |
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123 | then either an exception handler is found, or when the top of the |
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124 | call chain is reached. |
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125 | |
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126 | If no handler is found, an external library function named |
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127 | __terminate is called. If a handler is found, then we restart |
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128 | our search for a handler at the end of the call chain, and repeat |
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129 | the search process, but instead of just walking up the call chain, |
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130 | we unwind the call chain as we walk up it. |
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131 | |
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132 | Internal implementation details: |
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133 | |
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134 | To associate a user-defined handler with a block of statements, the |
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135 | function expand_start_try_stmts is used to mark the start of the |
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136 | block of statements with which the handler is to be associated |
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137 | (which is known as a "try block"). All statements that appear |
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138 | afterwards will be associated with the try block. |
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139 | |
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140 | A call to expand_start_all_catch marks the end of the try block, |
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141 | and also marks the start of the "catch block" (the user-defined |
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142 | handler) associated with the try block. |
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143 | |
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144 | This user-defined handler will be invoked for *every* exception |
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145 | thrown with the context of the try block. It is up to the handler |
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146 | to decide whether or not it wishes to handle any given exception, |
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147 | as there is currently no mechanism in this implementation for doing |
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148 | this. (There are plans for conditionally processing an exception |
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149 | based on its "type", which will provide a language-independent |
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150 | mechanism). |
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151 | |
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152 | If the handler chooses not to process the exception (perhaps by |
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153 | looking at an "exception type" or some other additional data |
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154 | supplied with the exception), it can fall through to the end of the |
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155 | handler. expand_end_all_catch and expand_leftover_cleanups |
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156 | add additional code to the end of each handler to take care of |
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157 | rethrowing to the outer exception handler. |
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158 | |
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159 | The handler also has the option to continue with "normal flow of |
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160 | code", or in other words to resume executing at the statement |
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161 | immediately after the end of the exception region. The variable |
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162 | caught_return_label_stack contains a stack of labels, and jumping |
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163 | to the topmost entry's label via expand_goto will resume normal |
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164 | flow to the statement immediately after the end of the exception |
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165 | region. If the handler falls through to the end, the exception will |
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166 | be rethrown to the outer exception region. |
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167 | |
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168 | The instructions for the catch block are kept as a separate |
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169 | sequence, and will be emitted at the end of the function along with |
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170 | the handlers specified via expand_eh_region_end. The end of the |
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171 | catch block is marked with expand_end_all_catch. |
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172 | |
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173 | Any data associated with the exception must currently be handled by |
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174 | some external mechanism maintained in the frontend. For example, |
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175 | the C++ exception mechanism passes an arbitrary value along with |
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176 | the exception, and this is handled in the C++ frontend by using a |
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177 | global variable to hold the value. (This will be changing in the |
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178 | future.) |
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179 | |
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180 | The mechanism in C++ for handling data associated with the |
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181 | exception is clearly not thread-safe. For a thread-based |
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182 | environment, another mechanism must be used (possibly using a |
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183 | per-thread allocation mechanism if the size of the area that needs |
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184 | to be allocated isn't known at compile time.) |
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185 | |
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186 | Internally-generated exception regions (cleanups) are marked by |
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187 | calling expand_eh_region_start to mark the start of the region, |
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188 | and expand_eh_region_end (handler) is used to both designate the |
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189 | end of the region and to associate a specified handler/cleanup with |
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190 | the region. The rtl code in HANDLER will be invoked whenever an |
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191 | exception occurs in the region between the calls to |
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192 | expand_eh_region_start and expand_eh_region_end. After HANDLER is |
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193 | executed, additional code is emitted to handle rethrowing the |
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194 | exception to the outer exception handler. The code for HANDLER will |
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195 | be emitted at the end of the function. |
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196 | |
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197 | TARGET_EXPRs can also be used to designate exception regions. A |
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198 | TARGET_EXPR gives an unwind-protect style interface commonly used |
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199 | in functional languages such as LISP. The associated expression is |
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200 | evaluated, and whether or not it (or any of the functions that it |
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201 | calls) throws an exception, the protect expression is always |
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202 | invoked. This implementation takes care of the details of |
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203 | associating an exception table entry with the expression and |
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204 | generating the necessary code (it actually emits the protect |
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205 | expression twice, once for normal flow and once for the exception |
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206 | case). As for the other handlers, the code for the exception case |
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207 | will be emitted at the end of the function. |
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208 | |
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209 | Cleanups can also be specified by using add_partial_entry (handler) |
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210 | and end_protect_partials. add_partial_entry creates the start of |
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211 | a new exception region; HANDLER will be invoked if an exception is |
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212 | thrown with the context of the region between the calls to |
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213 | add_partial_entry and end_protect_partials. end_protect_partials is |
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214 | used to mark the end of these regions. add_partial_entry can be |
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215 | called as many times as needed before calling end_protect_partials. |
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216 | However, end_protect_partials should only be invoked once for each |
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217 | group of calls to add_partial_entry as the entries are queued |
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218 | and all of the outstanding entries are processed simultaneously |
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219 | when end_protect_partials is invoked. Similarly to the other |
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220 | handlers, the code for HANDLER will be emitted at the end of the |
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221 | function. |
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222 | |
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223 | The generated RTL for an exception region includes |
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224 | NOTE_INSN_EH_REGION_BEG and NOTE_INSN_EH_REGION_END notes that mark |
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225 | the start and end of the exception region. A unique label is also |
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226 | generated at the start of the exception region, which is available |
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227 | by looking at the ehstack variable. The topmost entry corresponds |
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228 | to the current region. |
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229 | |
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230 | In the current implementation, an exception can only be thrown from |
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231 | a function call (since the mechanism used to actually throw an |
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232 | exception involves calling __throw). If an exception region is |
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233 | created but no function calls occur within that region, the region |
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234 | can be safely optimized away (along with its exception handlers) |
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235 | since no exceptions can ever be caught in that region. This |
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236 | optimization is performed unless -fasynchronous-exceptions is |
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237 | given. If the user wishes to throw from a signal handler, or other |
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238 | asynchronous place, -fasynchronous-exceptions should be used when |
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239 | compiling for maximally correct code, at the cost of additional |
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240 | exception regions. Using -fasynchronous-exceptions only produces |
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241 | code that is reasonably safe in such situations, but a correct |
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242 | program cannot rely upon this working. It can be used in failsafe |
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243 | code, where trying to continue on, and proceeding with potentially |
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244 | incorrect results is better than halting the program. |
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245 | |
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246 | |
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247 | Walking the stack: |
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248 | |
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249 | The stack is walked by starting with a pointer to the current |
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250 | frame, and finding the pointer to the callers frame. The unwind info |
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251 | tells __throw how to find it. |
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252 | |
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253 | Unwinding the stack: |
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254 | |
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255 | When we use the term unwinding the stack, we mean undoing the |
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256 | effects of the function prologue in a controlled fashion so that we |
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257 | still have the flow of control. Otherwise, we could just return |
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258 | (jump to the normal end of function epilogue). |
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259 | |
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260 | This is done in __throw in libgcc2.c when we know that a handler exists |
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261 | in a frame higher up the call stack than its immediate caller. |
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262 | |
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263 | To unwind, we find the unwind data associated with the frame, if any. |
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264 | If we don't find any, we call the library routine __terminate. If we do |
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265 | find it, we use the information to copy the saved register values from |
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266 | that frame into the register save area in the frame for __throw, return |
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267 | into a stub which updates the stack pointer, and jump to the handler. |
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268 | The normal function epilogue for __throw handles restoring the saved |
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269 | values into registers. |
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270 | |
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271 | When unwinding, we use this method if we know it will |
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272 | work (if DWARF2_UNWIND_INFO is defined). Otherwise, we know that |
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273 | an inline unwinder will have been emitted for any function that |
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274 | __unwind_function cannot unwind. The inline unwinder appears as a |
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275 | normal exception handler for the entire function, for any function |
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276 | that we know cannot be unwound by __unwind_function. We inform the |
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277 | compiler of whether a function can be unwound with |
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278 | __unwind_function by having DOESNT_NEED_UNWINDER evaluate to true |
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279 | when the unwinder isn't needed. __unwind_function is used as an |
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280 | action of last resort. If no other method can be used for |
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281 | unwinding, __unwind_function is used. If it cannot unwind, it |
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282 | should call __terminate. |
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283 | |
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284 | By default, if the target-specific backend doesn't supply a definition |
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285 | for __unwind_function and doesn't support DWARF2_UNWIND_INFO, inlined |
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286 | unwinders will be used instead. The main tradeoff here is in text space |
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287 | utilization. Obviously, if inline unwinders have to be generated |
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288 | repeatedly, this uses much more space than if a single routine is used. |
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289 | |
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290 | However, it is simply not possible on some platforms to write a |
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291 | generalized routine for doing stack unwinding without having some |
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292 | form of additional data associated with each function. The current |
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293 | implementation can encode this data in the form of additional |
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294 | machine instructions or as static data in tabular form. The later |
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295 | is called the unwind data. |
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296 | |
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297 | The backend macro DOESNT_NEED_UNWINDER is used to conditionalize whether |
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298 | or not per-function unwinders are needed. If DOESNT_NEED_UNWINDER is |
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299 | defined and has a non-zero value, a per-function unwinder is not emitted |
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300 | for the current function. If the static unwind data is supported, then |
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301 | a per-function unwinder is not emitted. |
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302 | |
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303 | On some platforms it is possible that neither __unwind_function |
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304 | nor inlined unwinders are available. For these platforms it is not |
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305 | possible to throw through a function call, and abort will be |
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306 | invoked instead of performing the throw. |
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307 | |
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308 | The reason the unwind data may be needed is that on some platforms |
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309 | the order and types of data stored on the stack can vary depending |
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310 | on the type of function, its arguments and returned values, and the |
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311 | compilation options used (optimization versus non-optimization, |
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312 | -fomit-frame-pointer, processor variations, etc). |
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313 | |
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314 | Unfortunately, this also means that throwing through functions that |
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315 | aren't compiled with exception handling support will still not be |
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316 | possible on some platforms. This problem is currently being |
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317 | investigated, but no solutions have been found that do not imply |
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318 | some unacceptable performance penalties. |
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319 | |
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320 | Future directions: |
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321 | |
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322 | Currently __throw makes no differentiation between cleanups and |
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323 | user-defined exception regions. While this makes the implementation |
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324 | simple, it also implies that it is impossible to determine if a |
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325 | user-defined exception handler exists for a given exception without |
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326 | completely unwinding the stack in the process. This is undesirable |
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327 | from the standpoint of debugging, as ideally it would be possible |
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328 | to trap unhandled exceptions in the debugger before the process of |
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329 | unwinding has even started. |
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330 | |
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331 | This problem can be solved by marking user-defined handlers in a |
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332 | special way (probably by adding additional bits to exception_table_list). |
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333 | A two-pass scheme could then be used by __throw to iterate |
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334 | through the table. The first pass would search for a relevant |
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335 | user-defined handler for the current context of the throw, and if |
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336 | one is found, the second pass would then invoke all needed cleanups |
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337 | before jumping to the user-defined handler. |
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338 | |
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339 | Many languages (including C++ and Ada) make execution of a |
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340 | user-defined handler conditional on the "type" of the exception |
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341 | thrown. (The type of the exception is actually the type of the data |
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342 | that is thrown with the exception.) It will thus be necessary for |
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343 | __throw to be able to determine if a given user-defined |
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344 | exception handler will actually be executed, given the type of |
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345 | exception. |
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346 | |
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347 | One scheme is to add additional information to exception_table_list |
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348 | as to the types of exceptions accepted by each handler. __throw |
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349 | can do the type comparisons and then determine if the handler is |
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350 | actually going to be executed. |
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351 | |
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352 | There is currently no significant level of debugging support |
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353 | available, other than to place a breakpoint on __throw. While |
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354 | this is sufficient in most cases, it would be helpful to be able to |
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355 | know where a given exception was going to be thrown to before it is |
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356 | actually thrown, and to be able to choose between stopping before |
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357 | every exception region (including cleanups), or just user-defined |
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358 | exception regions. This should be possible to do in the two-pass |
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359 | scheme by adding additional labels to __throw for appropriate |
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360 | breakpoints, and additional debugger commands could be added to |
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361 | query various state variables to determine what actions are to be |
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362 | performed next. |
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363 | |
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364 | Another major problem that is being worked on is the issue with stack |
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365 | unwinding on various platforms. Currently the only platforms that have |
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366 | support for the generation of a generic unwinder are the SPARC and MIPS. |
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367 | All other ports require per-function unwinders, which produce large |
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368 | amounts of code bloat. |
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369 | |
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370 | For setjmp/longjmp based exception handling, some of the details |
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371 | are as above, but there are some additional details. This section |
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372 | discusses the details. |
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373 | |
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374 | We don't use NOTE_INSN_EH_REGION_{BEG,END} pairs. We don't |
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375 | optimize EH regions yet. We don't have to worry about machine |
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376 | specific issues with unwinding the stack, as we rely upon longjmp |
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377 | for all the machine specific details. There is no variable context |
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378 | of a throw, just the one implied by the dynamic handler stack |
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379 | pointed to by the dynamic handler chain. There is no exception |
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380 | table, and no calls to __register_exceptions. __sjthrow is used |
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381 | instead of __throw, and it works by using the dynamic handler |
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382 | chain, and longjmp. -fasynchronous-exceptions has no effect, as |
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383 | the elimination of trivial exception regions is not yet performed. |
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384 | |
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385 | A frontend can set protect_cleanup_actions_with_terminate when all |
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386 | the cleanup actions should be protected with an EH region that |
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387 | calls terminate when an unhandled exception is throw. C++ does |
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388 | this, Ada does not. */ |
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389 | |
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390 | |
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391 | #include "config.h" |
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392 | #include "defaults.h" |
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393 | #include <stdio.h> |
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394 | #include "rtl.h" |
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395 | #include "tree.h" |
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396 | #include "flags.h" |
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397 | #include "except.h" |
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398 | #include "function.h" |
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399 | #include "insn-flags.h" |
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400 | #include "expr.h" |
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401 | #include "insn-codes.h" |
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402 | #include "regs.h" |
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403 | #include "hard-reg-set.h" |
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404 | #include "insn-config.h" |
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405 | #include "recog.h" |
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406 | #include "output.h" |
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407 | |
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408 | /* One to use setjmp/longjmp method of generating code for exception |
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409 | handling. */ |
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410 | |
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411 | int exceptions_via_longjmp = 2; |
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412 | |
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413 | /* One to enable asynchronous exception support. */ |
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414 | |
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415 | int asynchronous_exceptions = 0; |
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416 | |
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417 | /* One to protect cleanup actions with a handler that calls |
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418 | __terminate, zero otherwise. */ |
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419 | |
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420 | int protect_cleanup_actions_with_terminate = 0; |
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421 | |
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422 | /* A list of labels used for exception handlers. Created by |
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423 | find_exception_handler_labels for the optimization passes. */ |
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424 | |
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425 | rtx exception_handler_labels; |
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426 | |
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427 | /* Nonzero means that __throw was invoked. |
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428 | |
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429 | This is used by the C++ frontend to know if code needs to be emitted |
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430 | for __throw or not. */ |
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431 | |
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432 | int throw_used; |
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433 | |
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434 | /* The dynamic handler chain. Nonzero if the function has already |
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435 | fetched a pointer to the dynamic handler chain for exception |
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436 | handling. */ |
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437 | |
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438 | rtx current_function_dhc; |
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439 | |
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440 | /* The dynamic cleanup chain. Nonzero if the function has already |
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441 | fetched a pointer to the dynamic cleanup chain for exception |
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442 | handling. */ |
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443 | |
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444 | rtx current_function_dcc; |
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445 | |
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446 | /* A stack used for keeping track of the currently active exception |
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447 | handling region. As each exception region is started, an entry |
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448 | describing the region is pushed onto this stack. The current |
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449 | region can be found by looking at the top of the stack, and as we |
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450 | exit regions, the corresponding entries are popped. |
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451 | |
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452 | Entries cannot overlap; they can be nested. So there is only one |
---|
453 | entry at most that corresponds to the current instruction, and that |
---|
454 | is the entry on the top of the stack. */ |
---|
455 | |
---|
456 | static struct eh_stack ehstack; |
---|
457 | |
---|
458 | /* A queue used for tracking which exception regions have closed but |
---|
459 | whose handlers have not yet been expanded. Regions are emitted in |
---|
460 | groups in an attempt to improve paging performance. |
---|
461 | |
---|
462 | As we exit a region, we enqueue a new entry. The entries are then |
---|
463 | dequeued during expand_leftover_cleanups and expand_start_all_catch, |
---|
464 | |
---|
465 | We should redo things so that we either take RTL for the handler, |
---|
466 | or we expand the handler expressed as a tree immediately at region |
---|
467 | end time. */ |
---|
468 | |
---|
469 | static struct eh_queue ehqueue; |
---|
470 | |
---|
471 | /* Insns for all of the exception handlers for the current function. |
---|
472 | They are currently emitted by the frontend code. */ |
---|
473 | |
---|
474 | rtx catch_clauses; |
---|
475 | |
---|
476 | /* A TREE_CHAINed list of handlers for regions that are not yet |
---|
477 | closed. The TREE_VALUE of each entry contains the handler for the |
---|
478 | corresponding entry on the ehstack. */ |
---|
479 | |
---|
480 | static tree protect_list; |
---|
481 | |
---|
482 | /* Stacks to keep track of various labels. */ |
---|
483 | |
---|
484 | /* Keeps track of the label to resume to should one want to resume |
---|
485 | normal control flow out of a handler (instead of, say, returning to |
---|
486 | the caller of the current function or exiting the program). */ |
---|
487 | |
---|
488 | struct label_node *caught_return_label_stack = NULL; |
---|
489 | |
---|
490 | /* Keeps track of the label used as the context of a throw to rethrow an |
---|
491 | exception to the outer exception region. */ |
---|
492 | |
---|
493 | struct label_node *outer_context_label_stack = NULL; |
---|
494 | |
---|
495 | /* A random data area for the front end's own use. */ |
---|
496 | |
---|
497 | struct label_node *false_label_stack = NULL; |
---|
498 | |
---|
499 | /* The rtx and the tree for the saved PC value. */ |
---|
500 | |
---|
501 | rtx eh_saved_pc_rtx; |
---|
502 | tree eh_saved_pc; |
---|
503 | |
---|
504 | rtx expand_builtin_return_addr PROTO((enum built_in_function, int, rtx)); |
---|
505 | |
---|
506 | /* Various support routines to manipulate the various data structures |
---|
507 | used by the exception handling code. */ |
---|
508 | |
---|
509 | /* Push a label entry onto the given STACK. */ |
---|
510 | |
---|
511 | void |
---|
512 | push_label_entry (stack, rlabel, tlabel) |
---|
513 | struct label_node **stack; |
---|
514 | rtx rlabel; |
---|
515 | tree tlabel; |
---|
516 | { |
---|
517 | struct label_node *newnode |
---|
518 | = (struct label_node *) xmalloc (sizeof (struct label_node)); |
---|
519 | |
---|
520 | if (rlabel) |
---|
521 | newnode->u.rlabel = rlabel; |
---|
522 | else |
---|
523 | newnode->u.tlabel = tlabel; |
---|
524 | newnode->chain = *stack; |
---|
525 | *stack = newnode; |
---|
526 | } |
---|
527 | |
---|
528 | /* Pop a label entry from the given STACK. */ |
---|
529 | |
---|
530 | rtx |
---|
531 | pop_label_entry (stack) |
---|
532 | struct label_node **stack; |
---|
533 | { |
---|
534 | rtx label; |
---|
535 | struct label_node *tempnode; |
---|
536 | |
---|
537 | if (! *stack) |
---|
538 | return NULL_RTX; |
---|
539 | |
---|
540 | tempnode = *stack; |
---|
541 | label = tempnode->u.rlabel; |
---|
542 | *stack = (*stack)->chain; |
---|
543 | free (tempnode); |
---|
544 | |
---|
545 | return label; |
---|
546 | } |
---|
547 | |
---|
548 | /* Return the top element of the given STACK. */ |
---|
549 | |
---|
550 | tree |
---|
551 | top_label_entry (stack) |
---|
552 | struct label_node **stack; |
---|
553 | { |
---|
554 | if (! *stack) |
---|
555 | return NULL_TREE; |
---|
556 | |
---|
557 | return (*stack)->u.tlabel; |
---|
558 | } |
---|
559 | |
---|
560 | /* Make a copy of ENTRY using xmalloc to allocate the space. */ |
---|
561 | |
---|
562 | static struct eh_entry * |
---|
563 | copy_eh_entry (entry) |
---|
564 | struct eh_entry *entry; |
---|
565 | { |
---|
566 | struct eh_entry *newentry; |
---|
567 | |
---|
568 | newentry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry)); |
---|
569 | bcopy ((char *) entry, (char *) newentry, sizeof (struct eh_entry)); |
---|
570 | |
---|
571 | return newentry; |
---|
572 | } |
---|
573 | |
---|
574 | /* Push a new eh_node entry onto STACK. */ |
---|
575 | |
---|
576 | static void |
---|
577 | push_eh_entry (stack) |
---|
578 | struct eh_stack *stack; |
---|
579 | { |
---|
580 | struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node)); |
---|
581 | struct eh_entry *entry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry)); |
---|
582 | |
---|
583 | entry->outer_context = gen_label_rtx (); |
---|
584 | entry->exception_handler_label = gen_label_rtx (); |
---|
585 | entry->finalization = NULL_TREE; |
---|
586 | |
---|
587 | node->entry = entry; |
---|
588 | node->chain = stack->top; |
---|
589 | stack->top = node; |
---|
590 | } |
---|
591 | |
---|
592 | /* Pop an entry from the given STACK. */ |
---|
593 | |
---|
594 | static struct eh_entry * |
---|
595 | pop_eh_entry (stack) |
---|
596 | struct eh_stack *stack; |
---|
597 | { |
---|
598 | struct eh_node *tempnode; |
---|
599 | struct eh_entry *tempentry; |
---|
600 | |
---|
601 | tempnode = stack->top; |
---|
602 | tempentry = tempnode->entry; |
---|
603 | stack->top = stack->top->chain; |
---|
604 | free (tempnode); |
---|
605 | |
---|
606 | return tempentry; |
---|
607 | } |
---|
608 | |
---|
609 | /* Enqueue an ENTRY onto the given QUEUE. */ |
---|
610 | |
---|
611 | static void |
---|
612 | enqueue_eh_entry (queue, entry) |
---|
613 | struct eh_queue *queue; |
---|
614 | struct eh_entry *entry; |
---|
615 | { |
---|
616 | struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node)); |
---|
617 | |
---|
618 | node->entry = entry; |
---|
619 | node->chain = NULL; |
---|
620 | |
---|
621 | if (queue->head == NULL) |
---|
622 | { |
---|
623 | queue->head = node; |
---|
624 | } |
---|
625 | else |
---|
626 | { |
---|
627 | queue->tail->chain = node; |
---|
628 | } |
---|
629 | queue->tail = node; |
---|
630 | } |
---|
631 | |
---|
632 | /* Dequeue an entry from the given QUEUE. */ |
---|
633 | |
---|
634 | static struct eh_entry * |
---|
635 | dequeue_eh_entry (queue) |
---|
636 | struct eh_queue *queue; |
---|
637 | { |
---|
638 | struct eh_node *tempnode; |
---|
639 | struct eh_entry *tempentry; |
---|
640 | |
---|
641 | if (queue->head == NULL) |
---|
642 | return NULL; |
---|
643 | |
---|
644 | tempnode = queue->head; |
---|
645 | queue->head = queue->head->chain; |
---|
646 | |
---|
647 | tempentry = tempnode->entry; |
---|
648 | free (tempnode); |
---|
649 | |
---|
650 | return tempentry; |
---|
651 | } |
---|
652 | |
---|
653 | /* Routine to see if exception exception handling is turned on. |
---|
654 | DO_WARN is non-zero if we want to inform the user that exception |
---|
655 | handling is turned off. |
---|
656 | |
---|
657 | This is used to ensure that -fexceptions has been specified if the |
---|
658 | compiler tries to use any exception-specific functions. */ |
---|
659 | |
---|
660 | int |
---|
661 | doing_eh (do_warn) |
---|
662 | int do_warn; |
---|
663 | { |
---|
664 | if (! flag_exceptions) |
---|
665 | { |
---|
666 | static int warned = 0; |
---|
667 | if (! warned && do_warn) |
---|
668 | { |
---|
669 | error ("exception handling disabled, use -fexceptions to enable"); |
---|
670 | warned = 1; |
---|
671 | } |
---|
672 | return 0; |
---|
673 | } |
---|
674 | return 1; |
---|
675 | } |
---|
676 | |
---|
677 | /* Given a return address in ADDR, determine the address we should use |
---|
678 | to find the corresponding EH region. */ |
---|
679 | |
---|
680 | rtx |
---|
681 | eh_outer_context (addr) |
---|
682 | rtx addr; |
---|
683 | { |
---|
684 | /* First mask out any unwanted bits. */ |
---|
685 | #ifdef MASK_RETURN_ADDR |
---|
686 | expand_and (addr, MASK_RETURN_ADDR, addr); |
---|
687 | #endif |
---|
688 | |
---|
689 | /* Then adjust to find the real return address. */ |
---|
690 | #if defined (RETURN_ADDR_OFFSET) |
---|
691 | addr = plus_constant (addr, RETURN_ADDR_OFFSET); |
---|
692 | #endif |
---|
693 | |
---|
694 | return addr; |
---|
695 | } |
---|
696 | |
---|
697 | /* Start a new exception region for a region of code that has a |
---|
698 | cleanup action and push the HANDLER for the region onto |
---|
699 | protect_list. All of the regions created with add_partial_entry |
---|
700 | will be ended when end_protect_partials is invoked. */ |
---|
701 | |
---|
702 | void |
---|
703 | add_partial_entry (handler) |
---|
704 | tree handler; |
---|
705 | { |
---|
706 | expand_eh_region_start (); |
---|
707 | |
---|
708 | /* Make sure the entry is on the correct obstack. */ |
---|
709 | push_obstacks_nochange (); |
---|
710 | resume_temporary_allocation (); |
---|
711 | |
---|
712 | /* Because this is a cleanup action, we may have to protect the handler |
---|
713 | with __terminate. */ |
---|
714 | handler = protect_with_terminate (handler); |
---|
715 | |
---|
716 | protect_list = tree_cons (NULL_TREE, handler, protect_list); |
---|
717 | pop_obstacks (); |
---|
718 | } |
---|
719 | |
---|
720 | /* Get a reference to the dynamic handler chain. It points to the |
---|
721 | pointer to the next element in the dynamic handler chain. It ends |
---|
722 | when there are no more elements in the dynamic handler chain, when |
---|
723 | the value is &top_elt from libgcc2.c. Immediately after the |
---|
724 | pointer, is an area suitable for setjmp/longjmp when |
---|
725 | DONT_USE_BUILTIN_SETJMP is defined, and an area suitable for |
---|
726 | __builtin_setjmp/__builtin_longjmp when DONT_USE_BUILTIN_SETJMP |
---|
727 | isn't defined. |
---|
728 | |
---|
729 | This routine is here to facilitate the porting of this code to |
---|
730 | systems with threads. One can either replace the routine we emit a |
---|
731 | call for here in libgcc2.c, or one can modify this routine to work |
---|
732 | with their thread system. |
---|
733 | |
---|
734 | Ideally, we really only want one per real function, not one |
---|
735 | per inlined function. */ |
---|
736 | |
---|
737 | rtx |
---|
738 | get_dynamic_handler_chain () |
---|
739 | { |
---|
740 | static tree fn; |
---|
741 | tree expr; |
---|
742 | rtx insns; |
---|
743 | |
---|
744 | if (current_function_dhc) |
---|
745 | return current_function_dhc; |
---|
746 | |
---|
747 | if (fn == NULL_TREE) |
---|
748 | { |
---|
749 | tree fntype; |
---|
750 | fn = get_identifier ("__get_dynamic_handler_chain"); |
---|
751 | push_obstacks_nochange (); |
---|
752 | end_temporary_allocation (); |
---|
753 | fntype = build_pointer_type (build_pointer_type |
---|
754 | (build_pointer_type (void_type_node))); |
---|
755 | fntype = build_function_type (fntype, NULL_TREE); |
---|
756 | fn = build_decl (FUNCTION_DECL, fn, fntype); |
---|
757 | DECL_EXTERNAL (fn) = 1; |
---|
758 | TREE_PUBLIC (fn) = 1; |
---|
759 | DECL_ARTIFICIAL (fn) = 1; |
---|
760 | TREE_READONLY (fn) = 1; |
---|
761 | make_decl_rtl (fn, NULL_PTR, 1); |
---|
762 | assemble_external (fn); |
---|
763 | pop_obstacks (); |
---|
764 | } |
---|
765 | |
---|
766 | expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn); |
---|
767 | expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)), |
---|
768 | expr, NULL_TREE, NULL_TREE); |
---|
769 | TREE_SIDE_EFFECTS (expr) = 1; |
---|
770 | expr = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (expr)), expr); |
---|
771 | |
---|
772 | start_sequence (); |
---|
773 | current_function_dhc = expand_expr (expr, NULL_RTX, VOIDmode, 0); |
---|
774 | insns = get_insns (); |
---|
775 | end_sequence (); |
---|
776 | emit_insns_before (insns, get_first_nonparm_insn ()); |
---|
777 | |
---|
778 | return current_function_dhc; |
---|
779 | } |
---|
780 | |
---|
781 | /* Get a reference to the dynamic cleanup chain. It points to the |
---|
782 | pointer to the next element in the dynamic cleanup chain. |
---|
783 | Immediately after the pointer, are two Pmode variables, one for a |
---|
784 | pointer to a function that performs the cleanup action, and the |
---|
785 | second, the argument to pass to that function. */ |
---|
786 | |
---|
787 | rtx |
---|
788 | get_dynamic_cleanup_chain () |
---|
789 | { |
---|
790 | rtx dhc, dcc; |
---|
791 | |
---|
792 | dhc = get_dynamic_handler_chain (); |
---|
793 | dcc = plus_constant (dhc, GET_MODE_SIZE (Pmode)); |
---|
794 | |
---|
795 | current_function_dcc = copy_to_reg (dcc); |
---|
796 | |
---|
797 | /* We don't want a copy of the dcc, but rather, the single dcc. */ |
---|
798 | return gen_rtx (MEM, Pmode, current_function_dcc); |
---|
799 | } |
---|
800 | |
---|
801 | /* Generate code to evaluate X and jump to LABEL if the value is nonzero. |
---|
802 | LABEL is an rtx of code CODE_LABEL, in this function. */ |
---|
803 | |
---|
804 | void |
---|
805 | jumpif_rtx (x, label) |
---|
806 | rtx x; |
---|
807 | rtx label; |
---|
808 | { |
---|
809 | jumpif (make_tree (type_for_mode (GET_MODE (x), 0), x), label); |
---|
810 | } |
---|
811 | |
---|
812 | /* Generate code to evaluate X and jump to LABEL if the value is zero. |
---|
813 | LABEL is an rtx of code CODE_LABEL, in this function. */ |
---|
814 | |
---|
815 | void |
---|
816 | jumpifnot_rtx (x, label) |
---|
817 | rtx x; |
---|
818 | rtx label; |
---|
819 | { |
---|
820 | jumpifnot (make_tree (type_for_mode (GET_MODE (x), 0), x), label); |
---|
821 | } |
---|
822 | |
---|
823 | /* Start a dynamic cleanup on the EH runtime dynamic cleanup stack. |
---|
824 | We just need to create an element for the cleanup list, and push it |
---|
825 | into the chain. |
---|
826 | |
---|
827 | A dynamic cleanup is a cleanup action implied by the presence of an |
---|
828 | element on the EH runtime dynamic cleanup stack that is to be |
---|
829 | performed when an exception is thrown. The cleanup action is |
---|
830 | performed by __sjthrow when an exception is thrown. Only certain |
---|
831 | actions can be optimized into dynamic cleanup actions. For the |
---|
832 | restrictions on what actions can be performed using this routine, |
---|
833 | see expand_eh_region_start_tree. */ |
---|
834 | |
---|
835 | static void |
---|
836 | start_dynamic_cleanup (func, arg) |
---|
837 | tree func; |
---|
838 | tree arg; |
---|
839 | { |
---|
840 | rtx dhc, dcc; |
---|
841 | rtx new_func, new_arg; |
---|
842 | rtx x, buf; |
---|
843 | int size; |
---|
844 | |
---|
845 | /* We allocate enough room for a pointer to the function, and |
---|
846 | one argument. */ |
---|
847 | size = 2; |
---|
848 | |
---|
849 | /* XXX, FIXME: The stack space allocated this way is too long lived, |
---|
850 | but there is no allocation routine that allocates at the level of |
---|
851 | the last binding contour. */ |
---|
852 | buf = assign_stack_local (BLKmode, |
---|
853 | GET_MODE_SIZE (Pmode)*(size+1), |
---|
854 | 0); |
---|
855 | |
---|
856 | buf = change_address (buf, Pmode, NULL_RTX); |
---|
857 | |
---|
858 | /* Store dcc into the first word of the newly allocated buffer. */ |
---|
859 | |
---|
860 | dcc = get_dynamic_cleanup_chain (); |
---|
861 | emit_move_insn (buf, dcc); |
---|
862 | |
---|
863 | /* Store func and arg into the cleanup list element. */ |
---|
864 | |
---|
865 | new_func = gen_rtx (MEM, Pmode, plus_constant (XEXP (buf, 0), |
---|
866 | GET_MODE_SIZE (Pmode))); |
---|
867 | new_arg = gen_rtx (MEM, Pmode, plus_constant (XEXP (buf, 0), |
---|
868 | GET_MODE_SIZE (Pmode)*2)); |
---|
869 | x = expand_expr (func, new_func, Pmode, 0); |
---|
870 | if (x != new_func) |
---|
871 | emit_move_insn (new_func, x); |
---|
872 | |
---|
873 | x = expand_expr (arg, new_arg, Pmode, 0); |
---|
874 | if (x != new_arg) |
---|
875 | emit_move_insn (new_arg, x); |
---|
876 | |
---|
877 | /* Update the cleanup chain. */ |
---|
878 | |
---|
879 | emit_move_insn (dcc, XEXP (buf, 0)); |
---|
880 | } |
---|
881 | |
---|
882 | /* Emit RTL to start a dynamic handler on the EH runtime dynamic |
---|
883 | handler stack. This should only be used by expand_eh_region_start |
---|
884 | or expand_eh_region_start_tree. */ |
---|
885 | |
---|
886 | static void |
---|
887 | start_dynamic_handler () |
---|
888 | { |
---|
889 | rtx dhc, dcc; |
---|
890 | rtx x, arg, buf; |
---|
891 | int size; |
---|
892 | |
---|
893 | #ifndef DONT_USE_BUILTIN_SETJMP |
---|
894 | /* The number of Pmode words for the setjmp buffer, when using the |
---|
895 | builtin setjmp/longjmp, see expand_builtin, case |
---|
896 | BUILT_IN_LONGJMP. */ |
---|
897 | size = 5; |
---|
898 | #else |
---|
899 | #ifdef JMP_BUF_SIZE |
---|
900 | size = JMP_BUF_SIZE; |
---|
901 | #else |
---|
902 | /* Should be large enough for most systems, if it is not, |
---|
903 | JMP_BUF_SIZE should be defined with the proper value. It will |
---|
904 | also tend to be larger than necessary for most systems, a more |
---|
905 | optimal port will define JMP_BUF_SIZE. */ |
---|
906 | size = FIRST_PSEUDO_REGISTER+2; |
---|
907 | #endif |
---|
908 | #endif |
---|
909 | /* XXX, FIXME: The stack space allocated this way is too long lived, |
---|
910 | but there is no allocation routine that allocates at the level of |
---|
911 | the last binding contour. */ |
---|
912 | arg = assign_stack_local (BLKmode, |
---|
913 | GET_MODE_SIZE (Pmode)*(size+1), |
---|
914 | 0); |
---|
915 | |
---|
916 | arg = change_address (arg, Pmode, NULL_RTX); |
---|
917 | |
---|
918 | /* Store dhc into the first word of the newly allocated buffer. */ |
---|
919 | |
---|
920 | dhc = get_dynamic_handler_chain (); |
---|
921 | dcc = gen_rtx (MEM, Pmode, plus_constant (XEXP (arg, 0), |
---|
922 | GET_MODE_SIZE (Pmode))); |
---|
923 | emit_move_insn (arg, dhc); |
---|
924 | |
---|
925 | /* Zero out the start of the cleanup chain. */ |
---|
926 | emit_move_insn (dcc, const0_rtx); |
---|
927 | |
---|
928 | /* The jmpbuf starts two words into the area allocated. */ |
---|
929 | buf = plus_constant (XEXP (arg, 0), GET_MODE_SIZE (Pmode)*2); |
---|
930 | |
---|
931 | #ifdef DONT_USE_BUILTIN_SETJMP |
---|
932 | x = emit_library_call_value (setjmp_libfunc, NULL_RTX, 1, SImode, 1, |
---|
933 | buf, Pmode); |
---|
934 | #else |
---|
935 | x = expand_builtin_setjmp (buf, NULL_RTX); |
---|
936 | #endif |
---|
937 | |
---|
938 | /* If we come back here for a catch, transfer control to the |
---|
939 | handler. */ |
---|
940 | |
---|
941 | jumpif_rtx (x, ehstack.top->entry->exception_handler_label); |
---|
942 | |
---|
943 | /* We are committed to this, so update the handler chain. */ |
---|
944 | |
---|
945 | emit_move_insn (dhc, XEXP (arg, 0)); |
---|
946 | } |
---|
947 | |
---|
948 | /* Start an exception handling region for the given cleanup action. |
---|
949 | All instructions emitted after this point are considered to be part |
---|
950 | of the region until expand_eh_region_end is invoked. CLEANUP is |
---|
951 | the cleanup action to perform. The return value is true if the |
---|
952 | exception region was optimized away. If that case, |
---|
953 | expand_eh_region_end does not need to be called for this cleanup, |
---|
954 | nor should it be. |
---|
955 | |
---|
956 | This routine notices one particular common case in C++ code |
---|
957 | generation, and optimizes it so as to not need the exception |
---|
958 | region. It works by creating a dynamic cleanup action, instead of |
---|
959 | of a using an exception region. */ |
---|
960 | |
---|
961 | int |
---|
962 | expand_eh_region_start_tree (decl, cleanup) |
---|
963 | tree decl; |
---|
964 | tree cleanup; |
---|
965 | { |
---|
966 | rtx note; |
---|
967 | |
---|
968 | /* This is the old code. */ |
---|
969 | if (! doing_eh (0)) |
---|
970 | return 0; |
---|
971 | |
---|
972 | /* The optimization only applies to actions protected with |
---|
973 | terminate, and only applies if we are using the setjmp/longjmp |
---|
974 | codegen method. */ |
---|
975 | if (exceptions_via_longjmp |
---|
976 | && protect_cleanup_actions_with_terminate) |
---|
977 | { |
---|
978 | tree func, arg; |
---|
979 | tree args; |
---|
980 | |
---|
981 | /* Ignore any UNSAVE_EXPR. */ |
---|
982 | if (TREE_CODE (cleanup) == UNSAVE_EXPR) |
---|
983 | cleanup = TREE_OPERAND (cleanup, 0); |
---|
984 | |
---|
985 | /* Further, it only applies if the action is a call, if there |
---|
986 | are 2 arguments, and if the second argument is 2. */ |
---|
987 | |
---|
988 | if (TREE_CODE (cleanup) == CALL_EXPR |
---|
989 | && (args = TREE_OPERAND (cleanup, 1)) |
---|
990 | && (func = TREE_OPERAND (cleanup, 0)) |
---|
991 | && (arg = TREE_VALUE (args)) |
---|
992 | && (args = TREE_CHAIN (args)) |
---|
993 | |
---|
994 | /* is the second argument 2? */ |
---|
995 | && TREE_CODE (TREE_VALUE (args)) == INTEGER_CST |
---|
996 | && TREE_INT_CST_LOW (TREE_VALUE (args)) == 2 |
---|
997 | && TREE_INT_CST_HIGH (TREE_VALUE (args)) == 0 |
---|
998 | |
---|
999 | /* Make sure there are no other arguments. */ |
---|
1000 | && TREE_CHAIN (args) == NULL_TREE) |
---|
1001 | { |
---|
1002 | /* Arrange for returns and gotos to pop the entry we make on the |
---|
1003 | dynamic cleanup stack. */ |
---|
1004 | expand_dcc_cleanup (decl); |
---|
1005 | start_dynamic_cleanup (func, arg); |
---|
1006 | return 1; |
---|
1007 | } |
---|
1008 | } |
---|
1009 | |
---|
1010 | expand_eh_region_start_for_decl (decl); |
---|
1011 | ehstack.top->entry->finalization = cleanup; |
---|
1012 | |
---|
1013 | return 0; |
---|
1014 | } |
---|
1015 | |
---|
1016 | /* Just like expand_eh_region_start, except if a cleanup action is |
---|
1017 | entered on the cleanup chain, the TREE_PURPOSE of the element put |
---|
1018 | on the chain is DECL. DECL should be the associated VAR_DECL, if |
---|
1019 | any, otherwise it should be NULL_TREE. */ |
---|
1020 | |
---|
1021 | void |
---|
1022 | expand_eh_region_start_for_decl (decl) |
---|
1023 | tree decl; |
---|
1024 | { |
---|
1025 | rtx note; |
---|
1026 | |
---|
1027 | /* This is the old code. */ |
---|
1028 | if (! doing_eh (0)) |
---|
1029 | return; |
---|
1030 | |
---|
1031 | if (exceptions_via_longjmp) |
---|
1032 | { |
---|
1033 | /* We need a new block to record the start and end of the |
---|
1034 | dynamic handler chain. We could always do this, but we |
---|
1035 | really want to permit jumping into such a block, and we want |
---|
1036 | to avoid any errors or performance impact in the SJ EH code |
---|
1037 | for now. */ |
---|
1038 | expand_start_bindings (0); |
---|
1039 | |
---|
1040 | /* But we don't need or want a new temporary level. */ |
---|
1041 | pop_temp_slots (); |
---|
1042 | |
---|
1043 | /* Mark this block as created by expand_eh_region_start. This |
---|
1044 | is so that we can pop the block with expand_end_bindings |
---|
1045 | automatically. */ |
---|
1046 | mark_block_as_eh_region (); |
---|
1047 | |
---|
1048 | /* Arrange for returns and gotos to pop the entry we make on the |
---|
1049 | dynamic handler stack. */ |
---|
1050 | expand_dhc_cleanup (decl); |
---|
1051 | } |
---|
1052 | |
---|
1053 | if (exceptions_via_longjmp == 0) |
---|
1054 | note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_BEG); |
---|
1055 | push_eh_entry (&ehstack); |
---|
1056 | if (exceptions_via_longjmp == 0) |
---|
1057 | NOTE_BLOCK_NUMBER (note) |
---|
1058 | = CODE_LABEL_NUMBER (ehstack.top->entry->exception_handler_label); |
---|
1059 | if (exceptions_via_longjmp) |
---|
1060 | start_dynamic_handler (); |
---|
1061 | } |
---|
1062 | |
---|
1063 | /* Start an exception handling region. All instructions emitted after |
---|
1064 | this point are considered to be part of the region until |
---|
1065 | expand_eh_region_end is invoked. */ |
---|
1066 | |
---|
1067 | void |
---|
1068 | expand_eh_region_start () |
---|
1069 | { |
---|
1070 | expand_eh_region_start_for_decl (NULL_TREE); |
---|
1071 | } |
---|
1072 | |
---|
1073 | /* End an exception handling region. The information about the region |
---|
1074 | is found on the top of ehstack. |
---|
1075 | |
---|
1076 | HANDLER is either the cleanup for the exception region, or if we're |
---|
1077 | marking the end of a try block, HANDLER is integer_zero_node. |
---|
1078 | |
---|
1079 | HANDLER will be transformed to rtl when expand_leftover_cleanups |
---|
1080 | is invoked. */ |
---|
1081 | |
---|
1082 | void |
---|
1083 | expand_eh_region_end (handler) |
---|
1084 | tree handler; |
---|
1085 | { |
---|
1086 | struct eh_entry *entry; |
---|
1087 | |
---|
1088 | if (! doing_eh (0)) |
---|
1089 | return; |
---|
1090 | |
---|
1091 | entry = pop_eh_entry (&ehstack); |
---|
1092 | |
---|
1093 | if (exceptions_via_longjmp == 0) |
---|
1094 | { |
---|
1095 | rtx label; |
---|
1096 | rtx note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_END); |
---|
1097 | NOTE_BLOCK_NUMBER (note) = CODE_LABEL_NUMBER (entry->exception_handler_label); |
---|
1098 | |
---|
1099 | label = gen_label_rtx (); |
---|
1100 | emit_jump (label); |
---|
1101 | |
---|
1102 | /* Emit a label marking the end of this exception region that |
---|
1103 | is used for rethrowing into the outer context. */ |
---|
1104 | emit_label (entry->outer_context); |
---|
1105 | |
---|
1106 | /* Put in something that takes up space, as otherwise the end |
---|
1107 | address for this EH region could have the exact same address as |
---|
1108 | its outer region. This would cause us to miss the fact that |
---|
1109 | resuming exception handling with this PC value would be inside |
---|
1110 | the outer region. */ |
---|
1111 | emit_insn (gen_nop ()); |
---|
1112 | emit_barrier (); |
---|
1113 | emit_label (label); |
---|
1114 | } |
---|
1115 | |
---|
1116 | entry->finalization = handler; |
---|
1117 | |
---|
1118 | enqueue_eh_entry (&ehqueue, entry); |
---|
1119 | |
---|
1120 | /* If we have already started ending the bindings, don't recurse. |
---|
1121 | This only happens when exceptions_via_longjmp is true. */ |
---|
1122 | if (is_eh_region ()) |
---|
1123 | { |
---|
1124 | /* Because we don't need or want a new temporary level and |
---|
1125 | because we didn't create one in expand_eh_region_start, |
---|
1126 | create a fake one now to avoid removing one in |
---|
1127 | expand_end_bindings. */ |
---|
1128 | push_temp_slots (); |
---|
1129 | |
---|
1130 | mark_block_as_not_eh_region (); |
---|
1131 | |
---|
1132 | /* Maybe do this to prevent jumping in and so on... */ |
---|
1133 | expand_end_bindings (NULL_TREE, 0, 0); |
---|
1134 | } |
---|
1135 | } |
---|
1136 | |
---|
1137 | /* End the EH region for a goto fixup. We only need them in the region-based |
---|
1138 | EH scheme. */ |
---|
1139 | |
---|
1140 | void |
---|
1141 | expand_fixup_region_start () |
---|
1142 | { |
---|
1143 | if (! doing_eh (0) || exceptions_via_longjmp) |
---|
1144 | return; |
---|
1145 | |
---|
1146 | expand_eh_region_start (); |
---|
1147 | } |
---|
1148 | |
---|
1149 | /* End the EH region for a goto fixup. CLEANUP is the cleanup we just |
---|
1150 | expanded; to avoid running it twice if it throws, we look through the |
---|
1151 | ehqueue for a matching region and rethrow from its outer_context. */ |
---|
1152 | |
---|
1153 | void |
---|
1154 | expand_fixup_region_end (cleanup) |
---|
1155 | tree cleanup; |
---|
1156 | { |
---|
1157 | tree t; |
---|
1158 | struct eh_node *node; |
---|
1159 | int yes; |
---|
1160 | |
---|
1161 | if (! doing_eh (0) || exceptions_via_longjmp) |
---|
1162 | return; |
---|
1163 | |
---|
1164 | for (node = ehstack.top; node && node->entry->finalization != cleanup; ) |
---|
1165 | node = node->chain; |
---|
1166 | if (node == 0) |
---|
1167 | for (node = ehqueue.head; node && node->entry->finalization != cleanup; ) |
---|
1168 | node = node->chain; |
---|
1169 | if (node == 0) |
---|
1170 | abort (); |
---|
1171 | |
---|
1172 | yes = suspend_momentary (); |
---|
1173 | |
---|
1174 | t = build (RTL_EXPR, void_type_node, NULL_RTX, const0_rtx); |
---|
1175 | TREE_SIDE_EFFECTS (t) = 1; |
---|
1176 | do_pending_stack_adjust (); |
---|
1177 | start_sequence_for_rtl_expr (t); |
---|
1178 | expand_internal_throw (node->entry->outer_context); |
---|
1179 | do_pending_stack_adjust (); |
---|
1180 | RTL_EXPR_SEQUENCE (t) = get_insns (); |
---|
1181 | end_sequence (); |
---|
1182 | |
---|
1183 | resume_momentary (yes); |
---|
1184 | |
---|
1185 | expand_eh_region_end (t); |
---|
1186 | } |
---|
1187 | |
---|
1188 | /* If we are using the setjmp/longjmp EH codegen method, we emit a |
---|
1189 | call to __sjthrow. |
---|
1190 | |
---|
1191 | Otherwise, we emit a call to __throw and note that we threw |
---|
1192 | something, so we know we need to generate the necessary code for |
---|
1193 | __throw. |
---|
1194 | |
---|
1195 | Before invoking throw, the __eh_pc variable must have been set up |
---|
1196 | to contain the PC being thrown from. This address is used by |
---|
1197 | __throw to determine which exception region (if any) is |
---|
1198 | responsible for handling the exception. */ |
---|
1199 | |
---|
1200 | void |
---|
1201 | emit_throw () |
---|
1202 | { |
---|
1203 | if (exceptions_via_longjmp) |
---|
1204 | { |
---|
1205 | emit_library_call (sjthrow_libfunc, 0, VOIDmode, 0); |
---|
1206 | } |
---|
1207 | else |
---|
1208 | { |
---|
1209 | #ifdef JUMP_TO_THROW |
---|
1210 | emit_indirect_jump (throw_libfunc); |
---|
1211 | #else |
---|
1212 | #ifndef DWARF2_UNWIND_INFO |
---|
1213 | /* Prevent assemble_external from doing anything with this symbol. */ |
---|
1214 | SYMBOL_REF_USED (throw_libfunc) = 1; |
---|
1215 | #endif |
---|
1216 | emit_library_call (throw_libfunc, 0, VOIDmode, 0); |
---|
1217 | #endif |
---|
1218 | throw_used = 1; |
---|
1219 | } |
---|
1220 | emit_barrier (); |
---|
1221 | } |
---|
1222 | |
---|
1223 | /* An internal throw with an indirect CONTEXT we want to throw from. |
---|
1224 | CONTEXT evaluates to the context of the throw. */ |
---|
1225 | |
---|
1226 | static void |
---|
1227 | expand_internal_throw_indirect (context) |
---|
1228 | rtx context; |
---|
1229 | { |
---|
1230 | assemble_external (eh_saved_pc); |
---|
1231 | emit_move_insn (eh_saved_pc_rtx, context); |
---|
1232 | emit_throw (); |
---|
1233 | } |
---|
1234 | |
---|
1235 | /* An internal throw with a direct CONTEXT we want to throw from. |
---|
1236 | CONTEXT must be a label; its address will be used as the context of |
---|
1237 | the throw. */ |
---|
1238 | |
---|
1239 | void |
---|
1240 | expand_internal_throw (context) |
---|
1241 | rtx context; |
---|
1242 | { |
---|
1243 | expand_internal_throw_indirect (gen_rtx (LABEL_REF, Pmode, context)); |
---|
1244 | } |
---|
1245 | |
---|
1246 | /* Called from expand_exception_blocks and expand_end_catch_block to |
---|
1247 | emit any pending handlers/cleanups queued from expand_eh_region_end. */ |
---|
1248 | |
---|
1249 | void |
---|
1250 | expand_leftover_cleanups () |
---|
1251 | { |
---|
1252 | struct eh_entry *entry; |
---|
1253 | |
---|
1254 | while ((entry = dequeue_eh_entry (&ehqueue)) != 0) |
---|
1255 | { |
---|
1256 | rtx prev; |
---|
1257 | |
---|
1258 | /* A leftover try block. Shouldn't be one here. */ |
---|
1259 | if (entry->finalization == integer_zero_node) |
---|
1260 | abort (); |
---|
1261 | |
---|
1262 | /* Output the label for the start of the exception handler. */ |
---|
1263 | emit_label (entry->exception_handler_label); |
---|
1264 | |
---|
1265 | #ifdef HAVE_exception_receiver |
---|
1266 | if (! exceptions_via_longjmp) |
---|
1267 | if (HAVE_exception_receiver) |
---|
1268 | emit_insn (gen_exception_receiver ()); |
---|
1269 | #endif |
---|
1270 | |
---|
1271 | #ifdef HAVE_nonlocal_goto_receiver |
---|
1272 | if (! exceptions_via_longjmp) |
---|
1273 | if (HAVE_nonlocal_goto_receiver) |
---|
1274 | emit_insn (gen_nonlocal_goto_receiver ()); |
---|
1275 | #endif |
---|
1276 | |
---|
1277 | /* And now generate the insns for the handler. */ |
---|
1278 | expand_expr (entry->finalization, const0_rtx, VOIDmode, 0); |
---|
1279 | |
---|
1280 | prev = get_last_insn (); |
---|
1281 | if (prev == NULL || GET_CODE (prev) != BARRIER) |
---|
1282 | { |
---|
1283 | if (exceptions_via_longjmp) |
---|
1284 | emit_throw (); |
---|
1285 | else |
---|
1286 | { |
---|
1287 | /* The below can be optimized away, and we could just |
---|
1288 | fall into the next EH handler, if we are certain they |
---|
1289 | are nested. */ |
---|
1290 | /* Emit code to throw to the outer context if we fall off |
---|
1291 | the end of the handler. */ |
---|
1292 | expand_internal_throw (entry->outer_context); |
---|
1293 | } |
---|
1294 | } |
---|
1295 | |
---|
1296 | do_pending_stack_adjust (); |
---|
1297 | free (entry); |
---|
1298 | } |
---|
1299 | } |
---|
1300 | |
---|
1301 | /* Called at the start of a block of try statements. */ |
---|
1302 | void |
---|
1303 | expand_start_try_stmts () |
---|
1304 | { |
---|
1305 | if (! doing_eh (1)) |
---|
1306 | return; |
---|
1307 | |
---|
1308 | expand_eh_region_start (); |
---|
1309 | } |
---|
1310 | |
---|
1311 | /* Generate RTL for the start of a group of catch clauses. |
---|
1312 | |
---|
1313 | It is responsible for starting a new instruction sequence for the |
---|
1314 | instructions in the catch block, and expanding the handlers for the |
---|
1315 | internally-generated exception regions nested within the try block |
---|
1316 | corresponding to this catch block. */ |
---|
1317 | |
---|
1318 | void |
---|
1319 | expand_start_all_catch () |
---|
1320 | { |
---|
1321 | struct eh_entry *entry; |
---|
1322 | tree label; |
---|
1323 | |
---|
1324 | if (! doing_eh (1)) |
---|
1325 | return; |
---|
1326 | |
---|
1327 | push_label_entry (&outer_context_label_stack, |
---|
1328 | ehstack.top->entry->outer_context, NULL_TREE); |
---|
1329 | |
---|
1330 | /* End the try block. */ |
---|
1331 | expand_eh_region_end (integer_zero_node); |
---|
1332 | |
---|
1333 | emit_line_note (input_filename, lineno); |
---|
1334 | label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE); |
---|
1335 | |
---|
1336 | /* The label for the exception handling block that we will save. |
---|
1337 | This is Lresume in the documentation. */ |
---|
1338 | expand_label (label); |
---|
1339 | |
---|
1340 | if (exceptions_via_longjmp == 0) |
---|
1341 | { |
---|
1342 | /* Put in something that takes up space, as otherwise the end |
---|
1343 | address for the EH region could have the exact same address as |
---|
1344 | the outer region, causing us to miss the fact that resuming |
---|
1345 | exception handling with this PC value would be inside the outer |
---|
1346 | region. */ |
---|
1347 | emit_insn (gen_nop ()); |
---|
1348 | } |
---|
1349 | |
---|
1350 | /* Push the label that points to where normal flow is resumed onto |
---|
1351 | the top of the label stack. */ |
---|
1352 | push_label_entry (&caught_return_label_stack, NULL_RTX, label); |
---|
1353 | |
---|
1354 | /* Start a new sequence for all the catch blocks. We will add this |
---|
1355 | to the global sequence catch_clauses when we have completed all |
---|
1356 | the handlers in this handler-seq. */ |
---|
1357 | start_sequence (); |
---|
1358 | |
---|
1359 | while (1) |
---|
1360 | { |
---|
1361 | rtx prev; |
---|
1362 | |
---|
1363 | entry = dequeue_eh_entry (&ehqueue); |
---|
1364 | /* Emit the label for the exception handler for this region, and |
---|
1365 | expand the code for the handler. |
---|
1366 | |
---|
1367 | Note that a catch region is handled as a side-effect here; |
---|
1368 | for a try block, entry->finalization will contain |
---|
1369 | integer_zero_node, so no code will be generated in the |
---|
1370 | expand_expr call below. But, the label for the handler will |
---|
1371 | still be emitted, so any code emitted after this point will |
---|
1372 | end up being the handler. */ |
---|
1373 | emit_label (entry->exception_handler_label); |
---|
1374 | |
---|
1375 | #ifdef HAVE_exception_receiver |
---|
1376 | if (! exceptions_via_longjmp) |
---|
1377 | if (HAVE_exception_receiver) |
---|
1378 | emit_insn (gen_exception_receiver ()); |
---|
1379 | #endif |
---|
1380 | |
---|
1381 | #ifdef HAVE_nonlocal_goto_receiver |
---|
1382 | if (! exceptions_via_longjmp) |
---|
1383 | if (HAVE_nonlocal_goto_receiver) |
---|
1384 | emit_insn (gen_nonlocal_goto_receiver ()); |
---|
1385 | #endif |
---|
1386 | |
---|
1387 | /* When we get down to the matching entry for this try block, stop. */ |
---|
1388 | if (entry->finalization == integer_zero_node) |
---|
1389 | { |
---|
1390 | /* Don't forget to free this entry. */ |
---|
1391 | free (entry); |
---|
1392 | break; |
---|
1393 | } |
---|
1394 | |
---|
1395 | /* And now generate the insns for the handler. */ |
---|
1396 | expand_expr (entry->finalization, const0_rtx, VOIDmode, 0); |
---|
1397 | |
---|
1398 | prev = get_last_insn (); |
---|
1399 | if (prev == NULL || GET_CODE (prev) != BARRIER) |
---|
1400 | { |
---|
1401 | if (exceptions_via_longjmp) |
---|
1402 | emit_throw (); |
---|
1403 | else |
---|
1404 | { |
---|
1405 | /* Code to throw out to outer context when we fall off end |
---|
1406 | of the handler. We can't do this here for catch blocks, |
---|
1407 | so it's done in expand_end_all_catch instead. |
---|
1408 | |
---|
1409 | The below can be optimized away (and we could just fall |
---|
1410 | into the next EH handler) if we are certain they are |
---|
1411 | nested. */ |
---|
1412 | |
---|
1413 | expand_internal_throw (entry->outer_context); |
---|
1414 | } |
---|
1415 | } |
---|
1416 | do_pending_stack_adjust (); |
---|
1417 | free (entry); |
---|
1418 | } |
---|
1419 | } |
---|
1420 | |
---|
1421 | /* Finish up the catch block. At this point all the insns for the |
---|
1422 | catch clauses have already been generated, so we only have to add |
---|
1423 | them to the catch_clauses list. We also want to make sure that if |
---|
1424 | we fall off the end of the catch clauses that we rethrow to the |
---|
1425 | outer EH region. */ |
---|
1426 | |
---|
1427 | void |
---|
1428 | expand_end_all_catch () |
---|
1429 | { |
---|
1430 | rtx new_catch_clause; |
---|
1431 | |
---|
1432 | if (! doing_eh (1)) |
---|
1433 | return; |
---|
1434 | |
---|
1435 | if (exceptions_via_longjmp) |
---|
1436 | emit_throw (); |
---|
1437 | else |
---|
1438 | { |
---|
1439 | /* Code to throw out to outer context, if we fall off end of catch |
---|
1440 | handlers. This is rethrow (Lresume, same id, same obj) in the |
---|
1441 | documentation. We use Lresume because we know that it will throw |
---|
1442 | to the correct context. |
---|
1443 | |
---|
1444 | In other words, if the catch handler doesn't exit or return, we |
---|
1445 | do a "throw" (using the address of Lresume as the point being |
---|
1446 | thrown from) so that the outer EH region can then try to process |
---|
1447 | the exception. */ |
---|
1448 | |
---|
1449 | expand_internal_throw (outer_context_label_stack->u.rlabel); |
---|
1450 | } |
---|
1451 | |
---|
1452 | /* Now we have the complete catch sequence. */ |
---|
1453 | new_catch_clause = get_insns (); |
---|
1454 | end_sequence (); |
---|
1455 | |
---|
1456 | /* This level of catch blocks is done, so set up the successful |
---|
1457 | catch jump label for the next layer of catch blocks. */ |
---|
1458 | pop_label_entry (&caught_return_label_stack); |
---|
1459 | pop_label_entry (&outer_context_label_stack); |
---|
1460 | |
---|
1461 | /* Add the new sequence of catches to the main one for this function. */ |
---|
1462 | push_to_sequence (catch_clauses); |
---|
1463 | emit_insns (new_catch_clause); |
---|
1464 | catch_clauses = get_insns (); |
---|
1465 | end_sequence (); |
---|
1466 | |
---|
1467 | /* Here we fall through into the continuation code. */ |
---|
1468 | } |
---|
1469 | |
---|
1470 | /* End all the pending exception regions on protect_list. The handlers |
---|
1471 | will be emitted when expand_leftover_cleanups is invoked. */ |
---|
1472 | |
---|
1473 | void |
---|
1474 | end_protect_partials () |
---|
1475 | { |
---|
1476 | while (protect_list) |
---|
1477 | { |
---|
1478 | expand_eh_region_end (TREE_VALUE (protect_list)); |
---|
1479 | protect_list = TREE_CHAIN (protect_list); |
---|
1480 | } |
---|
1481 | } |
---|
1482 | |
---|
1483 | /* Arrange for __terminate to be called if there is an unhandled throw |
---|
1484 | from within E. */ |
---|
1485 | |
---|
1486 | tree |
---|
1487 | protect_with_terminate (e) |
---|
1488 | tree e; |
---|
1489 | { |
---|
1490 | /* We only need to do this when using setjmp/longjmp EH and the |
---|
1491 | language requires it, as otherwise we protect all of the handlers |
---|
1492 | at once, if we need to. */ |
---|
1493 | if (exceptions_via_longjmp && protect_cleanup_actions_with_terminate) |
---|
1494 | { |
---|
1495 | tree handler, result; |
---|
1496 | |
---|
1497 | /* All cleanups must be on the function_obstack. */ |
---|
1498 | push_obstacks_nochange (); |
---|
1499 | resume_temporary_allocation (); |
---|
1500 | |
---|
1501 | handler = make_node (RTL_EXPR); |
---|
1502 | TREE_TYPE (handler) = void_type_node; |
---|
1503 | RTL_EXPR_RTL (handler) = const0_rtx; |
---|
1504 | TREE_SIDE_EFFECTS (handler) = 1; |
---|
1505 | start_sequence_for_rtl_expr (handler); |
---|
1506 | |
---|
1507 | emit_library_call (terminate_libfunc, 0, VOIDmode, 0); |
---|
1508 | emit_barrier (); |
---|
1509 | |
---|
1510 | RTL_EXPR_SEQUENCE (handler) = get_insns (); |
---|
1511 | end_sequence (); |
---|
1512 | |
---|
1513 | result = build (TRY_CATCH_EXPR, TREE_TYPE (e), e, handler); |
---|
1514 | TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e); |
---|
1515 | TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e); |
---|
1516 | TREE_READONLY (result) = TREE_READONLY (e); |
---|
1517 | |
---|
1518 | pop_obstacks (); |
---|
1519 | |
---|
1520 | e = result; |
---|
1521 | } |
---|
1522 | |
---|
1523 | return e; |
---|
1524 | } |
---|
1525 | |
---|
1526 | /* The exception table that we build that is used for looking up and |
---|
1527 | dispatching exceptions, the current number of entries, and its |
---|
1528 | maximum size before we have to extend it. |
---|
1529 | |
---|
1530 | The number in eh_table is the code label number of the exception |
---|
1531 | handler for the region. This is added by add_eh_table_entry and |
---|
1532 | used by output_exception_table_entry. */ |
---|
1533 | |
---|
1534 | static int *eh_table; |
---|
1535 | static int eh_table_size; |
---|
1536 | static int eh_table_max_size; |
---|
1537 | |
---|
1538 | /* Note the need for an exception table entry for region N. If we |
---|
1539 | don't need to output an explicit exception table, avoid all of the |
---|
1540 | extra work. |
---|
1541 | |
---|
1542 | Called from final_scan_insn when a NOTE_INSN_EH_REGION_BEG is seen. |
---|
1543 | N is the NOTE_BLOCK_NUMBER of the note, which comes from the code |
---|
1544 | label number of the exception handler for the region. */ |
---|
1545 | |
---|
1546 | void |
---|
1547 | add_eh_table_entry (n) |
---|
1548 | int n; |
---|
1549 | { |
---|
1550 | #ifndef OMIT_EH_TABLE |
---|
1551 | if (eh_table_size >= eh_table_max_size) |
---|
1552 | { |
---|
1553 | if (eh_table) |
---|
1554 | { |
---|
1555 | eh_table_max_size += eh_table_max_size>>1; |
---|
1556 | |
---|
1557 | if (eh_table_max_size < 0) |
---|
1558 | abort (); |
---|
1559 | |
---|
1560 | eh_table = (int *) xrealloc (eh_table, |
---|
1561 | eh_table_max_size * sizeof (int)); |
---|
1562 | } |
---|
1563 | else |
---|
1564 | { |
---|
1565 | eh_table_max_size = 252; |
---|
1566 | eh_table = (int *) xmalloc (eh_table_max_size * sizeof (int)); |
---|
1567 | } |
---|
1568 | } |
---|
1569 | eh_table[eh_table_size++] = n; |
---|
1570 | #endif |
---|
1571 | } |
---|
1572 | |
---|
1573 | /* Return a non-zero value if we need to output an exception table. |
---|
1574 | |
---|
1575 | On some platforms, we don't have to output a table explicitly. |
---|
1576 | This routine doesn't mean we don't have one. */ |
---|
1577 | |
---|
1578 | int |
---|
1579 | exception_table_p () |
---|
1580 | { |
---|
1581 | if (eh_table) |
---|
1582 | return 1; |
---|
1583 | |
---|
1584 | return 0; |
---|
1585 | } |
---|
1586 | |
---|
1587 | /* 1 if we need a static constructor to register EH table info. */ |
---|
1588 | |
---|
1589 | int |
---|
1590 | register_exception_table_p () |
---|
1591 | { |
---|
1592 | #if defined (DWARF2_UNWIND_INFO) |
---|
1593 | return 0; |
---|
1594 | #endif |
---|
1595 | |
---|
1596 | return exception_table_p (); |
---|
1597 | } |
---|
1598 | |
---|
1599 | /* Output the entry of the exception table corresponding to to the |
---|
1600 | exception region numbered N to file FILE. |
---|
1601 | |
---|
1602 | N is the code label number corresponding to the handler of the |
---|
1603 | region. */ |
---|
1604 | |
---|
1605 | static void |
---|
1606 | output_exception_table_entry (file, n) |
---|
1607 | FILE *file; |
---|
1608 | int n; |
---|
1609 | { |
---|
1610 | char buf[256]; |
---|
1611 | rtx sym; |
---|
1612 | |
---|
1613 | ASM_GENERATE_INTERNAL_LABEL (buf, "LEHB", n); |
---|
1614 | sym = gen_rtx (SYMBOL_REF, Pmode, buf); |
---|
1615 | assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1); |
---|
1616 | |
---|
1617 | ASM_GENERATE_INTERNAL_LABEL (buf, "LEHE", n); |
---|
1618 | sym = gen_rtx (SYMBOL_REF, Pmode, buf); |
---|
1619 | assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1); |
---|
1620 | |
---|
1621 | ASM_GENERATE_INTERNAL_LABEL (buf, "L", n); |
---|
1622 | sym = gen_rtx (SYMBOL_REF, Pmode, buf); |
---|
1623 | assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1); |
---|
1624 | |
---|
1625 | putc ('\n', file); /* blank line */ |
---|
1626 | } |
---|
1627 | |
---|
1628 | /* Output the exception table if we have and need one. */ |
---|
1629 | |
---|
1630 | void |
---|
1631 | output_exception_table () |
---|
1632 | { |
---|
1633 | int i; |
---|
1634 | extern FILE *asm_out_file; |
---|
1635 | |
---|
1636 | if (! doing_eh (0) || ! eh_table) |
---|
1637 | return; |
---|
1638 | |
---|
1639 | exception_section (); |
---|
1640 | |
---|
1641 | /* Beginning marker for table. */ |
---|
1642 | assemble_align (GET_MODE_ALIGNMENT (ptr_mode)); |
---|
1643 | assemble_label ("__EXCEPTION_TABLE__"); |
---|
1644 | |
---|
1645 | for (i = 0; i < eh_table_size; ++i) |
---|
1646 | output_exception_table_entry (asm_out_file, eh_table[i]); |
---|
1647 | |
---|
1648 | free (eh_table); |
---|
1649 | |
---|
1650 | /* Ending marker for table. */ |
---|
1651 | assemble_label ("__EXCEPTION_END__"); |
---|
1652 | assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1); |
---|
1653 | assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1); |
---|
1654 | assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1); |
---|
1655 | putc ('\n', asm_out_file); /* blank line */ |
---|
1656 | } |
---|
1657 | |
---|
1658 | /* Generate code to initialize the exception table at program startup |
---|
1659 | time. */ |
---|
1660 | |
---|
1661 | void |
---|
1662 | register_exception_table () |
---|
1663 | { |
---|
1664 | emit_library_call (gen_rtx (SYMBOL_REF, Pmode, "__register_exceptions"), 0, |
---|
1665 | VOIDmode, 1, |
---|
1666 | gen_rtx (SYMBOL_REF, Pmode, "__EXCEPTION_TABLE__"), |
---|
1667 | Pmode); |
---|
1668 | } |
---|
1669 | |
---|
1670 | /* Emit the RTL for the start of the per-function unwinder for the |
---|
1671 | current function. See emit_unwinder for further information. |
---|
1672 | |
---|
1673 | DOESNT_NEED_UNWINDER is a target-specific macro that determines if |
---|
1674 | the current function actually needs a per-function unwinder or not. |
---|
1675 | By default, all functions need one. */ |
---|
1676 | |
---|
1677 | void |
---|
1678 | start_eh_unwinder () |
---|
1679 | { |
---|
1680 | #ifdef DOESNT_NEED_UNWINDER |
---|
1681 | if (DOESNT_NEED_UNWINDER) |
---|
1682 | return; |
---|
1683 | #endif |
---|
1684 | |
---|
1685 | /* If we are using the setjmp/longjmp implementation, we don't need a |
---|
1686 | per function unwinder. */ |
---|
1687 | |
---|
1688 | if (exceptions_via_longjmp) |
---|
1689 | return; |
---|
1690 | |
---|
1691 | #ifdef DWARF2_UNWIND_INFO |
---|
1692 | return; |
---|
1693 | #endif |
---|
1694 | |
---|
1695 | expand_eh_region_start (); |
---|
1696 | } |
---|
1697 | |
---|
1698 | /* Emit insns for the end of the per-function unwinder for the |
---|
1699 | current function. */ |
---|
1700 | |
---|
1701 | void |
---|
1702 | end_eh_unwinder () |
---|
1703 | { |
---|
1704 | tree expr; |
---|
1705 | rtx return_val_rtx, ret_val, label, end, insns; |
---|
1706 | |
---|
1707 | if (! doing_eh (0)) |
---|
1708 | return; |
---|
1709 | |
---|
1710 | #ifdef DOESNT_NEED_UNWINDER |
---|
1711 | if (DOESNT_NEED_UNWINDER) |
---|
1712 | return; |
---|
1713 | #endif |
---|
1714 | |
---|
1715 | /* If we are using the setjmp/longjmp implementation, we don't need a |
---|
1716 | per function unwinder. */ |
---|
1717 | |
---|
1718 | if (exceptions_via_longjmp) |
---|
1719 | return; |
---|
1720 | |
---|
1721 | #ifdef DWARF2_UNWIND_INFO |
---|
1722 | return; |
---|
1723 | #else /* DWARF2_UNWIND_INFO */ |
---|
1724 | |
---|
1725 | assemble_external (eh_saved_pc); |
---|
1726 | |
---|
1727 | expr = make_node (RTL_EXPR); |
---|
1728 | TREE_TYPE (expr) = void_type_node; |
---|
1729 | RTL_EXPR_RTL (expr) = const0_rtx; |
---|
1730 | TREE_SIDE_EFFECTS (expr) = 1; |
---|
1731 | start_sequence_for_rtl_expr (expr); |
---|
1732 | |
---|
1733 | /* ret_val will contain the address of the code where the call |
---|
1734 | to the current function occurred. */ |
---|
1735 | ret_val = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS, |
---|
1736 | 0, hard_frame_pointer_rtx); |
---|
1737 | return_val_rtx = copy_to_reg (ret_val); |
---|
1738 | |
---|
1739 | /* Get the address we need to use to determine what exception |
---|
1740 | handler should be invoked, and store it in __eh_pc. */ |
---|
1741 | return_val_rtx = eh_outer_context (return_val_rtx); |
---|
1742 | return_val_rtx = expand_binop (Pmode, sub_optab, return_val_rtx, GEN_INT (1), |
---|
1743 | NULL_RTX, 0, OPTAB_LIB_WIDEN); |
---|
1744 | emit_move_insn (eh_saved_pc_rtx, return_val_rtx); |
---|
1745 | |
---|
1746 | /* Either set things up so we do a return directly to __throw, or |
---|
1747 | we return here instead. */ |
---|
1748 | #ifdef JUMP_TO_THROW |
---|
1749 | emit_move_insn (ret_val, throw_libfunc); |
---|
1750 | #else |
---|
1751 | label = gen_label_rtx (); |
---|
1752 | emit_move_insn (ret_val, gen_rtx (LABEL_REF, Pmode, label)); |
---|
1753 | #endif |
---|
1754 | |
---|
1755 | #ifdef RETURN_ADDR_OFFSET |
---|
1756 | return_val_rtx = plus_constant (ret_val, -RETURN_ADDR_OFFSET); |
---|
1757 | if (return_val_rtx != ret_val) |
---|
1758 | emit_move_insn (ret_val, return_val_rtx); |
---|
1759 | #endif |
---|
1760 | |
---|
1761 | end = gen_label_rtx (); |
---|
1762 | emit_jump (end); |
---|
1763 | |
---|
1764 | RTL_EXPR_SEQUENCE (expr) = get_insns (); |
---|
1765 | end_sequence (); |
---|
1766 | |
---|
1767 | expand_eh_region_end (expr); |
---|
1768 | |
---|
1769 | emit_jump (end); |
---|
1770 | |
---|
1771 | #ifndef JUMP_TO_THROW |
---|
1772 | emit_label (label); |
---|
1773 | emit_throw (); |
---|
1774 | #endif |
---|
1775 | |
---|
1776 | expand_leftover_cleanups (); |
---|
1777 | |
---|
1778 | emit_label (end); |
---|
1779 | |
---|
1780 | #ifdef HAVE_return |
---|
1781 | if (HAVE_return) |
---|
1782 | { |
---|
1783 | emit_jump_insn (gen_return ()); |
---|
1784 | emit_barrier (); |
---|
1785 | } |
---|
1786 | #endif |
---|
1787 | #endif /* DWARF2_UNWIND_INFO */ |
---|
1788 | } |
---|
1789 | |
---|
1790 | /* If necessary, emit insns for the per function unwinder for the |
---|
1791 | current function. Called after all the code that needs unwind |
---|
1792 | protection is output. |
---|
1793 | |
---|
1794 | The unwinder takes care of catching any exceptions that have not |
---|
1795 | been previously caught within the function, unwinding the stack to |
---|
1796 | the next frame, and rethrowing using the address of the current |
---|
1797 | function's caller as the context of the throw. |
---|
1798 | |
---|
1799 | On some platforms __throw can do this by itself (or with the help |
---|
1800 | of __unwind_function) so the per-function unwinder is |
---|
1801 | unnecessary. |
---|
1802 | |
---|
1803 | We cannot place the unwinder into the function until after we know |
---|
1804 | we are done inlining, as we don't want to have more than one |
---|
1805 | unwinder per non-inlined function. */ |
---|
1806 | |
---|
1807 | void |
---|
1808 | emit_unwinder () |
---|
1809 | { |
---|
1810 | rtx insns, insn; |
---|
1811 | |
---|
1812 | start_sequence (); |
---|
1813 | start_eh_unwinder (); |
---|
1814 | insns = get_insns (); |
---|
1815 | end_sequence (); |
---|
1816 | |
---|
1817 | /* We place the start of the exception region associated with the |
---|
1818 | per function unwinder at the top of the function. */ |
---|
1819 | if (insns) |
---|
1820 | emit_insns_after (insns, get_insns ()); |
---|
1821 | |
---|
1822 | start_sequence (); |
---|
1823 | end_eh_unwinder (); |
---|
1824 | insns = get_insns (); |
---|
1825 | end_sequence (); |
---|
1826 | |
---|
1827 | /* And we place the end of the exception region before the USE and |
---|
1828 | CLOBBER insns that may come at the end of the function. */ |
---|
1829 | if (insns == 0) |
---|
1830 | return; |
---|
1831 | |
---|
1832 | insn = get_last_insn (); |
---|
1833 | while (GET_CODE (insn) == NOTE |
---|
1834 | || (GET_CODE (insn) == INSN |
---|
1835 | && (GET_CODE (PATTERN (insn)) == USE |
---|
1836 | || GET_CODE (PATTERN (insn)) == CLOBBER))) |
---|
1837 | insn = PREV_INSN (insn); |
---|
1838 | |
---|
1839 | if (GET_CODE (insn) == CODE_LABEL |
---|
1840 | && GET_CODE (PREV_INSN (insn)) == BARRIER) |
---|
1841 | { |
---|
1842 | insn = PREV_INSN (insn); |
---|
1843 | } |
---|
1844 | else |
---|
1845 | { |
---|
1846 | rtx label = gen_label_rtx (); |
---|
1847 | emit_label_after (label, insn); |
---|
1848 | insn = emit_jump_insn_after (gen_jump (label), insn); |
---|
1849 | insn = emit_barrier_after (insn); |
---|
1850 | } |
---|
1851 | |
---|
1852 | emit_insns_after (insns, insn); |
---|
1853 | } |
---|
1854 | |
---|
1855 | /* Scan the current insns and build a list of handler labels. The |
---|
1856 | resulting list is placed in the global variable exception_handler_labels. |
---|
1857 | |
---|
1858 | It is called after the last exception handling region is added to |
---|
1859 | the current function (when the rtl is almost all built for the |
---|
1860 | current function) and before the jump optimization pass. */ |
---|
1861 | |
---|
1862 | void |
---|
1863 | find_exception_handler_labels () |
---|
1864 | { |
---|
1865 | rtx insn; |
---|
1866 | int max_labelno = max_label_num (); |
---|
1867 | int min_labelno = get_first_label_num (); |
---|
1868 | rtx *labels; |
---|
1869 | |
---|
1870 | exception_handler_labels = NULL_RTX; |
---|
1871 | |
---|
1872 | /* If we aren't doing exception handling, there isn't much to check. */ |
---|
1873 | if (! doing_eh (0)) |
---|
1874 | return; |
---|
1875 | |
---|
1876 | /* Generate a handy reference to each label. */ |
---|
1877 | |
---|
1878 | /* We call xmalloc here instead of alloca; we did the latter in the past, |
---|
1879 | but found that it can sometimes end up being asked to allocate space |
---|
1880 | for more than 1 million labels. */ |
---|
1881 | labels = (rtx *) xmalloc ((max_labelno - min_labelno) * sizeof (rtx)); |
---|
1882 | bzero ((char *) labels, (max_labelno - min_labelno) * sizeof (rtx)); |
---|
1883 | |
---|
1884 | /* Arrange for labels to be indexed directly by CODE_LABEL_NUMBER. */ |
---|
1885 | labels -= min_labelno; |
---|
1886 | |
---|
1887 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
---|
1888 | { |
---|
1889 | if (GET_CODE (insn) == CODE_LABEL) |
---|
1890 | if (CODE_LABEL_NUMBER (insn) >= min_labelno |
---|
1891 | && CODE_LABEL_NUMBER (insn) < max_labelno) |
---|
1892 | labels[CODE_LABEL_NUMBER (insn)] = insn; |
---|
1893 | } |
---|
1894 | |
---|
1895 | /* For each start of a region, add its label to the list. */ |
---|
1896 | |
---|
1897 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
---|
1898 | { |
---|
1899 | if (GET_CODE (insn) == NOTE |
---|
1900 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) |
---|
1901 | { |
---|
1902 | rtx label = NULL_RTX; |
---|
1903 | |
---|
1904 | if (NOTE_BLOCK_NUMBER (insn) >= min_labelno |
---|
1905 | && NOTE_BLOCK_NUMBER (insn) < max_labelno) |
---|
1906 | { |
---|
1907 | label = labels[NOTE_BLOCK_NUMBER (insn)]; |
---|
1908 | |
---|
1909 | if (label) |
---|
1910 | exception_handler_labels |
---|
1911 | = gen_rtx (EXPR_LIST, VOIDmode, |
---|
1912 | label, exception_handler_labels); |
---|
1913 | else |
---|
1914 | warning ("didn't find handler for EH region %d", |
---|
1915 | NOTE_BLOCK_NUMBER (insn)); |
---|
1916 | } |
---|
1917 | else |
---|
1918 | warning ("mismatched EH region %d", NOTE_BLOCK_NUMBER (insn)); |
---|
1919 | } |
---|
1920 | } |
---|
1921 | |
---|
1922 | free (labels + min_labelno); |
---|
1923 | } |
---|
1924 | |
---|
1925 | /* Perform sanity checking on the exception_handler_labels list. |
---|
1926 | |
---|
1927 | Can be called after find_exception_handler_labels is called to |
---|
1928 | build the list of exception handlers for the current function and |
---|
1929 | before we finish processing the current function. */ |
---|
1930 | |
---|
1931 | void |
---|
1932 | check_exception_handler_labels () |
---|
1933 | { |
---|
1934 | rtx insn, handler; |
---|
1935 | |
---|
1936 | /* If we aren't doing exception handling, there isn't much to check. */ |
---|
1937 | if (! doing_eh (0)) |
---|
1938 | return; |
---|
1939 | |
---|
1940 | /* Ensure that the CODE_LABEL_NUMBER for the CODE_LABEL entry point |
---|
1941 | in each handler corresponds to the CODE_LABEL_NUMBER of the |
---|
1942 | handler. */ |
---|
1943 | |
---|
1944 | for (handler = exception_handler_labels; |
---|
1945 | handler; |
---|
1946 | handler = XEXP (handler, 1)) |
---|
1947 | { |
---|
1948 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
---|
1949 | { |
---|
1950 | if (GET_CODE (insn) == CODE_LABEL) |
---|
1951 | { |
---|
1952 | if (CODE_LABEL_NUMBER (insn) |
---|
1953 | == CODE_LABEL_NUMBER (XEXP (handler, 0))) |
---|
1954 | { |
---|
1955 | if (insn != XEXP (handler, 0)) |
---|
1956 | warning ("mismatched handler %d", |
---|
1957 | CODE_LABEL_NUMBER (insn)); |
---|
1958 | break; |
---|
1959 | } |
---|
1960 | } |
---|
1961 | } |
---|
1962 | if (insn == NULL_RTX) |
---|
1963 | warning ("handler not found %d", |
---|
1964 | CODE_LABEL_NUMBER (XEXP (handler, 0))); |
---|
1965 | } |
---|
1966 | |
---|
1967 | /* Now go through and make sure that for each region there is a |
---|
1968 | corresponding label. */ |
---|
1969 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
---|
1970 | { |
---|
1971 | if (GET_CODE (insn) == NOTE |
---|
1972 | && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG |
---|
1973 | || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)) |
---|
1974 | { |
---|
1975 | for (handler = exception_handler_labels; |
---|
1976 | handler; |
---|
1977 | handler = XEXP (handler, 1)) |
---|
1978 | { |
---|
1979 | if (CODE_LABEL_NUMBER (XEXP (handler, 0)) |
---|
1980 | == NOTE_BLOCK_NUMBER (insn)) |
---|
1981 | break; |
---|
1982 | } |
---|
1983 | if (handler == NULL_RTX) |
---|
1984 | warning ("region exists, no handler %d", |
---|
1985 | NOTE_BLOCK_NUMBER (insn)); |
---|
1986 | } |
---|
1987 | } |
---|
1988 | } |
---|
1989 | |
---|
1990 | /* This group of functions initializes the exception handling data |
---|
1991 | structures at the start of the compilation, initializes the data |
---|
1992 | structures at the start of a function, and saves and restores the |
---|
1993 | exception handling data structures for the start/end of a nested |
---|
1994 | function. */ |
---|
1995 | |
---|
1996 | /* Toplevel initialization for EH things. */ |
---|
1997 | |
---|
1998 | void |
---|
1999 | init_eh () |
---|
2000 | { |
---|
2001 | /* Generate rtl to reference the variable in which the PC of the |
---|
2002 | current context is saved. */ |
---|
2003 | tree type = build_pointer_type (make_node (VOID_TYPE)); |
---|
2004 | |
---|
2005 | eh_saved_pc = build_decl (VAR_DECL, get_identifier ("__eh_pc"), type); |
---|
2006 | DECL_EXTERNAL (eh_saved_pc) = 1; |
---|
2007 | TREE_PUBLIC (eh_saved_pc) = 1; |
---|
2008 | make_decl_rtl (eh_saved_pc, NULL_PTR, 1); |
---|
2009 | eh_saved_pc_rtx = DECL_RTL (eh_saved_pc); |
---|
2010 | } |
---|
2011 | |
---|
2012 | /* Initialize the per-function EH information. */ |
---|
2013 | |
---|
2014 | void |
---|
2015 | init_eh_for_function () |
---|
2016 | { |
---|
2017 | ehstack.top = 0; |
---|
2018 | ehqueue.head = ehqueue.tail = 0; |
---|
2019 | catch_clauses = NULL_RTX; |
---|
2020 | false_label_stack = 0; |
---|
2021 | caught_return_label_stack = 0; |
---|
2022 | protect_list = NULL_TREE; |
---|
2023 | current_function_dhc = NULL_RTX; |
---|
2024 | current_function_dcc = NULL_RTX; |
---|
2025 | } |
---|
2026 | |
---|
2027 | /* Save some of the per-function EH info into the save area denoted by |
---|
2028 | P. |
---|
2029 | |
---|
2030 | This is currently called from save_stmt_status. */ |
---|
2031 | |
---|
2032 | void |
---|
2033 | save_eh_status (p) |
---|
2034 | struct function *p; |
---|
2035 | { |
---|
2036 | p->ehstack = ehstack; |
---|
2037 | p->ehqueue = ehqueue; |
---|
2038 | p->catch_clauses = catch_clauses; |
---|
2039 | p->false_label_stack = false_label_stack; |
---|
2040 | p->caught_return_label_stack = caught_return_label_stack; |
---|
2041 | p->protect_list = protect_list; |
---|
2042 | p->dhc = current_function_dhc; |
---|
2043 | p->dcc = current_function_dcc; |
---|
2044 | |
---|
2045 | init_eh (); |
---|
2046 | } |
---|
2047 | |
---|
2048 | /* Restore the per-function EH info saved into the area denoted by P. |
---|
2049 | |
---|
2050 | This is currently called from restore_stmt_status. */ |
---|
2051 | |
---|
2052 | void |
---|
2053 | restore_eh_status (p) |
---|
2054 | struct function *p; |
---|
2055 | { |
---|
2056 | protect_list = p->protect_list; |
---|
2057 | caught_return_label_stack = p->caught_return_label_stack; |
---|
2058 | false_label_stack = p->false_label_stack; |
---|
2059 | catch_clauses = p->catch_clauses; |
---|
2060 | ehqueue = p->ehqueue; |
---|
2061 | ehstack = p->ehstack; |
---|
2062 | current_function_dhc = p->dhc; |
---|
2063 | current_function_dcc = p->dcc; |
---|
2064 | } |
---|
2065 | |
---|
2066 | /* This section is for the exception handling specific optimization |
---|
2067 | pass. First are the internal routines, and then the main |
---|
2068 | optimization pass. */ |
---|
2069 | |
---|
2070 | /* Determine if the given INSN can throw an exception. */ |
---|
2071 | |
---|
2072 | static int |
---|
2073 | can_throw (insn) |
---|
2074 | rtx insn; |
---|
2075 | { |
---|
2076 | /* Calls can always potentially throw exceptions. */ |
---|
2077 | if (GET_CODE (insn) == CALL_INSN) |
---|
2078 | return 1; |
---|
2079 | |
---|
2080 | if (asynchronous_exceptions) |
---|
2081 | { |
---|
2082 | /* If we wanted asynchronous exceptions, then everything but NOTEs |
---|
2083 | and CODE_LABELs could throw. */ |
---|
2084 | if (GET_CODE (insn) != NOTE && GET_CODE (insn) != CODE_LABEL) |
---|
2085 | return 1; |
---|
2086 | } |
---|
2087 | |
---|
2088 | return 0; |
---|
2089 | } |
---|
2090 | |
---|
2091 | /* Scan a exception region looking for the matching end and then |
---|
2092 | remove it if possible. INSN is the start of the region, N is the |
---|
2093 | region number, and DELETE_OUTER is to note if anything in this |
---|
2094 | region can throw. |
---|
2095 | |
---|
2096 | Regions are removed if they cannot possibly catch an exception. |
---|
2097 | This is determined by invoking can_throw on each insn within the |
---|
2098 | region; if can_throw returns true for any of the instructions, the |
---|
2099 | region can catch an exception, since there is an insn within the |
---|
2100 | region that is capable of throwing an exception. |
---|
2101 | |
---|
2102 | Returns the NOTE_INSN_EH_REGION_END corresponding to this region, or |
---|
2103 | calls abort if it can't find one. |
---|
2104 | |
---|
2105 | Can abort if INSN is not a NOTE_INSN_EH_REGION_BEGIN, or if N doesn't |
---|
2106 | correspond to the region number, or if DELETE_OUTER is NULL. */ |
---|
2107 | |
---|
2108 | static rtx |
---|
2109 | scan_region (insn, n, delete_outer) |
---|
2110 | rtx insn; |
---|
2111 | int n; |
---|
2112 | int *delete_outer; |
---|
2113 | { |
---|
2114 | rtx start = insn; |
---|
2115 | |
---|
2116 | /* Assume we can delete the region. */ |
---|
2117 | int delete = 1; |
---|
2118 | |
---|
2119 | if (! (GET_CODE (insn) == NOTE |
---|
2120 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG |
---|
2121 | && NOTE_BLOCK_NUMBER (insn) == n |
---|
2122 | && delete_outer != NULL)) |
---|
2123 | abort (); |
---|
2124 | |
---|
2125 | insn = NEXT_INSN (insn); |
---|
2126 | |
---|
2127 | /* Look for the matching end. */ |
---|
2128 | while (! (GET_CODE (insn) == NOTE |
---|
2129 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)) |
---|
2130 | { |
---|
2131 | /* If anything can throw, we can't remove the region. */ |
---|
2132 | if (delete && can_throw (insn)) |
---|
2133 | { |
---|
2134 | delete = 0; |
---|
2135 | } |
---|
2136 | |
---|
2137 | /* Watch out for and handle nested regions. */ |
---|
2138 | if (GET_CODE (insn) == NOTE |
---|
2139 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) |
---|
2140 | { |
---|
2141 | insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &delete); |
---|
2142 | } |
---|
2143 | |
---|
2144 | insn = NEXT_INSN (insn); |
---|
2145 | } |
---|
2146 | |
---|
2147 | /* The _BEG/_END NOTEs must match and nest. */ |
---|
2148 | if (NOTE_BLOCK_NUMBER (insn) != n) |
---|
2149 | abort (); |
---|
2150 | |
---|
2151 | /* If anything in this exception region can throw, we can throw. */ |
---|
2152 | if (! delete) |
---|
2153 | *delete_outer = 0; |
---|
2154 | else |
---|
2155 | { |
---|
2156 | /* Delete the start and end of the region. */ |
---|
2157 | delete_insn (start); |
---|
2158 | delete_insn (insn); |
---|
2159 | |
---|
2160 | /* Only do this part if we have built the exception handler |
---|
2161 | labels. */ |
---|
2162 | if (exception_handler_labels) |
---|
2163 | { |
---|
2164 | rtx x, *prev = &exception_handler_labels; |
---|
2165 | |
---|
2166 | /* Find it in the list of handlers. */ |
---|
2167 | for (x = exception_handler_labels; x; x = XEXP (x, 1)) |
---|
2168 | { |
---|
2169 | rtx label = XEXP (x, 0); |
---|
2170 | if (CODE_LABEL_NUMBER (label) == n) |
---|
2171 | { |
---|
2172 | /* If we are the last reference to the handler, |
---|
2173 | delete it. */ |
---|
2174 | if (--LABEL_NUSES (label) == 0) |
---|
2175 | delete_insn (label); |
---|
2176 | |
---|
2177 | if (optimize) |
---|
2178 | { |
---|
2179 | /* Remove it from the list of exception handler |
---|
2180 | labels, if we are optimizing. If we are not, then |
---|
2181 | leave it in the list, as we are not really going to |
---|
2182 | remove the region. */ |
---|
2183 | *prev = XEXP (x, 1); |
---|
2184 | XEXP (x, 1) = 0; |
---|
2185 | XEXP (x, 0) = 0; |
---|
2186 | } |
---|
2187 | |
---|
2188 | break; |
---|
2189 | } |
---|
2190 | prev = &XEXP (x, 1); |
---|
2191 | } |
---|
2192 | } |
---|
2193 | } |
---|
2194 | return insn; |
---|
2195 | } |
---|
2196 | |
---|
2197 | /* Perform various interesting optimizations for exception handling |
---|
2198 | code. |
---|
2199 | |
---|
2200 | We look for empty exception regions and make them go (away). The |
---|
2201 | jump optimization code will remove the handler if nothing else uses |
---|
2202 | it. */ |
---|
2203 | |
---|
2204 | void |
---|
2205 | exception_optimize () |
---|
2206 | { |
---|
2207 | rtx insn, regions = NULL_RTX; |
---|
2208 | int n; |
---|
2209 | |
---|
2210 | /* The below doesn't apply to setjmp/longjmp EH. */ |
---|
2211 | if (exceptions_via_longjmp) |
---|
2212 | return; |
---|
2213 | |
---|
2214 | /* Remove empty regions. */ |
---|
2215 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
---|
2216 | { |
---|
2217 | if (GET_CODE (insn) == NOTE |
---|
2218 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) |
---|
2219 | { |
---|
2220 | /* Since scan_region will return the NOTE_INSN_EH_REGION_END |
---|
2221 | insn, we will indirectly skip through all the insns |
---|
2222 | inbetween. We are also guaranteed that the value of insn |
---|
2223 | returned will be valid, as otherwise scan_region won't |
---|
2224 | return. */ |
---|
2225 | insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &n); |
---|
2226 | } |
---|
2227 | } |
---|
2228 | } |
---|
2229 | |
---|
2230 | /* Various hooks for the DWARF 2 __throw routine. */ |
---|
2231 | |
---|
2232 | /* Do any necessary initialization to access arbitrary stack frames. |
---|
2233 | On the SPARC, this means flushing the register windows. */ |
---|
2234 | |
---|
2235 | void |
---|
2236 | expand_builtin_unwind_init () |
---|
2237 | { |
---|
2238 | /* Set this so all the registers get saved in our frame; we need to be |
---|
2239 | able to copy the saved values for any registers from frames we unwind. */ |
---|
2240 | current_function_has_nonlocal_label = 1; |
---|
2241 | |
---|
2242 | #ifdef SETUP_FRAME_ADDRESSES |
---|
2243 | SETUP_FRAME_ADDRESSES (); |
---|
2244 | #endif |
---|
2245 | } |
---|
2246 | |
---|
2247 | /* Given a value extracted from the return address register or stack slot, |
---|
2248 | return the actual address encoded in that value. */ |
---|
2249 | |
---|
2250 | rtx |
---|
2251 | expand_builtin_extract_return_addr (addr_tree) |
---|
2252 | tree addr_tree; |
---|
2253 | { |
---|
2254 | rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0); |
---|
2255 | return eh_outer_context (addr); |
---|
2256 | } |
---|
2257 | |
---|
2258 | /* Given an actual address in addr_tree, do any necessary encoding |
---|
2259 | and return the value to be stored in the return address register or |
---|
2260 | stack slot so the epilogue will return to that address. */ |
---|
2261 | |
---|
2262 | rtx |
---|
2263 | expand_builtin_frob_return_addr (addr_tree) |
---|
2264 | tree addr_tree; |
---|
2265 | { |
---|
2266 | rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0); |
---|
2267 | #ifdef RETURN_ADDR_OFFSET |
---|
2268 | addr = plus_constant (addr, -RETURN_ADDR_OFFSET); |
---|
2269 | #endif |
---|
2270 | return addr; |
---|
2271 | } |
---|
2272 | |
---|
2273 | /* Given an actual address in addr_tree, set the return address register up |
---|
2274 | so the epilogue will return to that address. If the return address is |
---|
2275 | not in a register, do nothing. */ |
---|
2276 | |
---|
2277 | void |
---|
2278 | expand_builtin_set_return_addr_reg (addr_tree) |
---|
2279 | tree addr_tree; |
---|
2280 | { |
---|
2281 | rtx tmp; |
---|
2282 | rtx ra = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS, |
---|
2283 | 0, hard_frame_pointer_rtx); |
---|
2284 | |
---|
2285 | if (GET_CODE (ra) != REG || REGNO (ra) >= FIRST_PSEUDO_REGISTER) |
---|
2286 | return; |
---|
2287 | |
---|
2288 | tmp = force_operand (expand_builtin_frob_return_addr (addr_tree), ra); |
---|
2289 | if (tmp != ra) |
---|
2290 | emit_move_insn (ra, tmp); |
---|
2291 | } |
---|
2292 | |
---|
2293 | /* Choose two registers for communication between the main body of |
---|
2294 | __throw and the stub for adjusting the stack pointer. The first register |
---|
2295 | is used to pass the address of the exception handler; the second register |
---|
2296 | is used to pass the stack pointer offset. |
---|
2297 | |
---|
2298 | For register 1 we use the return value register for a void *. |
---|
2299 | For register 2 we use the static chain register if it exists and is |
---|
2300 | different from register 1, otherwise some arbitrary call-clobbered |
---|
2301 | register. */ |
---|
2302 | |
---|
2303 | static void |
---|
2304 | eh_regs (r1, r2, outgoing) |
---|
2305 | rtx *r1, *r2; |
---|
2306 | int outgoing; |
---|
2307 | { |
---|
2308 | rtx reg1, reg2; |
---|
2309 | |
---|
2310 | #ifdef FUNCTION_OUTGOING_VALUE |
---|
2311 | if (outgoing) |
---|
2312 | reg1 = FUNCTION_OUTGOING_VALUE (build_pointer_type (void_type_node), |
---|
2313 | current_function_decl); |
---|
2314 | else |
---|
2315 | #endif |
---|
2316 | reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node), |
---|
2317 | current_function_decl); |
---|
2318 | |
---|
2319 | #ifdef STATIC_CHAIN_REGNUM |
---|
2320 | if (outgoing) |
---|
2321 | reg2 = static_chain_incoming_rtx; |
---|
2322 | else |
---|
2323 | reg2 = static_chain_rtx; |
---|
2324 | if (REGNO (reg2) == REGNO (reg1)) |
---|
2325 | #endif /* STATIC_CHAIN_REGNUM */ |
---|
2326 | reg2 = NULL_RTX; |
---|
2327 | |
---|
2328 | if (reg2 == NULL_RTX) |
---|
2329 | { |
---|
2330 | int i; |
---|
2331 | for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) |
---|
2332 | if (call_used_regs[i] && ! fixed_regs[i] && i != REGNO (reg1)) |
---|
2333 | { |
---|
2334 | reg2 = gen_rtx (REG, Pmode, i); |
---|
2335 | break; |
---|
2336 | } |
---|
2337 | |
---|
2338 | if (reg2 == NULL_RTX) |
---|
2339 | abort (); |
---|
2340 | } |
---|
2341 | |
---|
2342 | *r1 = reg1; |
---|
2343 | *r2 = reg2; |
---|
2344 | } |
---|
2345 | |
---|
2346 | /* Emit inside of __throw a stub which adjusts the stack pointer and jumps |
---|
2347 | to the exception handler. __throw will set up the necessary values |
---|
2348 | and then return to the stub. */ |
---|
2349 | |
---|
2350 | rtx |
---|
2351 | expand_builtin_eh_stub () |
---|
2352 | { |
---|
2353 | rtx stub_start = gen_label_rtx (); |
---|
2354 | rtx after_stub = gen_label_rtx (); |
---|
2355 | rtx handler, offset, temp; |
---|
2356 | |
---|
2357 | emit_jump (after_stub); |
---|
2358 | emit_label (stub_start); |
---|
2359 | |
---|
2360 | eh_regs (&handler, &offset, 0); |
---|
2361 | |
---|
2362 | adjust_stack (offset); |
---|
2363 | emit_indirect_jump (handler); |
---|
2364 | |
---|
2365 | emit_label (after_stub); |
---|
2366 | return gen_rtx (LABEL_REF, Pmode, stub_start); |
---|
2367 | } |
---|
2368 | |
---|
2369 | /* Set up the registers for passing the handler address and stack offset |
---|
2370 | to the stub above. */ |
---|
2371 | |
---|
2372 | void |
---|
2373 | expand_builtin_set_eh_regs (handler, offset) |
---|
2374 | tree handler, offset; |
---|
2375 | { |
---|
2376 | rtx reg1, reg2; |
---|
2377 | |
---|
2378 | eh_regs (®1, ®2, 1); |
---|
2379 | |
---|
2380 | store_expr (offset, reg2, 0); |
---|
2381 | store_expr (handler, reg1, 0); |
---|
2382 | |
---|
2383 | /* These will be used by the stub. */ |
---|
2384 | emit_insn (gen_rtx (USE, VOIDmode, reg1)); |
---|
2385 | emit_insn (gen_rtx (USE, VOIDmode, reg2)); |
---|
2386 | } |
---|