[465ed18] | 1 | /* Translation rules for exception handling code, from Cforall to C. |
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| 2 | * |
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| 3 | * Note that these are not final. Names, syntax and the exact translation |
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[8d50e34] | 4 | * will be updated. The first section is the shared definitions, not generated |
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| 5 | * by the local translations but used by the translated code. |
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| 6 | * |
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| 7 | * Most of these exist only after translation (in C code). The first (the |
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| 8 | * exception type) has to exist in Cforall code so that it can be used |
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| 9 | * directly in Cforall. The two __throw_* functions might have wrappers in |
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| 10 | * Cforall, but the underlying functions should probably be C. struct |
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| 11 | * stack_exception_data has to exist inside of the coroutine data structures |
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| 12 | * and so should be compiled as they are. |
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[465ed18] | 13 | */ |
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| 14 | |
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[8d50e34] | 15 | // Currently it is a typedef for int, but later it will be a new type. |
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[465ed18] | 16 | typedef int exception; |
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| 17 | |
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| 18 | void __throw_terminate(exception except) __attribute__((noreturn)); |
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| 19 | void __throw_resume(exception except); |
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| 20 | |
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| 21 | void __try_terminate(void (*try_block)(), |
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| 22 | void (*catch_block)(int index, exception except), |
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| 23 | int (*match_block)(exception except)); |
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| 24 | |
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| 25 | struct __try_resume_node { |
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| 26 | struct __try_resume_node * next; |
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| 27 | bool (*try_to_handle)(exception except); |
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| 28 | }; |
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| 29 | |
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| 30 | struct __cleanup_hook {}; |
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| 31 | |
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| 32 | // An instance of the following must be paired with every stack. |
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| 33 | struct stack_exception_data { |
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| 34 | __try_resume_node * top_resume_data; |
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| 35 | // Other pointers may be required for re-resume. |
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| 36 | |
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| 37 | exception current_exception; |
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| 38 | int handler_index; |
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| 39 | }; |
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| 40 | |
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| 41 | |
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| 42 | // Translations: |
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| 43 | |
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| 44 | // Throws: |
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| 45 | "Cforall" |
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| 46 | |
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| 47 | throw exception_instance; |
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| 48 | |
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| 49 | resume exception_instance; |
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| 50 | |
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| 51 | "C" |
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| 52 | |
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| 53 | __throw_terminate(exception_instance); |
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| 54 | |
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| 55 | __throw_resume(exception_instance); |
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| 56 | |
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| 57 | |
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[35ba584c] | 58 | |
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| 59 | // Rethrows (inside matching handlers): |
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| 60 | "Cforall" |
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| 61 | |
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| 62 | throw; |
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| 63 | |
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| 64 | resume; |
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| 65 | |
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| 66 | "C" |
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| 67 | |
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| 68 | __rethrow_terminate(); |
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| 69 | |
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| 70 | return false; |
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| 71 | |
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| 72 | |
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[465ed18] | 73 | // Termination Handlers: |
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| 74 | "Cforall" |
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| 75 | |
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| 76 | void try_terminate() { |
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| 77 | try { |
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| 78 | insideTry(); |
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| 79 | } |
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| 80 | catch (SomeException) { |
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| 81 | fiddleThing(); |
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| 82 | } |
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| 83 | catch (OtherException err ; err.priority > 3) { |
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| 84 | twiddleWidget(); |
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| 85 | } |
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| 86 | } |
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| 87 | |
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| 88 | "C" |
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| 89 | |
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| 90 | void try_terminate() { |
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| 91 | { |
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| 92 | void try1() { |
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| 93 | insideTry(); |
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| 94 | } |
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| 95 | // index is not nessasary, but should be much faster than going over |
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| 96 | // all the checks in if we can find a way to pass it in. |
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| 97 | void catch1(exception except, int index) { |
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| 98 | switch (index) { |
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| 99 | case 1: |
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| 100 | // if it is referenced in the handler, cast except. |
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| 101 | { |
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| 102 | fiddleThing(); |
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| 103 | } |
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| 104 | return; |
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| 105 | case 2: |
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| 106 | { |
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| 107 | twiddleWidget(); |
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| 108 | } |
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| 109 | return; |
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| 110 | default: |
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| 111 | // Error, should never be reached. |
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| 112 | } |
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| 113 | } |
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| 114 | int match1(exception except) { |
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| 115 | OtherException inner_except; |
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| 116 | if (dynamic_cast__SomeException(except)) { |
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| 117 | return 1; |
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| 118 | } |
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| 119 | else if ( (inner_except = dynamic_cast__OtherException(except)) && |
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| 120 | inner_except.priority > 3) { |
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| 121 | return 2; |
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| 122 | } |
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| 123 | else return 0; |
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| 124 | } |
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| 125 | __try_terminate(try1, catch1, match1); |
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| 126 | } |
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| 127 | } |
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| 128 | |
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| 129 | |
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| 130 | // Resumption Handlers: |
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| 131 | "Cforall" |
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| 132 | |
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| 133 | void try_resume() { |
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| 134 | try { |
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| 135 | insideTry(); |
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| 136 | } |
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| 137 | catch resume (SomeException) { |
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| 138 | fiddleThing(); |
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| 139 | } |
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| 140 | catch resume (OtherException err ; err.priority > 3) { |
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| 141 | twiddleWidget(); |
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| 142 | } |
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| 143 | } |
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| 144 | |
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| 145 | "C" |
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| 146 | |
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| 147 | void try_resume() { |
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| 148 | { |
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| 149 | bool catch1(exception except) { |
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| 150 | OtherException inner_except; |
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| 151 | if (dynamic_cast__SomeException(except)) { |
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| 152 | fiddleThing(); |
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| 153 | return true; |
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| 154 | } else if (dynamic_cast__OtherException(except) && |
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| 155 | inner_except.priority > 3) { |
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| 156 | twiddleWidget(); |
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| 157 | return true; |
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| 158 | } else { |
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| 159 | return false; |
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| 160 | } |
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| 161 | } |
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| 162 | struct __try_resume_node data = |
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| 163 | {.next = stack.except.top_resume, .try_to_handle = catch1}; |
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| 164 | stack.except.top_resume = &data; |
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| 165 | |
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| 166 | struct __cleanup_hook generated_name |
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| 167 | __attribute__((cleanup(__try_resume_cleanup))); |
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| 168 | |
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| 169 | { |
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| 170 | insideTry(); |
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| 171 | } |
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| 172 | } |
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| 173 | } |
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| 174 | |
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| 175 | |
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| 176 | // Finally Clause: |
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| 177 | "Cforall" |
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| 178 | |
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| 179 | void try_finally() { |
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| 180 | try { |
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| 181 | insideTry(); |
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| 182 | } |
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| 183 | finally { |
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| 184 | twiddleWidget(); |
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| 185 | } |
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| 186 | } |
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| 187 | |
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| 188 | "C" |
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| 189 | |
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| 190 | void try_finally() { |
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| 191 | { |
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| 192 | void finally1() { |
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| 193 | twiddleWidget(); |
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| 194 | } |
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| 195 | |
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| 196 | struct __cleanup_hook generated_name |
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| 197 | __attribute__((cleanup(finally1))); |
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| 198 | |
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| 199 | { |
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| 200 | insideTry(); |
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| 201 | } |
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| 202 | } |
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| 203 | } |
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| 204 | |
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| 205 | |
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| 206 | // Combining the Above: |
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| 207 | "Cforall" |
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| 208 | |
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| 209 | void try_all() { |
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| 210 | try { |
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| 211 | insideTry(); |
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| 212 | } |
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| 213 | catch (SomeException) { |
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| 214 | fiddleThing(); |
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| 215 | } |
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| 216 | catch resume (OtherException) { |
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| 217 | twiddleWidget(); |
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| 218 | } |
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| 219 | finally { |
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| 220 | twiddleWidget(); |
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| 221 | } |
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| 222 | } |
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| 223 | |
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| 224 | "C" |
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| 225 | |
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| 226 | void try_all() { |
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| 227 | { |
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| 228 | void try1 () { |
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| 229 | insideTry(); |
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| 230 | } |
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| 231 | void catch1(exception except, int index) { |
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| 232 | switch (index) { |
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| 233 | case 1: |
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| 234 | fiddleThing(); |
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| 235 | break; |
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| 236 | default: |
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| 237 | // Error if reached. |
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| 238 | } |
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| 239 | } |
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| 240 | int match1(exception except) { |
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| 241 | if (dynamic_cast__SomeException(except)) { |
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| 242 | return 1; |
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| 243 | } |
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| 244 | return 0; |
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| 245 | } |
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| 246 | bool catch2() { |
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| 247 | if (dynamic_cast__OtherException(except)) { |
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| 248 | twiddleWidget(); |
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| 249 | return true; |
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| 250 | } |
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| 251 | return false; |
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| 252 | } |
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| 253 | void finally1() { |
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[6a48cc9] | 254 | // Finally, because of timing, also works for resume. |
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| 255 | // However this might not actually be better in any way. |
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[465ed18] | 256 | __try_resume_cleanup(); |
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| 257 | |
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| 258 | twiddleWidget(); |
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| 259 | } |
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| 260 | |
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| 261 | struct __try_resume_node generated_name = |
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| 262 | {.next = stack.except.top_resume, .try_to_handle = catch2}; |
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| 263 | stack.except.top_resume = &data; |
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| 264 | struct __cleanup_hook generated_name |
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| 265 | __attribute__((cleanup(finally1))); |
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| 266 | |
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| 267 | __try_terminate(try1, catch1, match1); |
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| 268 | } |
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| 269 | } |
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