source: doc/working/exception/reference.c @ 6b72040

aaron-thesisarm-ehcleanup-dtorsdeferred_resndemanglerjacob/cs343-translationjenkins-sandboxnew-astnew-ast-unique-exprnew-envno_listpersistent-indexerresolv-newwith_gc
Last change on this file since 6b72040 was 6b72040, checked in by Andrew Beach <ajbeach@…>, 5 years ago

The try exception handler function is now generic.

  • Property mode set to 100644
File size: 4.7 KB
Line 
1// Reference to all sorts of information for exception handling.
2
3// C++ Interface to exception handlers.
4
5void * __cxa_allocate_exception(size_t thrown_size);
6// Creates space for the exception.
7
8void __cxa_free_exception(void * thrown_exception);
9
10void __cxa_throw(void * thrown_exception, struct type_info * tinfo,
11                void (*dest)(void*));
12// Throws the exception, is not supposed to return but ours should,
13// to handle resumption exceptions.
14
15void __cxa_begin_catch(); -> void * __cxa_begin_catch(void * exceptionObject);
16void __cxa_end_catch();
17// Not sure, beginning and end of catch block maybe?
18
19
20/* Unwind Module
21 * Full list: https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
22 * Avaible at: /usr/lib/gcc/x86_64-linux-gnu/{5}/include/unwind.h
23 */
24
25typedef _Unwind_Reason_Code (*_Unwind_Personality_Fn)
26     (int, _Unwind_Action, _Unwind_Exception_Class,
27      struct _Unwind_Exception *, struct _Unwind_Context *);
28/* Type of the personality function, which does not have a set name.
29 *   So far `__gcfa_personality_v0` has been used.
30 * Called by _Unwind_RaiseException (called by __cxa_throw)
31 *   or by _Unwind_ForcedUnwind's personality wrapper.
32 * Params:
33 *   int version: Repersents unwind convention standard.
34 *   _Unwind_Action actions: Set of actions, used as instructions.
35 *   _Unwind_Exception_Class: 8-byte identifer: high 4 vendor, low 4 language.
36 *   _Unwind_Exception unwind_exception: Pointer to exception data.
37 *   _Unwind_Context context: Information on the current stack frame.
38 * Return:
39 *   _Unwind_Reason_Code: Requests an action from the unwinder.
40 */
41
42
43// _Unwind_Action flags (multiple may be set):
44_UA_SEARCH_PHASE  // Seaching for the handler
45_UA_CLEANUP_PHASE // Cleanup until handler found.
46_UA_HANDLER_FRAME // Previous search found handler here.
47_UA_FORCE_UNWIND  // Unwind, do not decide if we have reached the handler.
48_UA_END_OF_STACK  // We have reached the end of the stack.
49
50
51// _Unwind_Reason_Code values (one may be selected):
52_URC_NO_REASON          // Containues force unwind.
53_URC_FOREIGN_EXCEPTION_CAUGHT // Cross between runtime environments.
54_URC_FATAL_PHASE2_ERROR // Error in cleanup, not otherwise defined. (Rare?)
55_URC_FATAL_PHASE1_ERROR // Error in search, not otherwise defined.
56_URC_NORMAL_STOP
57_URC_END_OF_STACK       // eos found before a handler.
58_URC_HANDLER_FOUND      // Just the signal (search?)
59_URC_INSTALL_CONTEXT    // Handler found, resume execution (cleanup?)
60_URC_CONTINUE_UNWIND    // No handler found (search&cleanup)
61
62
63// Exception Header: (?)
64typedef void (*_Unwind_Exception_Cleanup_Fn)
65                (_Unwind_Reason_Code reason, struct _Unwind_Exception *exc);
66
67struct _Unwind_Exception {
68        uint64 exception_class;
69        _Unwind_Exception_Cleanup_Fn exception_cleanup;
70        uint64 private_1; // Do not access.
71        uint64 private_2; // Do not access.
72};
73
74
75// There are two functions to access the unwind "operation".
76// The standard exception handler, uses the personality function.
77_Unwind_Reason_Code _Unwind_RaiseException(
78        struct _Unwind_Exception * exception_object);
79
80// Helper for force unwind.
81typedef _Unwind_Reason_Code (*_Unwind_Stop_Fn)(
82        int version,
83        _Unwind_Action actions,
84        uint64 exceptionClass,
85        struct _Unwind_Exception * exceptionObject,
86        struct _Unwind_Context * context,
87        void * stop_parameter);
88
89// Special unwinder, wraps the personality function.
90_Unwind_Reason_Code _Unwind_ForcedUnwind(
91        struct _Unwind_Exception * exception_object,
92        _Unwind_Stop_Fn stop,
93        void * stop_parameter);
94
95// Continues unwinding
96void _Unwind_Resume(struct _Unwind_Exception * exception_object);
97// Seems to be for finally and deconstrctors, not so much rethrow.
98// However I haven't figured out the difference.
99
100
101/* _Unwind Helper functions:
102 *
103 * _Unwind_GetLanguageSpecificData - LSDA (destructors and landing pads)
104 * _Unwind_GetRegionStart - Function pointer to current stack frame.
105 * _Unwind_GetIP - Get frame's instruction pointer
106 *   This might be the actual function pointer or the call site up stack.
107 *
108 * All three have the same signature. */
109uint64 _Unwind_Get*(struct _Unwind_Context * context);
110
111void _Unwind_SetIP(struct _Unwind_Context * context, uint64 new_value);
112uint64 _Unwind_GetGR(struct _Unwind_Context * context, int index);
113void _Unwind_SetGR(struct _Unwind_Context * <>, int index, uint64 <>);
114// __builtin_eh_return_data_regno(^) ^=[0..3]? gives index.
115
116// Locally we also seem to have:
117_Unwind_Word _Unwind_GetCFA (struct _Unwind_Context *);
118
119// GCC (Dwarf2 ?) Frame Layout Macros
120// See: https://gcc.gnu.org/onlinedocs/gccint/Frame-Layout.html
121// Include from: ???
122
123FIRST_PARAM_OFFSET(fundecl)
124// Offset from argument pointer to first arguments address, or above that
125// address if ARGS_GROW_DOWNWARD.
126
127ARG_POINTER_CFA_OFFSET(fundecl)
128// Default: FIRST_PARM_OFFSET(fundecl) + crtl->args.pretend_args_size
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