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[/] [scarts/] [trunk/] [toolchain/] [scarts-gcc/] [gcc-4.1.1/] [libobjc/] [exception.c] - Rev 19
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/* The implementation of exception handling primitives for Objective-C. Copyright (C) 2004 Free Software Foundation, Inc. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING. If not, write to the Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ /* As a special exception, if you link this library with files compiled with GCC to produce an executable, this does not cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU General Public License. */ #include <stdlib.h> #include "config.h" #include "objc/objc-api.h" #include "unwind.h" #include "unwind-pe.h" /* This is the exception class we report -- "GNUCOBJC". */ #define __objc_exception_class \ ((((((((_Unwind_Exception_Class) 'G' \ << 8 | (_Unwind_Exception_Class) 'N') \ << 8 | (_Unwind_Exception_Class) 'U') \ << 8 | (_Unwind_Exception_Class) 'C') \ << 8 | (_Unwind_Exception_Class) 'O') \ << 8 | (_Unwind_Exception_Class) 'B') \ << 8 | (_Unwind_Exception_Class) 'J') \ << 8 | (_Unwind_Exception_Class) 'C') /* This is the object that is passed around by the Objective C runtime to represent the exception in flight. */ struct ObjcException { /* This bit is needed in order to interact with the unwind runtime. */ struct _Unwind_Exception base; /* The actual object we want to throw. */ id value; /* Cache some internal unwind data between phase 1 and phase 2. */ _Unwind_Ptr landingPad; int handlerSwitchValue; }; struct lsda_header_info { _Unwind_Ptr Start; _Unwind_Ptr LPStart; _Unwind_Ptr ttype_base; const unsigned char *TType; const unsigned char *action_table; unsigned char ttype_encoding; unsigned char call_site_encoding; }; static const unsigned char * parse_lsda_header (struct _Unwind_Context *context, const unsigned char *p, struct lsda_header_info *info) { _Unwind_Word tmp; unsigned char lpstart_encoding; info->Start = (context ? _Unwind_GetRegionStart (context) : 0); /* Find @LPStart, the base to which landing pad offsets are relative. */ lpstart_encoding = *p++; if (lpstart_encoding != DW_EH_PE_omit) p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart); else info->LPStart = info->Start; /* Find @TType, the base of the handler and exception spec type data. */ info->ttype_encoding = *p++; if (info->ttype_encoding != DW_EH_PE_omit) { p = read_uleb128 (p, &tmp); info->TType = p + tmp; } else info->TType = 0; /* The encoding and length of the call-site table; the action table immediately follows. */ info->call_site_encoding = *p++; p = read_uleb128 (p, &tmp); info->action_table = p + tmp; return p; } static Class get_ttype_entry (struct lsda_header_info *info, _Unwind_Word i) { _Unwind_Ptr ptr; i *= size_of_encoded_value (info->ttype_encoding); read_encoded_value_with_base (info->ttype_encoding, info->ttype_base, info->TType - i, &ptr); /* NULL ptr means catch-all. */ if (ptr) return objc_get_class ((const char *) ptr); else return 0; } /* Like unto the method of the same name on Object, but takes an id. */ /* ??? Does this bork the meta-type system? Can/should we look up an isKindOf method on the id? */ static int isKindOf (id value, Class target) { Class c; /* NULL target is catch-all. */ if (target == 0) return 1; for (c = value->class_pointer; c; c = class_get_super_class (c)) if (c == target) return 1; return 0; } /* Using a different personality function name causes link failures when trying to mix code using different exception handling models. */ #ifdef SJLJ_EXCEPTIONS #define PERSONALITY_FUNCTION __gnu_objc_personality_sj0 #define __builtin_eh_return_data_regno(x) x #else #define PERSONALITY_FUNCTION __gnu_objc_personality_v0 #endif _Unwind_Reason_Code PERSONALITY_FUNCTION (int version, _Unwind_Action actions, _Unwind_Exception_Class exception_class, struct _Unwind_Exception *ue_header, struct _Unwind_Context *context) { struct ObjcException *xh = (struct ObjcException *) ue_header; struct lsda_header_info info; const unsigned char *language_specific_data; const unsigned char *action_record; const unsigned char *p; _Unwind_Ptr landing_pad, ip; int handler_switch_value; int saw_cleanup = 0, saw_handler; void *return_object; /* Interface version check. */ if (version != 1) return _URC_FATAL_PHASE1_ERROR; /* Shortcut for phase 2 found handler for domestic exception. */ if (actions == (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME) && exception_class == __objc_exception_class) { handler_switch_value = xh->handlerSwitchValue; landing_pad = xh->landingPad; goto install_context; } language_specific_data = (const unsigned char *) _Unwind_GetLanguageSpecificData (context); /* If no LSDA, then there are no handlers or cleanups. */ if (! language_specific_data) return _URC_CONTINUE_UNWIND; /* Parse the LSDA header. */ p = parse_lsda_header (context, language_specific_data, &info); info.ttype_base = base_of_encoded_value (info.ttype_encoding, context); ip = _Unwind_GetIP (context) - 1; landing_pad = 0; action_record = 0; handler_switch_value = 0; #ifdef SJLJ_EXCEPTIONS /* The given "IP" is an index into the call-site table, with two exceptions -- -1 means no-action, and 0 means terminate. But since we're using uleb128 values, we've not got random access to the array. */ if ((int) ip < 0) return _URC_CONTINUE_UNWIND; else { _Unwind_Word cs_lp, cs_action; do { p = read_uleb128 (p, &cs_lp); p = read_uleb128 (p, &cs_action); } while (--ip); /* Can never have null landing pad for sjlj -- that would have been indicated by a -1 call site index. */ landing_pad = cs_lp + 1; if (cs_action) action_record = info.action_table + cs_action - 1; goto found_something; } #else /* Search the call-site table for the action associated with this IP. */ while (p < info.action_table) { _Unwind_Ptr cs_start, cs_len, cs_lp; _Unwind_Word cs_action; /* Note that all call-site encodings are "absolute" displacements. */ p = read_encoded_value (0, info.call_site_encoding, p, &cs_start); p = read_encoded_value (0, info.call_site_encoding, p, &cs_len); p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp); p = read_uleb128 (p, &cs_action); /* The table is sorted, so if we've passed the ip, stop. */ if (ip < info.Start + cs_start) p = info.action_table; else if (ip < info.Start + cs_start + cs_len) { if (cs_lp) landing_pad = info.LPStart + cs_lp; if (cs_action) action_record = info.action_table + cs_action - 1; goto found_something; } } #endif /* SJLJ_EXCEPTIONS */ /* If ip is not present in the table, C++ would call terminate. */ /* ??? As with Java, it's perhaps better to tweek the LSDA to that no-action is mapped to no-entry. */ return _URC_CONTINUE_UNWIND; found_something: saw_cleanup = 0; saw_handler = 0; if (landing_pad == 0) { /* If ip is present, and has a null landing pad, there are no cleanups or handlers to be run. */ } else if (action_record == 0) { /* If ip is present, has a non-null landing pad, and a null action table offset, then there are only cleanups present. Cleanups use a zero switch value, as set above. */ saw_cleanup = 1; } else { /* Otherwise we have a catch handler. */ _Unwind_Sword ar_filter, ar_disp; while (1) { p = action_record; p = read_sleb128 (p, &ar_filter); read_sleb128 (p, &ar_disp); if (ar_filter == 0) { /* Zero filter values are cleanups. */ saw_cleanup = 1; } /* During forced unwinding, we only run cleanups. With a foreign exception class, we have no class info to match. */ else if ((actions & _UA_FORCE_UNWIND) || exception_class != __objc_exception_class) ; else if (ar_filter > 0) { /* Positive filter values are handlers. */ Class catch_type = get_ttype_entry (&info, ar_filter); if (isKindOf (xh->value, catch_type)) { handler_switch_value = ar_filter; saw_handler = 1; break; } } else { /* Negative filter values are exception specifications, which Objective-C does not use. */ abort (); } if (ar_disp == 0) break; action_record = p + ar_disp; } } if (! saw_handler && ! saw_cleanup) return _URC_CONTINUE_UNWIND; if (actions & _UA_SEARCH_PHASE) { if (!saw_handler) return _URC_CONTINUE_UNWIND; /* For domestic exceptions, we cache data from phase 1 for phase 2. */ if (exception_class == __objc_exception_class) { xh->handlerSwitchValue = handler_switch_value; xh->landingPad = landing_pad; } return _URC_HANDLER_FOUND; } install_context: if (saw_cleanup == 0) { return_object = xh->value; if (!(actions & _UA_SEARCH_PHASE)) _Unwind_DeleteException(&xh->base); } _Unwind_SetGR (context, __builtin_eh_return_data_regno (0), __builtin_extend_pointer (saw_cleanup ? xh : return_object)); _Unwind_SetGR (context, __builtin_eh_return_data_regno (1), handler_switch_value); _Unwind_SetIP (context, landing_pad); return _URC_INSTALL_CONTEXT; } static void __objc_exception_cleanup (_Unwind_Reason_Code code __attribute__((unused)), struct _Unwind_Exception *exc) { free (exc); } void objc_exception_throw (id value) { struct ObjcException *header = calloc (1, sizeof (*header)); header->base.exception_class = __objc_exception_class; header->base.exception_cleanup = __objc_exception_cleanup; header->value = value; #ifdef SJLJ_EXCEPTIONS _Unwind_SjLj_RaiseException (&header->base); #else _Unwind_RaiseException (&header->base); #endif /* Some sort of unwinding error. */ abort (); }
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