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537 lines
15 KiB
C
537 lines
15 KiB
C
/* The implementation of exception handling primitives for Objective-C.
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Copyright (C) 2004-2018 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 3, or (at your option) any
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later version.
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GCC is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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License for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#include "objc-private/common.h"
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#include <stdlib.h>
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#include "config.h"
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#include "objc/runtime.h"
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#include "objc/objc-exception.h"
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#include "unwind.h"
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#include "unwind-pe.h"
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#include <string.h> /* For memcpy */
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/* 'is_kind_of_exception_matcher' is our default exception matcher -
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it determines if the object 'exception' is of class 'catch_class',
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or of a subclass. */
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static int
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is_kind_of_exception_matcher (Class catch_class, id exception)
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{
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/* NULL catch_class is catch-all (eg, @catch (id object)). */
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if (catch_class == Nil)
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return 1;
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/* If exception is nil (eg, @throw nil;), then it can only be
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catched by a catch-all (eg, @catch (id object)). */
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if (exception != nil)
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{
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Class c;
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for (c = exception->class_pointer; c != Nil;
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c = class_getSuperclass (c))
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if (c == catch_class)
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return 1;
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}
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return 0;
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}
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/* The exception matcher currently in use. */
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static objc_exception_matcher
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__objc_exception_matcher = is_kind_of_exception_matcher;
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objc_exception_matcher
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objc_setExceptionMatcher (objc_exception_matcher new_matcher)
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{
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objc_exception_matcher old_matcher = __objc_exception_matcher;
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__objc_exception_matcher = new_matcher;
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return old_matcher;
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}
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/* The uncaught exception handler currently in use. */
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static objc_uncaught_exception_handler
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__objc_uncaught_exception_handler = NULL;
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objc_uncaught_exception_handler
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objc_setUncaughtExceptionHandler (objc_uncaught_exception_handler
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new_handler)
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{
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objc_uncaught_exception_handler old_handler
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= __objc_uncaught_exception_handler;
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__objc_uncaught_exception_handler = new_handler;
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return old_handler;
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}
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#ifdef __ARM_EABI_UNWINDER__
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const _Unwind_Exception_Class __objc_exception_class
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= {'G', 'N', 'U', 'C', 'O', 'B', 'J', 'C'};
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#else
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/* This is the exception class we report -- "GNUCOBJC". */
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static const _Unwind_Exception_Class __objc_exception_class
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= ((((((((_Unwind_Exception_Class) 'G'
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<< 8 | (_Unwind_Exception_Class) 'N')
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<< 8 | (_Unwind_Exception_Class) 'U')
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<< 8 | (_Unwind_Exception_Class) 'C')
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<< 8 | (_Unwind_Exception_Class) 'O')
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<< 8 | (_Unwind_Exception_Class) 'B')
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<< 8 | (_Unwind_Exception_Class) 'J')
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<< 8 | (_Unwind_Exception_Class) 'C');
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#endif
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/* This is the object that is passed around by the Objective C runtime
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to represent the exception in flight. */
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struct ObjcException
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{
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/* This bit is needed in order to interact with the unwind runtime. */
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struct _Unwind_Exception base;
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/* The actual object we want to throw. Note: must come immediately
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after unwind header. */
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id value;
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#ifdef __ARM_EABI_UNWINDER__
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/* Note: we use the barrier cache defined in the unwind control
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block for ARM EABI. */
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#else
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/* Cache some internal unwind data between phase 1 and phase 2. */
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_Unwind_Ptr landingPad;
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int handlerSwitchValue;
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#endif
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};
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struct lsda_header_info
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{
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_Unwind_Ptr Start;
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_Unwind_Ptr LPStart;
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_Unwind_Ptr ttype_base;
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const unsigned char *TType;
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const unsigned char *action_table;
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unsigned char ttype_encoding;
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unsigned char call_site_encoding;
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};
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static const unsigned char *
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parse_lsda_header (struct _Unwind_Context *context, const unsigned char *p,
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struct lsda_header_info *info)
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{
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_uleb128_t tmp;
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unsigned char lpstart_encoding;
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info->Start = (context ? _Unwind_GetRegionStart (context) : 0);
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/* Find @LPStart, the base to which landing pad offsets are
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relative. */
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lpstart_encoding = *p++;
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if (lpstart_encoding != DW_EH_PE_omit)
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p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart);
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else
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info->LPStart = info->Start;
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/* Find @TType, the base of the handler and exception spec type
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data. */
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info->ttype_encoding = *p++;
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if (info->ttype_encoding != DW_EH_PE_omit)
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{
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#if _GLIBCXX_OVERRIDE_TTYPE_ENCODING
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/* Older ARM EABI toolchains set this value incorrectly, so use a
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hardcoded OS-specific format. */
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info->ttype_encoding = _GLIBCXX_OVERRIDE_TTYPE_ENCODING;
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#endif
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p = read_uleb128 (p, &tmp);
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info->TType = p + tmp;
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}
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else
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info->TType = 0;
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/* The encoding and length of the call-site table; the action table
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immediately follows. */
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info->call_site_encoding = *p++;
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p = read_uleb128 (p, &tmp);
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info->action_table = p + tmp;
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return p;
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}
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static Class
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get_ttype_entry (struct lsda_header_info *info, _Unwind_Word i)
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{
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_Unwind_Ptr ptr;
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i *= size_of_encoded_value (info->ttype_encoding);
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read_encoded_value_with_base (info->ttype_encoding, info->ttype_base,
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info->TType - i, &ptr);
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/* NULL ptr means catch-all. Note that if the class is not found,
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this will abort the program. */
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if (ptr)
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return objc_getRequiredClass ((const char *) ptr);
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else
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return 0;
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}
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/* Using a different personality function name causes link failures
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when trying to mix code using different exception handling
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models. */
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#ifdef __USING_SJLJ_EXCEPTIONS__
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#define PERSONALITY_FUNCTION __gnu_objc_personality_sj0
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#define __builtin_eh_return_data_regno(x) x
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#elif defined(__SEH__)
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#define PERSONALITY_FUNCTION __gnu_objc_personality_imp
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#else
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#define PERSONALITY_FUNCTION __gnu_objc_personality_v0
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#endif
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#ifdef __ARM_EABI_UNWINDER__
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#define CONTINUE_UNWINDING \
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do \
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{ \
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if (__gnu_unwind_frame(ue_header, context) != _URC_OK) \
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return _URC_FAILURE; \
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return _URC_CONTINUE_UNWIND; \
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} \
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while (0)
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_Unwind_Reason_Code
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PERSONALITY_FUNCTION (_Unwind_State state,
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struct _Unwind_Exception *ue_header,
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struct _Unwind_Context *context)
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#else
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#define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND
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#if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__)
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static
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#endif
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_Unwind_Reason_Code
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PERSONALITY_FUNCTION (int version,
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_Unwind_Action actions,
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_Unwind_Exception_Class exception_class,
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struct _Unwind_Exception *ue_header,
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struct _Unwind_Context *context)
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#endif
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{
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struct ObjcException *xh = (struct ObjcException *) ue_header;
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struct lsda_header_info info;
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const unsigned char *language_specific_data;
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const unsigned char *action_record;
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const unsigned char *p;
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_Unwind_Ptr landing_pad, ip;
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int handler_switch_value;
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int saw_cleanup = 0, saw_handler, foreign_exception;
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void *return_object;
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int ip_before_insn = 0;
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#ifdef __ARM_EABI_UNWINDER__
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_Unwind_Action actions;
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switch (state & _US_ACTION_MASK)
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{
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case _US_VIRTUAL_UNWIND_FRAME:
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actions = _UA_SEARCH_PHASE;
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break;
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case _US_UNWIND_FRAME_STARTING:
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actions = _UA_CLEANUP_PHASE;
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if (!(state & _US_FORCE_UNWIND)
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&& ue_header->barrier_cache.sp == _Unwind_GetGR (context, 13))
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actions |= _UA_HANDLER_FRAME;
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break;
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case _US_UNWIND_FRAME_RESUME:
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CONTINUE_UNWINDING;
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break;
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default:
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abort();
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}
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actions |= state & _US_FORCE_UNWIND;
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/* TODO: Foreign exceptions need some attention (e.g. rethrowing
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doesn't work). */
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foreign_exception = 0;
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/* The dwarf unwinder assumes the context structure holds things
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like the function and LSDA pointers. The ARM implementation
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caches these in the exception header (UCB). To avoid rewriting
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everything we make the virtual IP register point at the UCB. */
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ip = (_Unwind_Ptr) ue_header;
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_Unwind_SetGR (context, 12, ip);
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#else /* !__ARM_EABI_UNWINDER. */
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/* Interface version check. */
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if (version != 1)
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return _URC_FATAL_PHASE1_ERROR;
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foreign_exception = (exception_class != __objc_exception_class);
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#endif
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/* Shortcut for phase 2 found handler for domestic exception. */
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if (actions == (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME)
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&& !foreign_exception)
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{
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#ifdef __ARM_EABI_UNWINDER__
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handler_switch_value = (int) ue_header->barrier_cache.bitpattern[1];
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landing_pad = (_Unwind_Ptr) ue_header->barrier_cache.bitpattern[3];
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#else
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handler_switch_value = xh->handlerSwitchValue;
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landing_pad = xh->landingPad;
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#endif
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goto install_context;
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}
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language_specific_data = (const unsigned char *)
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_Unwind_GetLanguageSpecificData (context);
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/* If no LSDA, then there are no handlers or cleanups. */
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if (! language_specific_data)
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CONTINUE_UNWINDING;
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/* Parse the LSDA header. */
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p = parse_lsda_header (context, language_specific_data, &info);
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info.ttype_base = base_of_encoded_value (info.ttype_encoding, context);
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#ifdef HAVE_GETIPINFO
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ip = _Unwind_GetIPInfo (context, &ip_before_insn);
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#else
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ip = _Unwind_GetIP (context);
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#endif
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if (!ip_before_insn)
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--ip;
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landing_pad = 0;
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action_record = 0;
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handler_switch_value = 0;
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#ifdef __USING_SJLJ_EXCEPTIONS__
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/* The given "IP" is an index into the call-site table, with two
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exceptions -- -1 means no-action, and 0 means terminate. But
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since we're using uleb128 values, we've not got random access to
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the array. */
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if ((int) ip < 0)
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return _URC_CONTINUE_UNWIND;
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else
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{
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_uleb128_t cs_lp, cs_action;
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do
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{
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p = read_uleb128 (p, &cs_lp);
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p = read_uleb128 (p, &cs_action);
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}
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while (--ip);
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/* Can never have null landing pad for sjlj -- that would have
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been indicated by a -1 call site index. */
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landing_pad = cs_lp + 1;
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if (cs_action)
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action_record = info.action_table + cs_action - 1;
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goto found_something;
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}
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#else
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/* Search the call-site table for the action associated with this
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IP. */
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while (p < info.action_table)
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{
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_Unwind_Ptr cs_start, cs_len, cs_lp;
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_uleb128_t cs_action;
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/* Note that all call-site encodings are "absolute"
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displacements. */
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p = read_encoded_value (0, info.call_site_encoding, p, &cs_start);
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p = read_encoded_value (0, info.call_site_encoding, p, &cs_len);
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p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp);
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p = read_uleb128 (p, &cs_action);
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/* The table is sorted, so if we've passed the ip, stop. */
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if (ip < info.Start + cs_start)
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p = info.action_table;
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else if (ip < info.Start + cs_start + cs_len)
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{
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if (cs_lp)
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landing_pad = info.LPStart + cs_lp;
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if (cs_action)
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action_record = info.action_table + cs_action - 1;
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goto found_something;
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}
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}
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#endif /* __USING_SJLJ_EXCEPTIONS__ */
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/* If ip is not present in the table, C++ would call terminate. */
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/* ??? As with Java, it's perhaps better to tweek the LSDA to that
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no-action is mapped to no-entry. */
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CONTINUE_UNWINDING;
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found_something:
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saw_cleanup = 0;
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saw_handler = 0;
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if (landing_pad == 0)
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{
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/* If ip is present, and has a null landing pad, there are no
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cleanups or handlers to be run. */
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}
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else if (action_record == 0)
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{
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/* If ip is present, has a non-null landing pad, and a null
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action table offset, then there are only cleanups present.
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Cleanups use a zero switch value, as set above. */
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saw_cleanup = 1;
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}
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else
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{
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/* Otherwise we have a catch handler. */
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_sleb128_t ar_filter, ar_disp;
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while (1)
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{
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p = action_record;
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p = read_sleb128 (p, &ar_filter);
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read_sleb128 (p, &ar_disp);
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if (ar_filter == 0)
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{
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/* Zero filter values are cleanups. */
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saw_cleanup = 1;
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}
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/* During forced unwinding, we only run cleanups. With a
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foreign exception class, we have no class info to
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match. */
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else if ((actions & _UA_FORCE_UNWIND) || foreign_exception)
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;
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else if (ar_filter > 0)
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{
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/* Positive filter values are handlers. */
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Class catch_type = get_ttype_entry (&info, ar_filter);
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if ((*__objc_exception_matcher) (catch_type, xh->value))
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{
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handler_switch_value = ar_filter;
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saw_handler = 1;
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break;
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}
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}
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else
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{
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/* Negative filter values are exception specifications,
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which Objective-C does not use. */
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abort ();
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}
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if (ar_disp == 0)
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break;
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action_record = p + ar_disp;
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}
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}
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if (! saw_handler && ! saw_cleanup)
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CONTINUE_UNWINDING;
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if (actions & _UA_SEARCH_PHASE)
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{
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if (!saw_handler)
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CONTINUE_UNWINDING;
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/* For domestic exceptions, we cache data from phase 1 for phase
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2. */
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if (!foreign_exception)
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{
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#ifdef __ARM_EABI_UNWINDER__
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ue_header->barrier_cache.sp = _Unwind_GetGR (context, 13);
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ue_header->barrier_cache.bitpattern[1] = (_uw) handler_switch_value;
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ue_header->barrier_cache.bitpattern[3] = (_uw) landing_pad;
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#else
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xh->handlerSwitchValue = handler_switch_value;
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xh->landingPad = landing_pad;
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#endif
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}
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return _URC_HANDLER_FOUND;
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}
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install_context:
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if (saw_cleanup == 0)
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{
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return_object = xh->value;
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if (!(actions & _UA_SEARCH_PHASE))
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_Unwind_DeleteException(&xh->base);
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}
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_Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
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__builtin_extend_pointer (saw_cleanup ? xh : return_object));
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_Unwind_SetGR (context, __builtin_eh_return_data_regno (1),
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handler_switch_value);
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_Unwind_SetIP (context, landing_pad);
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return _URC_INSTALL_CONTEXT;
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}
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static void
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__objc_exception_cleanup (_Unwind_Reason_Code code __attribute__((unused)),
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struct _Unwind_Exception *exc)
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{
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free (exc);
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}
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|
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void
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objc_exception_throw (id exception)
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{
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struct ObjcException *header = calloc (1, sizeof (*header));
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|
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memcpy (&header->base.exception_class, &__objc_exception_class,
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sizeof (__objc_exception_class));
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header->base.exception_cleanup = __objc_exception_cleanup;
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header->value = exception;
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#ifdef __USING_SJLJ_EXCEPTIONS__
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_Unwind_SjLj_RaiseException (&header->base);
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#else
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_Unwind_RaiseException (&header->base);
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#endif
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/* No exception handler was installed. Call the uncaught exception
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handler if any is defined. */
|
||
if (__objc_uncaught_exception_handler != 0)
|
||
{
|
||
(*__objc_uncaught_exception_handler) (exception);
|
||
}
|
||
|
||
abort ();
|
||
}
|
||
|
||
#if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__)
|
||
EXCEPTION_DISPOSITION
|
||
__gnu_objc_personality_seh0 (PEXCEPTION_RECORD ms_exc, void *this_frame,
|
||
PCONTEXT ms_orig_context,
|
||
PDISPATCHER_CONTEXT ms_disp)
|
||
{
|
||
return _GCC_specific_handler (ms_exc, this_frame, ms_orig_context,
|
||
ms_disp, __gnu_objc_personality_imp);
|
||
}
|
||
#endif
|