486 lines
15 KiB
C++
486 lines
15 KiB
C++
// -*- C++ -*- The GNU C++ exception personality routine.
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// Copyright (C) 2001, 2002 Free Software Foundation, Inc.
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//
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// This file is part of GNU CC.
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//
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// GNU CC is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2, or (at your option)
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// any later version.
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//
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// GNU CC is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with GNU CC; see the file COPYING. If not, write to
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// the Free Software Foundation, 59 Temple Place - Suite 330,
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// Boston, MA 02111-1307, USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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#include <bits/c++config.h>
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#include <cstdlib>
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#include <exception_defines.h>
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#include "unwind-cxx.h"
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using namespace __cxxabiv1;
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#include "unwind-pe.h"
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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 (_Unwind_Context *context, const unsigned char *p,
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lsda_header_info *info)
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{
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_Unwind_Word 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 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 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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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 const std::type_info *
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get_ttype_entry (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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return reinterpret_cast<const std::type_info *>(ptr);
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}
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// Given the thrown type THROW_TYPE, pointer to a variable containing a
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// pointer to the exception object THROWN_PTR_P and a type CATCH_TYPE to
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// compare against, return whether or not there is a match and if so,
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// update *THROWN_PTR_P.
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static bool
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get_adjusted_ptr (const std::type_info *catch_type,
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const std::type_info *throw_type,
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void **thrown_ptr_p)
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{
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void *thrown_ptr = *thrown_ptr_p;
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// Pointer types need to adjust the actual pointer, not
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// the pointer to pointer that is the exception object.
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// This also has the effect of passing pointer types
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// "by value" through the __cxa_begin_catch return value.
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if (throw_type->__is_pointer_p ())
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thrown_ptr = *(void **) thrown_ptr;
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if (catch_type->__do_catch (throw_type, &thrown_ptr, 1))
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{
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*thrown_ptr_p = thrown_ptr;
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return true;
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}
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return false;
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}
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static bool
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check_exception_spec (lsda_header_info *info, const std::type_info *throw_type,
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void *thrown_ptr, _Unwind_Sword filter_value)
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{
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const unsigned char *e = info->TType - filter_value - 1;
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while (1)
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{
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const std::type_info *catch_type;
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_Unwind_Word tmp;
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e = read_uleb128 (e, &tmp);
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// Zero signals the end of the list. If we've not found
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// a match by now, then we've failed the specification.
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if (tmp == 0)
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return false;
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// Match a ttype entry.
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catch_type = get_ttype_entry (info, tmp);
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// ??? There is currently no way to ask the RTTI code about the
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// relationship between two types without reference to a specific
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// object. There should be; then we wouldn't need to mess with
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// thrown_ptr here.
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if (get_adjusted_ptr (catch_type, throw_type, &thrown_ptr))
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return true;
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}
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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 models.
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#ifdef _GLIBCPP_SJLJ_EXCEPTIONS
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#define PERSONALITY_FUNCTION __gxx_personality_sj0
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#define __builtin_eh_return_data_regno(x) x
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#else
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#define PERSONALITY_FUNCTION __gxx_personality_v0
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#endif
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extern "C" _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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{
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__cxa_exception *xh = __get_exception_header_from_ue (ue_header);
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enum found_handler_type
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{
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found_nothing,
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found_terminate,
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found_cleanup,
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found_handler
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} found_type;
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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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void *thrown_ptr = xh + 1;
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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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// 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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&& exception_class == __gxx_exception_class)
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{
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handler_switch_value = xh->handlerSwitchValue;
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landing_pad = (_Unwind_Ptr) xh->catchTemp;
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found_type = (landing_pad == 0 ? found_terminate : found_handler);
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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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return _URC_CONTINUE_UNWIND;
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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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ip = _Unwind_GetIP (context) - 1;
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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 _GLIBCPP_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
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// to the array.
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if ((int) ip < 0)
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return _URC_CONTINUE_UNWIND;
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else if (ip == 0)
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{
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// Fall through to set found_terminate.
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}
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else
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{
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_Unwind_Word 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 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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_Unwind_Word cs_action;
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// Note that all call-site encodings are "absolute" 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 // _GLIBCPP_SJLJ_EXCEPTIONS
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// If ip is not present in the table, call terminate. This is for
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// a destructor inside a cleanup, or a library routine the compiler
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// was not expecting to throw.
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found_type = (actions & _UA_FORCE_UNWIND ? found_nothing : found_terminate);
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goto do_something;
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found_something:
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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
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// no cleanups or handlers to be run.
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found_type = found_nothing;
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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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found_type = found_cleanup;
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}
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else
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{
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// Otherwise we have a catch handler or exception specification.
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_Unwind_Sword ar_filter, ar_disp;
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const std::type_info *throw_type, *catch_type;
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bool saw_cleanup = false;
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bool saw_handler = false;
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// During forced unwinding, we only run cleanups. With a foreign
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// exception class, there's no exception type.
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// ??? What to do about GNU Java and GNU Ada exceptions.
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if ((actions & _UA_FORCE_UNWIND)
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|| exception_class != __gxx_exception_class)
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throw_type = 0;
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else
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throw_type = xh->exceptionType;
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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 = true;
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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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catch_type = get_ttype_entry (&info, ar_filter);
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// Null catch type is a catch-all handler. We can catch
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// foreign exceptions with this.
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if (! catch_type)
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{
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if (!(actions & _UA_FORCE_UNWIND))
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{
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saw_handler = true;
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break;
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}
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}
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else if (throw_type)
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{
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if (get_adjusted_ptr (catch_type, throw_type, &thrown_ptr))
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{
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saw_handler = true;
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break;
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}
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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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// ??? How do foreign exceptions fit in? As far as I can
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// see we can't match because there's no __cxa_exception
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// object to stuff bits in for __cxa_call_unexpected to use.
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if (throw_type
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&& ! check_exception_spec (&info, throw_type, thrown_ptr,
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ar_filter))
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{
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saw_handler = true;
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break;
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}
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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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if (saw_handler)
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{
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handler_switch_value = ar_filter;
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found_type = found_handler;
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}
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else
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found_type = (saw_cleanup ? found_cleanup : found_nothing);
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}
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do_something:
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if (found_type == found_nothing)
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return _URC_CONTINUE_UNWIND;
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if (actions & _UA_SEARCH_PHASE)
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{
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if (found_type == found_cleanup)
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return _URC_CONTINUE_UNWIND;
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// For domestic exceptions, we cache data from phase 1 for phase 2.
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if (exception_class == __gxx_exception_class)
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{
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xh->handlerSwitchValue = handler_switch_value;
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xh->actionRecord = action_record;
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xh->languageSpecificData = language_specific_data;
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xh->adjustedPtr = thrown_ptr;
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// ??? Completely unknown what this field is supposed to be for.
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// ??? Need to cache TType encoding base for call_unexpected.
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xh->catchTemp = (void *) (_Unwind_Ptr) landing_pad;
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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 (found_type == found_terminate)
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{
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__cxa_begin_catch (&xh->unwindHeader);
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__terminate (xh->terminateHandler);
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}
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// Cache the TType base value for __cxa_call_unexpected, as we won't
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// have an _Unwind_Context then.
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if (handler_switch_value < 0)
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{
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parse_lsda_header (context, xh->languageSpecificData, &info);
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xh->catchTemp = (void *) base_of_encoded_value (info.ttype_encoding,
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context);
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}
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_Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
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(_Unwind_Ptr) &xh->unwindHeader);
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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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extern "C" void
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__cxa_call_unexpected (void *exc_obj_in)
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{
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_Unwind_Exception *exc_obj
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= reinterpret_cast <_Unwind_Exception *>(exc_obj_in);
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__cxa_begin_catch (exc_obj);
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// This function is a handler for our exception argument. If we exit
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// by throwing a different exception, we'll need the original cleaned up.
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struct end_catch_protect
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{
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end_catch_protect() { }
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~end_catch_protect() { __cxa_end_catch(); }
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} end_catch_protect_obj;
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lsda_header_info info;
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__cxa_exception *xh = __get_exception_header_from_ue (exc_obj);
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const unsigned char *xh_lsda;
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_Unwind_Sword xh_switch_value;
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std::terminate_handler xh_terminate_handler;
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// If the unexpectedHandler rethrows the exception (e.g. to categorize it),
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// it will clobber data about the current handler. So copy the data out now.
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xh_lsda = xh->languageSpecificData;
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xh_switch_value = xh->handlerSwitchValue;
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xh_terminate_handler = xh->terminateHandler;
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info.ttype_base = (_Unwind_Ptr) xh->catchTemp;
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try
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{ __unexpected (xh->unexpectedHandler); }
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catch(...)
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{
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// Get the exception thrown from unexpected.
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// ??? Foreign exceptions can't be stacked this way.
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__cxa_eh_globals *globals = __cxa_get_globals_fast ();
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__cxa_exception *new_xh = globals->caughtExceptions;
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void *new_ptr = new_xh + 1;
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// We don't quite have enough stuff cached; re-parse the LSDA.
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parse_lsda_header (0, xh_lsda, &info);
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// If this new exception meets the exception spec, allow it.
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if (check_exception_spec (&info, new_xh->exceptionType,
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new_ptr, xh_switch_value))
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__throw_exception_again;
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// If the exception spec allows std::bad_exception, throw that.
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// We don't have a thrown object to compare against, but since
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// bad_exception doesn't have virtual bases, that's OK; just pass 0.
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#ifdef __EXCEPTIONS
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const std::type_info &bad_exc = typeid (std::bad_exception);
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if (check_exception_spec (&info, &bad_exc, 0, xh_switch_value))
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throw std::bad_exception();
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#endif
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// Otherwise, die.
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__terminate (xh_terminate_handler);
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}
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}
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