196 lines
6.0 KiB
C
196 lines
6.0 KiB
C
/* Supporting functions for C exception handling.
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Copyright (C) 2002, 2003 Free Software Foundation, Inc.
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Contributed by Aldy Hernandez <aldy@quesejoda.com>.
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Shamelessly stolen from the Java front end.
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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 under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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In addition to the permissions in the GNU General Public License, the
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Free Software Foundation gives you unlimited permission to link the
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compiled version of this file into combinations with other programs,
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and to distribute those combinations without any restriction coming
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from the use of this file. (The General Public License restrictions
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do apply in other respects; for example, they cover modification of
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the file, and distribution when not linked into a combined
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executable.)
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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#include "tconfig.h"
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#include "tsystem.h"
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#include "unwind.h"
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#define NO_SIZE_OF_ENCODED_VALUE
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#include "unwind-pe.h"
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typedef struct
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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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} lsda_header_info;
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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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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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#ifdef __USING_SJLJ_EXCEPTIONS__
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#define PERSONALITY_FUNCTION __gcc_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 __gcc_personality_v0
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#endif
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_Unwind_Reason_Code
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PERSONALITY_FUNCTION (int, _Unwind_Action, _Unwind_Exception_Class,
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struct _Unwind_Exception *, struct _Unwind_Context *);
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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 ATTRIBUTE_UNUSED,
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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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lsda_header_info info;
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const unsigned char *language_specific_data, *p, *action_record;
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_Unwind_Ptr landing_pad, ip;
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if (version != 1)
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return _URC_FATAL_PHASE1_ERROR;
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/* Currently we only support cleanups for C. */
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if ((actions & _UA_CLEANUP_PHASE) == 0)
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return _URC_CONTINUE_UNWIND;
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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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ip = _Unwind_GetIP (context) - 1;
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landing_pad = 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
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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
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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
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/* IP is not in table. No associated cleanups. */
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/* ??? This is where C++ calls std::terminate to catch throw
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from a destructor. */
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return _URC_CONTINUE_UNWIND;
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found_something:
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if (landing_pad == 0)
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{
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/* IP is present, but has a null landing pad.
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No handler to be run. */
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return _URC_CONTINUE_UNWIND;
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}
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_Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
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(_Unwind_Ptr) ue_header);
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_Unwind_SetGR (context, __builtin_eh_return_data_regno (1), 0);
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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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