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/* Supporting functions for C exception handling.

   Copyright (C) 2002, 2003, 2009 Free Software Foundation, Inc.

   Contributed by Aldy Hernandez <aldy@quesejoda.com>.

   Shamelessly stolen from the Java front end.

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 3, 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.

Under Section 7 of GPL version 3, you are granted additional

permissions described in the GCC Runtime Library Exception, version

3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and

a copy of the GCC Runtime Library Exception along with this program;

see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

<http://www.gnu.org/licenses/>.  */

#include "tconfig.h"

#include "tsystem.h"

#include "unwind.h"

#define NO_SIZE_OF_ENCODED_VALUE

#include "unwind-pe.h"

typedef struct

{

  _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;

} lsda_header_info;

static const unsigned char *

parse_lsda_header (struct _Unwind_Context *context, const unsigned char *p,

                   lsda_header_info *info)

{

  _uleb128_t 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;

}

#ifdef __ARM_EABI_UNWINDER__

/* ARM EABI personality routines must also unwind the stack.  */

#define CONTINUE_UNWINDING \

  do                                                            \

    {                                                           \

      if (__gnu_unwind_frame (ue_header, context) != _URC_OK)   \

        return _URC_FAILURE;                                    \

      return _URC_CONTINUE_UNWIND;                              \

    }                                                           \

  while (0)

#else

#define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND

#endif

#ifdef __USING_SJLJ_EXCEPTIONS__

#define PERSONALITY_FUNCTION    __gcc_personality_sj0

#define __builtin_eh_return_data_regno(x) x

#else

#define PERSONALITY_FUNCTION    __gcc_personality_v0

#endif

#ifdef __ARM_EABI_UNWINDER__

_Unwind_Reason_Code

PERSONALITY_FUNCTION (_Unwind_State, struct _Unwind_Exception *,

                      struct _Unwind_Context *);

_Unwind_Reason_Code

PERSONALITY_FUNCTION (_Unwind_State state,

                      struct _Unwind_Exception * ue_header,

                      struct _Unwind_Context * context)

#else

_Unwind_Reason_Code

PERSONALITY_FUNCTION (int, _Unwind_Action, _Unwind_Exception_Class,

                      struct _Unwind_Exception *, struct _Unwind_Context *);

_Unwind_Reason_Code

PERSONALITY_FUNCTION (int version,

                      _Unwind_Action actions,

                      _Unwind_Exception_Class exception_class ATTRIBUTE_UNUSED,

                      struct _Unwind_Exception *ue_header,

                      struct _Unwind_Context *context)

#endif

{

  lsda_header_info info;

  const unsigned char *language_specific_data, *p;

  _Unwind_Ptr landing_pad, ip;

  int ip_before_insn = 0;

#ifdef __ARM_EABI_UNWINDER__

  if ((state & _US_ACTION_MASK) != _US_UNWIND_FRAME_STARTING)

    CONTINUE_UNWINDING;

  /* The dwarf unwinder assumes the context structure holds things like the

     function and LSDA pointers.  The ARM implementation caches these in

     the exception header (UCB).  To avoid rewriting everything we make a

     virtual scratch register point at the UCB.  */

  ip = (_Unwind_Ptr) ue_header;

  _Unwind_SetGR (context, UNWIND_POINTER_REG, ip);

#else

  if (version != 1)

    return _URC_FATAL_PHASE1_ERROR;

  /* Currently we only support cleanups for C.  */

  if ((actions & _UA_CLEANUP_PHASE) == 0)

    CONTINUE_UNWINDING;

#endif

  language_specific_data = (const unsigned char *)

    _Unwind_GetLanguageSpecificData (context);

  /* If no LSDA, then there are no handlers or cleanups.  */

  if (! language_specific_data)

    CONTINUE_UNWINDING;

  /* Parse the LSDA header.  */

  p = parse_lsda_header (context, language_specific_data, &info);

#ifdef HAVE_GETIPINFO

  ip = _Unwind_GetIPInfo (context, &ip_before_insn);

#else

  ip = _Unwind_GetIP (context);

#endif

  if (! ip_before_insn)

    --ip;

  landing_pad = 0;

#ifdef __USING_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

    {

      _uleb128_t 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 = (_Unwind_Ptr)cs_lp + 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;

      _uleb128_t 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;

          goto found_something;

        }

    }

#endif

  /* IP is not in table.  No associated cleanups.  */

  /* ??? This is where C++ calls std::terminate to catch throw

     from a destructor.  */

  CONTINUE_UNWINDING;

 found_something:

  if (landing_pad == 0)

    {

      /* IP is present, but has a null landing pad.

         No handler to be run.  */

      CONTINUE_UNWINDING;

    }

  _Unwind_SetGR (context, __builtin_eh_return_data_regno (0),

                 (_Unwind_Ptr) ue_header);

  _Unwind_SetGR (context, __builtin_eh_return_data_regno (1), 0);

  _Unwind_SetIP (context, landing_pad);

  return _URC_INSTALL_CONTEXT;

}