eh_arm.cc   [plain text]

// -*- C++ -*- ARM specific Exception handling support routines.
// Copyright (C) 2004, 2005 Free Software Foundation, Inc.
//
// This file is part of GCC.
//
// GCC is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// GCC is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with GCC; see the file COPYING.  If not, write to
// the Free Software Foundation, 51 Franklin Street, Fifth Floor,
// Boston, MA 02110-1301, USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

#include <cxxabi.h>
#include "unwind-cxx.h"

#ifdef __ARM_EABI_UNWINDER__

using namespace __cxxabiv1;


// Given the thrown type THROW_TYPE, pointer to a variable containing a
// pointer to the exception object THROWN_PTR_P and a type CATCH_TYPE to
// compare against, return whether or not there is a match and if so,
// update *THROWN_PTR_P.

extern "C" __cxa_type_match_result
__cxa_type_match(_Unwind_Exception* ue_header,
		 const std::type_info* catch_type,
		 bool is_reference __attribute__((__unused__)),
		 void** thrown_ptr_p)
{
  if (!__is_gxx_exception_class(ue_header->exception_class))
    return ctm_failed;

  __cxa_exception* xh = __get_exception_header_from_ue(ue_header);
  const std::type_info* throw_type = xh->exceptionType;
  void* thrown_ptr = *thrown_ptr_p;

  // Pointer types need to adjust the actual pointer, not
  // the pointer to pointer that is the exception object.
  // This also has the effect of passing pointer types
  // "by value" through the __cxa_begin_catch return value.
  if (throw_type->__is_pointer_p())
    thrown_ptr = *(void**) thrown_ptr;

  if (catch_type->__do_catch(throw_type, &thrown_ptr, 1))
    {
      *thrown_ptr_p = thrown_ptr;

      if (typeid(*catch_type) == typeid (typeid(void*)))
	{
	  const __pointer_type_info *catch_pointer_type =
	    static_cast<const __pointer_type_info *> (catch_type);
	  const __pointer_type_info *throw_pointer_type =
	    static_cast<const __pointer_type_info *> (throw_type);

	  if (typeid (*catch_pointer_type->__pointee) != typeid (void)
	      && (*catch_pointer_type->__pointee != 
		  *throw_pointer_type->__pointee))
	    return ctm_succeeded_with_ptr_to_base;
	}

      return ctm_succeeded;
    }

  return ctm_failed;
}

// ABI defined routine called at the start of a cleanup handler.
extern "C" bool
__cxa_begin_cleanup(_Unwind_Exception* ue_header)
{
  __cxa_eh_globals *globals = __cxa_get_globals();
  __cxa_exception *header = __get_exception_header_from_ue(ue_header);
  bool native = __is_gxx_exception_class(header->unwindHeader.exception_class);


  if (native)
    {
      header->propagationCount++;
      // Add it to the chain if this is the first time we've seen this
      // exception.
      if (header->propagationCount == 1)
	{
	  header->nextPropagatingException = globals->propagatingExceptions;
	  globals->propagatingExceptions = header;
	}
    }
  else
    {
      // Remember the exception object, so end_cleanup can return it.
      // These cannot be stacked, so we must abort if we already have
      // a propagating exception.
      if (globals->propagatingExceptions)
	std::terminate ();
      globals->propagatingExceptions = header;
    }

  return true;
}

// Do the work for __cxa_end_cleanup.  Returns the currently propagating
// exception object.
extern "C" _Unwind_Exception *
__gnu_end_cleanup(void)
{
  __cxa_exception *header;
  __cxa_eh_globals *globals = __cxa_get_globals();

  header = globals->propagatingExceptions;

  // Check something hasn't gone horribly wrong.
  if (!header)
    std::terminate();

  if (__is_gxx_exception_class(header->unwindHeader.exception_class))
    {
      header->propagationCount--;
      if (header->propagationCount == 0)
	{
	  // Remove exception from chain.
	  globals->propagatingExceptions = header->nextPropagatingException;
	  header->nextPropagatingException = NULL;
	}
    }
  else
    globals->propagatingExceptions = NULL;

  return &header->unwindHeader;
}

// Assembly wrapper to call __gnu_end_cleanup without clobbering r1-r3.
// Also push r4 to preserve stack alignment.
#ifdef __thumb__
asm (".global __cxa_end_cleanup\n"
"	.type __cxa_end_cleanup, \"function\"\n"
"	.thumb_func\n"
"__cxa_end_cleanup:\n"
"	push\t{r1, r2, r3, r4}\n"
"	bl\t__gnu_end_cleanup\n"
"	pop\t{r1, r2, r3, r4}\n"
"	bl\t_Unwind_Resume @ Never returns\n");
#else
asm (".global __cxa_end_cleanup\n"
"	.type __cxa_end_cleanup, \"function\"\n"
"__cxa_end_cleanup:\n"
"	stmfd\tsp!, {r1, r2, r3, r4}\n"
"	bl\t__gnu_end_cleanup\n"
"	ldmfd\tsp!, {r1, r2, r3, r4}\n"
"	bl\t_Unwind_Resume @ Never returns\n");
#endif

#endif