src/libdw/dwarf_aggregate_size.c

/* Compute size of an aggregate type from DWARF.
   Copyright (C) 2010 Red Hat, Inc.
   This file is part of Red Hat elfutils.

   Red Hat elfutils 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; version 2 of the License.

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   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 Red Hat elfutils; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

   In addition, as a special exception, Red Hat, Inc. gives You the
   additional right to link the code of Red Hat elfutils with code licensed
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   this file solely under the GPL without exception.

   Red Hat elfutils is an included package of the Open Invention Network.
   An included package of the Open Invention Network is a package for which
   Open Invention Network licensees cross-license their patents.  No patent
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#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <dwarf.h>
#include "libdwP.h"


static Dwarf_Die *
get_type (Dwarf_Die *die, Dwarf_Attribute *attr_mem, Dwarf_Die *type_mem)
{
  return INTUSE(dwarf_formref_die)
    (INTUSE(dwarf_attr_integrate) (die, DW_AT_type, attr_mem), type_mem);
}

static int
array_size (Dwarf_Die *die, Dwarf_Word *size,
	    Dwarf_Attribute *attr_mem, Dwarf_Die *type_mem)
{
  Dwarf_Word eltsize;
  if (INTUSE(dwarf_aggregate_size) (get_type (die, attr_mem, type_mem),
				    &eltsize) != 0)
      return -1;

  /* An array can have DW_TAG_subrange_type or DW_TAG_enumeration_type
     children instead that give the size of each dimension.  */

  Dwarf_Die child;
  if (INTUSE(dwarf_child) (die, &child) != 0)
    return -1;

  bool any = false;
  Dwarf_Word total = 0;
  do
    {
      Dwarf_Word count;
      switch (INTUSE(dwarf_tag) (&child))
	{
	case DW_TAG_subrange_type:
	  /* This has either DW_AT_count or DW_AT_upper_bound.  */
	  if (INTUSE(dwarf_attr_integrate) (&child, DW_AT_count,
					    attr_mem) != NULL)
	    {
	      if (INTUSE(dwarf_formudata) (attr_mem, &count) != 0)
		return -1;
	    }
	  else
	    {
	      Dwarf_Sword upper;
	      Dwarf_Sword lower;
	      if (INTUSE(dwarf_formsdata) (INTUSE(dwarf_attr_integrate)
					   (&child, DW_AT_upper_bound,
					    attr_mem), &upper) != 0)
		return -1;

	      /* Having DW_AT_lower_bound is optional.  */
	      if (INTUSE(dwarf_attr_integrate) (&child, DW_AT_lower_bound,
						attr_mem) != NULL)
		{
		  if (INTUSE(dwarf_formsdata) (attr_mem, &lower) != 0)
		    return -1;
		}
	      else
		{
		  /* Determine default lower bound from language,
		     as per "4.12 Subrange Type Entries".  */
		  Dwarf_Die cu = CUDIE (die->cu);
		  switch (INTUSE(dwarf_srclang) (&cu))
		    {
		    case DW_LANG_C:
		    case DW_LANG_C89:
		    case DW_LANG_C99:
		    case DW_LANG_C_plus_plus:
		    case DW_LANG_Objc:
		    case DW_LANG_ObjC_plus_plus:
		    case DW_LANG_Java:
		    case DW_LANG_D:
		    case DW_LANG_UPC:
		      lower = 0;
		      break;

		    case DW_LANG_Ada83:
		    case DW_LANG_Ada95:
		    case DW_LANG_Cobol74:
		    case DW_LANG_Cobol85:
		    case DW_LANG_Fortran77:
		    case DW_LANG_Fortran90:
		    case DW_LANG_Fortran95:
		    case DW_LANG_Pascal83:
		    case DW_LANG_Modula2:
		    case DW_LANG_PL1:
		      lower = 1;
		      break;

		    default:
		      return -1;
		    }
		}
	      if (unlikely (lower > upper))
		return -1;
	      count = upper - lower + 1;
	    }
	  break;

	case DW_TAG_enumeration_type:
	  /* We have to find the DW_TAG_enumerator child with the
	     highest value to know the array's element count.  */
	  count = 0;
	  Dwarf_Die enum_child;
	  int has_children = INTUSE(dwarf_child) (die, &enum_child);
	  if (has_children < 0)
	    return -1;
	  if (has_children > 0)
	    do
	      if (INTUSE(dwarf_tag) (&enum_child) == DW_TAG_enumerator)
		{
		  Dwarf_Word value;
		  if (INTUSE(dwarf_formudata) (INTUSE(dwarf_attr_integrate)
					       (&enum_child, DW_AT_const_value,
						attr_mem), &value) != 0)
		    return -1;
		  if (value >= count)
		    count = value + 1;
		}
	    while (INTUSE(dwarf_siblingof) (&enum_child, &enum_child) > 0);
	  break;

	default:
	  continue;
	}

      /* This is a subrange_type or enumeration_type and we've set COUNT.
	 Now determine the stride for this array dimension.  */
      Dwarf_Word stride = eltsize;
      if (INTUSE(dwarf_attr_integrate) (&child, DW_AT_byte_stride,
					attr_mem) != NULL)
	{
	  if (INTUSE(dwarf_formudata) (attr_mem, &stride) != 0)
	    return -1;
	}
      else if (INTUSE(dwarf_attr_integrate) (&child, DW_AT_bit_stride,
					     attr_mem) != NULL)
	{
	  if (INTUSE(dwarf_formudata) (attr_mem, &stride) != 0)
	    return -1;
	  if (stride % 8) 	/* XXX maybe compute in bits? */
	    return -1;
	  stride /= 8;
	}

      any = true;
      total += stride * count;
    }
  while (INTUSE(dwarf_siblingof) (&child, &child) == 0);

  if (!any)
    return -1;

  *size = total;
  return 0;
}

static int
aggregate_size (Dwarf_Die *die, Dwarf_Word *size, Dwarf_Die *type_mem)
{
  Dwarf_Attribute attr_mem;

  if (INTUSE(dwarf_attr_integrate) (die, DW_AT_byte_size, &attr_mem) != NULL)
    return INTUSE(dwarf_formudata) (&attr_mem, size);

  switch (INTUSE(dwarf_tag) (die))
    {
    case DW_TAG_typedef:
    case DW_TAG_subrange_type:
      return aggregate_size (get_type (die, &attr_mem, type_mem),
			     size, type_mem); /* Tail call.  */

    case DW_TAG_array_type:
      return array_size (die, size, &attr_mem, type_mem);
    }

  /* Most types must give their size directly.  */
  return -1;
}

int
dwarf_aggregate_size (die, size)
     Dwarf_Die *die;
     Dwarf_Word *size;
{
  Dwarf_Die type_mem;
  return aggregate_size (die, size, &type_mem);
}
INTDEF (dwarf_aggregate_size)