dwarfread.c

早期freebsd实现

  
  /* Decode the type that this subroutine returns */

  type = decode_die_type (dip);

  /* Check to see if we already have a partially constructed user
     defined type for this DIE, from a forward reference. */

  if ((ftype = lookup_utype (dip -> die_ref)) == NULL)
    {
      /* This is the first reference to one of these types.  Make
	 a new one and place it in the user defined types. */
      ftype = lookup_function_type (type);
      alloc_utype (dip -> die_ref, ftype);
    }
  else
    {
      /* We have an existing partially constructed type, so bash it
	 into the correct type. */
      TYPE_TARGET_TYPE (ftype) = type;
      TYPE_FUNCTION_TYPE (type) = ftype;
      TYPE_LENGTH (ftype) = 1;
      TYPE_CODE (ftype) = TYPE_CODE_FUNC;
    }
}

/*

LOCAL FUNCTION

	read_enumeration -- process dies which define an enumeration

SYNOPSIS

	static void read_enumeration (struct dieinfo *dip, char *thisdie,
		char *enddie, struct objfile *objfile)

DESCRIPTION

	Given a pointer to a die which begins an enumeration, process all
	the dies that define the members of the enumeration.

NOTES

	Note that we need to call enum_type regardless of whether or not we
	have a symbol, since we might have an enum without a tag name (thus
	no symbol for the tagname).
 */

static void
read_enumeration (dip, thisdie, enddie, objfile)
     struct dieinfo *dip;
     char *thisdie;
     char *enddie;
     struct objfile *objfile;
{
  struct type *type;
  struct symbol *sym;
  
  type = enum_type (dip, objfile);
  sym = new_symbol (dip, objfile);
  if (sym != NULL)
    {
      SYMBOL_TYPE (sym) = type;
      if (cu_language == language_cplus)
	{
	  synthesize_typedef (dip, objfile, type);
	}
    }
}

/*

LOCAL FUNCTION

	enum_type -- decode and return a type for an enumeration

SYNOPSIS

	static type *enum_type (struct dieinfo *dip, struct objfile *objfile)

DESCRIPTION

	Given a pointer to a die information structure for the die which
	starts an enumeration, process all the dies that define the members
	of the enumeration and return a type pointer for the enumeration.

	At the same time, for each member of the enumeration, create a
	symbol for it with namespace VAR_NAMESPACE and class LOC_CONST,
	and give it the type of the enumeration itself.

NOTES

	Note that the DWARF specification explicitly mandates that enum
	constants occur in reverse order from the source program order,
	for "consistency" and because this ordering is easier for many
	compilers to generate. (Draft 6, sec 3.8.5, Enumeration type
	Entries).  Because gdb wants to see the enum members in program
	source order, we have to ensure that the order gets reversed while
	we are processing them.
 */

static struct type *
enum_type (dip, objfile)
     struct dieinfo *dip;
     struct objfile *objfile;
{
  struct type *type;
  struct nextfield {
    struct nextfield *next;
    struct field field;
  };
  struct nextfield *list = NULL;
  struct nextfield *new;
  int nfields = 0;
  int n;
  char *scan;
  char *listend;
  unsigned short blocksz;
  struct symbol *sym;
  int nbytes;
  
  if ((type = lookup_utype (dip -> die_ref)) == NULL)
    {
      /* No forward references created an empty type, so install one now */
      type = alloc_utype (dip -> die_ref, NULL);
    }
  TYPE_CODE (type) = TYPE_CODE_ENUM;
  /* Some compilers try to be helpful by inventing "fake" names for
     anonymous enums, structures, and unions, like "~0fake" or ".0fake".
     Thanks, but no thanks... */
  if (dip -> at_name != NULL
      && *dip -> at_name != '~'
      && *dip -> at_name != '.')
    {
      TYPE_NAME (type) = obconcat (&objfile -> type_obstack, "enum",
				   " ", dip -> at_name);
    }
  if (dip -> at_byte_size != 0)
    {
      TYPE_LENGTH (type) = dip -> at_byte_size;
    }
  if ((scan = dip -> at_element_list) != NULL)
    {
      if (dip -> short_element_list)
	{
	  nbytes = attribute_size (AT_short_element_list);
	}
      else
	{
	  nbytes = attribute_size (AT_element_list);
	}
      blocksz = target_to_host (scan, nbytes, GET_UNSIGNED, objfile);
      listend = scan + nbytes + blocksz;
      scan += nbytes;
      while (scan < listend)
	{
	  new = (struct nextfield *) alloca (sizeof (struct nextfield));
	  new -> next = list;
	  list = new;
	  list -> field.type = NULL;
	  list -> field.bitsize = 0;
	  list -> field.bitpos =
	    target_to_host (scan, TARGET_FT_LONG_SIZE (objfile), GET_SIGNED,
			    objfile);
	  scan += TARGET_FT_LONG_SIZE (objfile);
	  list -> field.name = obsavestring (scan, strlen (scan),
					     &objfile -> type_obstack);
	  scan += strlen (scan) + 1;
	  nfields++;
	  /* Handcraft a new symbol for this enum member. */
	  sym = (struct symbol *) obstack_alloc (&objfile->symbol_obstack,
						 sizeof (struct symbol));
	  memset (sym, 0, sizeof (struct symbol));
	  SYMBOL_NAME (sym) = create_name (list -> field.name,
					   &objfile->symbol_obstack);
	  SYMBOL_NAMESPACE (sym) = VAR_NAMESPACE;
	  SYMBOL_CLASS (sym) = LOC_CONST;
	  SYMBOL_TYPE (sym) = type;
	  SYMBOL_VALUE (sym) = list -> field.bitpos;
	  add_symbol_to_list (sym, list_in_scope);
	}
      /* Now create the vector of fields, and record how big it is. This is
	 where we reverse the order, by pulling the members off the list in
	 reverse order from how they were inserted.  If we have no fields
	 (this is apparently possible in C++) then skip building a field
	 vector. */
      if (nfields > 0)
	{
	  TYPE_NFIELDS (type) = nfields;
	  TYPE_FIELDS (type) = (struct field *)
	    obstack_alloc (&objfile->symbol_obstack, sizeof (struct field) * nfields);
	  /* Copy the saved-up fields into the field vector.  */
	  for (n = 0; (n < nfields) && (list != NULL); list = list -> next)
	    {
	      TYPE_FIELD (type, n++) = list -> field;
	    }	
	}
    }
  return (type);
}

/*

LOCAL FUNCTION

	read_func_scope -- process all dies within a function scope

DESCRIPTION

	Process all dies within a given function scope.  We are passed
	a die information structure pointer DIP for the die which
	starts the function scope, and pointers into the raw die data
	that define the dies within the function scope.

	For now, we ignore lexical block scopes within the function.
	The problem is that AT&T cc does not define a DWARF lexical
	block scope for the function itself, while gcc defines a
	lexical block scope for the function.  We need to think about
	how to handle this difference, or if it is even a problem.
	(FIXME)
 */

static void
read_func_scope (dip, thisdie, enddie, objfile)
     struct dieinfo *dip;
     char *thisdie;
     char *enddie;
     struct objfile *objfile;
{
  register struct context_stack *new;
  
  if (objfile -> ei.entry_point >= dip -> at_low_pc &&
      objfile -> ei.entry_point <  dip -> at_high_pc)
    {
      objfile -> ei.entry_func_lowpc = dip -> at_low_pc;
      objfile -> ei.entry_func_highpc = dip -> at_high_pc;
    }
  if (STREQ (dip -> at_name, "main"))	/* FIXME: hardwired name */
    {
      objfile -> ei.main_func_lowpc = dip -> at_low_pc;
      objfile -> ei.main_func_highpc = dip -> at_high_pc;
    }
  new = push_context (0, dip -> at_low_pc);
  new -> name = new_symbol (dip, objfile);
  list_in_scope = &local_symbols;
  process_dies (thisdie + dip -> die_length, enddie, objfile);
  new = pop_context ();
  /* Make a block for the local symbols within.  */
  finish_block (new -> name, &local_symbols, new -> old_blocks,
		new -> start_addr, dip -> at_high_pc, objfile);
  list_in_scope = &file_symbols;
}


/*

LOCAL FUNCTION

	handle_producer -- process the AT_producer attribute

DESCRIPTION

	Perform any operations that depend on finding a particular
	AT_producer attribute.

 */

static void
handle_producer (producer)
     char *producer;
{

  /* If this compilation unit was compiled with g++ or gcc, then set the
     processing_gcc_compilation flag. */

  processing_gcc_compilation =
    STREQN (producer, GPLUS_PRODUCER, strlen (GPLUS_PRODUCER))
      || STREQN (producer, GCC_PRODUCER, strlen (GCC_PRODUCER));

  /* Select a demangling style if we can identify the producer and if
     the current style is auto.  We leave the current style alone if it
     is not auto.  We also leave the demangling style alone if we find a
     gcc (cc1) producer, as opposed to a g++ (cc1plus) producer. */

#if 1 /* Works, but is experimental.  -fnf */
  if (AUTO_DEMANGLING)
    {
      if (STREQN (producer, GPLUS_PRODUCER, strlen (GPLUS_PRODUCER)))
	{
	  set_demangling_style (GNU_DEMANGLING_STYLE_STRING);
	}
      else if (STREQN (producer, LCC_PRODUCER, strlen (LCC_PRODUCER)))
	{
	  set_demangling_style (LUCID_DEMANGLING_STYLE_STRING);
	}
      else if (STREQN (producer, CFRONT_PRODUCER, strlen (CFRONT_PRODUCER)))
	{
	  set_demangling_style (CFRONT_DEMANGLING_STYLE_STRING);
	}
    }
#endif
}


/*

LOCAL FUNCTION

	read_file_scope -- process all dies within a file scope

DESCRIPTION

	Process all dies within a given file scope.  We are passed a
	pointer to the die information structure for the die which
	starts the file scope, and pointers into the raw die data which
	mark the range of dies within the file scope.

	When the partial symbol table is built, the file offset for the line
	number table for each compilation unit is saved in the partial symbol
	table entry for that compilation unit.  As the symbols for each
	compilation unit are read, the line number table is read into memory
	and the variable lnbase is set to point to it.  Thus all we have to
	do is use lnbase to access the line number table for the current
	compilation unit.
 */

static void
read_file_scope (dip, thisdie, enddie, objfile)
     struct dieinfo *dip;
     char *thisdie;
     char *enddie;
     struct objfile *objfile;
{
  struct cleanup *back_to;
  struct symtab *symtab;
  
  if (objfile -> ei.entry_point >= dip -> at_low_pc &&
      objfile -> ei.entry_point <  dip -> at_high_pc)
    {
      objfile -> ei.entry_file_lowpc = dip -> at_low_pc;
      objfile -> ei.entry_file_highpc = dip -> at_high_pc;
    }
  set_cu_language (dip);
  if (dip -> at_producer != NULL)
    {
      handle_producer (dip -> at_producer);
    }
  numutypes = (enddie - thisdie) / 4;
  utypes = (struct type **) xmalloc (numutypes * sizeof (struct type *));
  back_to = make_cleanup (free, utypes);
  memset (utypes, 0, numutypes * sizeof (struct type *));
  start_symtab (dip -> at_name, dip -> at_comp_dir, dip -> at_low_pc);
  decode_line_numbers (lnbase);
  process_dies (thisdie + dip -> die_length, enddie, objfile);
  symtab = end_symtab (dip -> at_high_pc, 0, 0, objfile);
  if (symtab != NULL)
    {
      symtab -> language = cu_language;
    }      
  do_cleanups (back_to);
  utypes = NULL;
  numutypes = 0;
}

/*

LOCAL FUNCTION

	process_dies -- process a range of DWARF Information Entries

SYNOPSIS

	static void process_dies (char *thisdie, char *enddie,
				  struct objfile *objfile)

DESCRIPTION

	Process all DIE's in a specified range.  May be (and almost
	certainly will be) called recursively.
 */

static void
process_dies (thisdie, enddie, objfile)
     char *thisdie;
     char *enddie;
     struct objfile *objfile;
{
  char *nextdie;
  struct dieinfo di;
  
  while (thisdie < enddie)
    {
      basicdieinfo (&di, thisdie, objfile);
      if (di.die_length < SIZEOF_DIE_LENGTH)
	{
	  break;
	}
      else if (di.die_tag == TAG_padding)
	{
	  nextdie = thisdie + di.die_length;
	}
      else
	{
	  completedieinfo (&di, objfile);
	  if (di.at_sibling != 0)
	    {
	      nextdie = dbbase + di.at_sibling - dbroff;
	    }
	  else
	    {
	      nextdie = thisdie + di.die_length;
	    }
	  switch (di.die_tag)
	    {
	    case TAG_compile_unit:
	      read_file_scope (&di, thisdie, nextdie, objfile);
	      break;
	    case TAG_global_subroutine:
	    case TAG_subroutine:
	      if (di.has_at_low_pc)
		{
		  read_func_scope (&di, thisdie, nextdie, objfile);
		}
	      break;
	    case TAG_lexical_block:
	      read_lexical_block_scope (&di, thisdie, nextdie, objfile);
	      break;
	    case TAG_class_type:
	    case TAG_structure_type:
	    case TAG_union_type:
	      read_structure_scope (&di, thisdie, nextdie, objfile);
	      break;
	    case TAG_enumeration_type:
	      read_enumeration (&di, thisdie, nextdie, objfile);
	      break;
	    case TAG_subroutine_type:
	      read_subroutine_type (&di, thisdie, nextdie);
	      break;
	    case TAG_array_type:
	      dwarf_read_array_type (&di);
	      break;
	    case TAG_pointer_type:
	      read_tag_pointer_type (&di);
	      break;
	    default:
	      new_symbol (&di, objfile);
	      break;
	    }
	}
      thisdie = nextdie;
    }
}

/*

LOCAL FUNCTION

	decode_line_numbers -- decode a line number table fragment

SYNOPSIS

	static void decode_line_numbers (char *tblscan, char *tblend,
		long length, long base, long line, long pc)