source: branches/libc-0.6/src/gcc/libobjc/gc.c@ 2816

/* Basic data types for Objective C.
   Copyright (C) 1998, 2002 Free Software Foundation, Inc.
   Contributed by Ovidiu Predescu.

This file is part of GNU CC.

GNU CC 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.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* As a special exception, if you link this library with files
   compiled with GCC to produce an executable, this does not 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 "tconfig.h"
#include "objc.h"
#include "encoding.h"

#include <assert.h>
#include <string.h>

#if OBJC_WITH_GC

#include <gc.h>

/* gc_typed.h uses the following but doesn't declare them */
typedef GC_word word;
typedef GC_signed_word signed_word;

#if BITS_PER_WORD == 32
# define LOGWL  5
# define modWORDSZ(n) ((n) & 0x1f)        /* n mod size of word     */
#endif

#if BITS_PER_WORD == 64
# define LOGWL 6
# define modWORDSZ(n) ((n) & 0x3f)        /* n mod size of word     */
#endif

#define divWORDSZ(n) ((n) >> LOGWL)        /* divide n by size of word      */

#include <gc_typed.h>

/* The following functions set up in `mask` the corresponding pointers.
   The offset is incremented with the size of the type.  */

#define ROUND(V, A) \
  ({ typeof (V) __v = (V); typeof (A) __a = (A); \
     __a * ((__v+__a - 1)/__a); })

#define SET_BIT_FOR_OFFSET(mask, offset) \
  GC_set_bit (mask, offset / sizeof (void *))

/* Some prototypes */
static void
__objc_gc_setup_struct (GC_bitmap mask, const char *type, int offset);
static void
__objc_gc_setup_union (GC_bitmap mask, const char *type, int offset);


static void
__objc_gc_setup_array (GC_bitmap mask, const char *type, int offset)
{
  int i, len = atoi (type + 1);

  while (isdigit (*++type))
    /* do nothing */;           /* skip the size of the array */

  switch (*type) {
  case _C_ARY_B:
    for (i = 0; i < len; i++)
      __objc_gc_setup_array (mask, type, offset);
    break;

  case _C_STRUCT_B:
    for (i = 0; i < len; i++)
      __objc_gc_setup_struct (mask, type, offset);
    break;

  case _C_UNION_B:
    for (i = 0; i < len; i++)
      __objc_gc_setup_union (mask, type, offset);
    break;

  default:
    break;
  }
}

static void
__objc_gc_setup_struct (GC_bitmap mask, const char *type, int offset)
{
  struct objc_struct_layout layout;
  unsigned int position;
  const char *mtype;

  objc_layout_structure (type, &layout);

  while (objc_layout_structure_next_member (&layout))
    {
      BOOL gc_invisible = NO;

      objc_layout_structure_get_info (&layout, &position, NULL, &mtype);

      /* Skip the variable name */
      if (*mtype == '"')
        {
          for (mtype++; *mtype++ != '"';)
            /* do nothing */;
        }

      if (*mtype == _C_GCINVISIBLE)
        {
          gc_invisible = YES;
          mtype++;
        }

      /* Add to position the offset of this structure */
      position += offset;

      switch (*mtype) {
      case _C_ID:
      case _C_CLASS:
      case _C_SEL:
      case _C_PTR:
      case _C_CHARPTR:
      case _C_ATOM:
        if (! gc_invisible)
          SET_BIT_FOR_OFFSET (mask, position);
        break;

      case _C_ARY_B:
        __objc_gc_setup_array (mask, mtype, position);
        break;

      case _C_STRUCT_B:
        __objc_gc_setup_struct (mask, mtype, position);
        break;

      case _C_UNION_B:
        __objc_gc_setup_union (mask, mtype, position);
        break;

      default:
        break;
      }
    }
}

static void
__objc_gc_setup_union (GC_bitmap mask, const char *type, int offset)
{
  /* Sub-optimal, quick implementation: assume the union is made of
     pointers, set up the mask accordingly. */

  int i, size, align;

  /* Skip the variable name */
  if (*type == '"')
    {
      for (type++; *type++ != '"';)
        /* do nothing */;
    }

  size = objc_sizeof_type (type);
  align = objc_alignof_type (type);

  offset = ROUND (offset, align);
  for (i = 0; i < size; i += sizeof (void *))
    {
      SET_BIT_FOR_OFFSET (mask, offset);
      offset += sizeof (void *);
    }
}


/* Iterates over the types in the structure that represents the class
   encoding and sets the bits in mask according to each ivar type.  */
static void
__objc_gc_type_description_from_type (GC_bitmap mask, const char *type)
{
  struct objc_struct_layout layout;
  unsigned int offset, align;
  const char *ivar_type;

  objc_layout_structure (type, &layout);

  while (objc_layout_structure_next_member (&layout))
    {
      BOOL gc_invisible = NO;

      objc_layout_structure_get_info (&layout, &offset, &align, &ivar_type);

      /* Skip the variable name */
      if (*ivar_type == '"')
        {
          for (ivar_type++; *ivar_type++ != '"';)
            /* do nothing */;
        }

      if (*ivar_type == _C_GCINVISIBLE)
        {
          gc_invisible = YES;
          ivar_type++;
        }

      switch (*ivar_type) {
      case _C_ID:
      case _C_CLASS:
      case _C_SEL:
      case _C_PTR:
      case _C_CHARPTR:
        if (! gc_invisible)
          SET_BIT_FOR_OFFSET (mask, offset);
        break;

      case _C_ARY_B:
        __objc_gc_setup_array (mask, ivar_type, offset);
        break;

      case _C_STRUCT_B: