stor-layout.c

GUN开源阻止下的编译器GCC

	  /* A record which has any BLKmode members must itself be BLKmode;
	     it can't go in a register.
	     Unless the member is BLKmode only because it isn't aligned.  */
	  for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
	    {
	      int bitpos;

	      if (TREE_CODE (field) != FIELD_DECL)
		continue;

	      if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
		  && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
		goto record_lose;

	      if (TREE_CODE (DECL_FIELD_BITPOS (field)) != INTEGER_CST)
		goto record_lose;

	      bitpos = TREE_INT_CST_LOW (DECL_FIELD_BITPOS (field));

	      /* Must be BLKmode if any field crosses a word boundary,
		 since extract_bit_field can't handle that in registers.  */
	      if (bitpos / BITS_PER_WORD
		  != ((TREE_INT_CST_LOW (DECL_SIZE (field)) + bitpos - 1)
		      / BITS_PER_WORD)
		  /* But there is no problem if the field is entire words.  */
		  && TREE_INT_CST_LOW (DECL_SIZE (field)) % BITS_PER_WORD == 0)
		goto record_lose;
	    }

	  TYPE_MODE (type)
	    = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
			     MODE_INT, 1);

	  /* If structure's known alignment is less than
	     what the scalar mode would need, and it matters,
	     then stick with BLKmode.  */
	  if (STRICT_ALIGNMENT
	      && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
		    || (TYPE_ALIGN (type)
			>= TREE_INT_CST_LOW (TYPE_SIZE (type)))))
	    {
	      if (TYPE_MODE (type) != BLKmode)
		/* If this is the only reason this type is BLKmode,
		   then don't force containing types to be BLKmode.  */
		TYPE_NO_FORCE_BLK (type) = 1;
	      TYPE_MODE (type) = BLKmode;
	    }

	record_lose: ;
	}

      /* Lay out any static members.  This is done now
	 because their type may use the record's type.  */
      while (pending_statics)
	{
	  layout_decl (TREE_VALUE (pending_statics), 0);
	  pending_statics = TREE_CHAIN (pending_statics);
	}
      break;

    case UNION_TYPE:
    case QUAL_UNION_TYPE:
      layout_union (type);
      TYPE_MODE (type) = BLKmode;
      if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
	  /* If structure's known alignment is less than
	     what the scalar mode would need, and it matters,
	     then stick with BLKmode.  */
	  && (! STRICT_ALIGNMENT
	      || TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
	      || TYPE_ALIGN (type) >= TREE_INT_CST_LOW (TYPE_SIZE (type))))
	{
	  tree field;
	  /* A union which has any BLKmode members must itself be BLKmode;
	     it can't go in a register.
	     Unless the member is BLKmode only because it isn't aligned.  */
	  for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
	    {
	      if (TREE_CODE (field) != FIELD_DECL)
		continue;

	      if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
		  && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
		goto union_lose;
	    }

	  TYPE_MODE (type)
	    = mode_for_size (TREE_INT_CST_LOW (TYPE_SIZE (type)),
			     MODE_INT, 1);

	union_lose: ;
	}
      break;

    /* Pascal and Chill types */
    case BOOLEAN_TYPE:		 /* store one byte/boolean for now. */
      TYPE_MODE (type) = QImode;
      TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
      TYPE_PRECISION (type) = 1;
      TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
      if (TREE_CODE (TYPE_MIN_VALUE (type)) == INTEGER_CST
	  && tree_int_cst_sgn (TYPE_MIN_VALUE (type)) >= 0)
 	TREE_UNSIGNED (type) = 1;
      break;

    case CHAR_TYPE:
      TYPE_MODE (type) = QImode;
      TYPE_SIZE (type) = size_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
      TYPE_PRECISION (type) = GET_MODE_BITSIZE (TYPE_MODE (type));
      TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));
      break;

    case SET_TYPE:
      if (TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST
	  || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) != INTEGER_CST)
	abort();
      else
	{
#ifndef SET_WORD_SIZE
#define SET_WORD_SIZE BITS_PER_WORD
#endif
	  int alignment = set_alignment ? set_alignment : SET_WORD_SIZE;
	  int size_in_bits =
	    TREE_INT_CST_LOW (TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
	      - TREE_INT_CST_LOW (TYPE_MIN_VALUE (TYPE_DOMAIN (type))) + 1;
	  int rounded_size
	    = ((size_in_bits + alignment - 1) / alignment) * alignment;
	  if (rounded_size > alignment)
	    TYPE_MODE (type) = BLKmode;
	  else
	    TYPE_MODE (type) = mode_for_size (alignment, MODE_INT, 1);
	  TYPE_SIZE (type) = size_int (rounded_size);
	  TYPE_ALIGN (type) = alignment;
	  TYPE_PRECISION (type) = size_in_bits;
	}
      break;

    case FILE_TYPE:
      /* The size may vary in different languages, so the language front end
	 should fill in the size.  */
      TYPE_ALIGN (type) = BIGGEST_ALIGNMENT;
      TYPE_MODE  (type) = BLKmode;
      break;

    default:
      abort ();
    } /* end switch */

  /* Normally, use the alignment corresponding to the mode chosen.
     However, where strict alignment is not required, avoid
     over-aligning structures, since most compilers do not do this
     alignment.  */

  if (TYPE_MODE (type) != BLKmode && TYPE_MODE (type) != VOIDmode
      && (STRICT_ALIGNMENT
	  || (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
	      && TREE_CODE (type) != QUAL_UNION_TYPE
	      && TREE_CODE (type) != ARRAY_TYPE)))
    TYPE_ALIGN (type) = GET_MODE_ALIGNMENT (TYPE_MODE (type));

  /* Evaluate nonconstant size only once, either now or as soon as safe.  */
  if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
    TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));

  /* Also layout any other variants of the type.  */
  if (TYPE_NEXT_VARIANT (type)
      || type != TYPE_MAIN_VARIANT (type))
    {
      tree variant;
      /* Record layout info of this variant.  */
      tree size = TYPE_SIZE (type);
      int align = TYPE_ALIGN (type);
      enum machine_mode mode = TYPE_MODE (type);

      /* Copy it into all variants.  */
      for (variant = TYPE_MAIN_VARIANT (type);
	   variant;
	   variant = TYPE_NEXT_VARIANT (variant))
	{
	  TYPE_SIZE (variant) = size;
	  TYPE_ALIGN (variant) = align;
	  TYPE_MODE (variant) = mode;
	}
    }
	
  pop_obstacks ();
  resume_momentary (old);
}

/* Create and return a type for signed integers of PRECISION bits.  */

tree
make_signed_type (precision)
     int precision;
{
  register tree type = make_node (INTEGER_TYPE);

  TYPE_PRECISION (type) = precision;

  /* Create the extreme values based on the number of bits.  */

  TYPE_MIN_VALUE (type)
    = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
		    ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
		   (((HOST_WIDE_INT) (-1)
		     << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
			 ? precision - HOST_BITS_PER_WIDE_INT - 1
			 : 0))));
  TYPE_MAX_VALUE (type)
    = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
		    ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
		   (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
		    ? (((HOST_WIDE_INT) 1
			<< (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
		    : 0));

  /* Give this type's extreme values this type as their type.  */

  TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
  TREE_TYPE (TYPE_MAX_VALUE (type)) = type;

  /* The first type made with this or `make_unsigned_type'
     is the type for size values.  */

  if (sizetype == 0)
    {
      sizetype = type;
    }

  /* Lay out the type: set its alignment, size, etc.  */

  layout_type (type);

  return type;
}

/* Create and return a type for unsigned integers of PRECISION bits.  */

tree
make_unsigned_type (precision)
     int precision;
{
  register tree type = make_node (INTEGER_TYPE);

  TYPE_PRECISION (type) = precision;

  /* The first type made with this or `make_signed_type'
     is the type for size values.  */

  if (sizetype == 0)
    {
      sizetype = type;
    }

  fixup_unsigned_type (type);
  return type;
}

/* Set the extreme values of TYPE based on its precision in bits,
   then lay it out.  Used when make_signed_type won't do
   because the tree code is not INTEGER_TYPE.
   E.g. for Pascal, when the -fsigned-char option is given.  */

void
fixup_signed_type (type)
     tree type;
{
  register int precision = TYPE_PRECISION (type);

  TYPE_MIN_VALUE (type)
    = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
		    ? 0 : (HOST_WIDE_INT) (-1) << (precision - 1)),
		   (((HOST_WIDE_INT) (-1)
		     << (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
			 ? precision - HOST_BITS_PER_WIDE_INT - 1
			 : 0))));
  TYPE_MAX_VALUE (type)
    = build_int_2 ((precision - HOST_BITS_PER_WIDE_INT > 0
		    ? -1 : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
		   (precision - HOST_BITS_PER_WIDE_INT - 1 > 0
		    ? (((HOST_WIDE_INT) 1
			<< (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
		    : 0));

  TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
  TREE_TYPE (TYPE_MAX_VALUE (type)) = type;

  /* Lay out the type: set its alignment, size, etc.  */

  layout_type (type);
}

/* Set the extreme values of TYPE based on its precision in bits,
   then lay it out.  This is used both in `make_unsigned_type'
   and for enumeral types.  */

void
fixup_unsigned_type (type)
     tree type;
{
  register int precision = TYPE_PRECISION (type);

  TYPE_MIN_VALUE (type) = build_int_2 (0, 0);
  TYPE_MAX_VALUE (type)
    = build_int_2 (precision - HOST_BITS_PER_WIDE_INT >= 0
		   ? -1 : ((HOST_WIDE_INT) 1 << precision) - 1,
		   precision - HOST_BITS_PER_WIDE_INT > 0
		   ? ((unsigned HOST_WIDE_INT) ~0
		      >> (HOST_BITS_PER_WIDE_INT
			  - (precision - HOST_BITS_PER_WIDE_INT)))
		   : 0);
  TREE_TYPE (TYPE_MIN_VALUE (type)) = type;
  TREE_TYPE (TYPE_MAX_VALUE (type)) = type;

  /* Lay out the type: set its alignment, size, etc.  */

  layout_type (type);
}

/* Find the best machine mode to use when referencing a bit field of length
   BITSIZE bits starting at BITPOS.

   The underlying object is known to be aligned to a boundary of ALIGN bits.
   If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
   larger than LARGEST_MODE (usually SImode).

   If no mode meets all these conditions, we return VOIDmode.  Otherwise, if
   VOLATILEP is true or SLOW_BYTE_ACCESS is false, we return the smallest
   mode meeting these conditions.

   Otherwise (VOLATILEP is false and SLOW_BYTE_ACCESS is true), we return
   the largest mode (but a mode no wider than UNITS_PER_WORD) that meets
   all the conditions.  */

enum machine_mode
get_best_mode (bitsize, bitpos, align, largest_mode, volatilep)
     int bitsize, bitpos;
     int align;
     enum machine_mode largest_mode;
     int volatilep;
{
  enum machine_mode mode;
  int unit;

  /* Find the narrowest integer mode that contains the bit field.  */
  for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
       mode = GET_MODE_WIDER_MODE (mode))
    {
      unit = GET_MODE_BITSIZE (mode);
      if (bitpos / unit == (bitpos + bitsize - 1) / unit)
	break;
    }

  if (mode == MAX_MACHINE_MODE
      /* It is tempting to omit the following line
	 if STRICT_ALIGNMENT is true.
	 But that is incorrect, since if the bitfield uses part of 3 bytes
	 and we use a 4-byte mode, we could get a spurious segv
	 if the extra 4th byte is past the end of memory.
	 (Though at least one Unix compiler ignores this problem:
	 that on the Sequent 386 machine.  */
      || MIN (unit, BIGGEST_ALIGNMENT) > align
      || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
    return VOIDmode;

  if (SLOW_BYTE_ACCESS && ! volatilep)
    {
      enum machine_mode wide_mode = VOIDmode, tmode;

      for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT); tmode != VOIDmode;
	   tmode = GET_MODE_WIDER_MODE (tmode))
	{
	  unit = GET_MODE_BITSIZE (tmode);
	  if (bitpos / unit == (bitpos + bitsize - 1) / unit
	      && unit <= BITS_PER_WORD
	      && unit <= MIN (align, BIGGEST_ALIGNMENT)
	      && (largest_mode == VOIDmode
		  || unit <= GET_MODE_BITSIZE (largest_mode)))
	    wide_mode = tmode;
	}

      if (wide_mode != VOIDmode)
	return wide_mode;
    }

  return mode;
}

/* Save all variables describing the current status into the structure *P.
   This is used before starting a nested function.  */

void
save_storage_status (p)
     struct function *p;
{
#if 0  /* Need not save, since always 0 and non0 (resp.) within a function.  */
  p->pending_sizes = pending_sizes;
  p->immediate_size_expand = immediate_size_expand;
#endif /* 0 */
}

/* Restore all variables describing the current status from the structure *P.
   This is used after a nested function.  */

void
restore_storage_status (p)
     struct function *p;
{
#if 0
  pending_sizes = p->pending_sizes;
  immediate_size_expand = p->immediate_size_expand;
#endif /* 0 */
}