expr.c

GCC编译器源代码

				size_int (GET_MODE_BITSIZE (lowpart_mode) - 1),
				NULL_RTX, 0);
	      fill_value = convert_to_mode (word_mode, fill_value, 1);
	    }
	}

      /* Fill the remaining words.  */
      for (i = GET_MODE_SIZE (lowpart_mode) / UNITS_PER_WORD; i < nwords; i++)
	{
	  int index = (WORDS_BIG_ENDIAN ? nwords - i - 1 : i);
	  rtx subword = operand_subword (to, index, 1, to_mode);

	  if (subword == 0)
	    abort ();

	  if (fill_value != subword)
	    emit_move_insn (subword, fill_value);
	}

      insns = get_insns ();
      end_sequence ();

      emit_no_conflict_block (insns, to, from, NULL_RTX,
			      gen_rtx (equiv_code, to_mode, copy_rtx (from)));
      return;
    }

  /* Truncating multi-word to a word or less.  */
  if (GET_MODE_BITSIZE (from_mode) > BITS_PER_WORD
      && GET_MODE_BITSIZE (to_mode) <= BITS_PER_WORD)
    {
      if (!((GET_CODE (from) == MEM
	     && ! MEM_VOLATILE_P (from)
	     && direct_load[(int) to_mode]
	     && ! mode_dependent_address_p (XEXP (from, 0)))
	    || GET_CODE (from) == REG
	    || GET_CODE (from) == SUBREG))
	from = force_reg (from_mode, from);
      convert_move (to, gen_lowpart (word_mode, from), 0);
      return;
    }

  /* Handle pointer conversion */			/* SPEE 900220 */
  if (to_mode == PSImode)
    {
      if (from_mode != SImode)
	from = convert_to_mode (SImode, from, unsignedp);

#ifdef HAVE_truncsipsi2
      if (HAVE_truncsipsi2)
	{
	  emit_unop_insn (CODE_FOR_truncsipsi2, to, from, UNKNOWN);
	  return;
	}
#endif /* HAVE_truncsipsi2 */
      abort ();
    }

  if (from_mode == PSImode)
    {
      if (to_mode != SImode)
	{
	  from = convert_to_mode (SImode, from, unsignedp);
	  from_mode = SImode;
	}
      else
	{
#ifdef HAVE_extendpsisi2
	  if (HAVE_extendpsisi2)
	    {
	      emit_unop_insn (CODE_FOR_extendpsisi2, to, from, UNKNOWN);
	      return;
	    }
#endif /* HAVE_extendpsisi2 */
	  abort ();
	}
    }

  if (to_mode == PDImode)
    {
      if (from_mode != DImode)
	from = convert_to_mode (DImode, from, unsignedp);

#ifdef HAVE_truncdipdi2
      if (HAVE_truncdipdi2)
	{
	  emit_unop_insn (CODE_FOR_truncdipdi2, to, from, UNKNOWN);
	  return;
	}
#endif /* HAVE_truncdipdi2 */
      abort ();
    }

  if (from_mode == PDImode)
    {
      if (to_mode != DImode)
	{
	  from = convert_to_mode (DImode, from, unsignedp);
	  from_mode = DImode;
	}
      else
	{
#ifdef HAVE_extendpdidi2
	  if (HAVE_extendpdidi2)
	    {
	      emit_unop_insn (CODE_FOR_extendpdidi2, to, from, UNKNOWN);
	      return;
	    }
#endif /* HAVE_extendpdidi2 */
	  abort ();
	}
    }

  /* Now follow all the conversions between integers
     no more than a word long.  */

  /* For truncation, usually we can just refer to FROM in a narrower mode.  */
  if (GET_MODE_BITSIZE (to_mode) < GET_MODE_BITSIZE (from_mode)
      && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (to_mode),
				GET_MODE_BITSIZE (from_mode)))
    {
      if (!((GET_CODE (from) == MEM
	     && ! MEM_VOLATILE_P (from)
	     && direct_load[(int) to_mode]
	     && ! mode_dependent_address_p (XEXP (from, 0)))
	    || GET_CODE (from) == REG
	    || GET_CODE (from) == SUBREG))
	from = force_reg (from_mode, from);
      if (GET_CODE (from) == REG && REGNO (from) < FIRST_PSEUDO_REGISTER
	  && ! HARD_REGNO_MODE_OK (REGNO (from), to_mode))
	from = copy_to_reg (from);
      emit_move_insn (to, gen_lowpart (to_mode, from));
      return;
    }

  /* Handle extension.  */
  if (GET_MODE_BITSIZE (to_mode) > GET_MODE_BITSIZE (from_mode))
    {
      /* Convert directly if that works.  */
      if ((code = can_extend_p (to_mode, from_mode, unsignedp))
	  != CODE_FOR_nothing)
	{
	  emit_unop_insn (code, to, from, equiv_code);
	  return;
	}
      else
	{
	  enum machine_mode intermediate;

	  /* Search for a mode to convert via.  */
	  for (intermediate = from_mode; intermediate != VOIDmode;
	       intermediate = GET_MODE_WIDER_MODE (intermediate))
	    if (((can_extend_p (to_mode, intermediate, unsignedp)
		  != CODE_FOR_nothing)
		 || (GET_MODE_SIZE (to_mode) < GET_MODE_SIZE (intermediate)
		     && TRULY_NOOP_TRUNCATION (to_mode, intermediate)))
		&& (can_extend_p (intermediate, from_mode, unsignedp)
		    != CODE_FOR_nothing))
	      {
		convert_move (to, convert_to_mode (intermediate, from,
						   unsignedp), unsignedp);
		return;
	      }

	  /* No suitable intermediate mode.  */
	  abort ();
	}
    }

  /* Support special truncate insns for certain modes.  */ 

  if (from_mode == DImode && to_mode == SImode)
    {
#ifdef HAVE_truncdisi2
      if (HAVE_truncdisi2)
	{
	  emit_unop_insn (CODE_FOR_truncdisi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == DImode && to_mode == HImode)
    {
#ifdef HAVE_truncdihi2
      if (HAVE_truncdihi2)
	{
	  emit_unop_insn (CODE_FOR_truncdihi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == DImode && to_mode == QImode)
    {
#ifdef HAVE_truncdiqi2
      if (HAVE_truncdiqi2)
	{
	  emit_unop_insn (CODE_FOR_truncdiqi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == SImode && to_mode == HImode)
    {
#ifdef HAVE_truncsihi2
      if (HAVE_truncsihi2)
	{
	  emit_unop_insn (CODE_FOR_truncsihi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == SImode && to_mode == QImode)
    {
#ifdef HAVE_truncsiqi2
      if (HAVE_truncsiqi2)
	{
	  emit_unop_insn (CODE_FOR_truncsiqi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == HImode && to_mode == QImode)
    {
#ifdef HAVE_trunchiqi2
      if (HAVE_trunchiqi2)
	{
	  emit_unop_insn (CODE_FOR_trunchiqi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == TImode && to_mode == DImode)
    {
#ifdef HAVE_trunctidi2
      if (HAVE_trunctidi2)
	{
	  emit_unop_insn (CODE_FOR_trunctidi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == TImode && to_mode == SImode)
    {
#ifdef HAVE_trunctisi2
      if (HAVE_trunctisi2)
	{
	  emit_unop_insn (CODE_FOR_trunctisi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == TImode && to_mode == HImode)
    {
#ifdef HAVE_trunctihi2
      if (HAVE_trunctihi2)
	{
	  emit_unop_insn (CODE_FOR_trunctihi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == TImode && to_mode == QImode)
    {
#ifdef HAVE_trunctiqi2
      if (HAVE_trunctiqi2)
	{
	  emit_unop_insn (CODE_FOR_trunctiqi2, to, from, UNKNOWN);
	  return;
	}
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  /* Handle truncation of volatile memrefs, and so on;
     the things that couldn't be truncated directly,
     and for which there was no special instruction.  */
  if (GET_MODE_BITSIZE (to_mode) < GET_MODE_BITSIZE (from_mode))
    {
      rtx temp = force_reg (to_mode, gen_lowpart (to_mode, from));
      emit_move_insn (to, temp);
      return;
    }

  /* Mode combination is not recognized.  */
  abort ();
}

/* Return an rtx for a value that would result
   from converting X to mode MODE.
   Both X and MODE may be floating, or both integer.
   UNSIGNEDP is nonzero if X is an unsigned value.
   This can be done by referring to a part of X in place
   or by copying to a new temporary with conversion.

   This function *must not* call protect_from_queue
   except when putting X into an insn (in which case convert_move does it).  */

rtx
convert_to_mode (mode, x, unsignedp)
     enum machine_mode mode;
     rtx x;
     int unsignedp;
{
  return convert_modes (mode, VOIDmode, x, unsignedp);
}

/* Return an rtx for a value that would result
   from converting X from mode OLDMODE to mode MODE.
   Both modes may be floating, or both integer.
   UNSIGNEDP is nonzero if X is an unsigned value.

   This can be done by referring to a part of X in place
   or by copying to a new temporary with conversion.

   You can give VOIDmode for OLDMODE, if you are sure X has a nonvoid mode.

   This function *must not* call protect_from_queue
   except when putting X into an insn (in which case convert_move does it).  */

rtx
convert_modes (mode, oldmode, x, unsignedp)
     enum machine_mode mode, oldmode;
     rtx x;
     int unsignedp;
{
  register rtx temp;

  /* If FROM is a SUBREG that indicates that we have already done at least
     the required extension, strip it.  */

  if (GET_CODE (x) == SUBREG && SUBREG_PROMOTED_VAR_P (x)
      && GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))) >= GET_MODE_SIZE (mode)
      && SUBREG_PROMOTED_UNSIGNED_P (x) == unsignedp)
    x = gen_lowpart (mode, x);

  if (GET_MODE (x) != VOIDmode)
    oldmode = GET_MODE (x);
 
  if (mode == oldmode)
    return x;

  /* There is one case that we must handle specially: If we are converting
     a CONST_INT into a mode whose size is twice HOST_BITS_PER_WIDE_INT and
     we are to interpret the constant as unsigned, gen_lowpart will do
     the wrong if the constant appears negative.  What we want to do is
     make the high-order word of the constant zero, not all ones.  */

  if (unsignedp && GET_MODE_CLASS (mode) == MODE_INT
      && GET_MODE_BITSIZE (mode) == 2 * HOST_BITS_PER_WIDE_INT
      && GET_CODE (x) == CONST_INT && INTVAL (x) < 0)
    {
      HOST_WIDE_INT val = INTVAL (x);

      if (oldmode != VOIDmode
	  && HOST_BITS_PER_WIDE_INT > GET_MODE_BITSIZE (oldmode))
	{
	  int width = GET_MODE_BITSIZE (oldmode);

	  /* We need to zero extend VAL.  */
	  val &= ((HOST_WIDE_INT) 1 << width) - 1;
	}

      return immed_double_const (val, (HOST_WIDE_INT) 0, mode);
    }

  /* We can do this with a gen_lowpart if both desired and current modes
     are integer, and this is either a constant integer, a register, or a
     non-volatile MEM.  Except for the constant case where MODE is no
     wider than HOST_BITS_PER_WIDE_INT, we must be narrowing the operand.  */

  if ((GET_CODE (x) == CONST_INT
       && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
      || (GET_MODE_CLASS (mode) == MODE_INT
	  && GET_MODE_CLASS (oldmode) == MODE_INT
	  && (GET_CODE (x) == CONST_DOUBLE
	      || (GET_MODE_SIZE (mode) <= GET_MODE_SIZE (oldmode)
		  && ((GET_CODE (x) == MEM && ! MEM_VOLATILE_P (x)
		       && direct_load[(int) mode])
		      || (GET_CODE (x) == REG
			  && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
						    GET_MODE_BITSIZE (GET_MODE (x)))))))))
    {
      /* ?? If we don't know OLDMODE, we have to assume here that
	 X does not need sign- or zero-extension.   This may not be
	 the case, but it's the best we can do.  */
      if (GET_CODE (x) == CONST_INT && oldmode != VOIDmode
	  && GET_MODE_SIZE (mode) > GET_MODE_SIZE (oldmode))
	{
	  HOST_WIDE_INT val = INTVAL (x);
	  int width = GET_MODE_BITSIZE (oldmode);

	  /* We must sign or zero-extend in this case.  Start by
	     zero-extending, then sign extend if we need to.  */
	  val &= ((HOST_WIDE_INT) 1 << width) - 1;
	  if (! unsignedp
	      && (val & ((HOST_WIDE_INT) 1 << (width - 1))))
	    val |= (HOST_WIDE_INT) (-1) << width;

	  return GEN_INT (val);
	}

      return gen_lowpart (mode, x);
    }

  temp = gen_reg_rtx (mode);
  convert_move (temp, x, unsignedp);
  return temp;
}

/* Generate several move instructions to copy LEN bytes
   from block FROM to block TO.  (These are MEM rtx's with BLKmode).
   The caller must pass FROM and TO
    through protect_from_queue before calling.
   ALIGN (in bytes) is maximum alignment we can assume.  */

static void
move_by_pieces (to, from, len, align)
     rtx to, from;
     int len, align;
{
  struct move_by_pieces data;
  rtx to_addr = XEXP (to, 0), from_addr = XEXP (from, 0);
  int max_size = MOVE_MAX + 1;

  data.offset = 0;
  data.to_addr = to_addr;
  data.from_addr = from_addr;
  data.to = to;
  data.from = from;
  data.autinc_to
    = (GET_CODE (to_addr) == PRE_INC || GET_CODE (to_addr) == PRE_DEC
       || GET_CODE (to_addr) == POST_INC || GET_CODE (to_addr) == POST_DEC);
  data.autinc_from
    = (GET_CODE (from_addr) == PRE_INC || GET_CODE (from_addr) == PRE_DEC
       || GET_CODE (from_addr) == POST_INC
       || GET_CODE (from_addr) == POST_DEC);

  data.explicit_inc_from = 0;
  data.explicit_inc_to = 0;
  data.reverse