emit-rtl.c

GUN开源阻止下的编译器GCC

     approximation).  */

  if (reload_in_progress || reload_completed)
    abort ();

  if (GET_MODE_CLASS (mode) == MODE_COMPLEX_FLOAT
      || GET_MODE_CLASS (mode) == MODE_COMPLEX_INT)
    {
      /* For complex modes, don't make a single pseudo.
	 Instead, make a CONCAT of two pseudos.
	 This allows noncontiguous allocation of the real and imaginary parts,
	 which makes much better code.  Besides, allocating DCmode
	 pseudos overstrains reload on some machines like the 386.  */
      rtx realpart, imagpart;
      int size = GET_MODE_UNIT_SIZE (mode);
      enum machine_mode partmode
	= mode_for_size (size * BITS_PER_UNIT,
			 (GET_MODE_CLASS (mode) == MODE_COMPLEX_FLOAT
			  ? MODE_FLOAT : MODE_INT),
			 0);

      realpart = gen_reg_rtx (partmode);
      imagpart = gen_reg_rtx (partmode);
      return gen_rtx (CONCAT, mode, realpart, imagpart);
    }

  /* Make sure regno_pointer_flag and regno_reg_rtx are large
     enough to have an element for this pseudo reg number.  */

  if (reg_rtx_no == regno_pointer_flag_length)
    {
      rtx *new1;
      char *new =
	(char *) oballoc (regno_pointer_flag_length * 2);
      bcopy (regno_pointer_flag, new, regno_pointer_flag_length);
      bzero (&new[regno_pointer_flag_length], regno_pointer_flag_length);
      regno_pointer_flag = new;

      new1 = (rtx *) oballoc (regno_pointer_flag_length * 2 * sizeof (rtx));
      bcopy ((char *) regno_reg_rtx, (char *) new1,
	     regno_pointer_flag_length * sizeof (rtx));
      bzero ((char *) &new1[regno_pointer_flag_length],
	     regno_pointer_flag_length * sizeof (rtx));
      regno_reg_rtx = new1;

      regno_pointer_flag_length *= 2;
    }

  val = gen_rtx (REG, mode, reg_rtx_no);
  regno_reg_rtx[reg_rtx_no++] = val;
  return val;
}

/* Identify REG as a probable pointer register.  */

void
mark_reg_pointer (reg)
     rtx reg;
{
  REGNO_POINTER_FLAG (REGNO (reg)) = 1;
}

/* Return 1 plus largest pseudo reg number used in the current function.  */

int
max_reg_num ()
{
  return reg_rtx_no;
}

/* Return 1 + the largest label number used so far in the current function.  */

int
max_label_num ()
{
  if (last_label_num && label_num == base_label_num)
    return last_label_num;
  return label_num;
}

/* Return first label number used in this function (if any were used).  */

int
get_first_label_num ()
{
  return first_label_num;
}

/* Return a value representing some low-order bits of X, where the number
   of low-order bits is given by MODE.  Note that no conversion is done
   between floating-point and fixed-point values, rather, the bit 
   representation is returned.

   This function handles the cases in common between gen_lowpart, below,
   and two variants in cse.c and combine.c.  These are the cases that can
   be safely handled at all points in the compilation.

   If this is not a case we can handle, return 0.  */

rtx
gen_lowpart_common (mode, x)
     enum machine_mode mode;
     register rtx x;
{
  int word = 0;

  if (GET_MODE (x) == mode)
    return x;

  /* MODE must occupy no more words than the mode of X.  */
  if (GET_MODE (x) != VOIDmode
      && ((GET_MODE_SIZE (mode) + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD
	  > ((GET_MODE_SIZE (GET_MODE (x)) + (UNITS_PER_WORD - 1))
	     / UNITS_PER_WORD)))
    return 0;

  if (WORDS_BIG_ENDIAN && GET_MODE_SIZE (GET_MODE (x)) > UNITS_PER_WORD)
    word = ((GET_MODE_SIZE (GET_MODE (x))
	     - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD))
	    / UNITS_PER_WORD);

  if ((GET_CODE (x) == ZERO_EXTEND || GET_CODE (x) == SIGN_EXTEND)
      && (GET_MODE_CLASS (mode) == MODE_INT
	  || GET_MODE_CLASS (mode) == MODE_PARTIAL_INT))
    {
      /* If we are getting the low-order part of something that has been
	 sign- or zero-extended, we can either just use the object being
	 extended or make a narrower extension.  If we want an even smaller
	 piece than the size of the object being extended, call ourselves
	 recursively.

	 This case is used mostly by combine and cse.  */

      if (GET_MODE (XEXP (x, 0)) == mode)
	return XEXP (x, 0);
      else if (GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (XEXP (x, 0))))
	return gen_lowpart_common (mode, XEXP (x, 0));
      else if (GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (x)))
	return gen_rtx (GET_CODE (x), mode, XEXP (x, 0));
    }
  else if (GET_CODE (x) == SUBREG
	   && (GET_MODE_SIZE (mode) <= UNITS_PER_WORD
	       || GET_MODE_SIZE (mode) == GET_MODE_UNIT_SIZE (GET_MODE (x))))
    return (GET_MODE (SUBREG_REG (x)) == mode && SUBREG_WORD (x) == 0
	    ? SUBREG_REG (x)
	    : gen_rtx (SUBREG, mode, SUBREG_REG (x), SUBREG_WORD (x)));
  else if (GET_CODE (x) == REG)
    {
      /* If the register is not valid for MODE, return 0.  If we don't
	 do this, there is no way to fix up the resulting REG later.  
	 But we do do this if the current REG is not valid for its
	 mode.  This latter is a kludge, but is required due to the
	 way that parameters are passed on some machines, most
	 notably Sparc.  */
      if (REGNO (x) < FIRST_PSEUDO_REGISTER
	  && ! HARD_REGNO_MODE_OK (REGNO (x) + word, mode)
	  && HARD_REGNO_MODE_OK (REGNO (x), GET_MODE (x)))
	return 0;
      else if (REGNO (x) < FIRST_PSEUDO_REGISTER
	       /* integrate.c can't handle parts of a return value register. */
	       && (! REG_FUNCTION_VALUE_P (x)
		   || ! rtx_equal_function_value_matters)
	       /* We want to keep the stack, frame, and arg pointers
		  special.  */
	       && x != frame_pointer_rtx
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
	       && x != arg_pointer_rtx
#endif
	       && x != stack_pointer_rtx)
	return gen_rtx (REG, mode, REGNO (x) + word);
      else
	return gen_rtx (SUBREG, mode, x, word);
    }
  /* If X is a CONST_INT or a CONST_DOUBLE, extract the appropriate bits
     from the low-order part of the constant.  */
  else if ((GET_MODE_CLASS (mode) == MODE_INT
	    || GET_MODE_CLASS (mode) == MODE_PARTIAL_INT)
	   && GET_MODE (x) == VOIDmode
	   && (GET_CODE (x) == CONST_INT || GET_CODE (x) == CONST_DOUBLE))
    {
      /* If MODE is twice the host word size, X is already the desired
	 representation.  Otherwise, if MODE is wider than a word, we can't
	 do this.  If MODE is exactly a word, return just one CONST_INT.
	 If MODE is smaller than a word, clear the bits that don't belong
	 in our mode, unless they and our sign bit are all one.  So we get
	 either a reasonable negative value or a reasonable unsigned value
	 for this mode.  */

      if (GET_MODE_BITSIZE (mode) >= 2 * HOST_BITS_PER_WIDE_INT)
	return x;
      else if (GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT)
	return 0;
      else if (GET_MODE_BITSIZE (mode) == HOST_BITS_PER_WIDE_INT)
	return (GET_CODE (x) == CONST_INT ? x
		: GEN_INT (CONST_DOUBLE_LOW (x)));
      else
	{
	  /* MODE must be narrower than HOST_BITS_PER_INT.  */
	  int width = GET_MODE_BITSIZE (mode);
	  HOST_WIDE_INT val = (GET_CODE (x) == CONST_INT ? INTVAL (x)
			       : CONST_DOUBLE_LOW (x));

	  if (((val & ((HOST_WIDE_INT) (-1) << (width - 1)))
	       != ((HOST_WIDE_INT) (-1) << (width - 1))))
	    val &= ((HOST_WIDE_INT) 1 << width) - 1;

	  return (GET_CODE (x) == CONST_INT && INTVAL (x) == val ? x
		  : GEN_INT (val));
	}
    }

  /* If X is an integral constant but we want it in floating-point, it
     must be the case that we have a union of an integer and a floating-point
     value.  If the machine-parameters allow it, simulate that union here
     and return the result.  The two-word and single-word cases are 
     different.  */

  else if (((HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT
	     && HOST_BITS_PER_WIDE_INT == BITS_PER_WORD)
	    || flag_pretend_float)
	   && GET_MODE_CLASS (mode) == MODE_FLOAT
	   && GET_MODE_SIZE (mode) == UNITS_PER_WORD
	   && GET_CODE (x) == CONST_INT
	   && sizeof (float) * HOST_BITS_PER_CHAR == HOST_BITS_PER_WIDE_INT)
#ifdef REAL_ARITHMETIC
    {
      REAL_VALUE_TYPE r;
      HOST_WIDE_INT i;

      i = INTVAL (x);
      r = REAL_VALUE_FROM_TARGET_SINGLE (i);
      return CONST_DOUBLE_FROM_REAL_VALUE (r, mode);
    }
#else
    {
      union {HOST_WIDE_INT i; float d; } u;

      u.i = INTVAL (x);
      return CONST_DOUBLE_FROM_REAL_VALUE (u.d, mode);
    }
#endif
  else if (((HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT
	     && HOST_BITS_PER_WIDE_INT == BITS_PER_WORD)
	    || flag_pretend_float)
	   && GET_MODE_CLASS (mode) == MODE_FLOAT
	   && GET_MODE_SIZE (mode) == 2 * UNITS_PER_WORD
	   && (GET_CODE (x) == CONST_INT || GET_CODE (x) == CONST_DOUBLE)
	   && GET_MODE (x) == VOIDmode
	   && (sizeof (double) * HOST_BITS_PER_CHAR
	       == 2 * HOST_BITS_PER_WIDE_INT))
#ifdef REAL_ARITHMETIC
    {
      REAL_VALUE_TYPE r;
      HOST_WIDE_INT i[2];
      HOST_WIDE_INT low, high;

      if (GET_CODE (x) == CONST_INT)
	low = INTVAL (x), high = low >> (HOST_BITS_PER_WIDE_INT -1);
      else
	low = CONST_DOUBLE_LOW (x), high = CONST_DOUBLE_HIGH (x);

      /* REAL_VALUE_TARGET_DOUBLE takes the addressing order of the
	 target machine. */
      if (WORDS_BIG_ENDIAN)
	i[0] = high, i[1] = low;
      else
	i[0] = low, i[1] = high;

      r = REAL_VALUE_FROM_TARGET_DOUBLE (i);
      return CONST_DOUBLE_FROM_REAL_VALUE (r, mode);
    }
#else
    {
      union {HOST_WIDE_INT i[2]; double d; } u;
      HOST_WIDE_INT low, high;

      if (GET_CODE (x) == CONST_INT)
	low = INTVAL (x), high = low >> (HOST_BITS_PER_WIDE_INT -1);
      else
	low = CONST_DOUBLE_LOW (x), high = CONST_DOUBLE_HIGH (x);

#ifdef HOST_WORDS_BIG_ENDIAN
      u.i[0] = high, u.i[1] = low;
#else
      u.i[0] = low, u.i[1] = high;
#endif

      return CONST_DOUBLE_FROM_REAL_VALUE (u.d, mode);
    }
#endif
  /* Similarly, if this is converting a floating-point value into a
     single-word integer.  Only do this is the host and target parameters are
     compatible.  */

  else if (((HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT
	     && HOST_BITS_PER_WIDE_INT == BITS_PER_WORD)
	    || flag_pretend_float)
	   && (GET_MODE_CLASS (mode) == MODE_INT
	       || GET_MODE_CLASS (mode) == MODE_PARTIAL_INT)
	   && GET_CODE (x) == CONST_DOUBLE
	   && GET_MODE_CLASS (GET_MODE (x)) == MODE_FLOAT
	   && GET_MODE_BITSIZE (mode) == BITS_PER_WORD)
    return operand_subword (x, 0, 0, GET_MODE (x));

  /* Similarly, if this is converting a floating-point value into a
     two-word integer, we can do this one word at a time and make an
     integer.  Only do this is the host and target parameters are
     compatible.  */

  else if (((HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT
	     && HOST_BITS_PER_WIDE_INT == BITS_PER_WORD)
	    || flag_pretend_float)
	   && (GET_MODE_CLASS (mode) == MODE_INT
	       || GET_MODE_CLASS (mode) == MODE_PARTIAL_INT)
	   && GET_CODE (x) == CONST_DOUBLE
	   && GET_MODE_CLASS (GET_MODE (x)) == MODE_FLOAT
	   && GET_MODE_BITSIZE (mode) == 2 * BITS_PER_WORD)
    {
      rtx lowpart = operand_subword (x, WORDS_BIG_ENDIAN, 0, GET_MODE (x));
      rtx highpart = operand_subword (x, ! WORDS_BIG_ENDIAN, 0, GET_MODE (x));

      if (lowpart && GET_CODE (lowpart) == CONST_INT
	  && highpart && GET_CODE (highpart) == CONST_INT)
	return immed_double_const (INTVAL (lowpart), INTVAL (highpart), mode);
    }

  /* Otherwise, we can't do this.  */
  return 0;
}

/* Return the real part (which has mode MODE) of a complex value X.
   This always comes at the low address in memory.  */

rtx
gen_realpart (mode, x)
     enum machine_mode mode;
     register rtx x;
{
  if (GET_CODE (x) == CONCAT && GET_MODE (XEXP (x, 0)) == mode)
    return XEXP (x, 0);
  else if (WORDS_BIG_ENDIAN)
    return gen_highpart (mode, x);
  else
    return gen_lowpart (mode, x);
}

/* Return the imaginary part (which has mode MODE) of a complex value X.
   This always comes at the high address in memory.  */

rtx
gen_imagpart (mode, x)
     enum machine_mode mode;
     register rtx x;
{
  if (GET_CODE (x) == CONCAT && GET_MODE (XEXP (x, 0)) == mode)
    return XEXP (x, 1);
  else if (WORDS_BIG_ENDIAN)
    return gen_lowpart (mode, x);
  else
    return gen_highpart (mode, x);
}

/* Return 1 iff X, assumed to be a SUBREG,
   refers to the real part of the complex value in its containing reg.
   Complex values are always stored with the real part in the first word,
   regardless of WORDS_BIG_ENDIAN.  */

int
subreg_realpart_p (x)
     rtx x;
{
  if (GET_CODE (x) != SUBREG)
    abort ();

  return SUBREG_WORD (x) == 0;
}

/* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a value,
   return an rtx (MEM, SUBREG, or CONST_INT) that refers to the
   least-significant part of X.
   MODE specifies how big a part of X to return;
   it usually should not be larger than a word.
   If X is a MEM whose address is a QUEUED, the value may be so also.  */

rtx
gen_lowpart (mode, x)
     enum machine_mode mode;
     register rtx x;
{
  rtx result = gen_lowpart_common (mode, x);

  if (result)
    return result;
  else if (GET_CODE (x) == REG)
    {
      /* Must be a hard reg that's not valid in MODE.  */
      result = gen_lowpart_common (mode, copy_to_reg (x));
      if (result == 0)
	abort ();
    }
  else if (GET_CODE (x) == MEM)
    {
      /* The only additional case we can do is MEM.  */
      register int offset = 0;
      if (WORDS_BIG_ENDIAN)
	offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
		  - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));

      if (BYTES_BIG_ENDIAN)
	/* Adjust the address so that the address-after-the-data
	   is unchanged.  */
	offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
		   - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));

      return change_address (x, mode, plus_constant (XEXP (x, 0), offset));
    }
  else
    abort ();
}

/* Like `gen_lowpart', but refer to the most significant part. 
   This is used to access the imaginary part of a complex number.  */

rtx
gen_highpart (mode, x)
     enum machine_mode mode;
     register rtx x;
{
  /* This case loses if X is a subreg.  To catch bugs early,
     complain if an invalid MODE is used even in other cases.  */
  if (GET_MODE_SIZE (mode) > UNITS_PER_WORD
      && GET_MODE_SIZE (mode) != GET_MODE_UNIT_SIZE (GET_MODE (x)))
    abort ();
  if (GET_CODE (x) == CONST_DOUBLE
#if !(TARGET_FLOAT_FORMAT != HOST_FLOAT_FORMAT || defined (REAL_IS_NOT_DOUBLE))
      && GET_MODE_CLASS (GET_MODE (x)) != MODE_FLOAT
#endif
      )
    return gen_rtx (CONST_INT, VOIDmode,
		    CONST_DOUBLE_HIGH (x) & GET_MODE_MASK (mode));
  else if (GET_CODE (x) == CONST_INT)
    return const0_rtx;
  else if (GET_CODE (x) == MEM)
    {
      register int offset = 0;
      if (! WORDS_BIG_ENDIAN)
	offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
		  - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));

      if (! BYTES_BIG_ENDIAN
	  && GET_MODE_SIZE (mode) < UNITS_PER_WORD)
	offset -= (GET_MODE_SIZE (mode)
		   - MIN (UNITS_PER_WORD,
			  GET_MODE_SIZE (GET_MODE (x))));

      return change_address (x, mode, plus_constant (XEXP (x, 0), offset));
    }
  else if (GET_CODE (x) == SUBREG)
    {
      /* The only time this should occur is when we are looking at a
	 multi-word item with a SUBREG whose mode is the same as that of the
	 item.  It isn't clear what we would do if it wasn't.  */
      if (SUBREG_WORD (x) != 0)
	abort ();
      return gen_highpart (mode, SUBREG_REG (x));
    }