emit-rtl.c

GCC编译器源代码

  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 ();
      return result;
    }
  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 if (GET_CODE (x) == ADDRESSOF)
    return gen_lowpart (mode, force_reg (GET_MODE (x), x));
  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));
    }
  else if (GET_CODE (x) == REG)
    {
      int word = 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);

      /*
       * ??? This fails miserably for complex values being passed in registers
       * where the sizeof the real and imaginary part are not equal to the
       * sizeof SImode.  FIXME
       */

      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);
    }
  else
    abort ();
}

/* Return 1 iff X, assumed to be a SUBREG,
   refers to the least significant part of its containing reg.
   If X is not a SUBREG, always return 1 (it is its own low part!).  */

int
subreg_lowpart_p (x)
     rtx x;
{
  if (GET_CODE (x) != SUBREG)
    return 1;
  else if (GET_MODE (SUBREG_REG (x)) == VOIDmode)
    return 0;

  if (WORDS_BIG_ENDIAN
      && GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))) > UNITS_PER_WORD)
    return (SUBREG_WORD (x)
	    == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))
		 - MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD))
		/ UNITS_PER_WORD));

  return SUBREG_WORD (x) == 0;
}

/* Return subword I of operand OP.
   The word number, I, is interpreted as the word number starting at the
   low-order address.  Word 0 is the low-order word if not WORDS_BIG_ENDIAN,
   otherwise it is the high-order word.

   If we cannot extract the required word, we return zero.  Otherwise, an
   rtx corresponding to the requested word will be returned.

   VALIDATE_ADDRESS is nonzero if the address should be validated.  Before
   reload has completed, a valid address will always be returned.  After
   reload, if a valid address cannot be returned, we return zero.

   If VALIDATE_ADDRESS is zero, we simply form the required address; validating
   it is the responsibility of the caller.

   MODE is the mode of OP in case it is a CONST_INT.  */

rtx
operand_subword (op, i, validate_address, mode)
     rtx op;
     int i;
     int validate_address;
     enum machine_mode mode;
{
  HOST_WIDE_INT val;
  int size_ratio = HOST_BITS_PER_WIDE_INT / BITS_PER_WORD;

  if (mode == VOIDmode)
    mode = GET_MODE (op);

  if (mode == VOIDmode)
    abort ();

  /* If OP is narrower than a word or if we want a word outside OP, fail.  */
  if (mode != BLKmode
      && (GET_MODE_SIZE (mode) < UNITS_PER_WORD
	  || (i + 1) * UNITS_PER_WORD > GET_MODE_SIZE (mode)))
    return 0;

  /* If OP is already an integer word, return it.  */
  if (GET_MODE_CLASS (mode) == MODE_INT
      && GET_MODE_SIZE (mode) == UNITS_PER_WORD)
    return op;

  /* If OP is a REG or SUBREG, we can handle it very simply.  */
  if (GET_CODE (op) == 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.  */
      if (REGNO (op) < FIRST_PSEUDO_REGISTER
	  && ! HARD_REGNO_MODE_OK (REGNO (op) + i, word_mode))
	return 0;
      else if (REGNO (op) >= FIRST_PSEUDO_REGISTER
	       || (REG_FUNCTION_VALUE_P (op)
		   && rtx_equal_function_value_matters)
	       /* We want to keep the stack, frame, and arg pointers
		  special.  */
	       || op == frame_pointer_rtx
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
	       || op == arg_pointer_rtx
#endif
	       || op == stack_pointer_rtx)
	return gen_rtx (SUBREG, word_mode, op, i);
      else
	return gen_rtx (REG, word_mode, REGNO (op) + i);
    }
  else if (GET_CODE (op) == SUBREG)
    return gen_rtx (SUBREG, word_mode, SUBREG_REG (op), i + SUBREG_WORD (op));
  else if (GET_CODE (op) == CONCAT)
    {
      int partwords = GET_MODE_UNIT_SIZE (GET_MODE (op)) / UNITS_PER_WORD;
      if (i < partwords)
	return operand_subword (XEXP (op, 0), i, validate_address, mode);
      return operand_subword (XEXP (op, 1), i - partwords,
			      validate_address, mode);
    }

  /* Form a new MEM at the requested address.  */
  if (GET_CODE (op) == MEM)
    {
      rtx addr = plus_constant (XEXP (op, 0), i * UNITS_PER_WORD);
      rtx new;

      if (validate_address)
	{
	  if (reload_completed)
	    {
	      if (! strict_memory_address_p (word_mode, addr))
		return 0;
	    }
	  else
	    addr = memory_address (word_mode, addr);
	}

      new = gen_rtx (MEM, word_mode, addr);

      MEM_VOLATILE_P (new) = MEM_VOLATILE_P (op);
      MEM_IN_STRUCT_P (new) = MEM_IN_STRUCT_P (op);
      RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (op);

      return new;
    }

  /* The only remaining cases are when OP is a constant.  If the host and
     target floating formats are the same, handling two-word floating
     constants are easy.  Note that REAL_VALUE_TO_TARGET_{SINGLE,DOUBLE}
     are defined as returning one or two 32 bit values, respectively,
     and not values of BITS_PER_WORD bits.  */
#ifdef REAL_ARITHMETIC
/*  The output is some bits, the width of the target machine's word.
    A wider-word host can surely hold them in a CONST_INT. A narrower-word
    host can't.  */
  if (HOST_BITS_PER_WIDE_INT >= BITS_PER_WORD
      && GET_MODE_CLASS (mode) == MODE_FLOAT
      && GET_MODE_BITSIZE (mode) == 64
      && GET_CODE (op) == CONST_DOUBLE)
    {
      long k[2];
      REAL_VALUE_TYPE rv;

      REAL_VALUE_FROM_CONST_DOUBLE (rv, op);
      REAL_VALUE_TO_TARGET_DOUBLE (rv, k);

      /* We handle 32-bit and >= 64-bit words here.  Note that the order in
	 which the words are written depends on the word endianness.

	 ??? This is a potential portability problem and should
	 be fixed at some point.  */
      if (BITS_PER_WORD == 32)
	return GEN_INT ((HOST_WIDE_INT) k[i]);
#if HOST_BITS_PER_WIDE_INT > 32
      else if (BITS_PER_WORD >= 64 && i == 0)
	return GEN_INT ((((HOST_WIDE_INT) k[! WORDS_BIG_ENDIAN]) << 32)
			| (HOST_WIDE_INT) k[WORDS_BIG_ENDIAN]);
#endif
      else if (BITS_PER_WORD == 16)
	{
	  long value;
	  value = k[i >> 1];
	  if ((i & 0x1) == 0)
	    value >>= 16;
	  value &= 0xffff;
	  return GEN_INT ((HOST_WIDE_INT) value);
	}
      else
	abort ();
    }
  else if (HOST_BITS_PER_WIDE_INT >= BITS_PER_WORD
	   && GET_MODE_CLASS (mode) == MODE_FLOAT
	   && GET_MODE_BITSIZE (mode) > 64
	   && GET_CODE (op) == CONST_DOUBLE)
  {
    long k[4];
    REAL_VALUE_TYPE rv;

    REAL_VALUE_FROM_CONST_DOUBLE (rv, op);
    REAL_VALUE_TO_TARGET_LONG_DOUBLE (rv, k);

    if (BITS_PER_WORD == 32)
      return GEN_INT ((HOST_WIDE_INT) k[i]);
  }
#else /* no REAL_ARITHMETIC */
  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 (op) == CONST_DOUBLE)
    {
      /* The constant is stored in the host's word-ordering,
	 but we want to access it in the target's word-ordering.  Some
	 compilers don't like a conditional inside macro args, so we have two
	 copies of the return.  */
#ifdef HOST_WORDS_BIG_ENDIAN
      return GEN_INT (i == WORDS_BIG_ENDIAN
		      ? CONST_DOUBLE_HIGH (op) : CONST_DOUBLE_LOW (op));
#else
      return GEN_INT (i != WORDS_BIG_ENDIAN
		      ? CONST_DOUBLE_HIGH (op) : CONST_DOUBLE_LOW (op));
#endif
    }
#endif /* no REAL_ARITHMETIC */

  /* Single word float is a little harder, since single- and double-word
     values often do not have the same high-order bits.  We have already
     verified that we want the only defined word of the single-word value.  */
#ifdef REAL_ARITHMETIC
  if (GET_MODE_CLASS (mode) == MODE_FLOAT
      && GET_MODE_BITSIZE (mode) == 32
      && GET_CODE (op) == CONST_DOUBLE)
    {
      long l;
      REAL_VALUE_TYPE rv;

      REAL_VALUE_FROM_CONST_DOUBLE (rv, op);
      REAL_VALUE_TO_TARGET_SINGLE (rv, l);
      return GEN_INT ((HOST_WIDE_INT) l);
    }
#else
  if (((HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT
	&& HOST_BITS_PER_WIDE_INT == BITS_PER_WORD)
       || flag_pretend_float)
      && sizeof (float) * 8 == HOST_BITS_PER_WIDE_INT
      && GET_MODE_CLASS (mode) == MODE_FLOAT
      && GET_MODE_SIZE (mode) == UNITS_PER_WORD
      && GET_CODE (op) == CONST_DOUBLE)
    {
      double d;
      union {float f; HOST_WIDE_INT i; } u;

      REAL_VALUE_FROM_CONST_DOUBLE (d, op);

      u.f = d;
      return GEN_INT (u.i);
    }
  if (((HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT
	&& HOST_BITS_PER_WIDE_INT == BITS_PER_WORD)
       || flag_pretend_float)
      && sizeof (double) * 8 == HOST_BITS_PER_WIDE_INT
      && GET_MODE_CLASS (mode) == MODE_FLOAT
      && GET_MODE_SIZE (mode) == UNITS_PER_WORD
      && GET_CODE (op) == CONST_DOUBLE)
    {
      double d;
      union {double d; HOST_WIDE_INT i; } u;

      REAL_VALUE_FROM_CONST_DOUBLE (d, op);

      u.d = d;
      return GEN_INT (u.i);
    }
#endif /* no REAL_ARITHMETIC */
      
  /* The only remaining cases that we can handle are integers.
     Convert to proper endianness now since these cases need it.
     At this point, i == 0 means the low-order word.  

     We do not want to handle the case when BITS_PER_WORD <= HOST_BITS_PER_INT
     in general.  However, if OP is (const_int 0), we can just return
     it for any word.  */

  if (op == const0_rtx)
    return op;

  if (GET_MODE_CLASS (mode) != MODE_INT
      || (GET_CODE (op) != CONST_INT && GET_CODE (op) != CONST_DOUBLE)
      || BITS_PER_WORD > HOST_BITS_PER_WIDE_INT)
    return 0;

  if (WORDS_BIG_ENDIAN)
    i = GET_MODE_SIZE (mode) / UNITS_PER_WORD - 1 - i;

  /* Find out which word on the host machine this value is in and get
     it from the constant.  */
  val = (i / size_ratio == 0
	 ? (GET_CODE (op) == CONST_INT ? INTVAL (op) : CONST_DOUBLE_LOW (op))
	 : (GET_CODE (op) == CONST_INT
	    ? (INTVAL (op) < 0 ? ~0 : 0) : CONST_DOUBLE_HIGH (op)));

  /* If BITS_PER_WORD is smaller than an int, get the appropriate bits.  */
  if (BITS_PER_WORD < HOST_BITS_PER_WIDE_INT)
    val = ((val >> ((i % size_ratio) * BITS_PER_WORD))
	   & (((HOST_WIDE_INT) 1
	       << (BITS_PER_WORD % HOST_BITS_PER_WIDE_INT)) - 1));

  return GEN_INT (val);
}

/* Similar to `operand_subword', but never return 0.  If we can't extract
   the required subword, put OP into a register and try again.  If that fails,
   abort.  We always validate the address in this case.  It is not valid
   to call this function after reload; it is mostly meant for RTL
   generation. 

   MODE is the mode of OP, in case it is CONST_INT.  */

rtx
operand_subword_force (op, i, mode)
     rtx op;
     int i;
     enum machine_mode mode;
{
  rtx result = operand_subword (op, i, 1, mode);

  if (result)
    return result;

  if (mode != BLKmode && mode != VOIDmode)
    op = force_reg (mode, op);

  result = operand_subword (op, i, 1, mode);
  if (result == 0)
    abort ();

  return result;
}

/* Given a compare instruction, swap the operands.
   A test instruction is changed into a compare of 0 against the operand.  */

void
reverse_comparison (insn)
     rtx insn;
{
  rtx body = PATTERN (insn);
  rtx comp;