recog.c

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  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
	validate_replace_rtx_1 (&XEXP (x, i), from, to, object);
      else if (fmt[i] == 'E')
	for (j = XVECLEN (x, i) - 1; j >= 0; j--)
	  validate_replace_rtx_1 (&XVECEXP (x, i, j), from, to, object);
    }
}

/* Try replacing every occurrence of FROM in INSN with TO.  After all
   changes have been made, validate by seeing if INSN is still valid.  */

int
validate_replace_rtx (from, to, insn)
     rtx from, to, insn;
{
  validate_replace_rtx_1 (&PATTERN (insn), from, to, insn);
  return apply_change_group ();
}

#ifdef HAVE_cc0
/* Return 1 if the insn using CC0 set by INSN does not contain
   any ordered tests applied to the condition codes.
   EQ and NE tests do not count.  */

int
next_insn_tests_no_inequality (insn)
     rtx insn;
{
  register rtx next = next_cc0_user (insn);

  /* If there is no next insn, we have to take the conservative choice.  */
  if (next == 0)
    return 0;

  return ((GET_CODE (next) == JUMP_INSN
	   || GET_CODE (next) == INSN
	   || GET_CODE (next) == CALL_INSN)
	  && ! inequality_comparisons_p (PATTERN (next)));
}

#if 0  /* This is useless since the insn that sets the cc's
	  must be followed immediately by the use of them.  */
/* Return 1 if the CC value set up by INSN is not used.  */

int
next_insns_test_no_inequality (insn)
     rtx insn;
{
  register rtx next = NEXT_INSN (insn);

  for (; next != 0; next = NEXT_INSN (next))
    {
      if (GET_CODE (next) == CODE_LABEL
	  || GET_CODE (next) == BARRIER)
	return 1;
      if (GET_CODE (next) == NOTE)
	continue;
      if (inequality_comparisons_p (PATTERN (next)))
	return 0;
      if (sets_cc0_p (PATTERN (next)) == 1)
	return 1;
      if (! reg_mentioned_p (cc0_rtx, PATTERN (next)))
	return 1;
    }
  return 1;
}
#endif
#endif

/* This is used by find_single_use to locate an rtx that contains exactly one
   use of DEST, which is typically either a REG or CC0.  It returns a
   pointer to the innermost rtx expression containing DEST.  Appearances of
   DEST that are being used to totally replace it are not counted.  */

static rtx *
find_single_use_1 (dest, loc)
     rtx dest;
     rtx *loc;
{
  rtx x = *loc;
  enum rtx_code code = GET_CODE (x);
  rtx *result = 0;
  rtx *this_result;
  int i;
  char *fmt;

  switch (code)
    {
    case CONST_INT:
    case CONST:
    case LABEL_REF:
    case SYMBOL_REF:
    case CONST_DOUBLE:
    case CLOBBER:
      return 0;

    case SET:
      /* If the destination is anything other than CC0, PC, a REG or a SUBREG
	 of a REG that occupies all of the REG, the insn uses DEST if
	 it is mentioned in the destination or the source.  Otherwise, we
	 need just check the source.  */
      if (GET_CODE (SET_DEST (x)) != CC0
	  && GET_CODE (SET_DEST (x)) != PC
	  && GET_CODE (SET_DEST (x)) != REG
	  && ! (GET_CODE (SET_DEST (x)) == SUBREG
		&& GET_CODE (SUBREG_REG (SET_DEST (x))) == REG
		&& (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x))))
		      + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)
		    == ((GET_MODE_SIZE (GET_MODE (SET_DEST (x)))
			 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))))
	break;

      return find_single_use_1 (dest, &SET_SRC (x));

    case MEM:
    case SUBREG:
      return find_single_use_1 (dest, &XEXP (x, 0));
    }

  /* If it wasn't one of the common cases above, check each expression and
     vector of this code.  Look for a unique usage of DEST.  */

  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
	{
	  if (dest == XEXP (x, i)
	      || (GET_CODE (dest) == REG && GET_CODE (XEXP (x, i)) == REG
		  && REGNO (dest) == REGNO (XEXP (x, i))))
	    this_result = loc;
	  else
	    this_result = find_single_use_1 (dest, &XEXP (x, i));

	  if (result == 0)
	    result = this_result;
	  else if (this_result)
	    /* Duplicate usage.  */
	    return 0;
	}
      else if (fmt[i] == 'E')
	{
	  int j;

	  for (j = XVECLEN (x, i) - 1; j >= 0; j--)
	    {
	      if (XVECEXP (x, i, j) == dest
		  || (GET_CODE (dest) == REG
		      && GET_CODE (XVECEXP (x, i, j)) == REG
		      && REGNO (XVECEXP (x, i, j)) == REGNO (dest)))
		this_result = loc;
	      else
		this_result = find_single_use_1 (dest, &XVECEXP (x, i, j));

	      if (result == 0)
		result = this_result;
	      else if (this_result)
		return 0;
	    }
	}
    }

  return result;
}

/* See if DEST, produced in INSN, is used only a single time in the
   sequel.  If so, return a pointer to the innermost rtx expression in which
   it is used.

   If PLOC is non-zero, *PLOC is set to the insn containing the single use.

   This routine will return usually zero either before flow is called (because
   there will be no LOG_LINKS notes) or after reload (because the REG_DEAD
   note can't be trusted).

   If DEST is cc0_rtx, we look only at the next insn.  In that case, we don't
   care about REG_DEAD notes or LOG_LINKS.

   Otherwise, we find the single use by finding an insn that has a
   LOG_LINKS pointing at INSN and has a REG_DEAD note for DEST.  If DEST is
   only referenced once in that insn, we know that it must be the first
   and last insn referencing DEST.  */

rtx *
find_single_use (dest, insn, ploc)
     rtx dest;
     rtx insn;
     rtx *ploc;
{
  rtx next;
  rtx *result;
  rtx link;

#ifdef HAVE_cc0
  if (dest == cc0_rtx)
    {
      next = NEXT_INSN (insn);
      if (next == 0
	  || (GET_CODE (next) != INSN && GET_CODE (next) != JUMP_INSN))
	return 0;

      result = find_single_use_1 (dest, &PATTERN (next));
      if (result && ploc)
	*ploc = next;
      return result;
    }
#endif

  if (reload_completed || reload_in_progress || GET_CODE (dest) != REG)
    return 0;

  for (next = next_nonnote_insn (insn);
       next != 0 && GET_CODE (next) != CODE_LABEL;
       next = next_nonnote_insn (next))
    if (GET_RTX_CLASS (GET_CODE (next)) == 'i' && dead_or_set_p (next, dest))
      {
	for (link = LOG_LINKS (next); link; link = XEXP (link, 1))
	  if (XEXP (link, 0) == insn)
	    break;

	if (link)
	  {
	    result = find_single_use_1 (dest, &PATTERN (next));
	    if (ploc)
	      *ploc = next;
	    return result;
	  }
      }

  return 0;
}

/* Return 1 if OP is a valid general operand for machine mode MODE.
   This is either a register reference, a memory reference,
   or a constant.  In the case of a memory reference, the address
   is checked for general validity for the target machine.

   Register and memory references must have mode MODE in order to be valid,
   but some constants have no machine mode and are valid for any mode.

   If MODE is VOIDmode, OP is checked for validity for whatever mode
   it has.

   The main use of this function is as a predicate in match_operand
   expressions in the machine description.

   For an explanation of this function's behavior for registers of
   class NO_REGS, see the comment for `register_operand'.  */

int
general_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  register enum rtx_code code = GET_CODE (op);
  int mode_altering_drug = 0;

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

  /* Don't accept CONST_INT or anything similar
     if the caller wants something floating.  */
  if (GET_MODE (op) == VOIDmode && mode != VOIDmode
      && GET_MODE_CLASS (mode) != MODE_INT
      && GET_MODE_CLASS (mode) != MODE_PARTIAL_INT)
    return 0;

  if (CONSTANT_P (op))
    return ((GET_MODE (op) == VOIDmode || GET_MODE (op) == mode)
#ifdef LEGITIMATE_PIC_OPERAND_P
	    && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (op))
#endif
	    && LEGITIMATE_CONSTANT_P (op));

  /* Except for certain constants with VOIDmode, already checked for,
     OP's mode must match MODE if MODE specifies a mode.  */

  if (GET_MODE (op) != mode)
    return 0;

  if (code == SUBREG)
    {
#ifdef INSN_SCHEDULING
      /* On machines that have insn scheduling, we want all memory
	 reference to be explicit, so outlaw paradoxical SUBREGs.  */
      if (GET_CODE (SUBREG_REG (op)) == MEM
	  && GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op))))
	return 0;
#endif

      op = SUBREG_REG (op);
      code = GET_CODE (op);
#if 0
      /* No longer needed, since (SUBREG (MEM...))
	 will load the MEM into a reload reg in the MEM's own mode.  */
      mode_altering_drug = 1;
#endif
    }

  if (code == REG)
    /* A register whose class is NO_REGS is not a general operand.  */
    return (REGNO (op) >= FIRST_PSEUDO_REGISTER
	    || REGNO_REG_CLASS (REGNO (op)) != NO_REGS);

  if (code == MEM)
    {
      register rtx y = XEXP (op, 0);
      if (! volatile_ok && MEM_VOLATILE_P (op))
	return 0;
      /* Use the mem's mode, since it will be reloaded thus.  */
      mode = GET_MODE (op);
      GO_IF_LEGITIMATE_ADDRESS (mode, y, win);
    }
  return 0;

 win:
  if (mode_altering_drug)
    return ! mode_dependent_address_p (XEXP (op, 0));
  return 1;
}

/* Return 1 if OP is a valid memory address for a memory reference
   of mode MODE.

   The main use of this function is as a predicate in match_operand
   expressions in the machine description.  */

int
address_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return memory_address_p (mode, op);
}

/* Return 1 if OP is a register reference of mode MODE.
   If MODE is VOIDmode, accept a register in any mode.

   The main use of this function is as a predicate in match_operand
   expressions in the machine description.

   As a special exception, registers whose class is NO_REGS are
   not accepted by `register_operand'.  The reason for this change
   is to allow the representation of special architecture artifacts
   (such as a condition code register) without extending the rtl
   definitions.  Since registers of class NO_REGS cannot be used
   as registers in any case where register classes are examined,
   it is most consistent to keep this function from accepting them.  */

int
register_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  if (GET_MODE (op) != mode && mode != VOIDmode)
    return 0;

  if (GET_CODE (op) == SUBREG)
    {
      /* Before reload, we can allow (SUBREG (MEM...)) as a register operand
	 because it is guaranteed to be reloaded into one.
	 Just make sure the MEM is valid in itself.
	 (Ideally, (SUBREG (MEM)...) should not exist after reload,
	 but currently it does result from (SUBREG (REG)...) where the
	 reg went on the stack.)  */
      if (! reload_completed && GET_CODE (SUBREG_REG (op)) == MEM)
	return general_operand (op, mode);

#ifdef CLASS_CANNOT_CHANGE_SIZE
      if (GET_CODE (SUBREG_REG (op)) == REG
	  && REGNO (SUBREG_REG (op)) < FIRST_PSEUDO_REGISTER
	  && TEST_HARD_REG_BIT (reg_class_contents[(int) CLASS_CANNOT_CHANGE_SIZE],
				REGNO (SUBREG_REG (op)))
	  && (GET_MODE_SIZE (mode)
	      != GET_MODE_SIZE (GET_MODE (SUBREG_REG (op)))))
	return 0;
#endif

      op = SUBREG_REG (op);
    }

  /* We don't consider registers whose class is NO_REGS
     to be a register operand.  */
  return (GET_CODE (op) == REG
	  && (REGNO (op) >= FIRST_PSEUDO_REGISTER
	      || REGNO_REG_CLASS (REGNO (op)) != NO_REGS));
}

/* Return 1 if OP should match a MATCH_SCRATCH, i.e., if it is a SCRATCH
   or a hard register.  */

int
scratch_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (GET_MODE (op) == mode
	  && (GET_CODE (op) == SCRATCH
	      || (GET_CODE (op) == REG
		  && REGNO (op) < FIRST_PSEUDO_REGISTER)));
}

/* Return 1 if OP is a valid immediate operand for mode MODE.

   The main use of this function is as a predicate in match_operand
   expressions in the machine description.  */

int
immediate_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  /* Don't accept CONST_INT or anything similar
     if the caller wants something floating.  */
  if (GET_MODE (op) == VOIDmode && mode != VOIDmode
      && GET_MODE_CLASS (mode) != MODE_INT
      && GET_MODE_CLASS (mode) != MODE_PARTIAL_INT)
    return 0;

  return (CONSTANT_P (op)
	  && (GET_MODE (op) == mode || mode == VOIDmode
	      || GET_MODE (op) == VOIDmode)
#ifdef LEGITIMATE_PIC_OPERAND_P
	  && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (op))
#endif
	  && LEGITIMATE_CONSTANT_P (op));
}

/* Returns 1 if OP is an operand that is a CONST_INT.  */

int
const_int_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return GET_CODE (op) == CONST_INT;
}

/* Returns 1 if OP is an operand that is a constant integer or constant
   floating-point number.  */

int
const_double_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  /* Don't accept CONST_INT or anything similar
     if the caller wants something floating.  */
  if (GET_MODE (op) == VOIDmode && mode != VOIDmode
      && GET_MODE_CLASS (mode) != MODE_INT
      && GET_MODE_CLASS (mode) != MODE_PARTIAL_INT)
    return 0;

  return ((GET_CODE (op) == CONST_DOUBLE || GET_CODE (op) == CONST_INT)
	  && (mode == VOIDmode || GET_MODE (op) == mode
	      || GET_MODE (op) == VOIDmode));
}

/* Return 1 if OP is a general operand that is not an immediate operand.  */

int
nonimmediate_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  return (general_operand (op, mode) && ! CONSTANT_P (op));
}

/* Return 1 if OP is a register reference or immediate value of mode MODE.  */

int
nonmemory_operand (op, mode)
     register rtx op;
     enum machine_mode mode;
{
  if (CONSTANT_P (op))
    {
      /* Don't accept CONST_INT or anything similar
	 if the caller wants something floating.  */
      if (GET_MODE (op) == VOIDmode && mode != VOIDmode
	  && GET_MODE_CLASS (mode) != MODE_INT
	  && GET_MODE_CLASS (mode) != MODE_PARTIAL_INT)
	return 0;

      return ((GET_MODE (op) == VOIDmode || GET_MODE (op) == mode)
#ifdef LEGITIMATE_PIC_OPERAND_P
	      && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (op))
#endif
	      && LEGITIMATE_CONSTANT_P (op));
    }

  if (GET_MODE (op) != mode && mode != VOIDmode)
    return 0;