genattrtab.c

gcc库的原代码,对编程有很大帮助.

	    case SET_ATTR_ALTERNATIVE:
	      value = convert_set_attr_alternative (value,
						    id->num_alternatives,
						    id->insn_code,
						    id->insn_index);
	      break;

	    case SET_ATTR:
	      value = convert_set_attr (value, id->num_alternatives,
					id->insn_code, id->insn_index);
	      break;

	    default:
	      fatal ("Invalid attribute code `%s' for pattern %d",
		     GET_RTX_NAME (GET_CODE (value)), id->insn_index);
	    }

	  if ((attr = find_attr (XSTR (XEXP (value, 0), 0), 0)) == NULL)
	    fatal ("Unknown attribute `%s' for pattern number %d",
		   XSTR (XEXP (value, 0), 0), id->insn_index);

	  XVECEXP (id->def, id->vec_idx, i) = value;
	  XEXP (value, 1) = check_attr_value (XEXP (value, 1), attr);
	}
    }
}

/* Given a constant SYMBOL_REF expression, convert to a COND that
   explicitly tests each enumerated value.  */

static rtx
convert_const_symbol_ref (exp, attr)
     rtx exp;
     struct attr_desc *attr;
{
  rtx condexp;
  struct attr_value *av;
  int i;
  int num_alt = 0;

  for (av = attr->first_value; av; av = av->next)
    num_alt++;

  /* Make a COND with all tests but the last, and in the original order.
     Select the last value via the default.  Note that the attr values
     are constructed in reverse order.  */

  condexp = rtx_alloc (COND);
  XVEC (condexp, 0) = rtvec_alloc ((num_alt - 1) * 2);
  av = attr->first_value;
  XEXP (condexp, 1) = av->value;

  for (i = num_alt - 2; av = av->next, i >= 0; i--)
    {
      char *p, *string;
      rtx value;

      string = p = (char *) oballoc (2
				     + strlen (attr->name)
				     + strlen (XSTR (av->value, 0)));
      strcpy (p, attr->name);
      strcat (p, "_");
      strcat (p, XSTR (av->value, 0));
      for (; *p != '\0'; p++)
	if (*p >= 'a' && *p <= 'z')
	  *p -= 'a' - 'A';

      value = attr_rtx (SYMBOL_REF, string);
      RTX_UNCHANGING_P (value) = 1;
      
      XVECEXP (condexp, 0, 2 * i) = attr_rtx (EQ, exp, value);

      XVECEXP (condexp, 0, 2 * i + 1) = av->value;
    }

  return condexp;
}

/* Given a valid expression for an attribute value, remove any IF_THEN_ELSE
   expressions by converting them into a COND.  This removes cases from this
   program.  Also, replace an attribute value of "*" with the default attribute
   value.  */

static rtx
make_canonical (attr, exp)
     struct attr_desc *attr;
     rtx exp;
{
  int i;
  rtx newexp;

  switch (GET_CODE (exp))
    {
    case CONST_INT:
      exp = make_numeric_value (INTVAL (exp));
      break;

    case CONST_STRING:
      if (! strcmp (XSTR (exp, 0), "*"))
	{
	  if (attr == 0 || attr->default_val == 0)
	    fatal ("(attr_value \"*\") used in invalid context.");
	  exp = attr->default_val->value;
	}

      break;

    case SYMBOL_REF:
      if (!attr->is_const || RTX_UNCHANGING_P (exp))
	break;
      /* The SYMBOL_REF is constant for a given run, so mark it as unchanging.
	 This makes the COND something that won't be considered an arbitrary
	 expression by walk_attr_value.  */
      RTX_UNCHANGING_P (exp) = 1;
      exp = convert_const_symbol_ref (exp, attr);
      RTX_UNCHANGING_P (exp) = 1;
      exp = check_attr_value (exp, attr);
      /* Goto COND case since this is now a COND.  Note that while the
         new expression is rescanned, all symbol_ref notes are mared as
	 unchanging.  */
      goto cond;

    case IF_THEN_ELSE:
      newexp = rtx_alloc (COND);
      XVEC (newexp, 0) = rtvec_alloc (2);
      XVECEXP (newexp, 0, 0) = XEXP (exp, 0);
      XVECEXP (newexp, 0, 1) = XEXP (exp, 1);

      XEXP (newexp, 1) = XEXP (exp, 2);

      exp = newexp;
      /* Fall through to COND case since this is now a COND.  */

    case COND:
    cond:
      {
	int allsame = 1;
	rtx defval;

	/* First, check for degenerate COND. */
	if (XVECLEN (exp, 0) == 0)
	  return make_canonical (attr, XEXP (exp, 1));
	defval = XEXP (exp, 1) = make_canonical (attr, XEXP (exp, 1));

	for (i = 0; i < XVECLEN (exp, 0); i += 2)
	  {
	    XVECEXP (exp, 0, i) = copy_boolean (XVECEXP (exp, 0, i));
	    XVECEXP (exp, 0, i + 1)
	      = make_canonical (attr, XVECEXP (exp, 0, i + 1));
	    if (! rtx_equal_p (XVECEXP (exp, 0, i + 1), defval))
	      allsame = 0;
	  }
	if (allsame)
	  return defval;
	break;
      }
    }

  return exp;
}

static rtx
copy_boolean (exp)
     rtx exp;
{
  if (GET_CODE (exp) == AND || GET_CODE (exp) == IOR)
    return attr_rtx (GET_CODE (exp), copy_boolean (XEXP (exp, 0)),
		     copy_boolean (XEXP (exp, 1)));
  return exp;
}

/* Given a value and an attribute description, return a `struct attr_value *'
   that represents that value.  This is either an existing structure, if the
   value has been previously encountered, or a newly-created structure.

   `insn_code' is the code of an insn whose attribute has the specified
   value (-2 if not processing an insn).  We ensure that all insns for
   a given value have the same number of alternatives if the value checks
   alternatives.  */

static struct attr_value *
get_attr_value (value, attr, insn_code)
     rtx value;
     struct attr_desc *attr;
     int insn_code;
{
  struct attr_value *av;
  int num_alt = 0;

  value = make_canonical (attr, value);
  if (compares_alternatives_p (value))
    {
      if (insn_code < 0 || insn_alternatives == NULL)
	fatal ("(eq_attr \"alternatives\" ...) used in non-insn context");
      else
	num_alt = insn_alternatives[insn_code];
    }

  for (av = attr->first_value; av; av = av->next)
    if (rtx_equal_p (value, av->value)
	&& (num_alt == 0 || av->first_insn == NULL
	    || insn_alternatives[av->first_insn->insn_code]))
      return av;

  av = (struct attr_value *) oballoc (sizeof (struct attr_value));
  av->value = value;
  av->next = attr->first_value;
  attr->first_value = av;
  av->first_insn = NULL;
  av->num_insns = 0;
  av->has_asm_insn = 0;

  return av;
}

/* After all DEFINE_DELAYs have been read in, create internal attributes
   to generate the required routines.

   First, we compute the number of delay slots for each insn (as a COND of
   each of the test expressions in DEFINE_DELAYs).  Then, if more than one
   delay type is specified, we compute a similar function giving the
   DEFINE_DELAY ordinal for each insn.

   Finally, for each [DEFINE_DELAY, slot #] pair, we compute an attribute that
   tells whether a given insn can be in that delay slot.

   Normal attribute filling and optimization expands these to contain the
   information needed to handle delay slots.  */

static void
expand_delays ()
{
  struct delay_desc *delay;
  rtx condexp;
  rtx newexp;
  int i;
  char *p;

  /* First, generate data for `num_delay_slots' function.  */

  condexp = rtx_alloc (COND);
  XVEC (condexp, 0) = rtvec_alloc (num_delays * 2);
  XEXP (condexp, 1) = make_numeric_value (0);

  for (i = 0, delay = delays; delay; i += 2, delay = delay->next)
    {
      XVECEXP (condexp, 0, i) = XEXP (delay->def, 0);
      XVECEXP (condexp, 0, i + 1)
	= make_numeric_value (XVECLEN (delay->def, 1) / 3);
    }

  make_internal_attr ("*num_delay_slots", condexp, 0);

  /* If more than one delay type, do the same for computing the delay type.  */
  if (num_delays > 1)
    {
      condexp = rtx_alloc (COND);
      XVEC (condexp, 0) = rtvec_alloc (num_delays * 2);
      XEXP (condexp, 1) = make_numeric_value (0);

      for (i = 0, delay = delays; delay; i += 2, delay = delay->next)
	{
	  XVECEXP (condexp, 0, i) = XEXP (delay->def, 0);
	  XVECEXP (condexp, 0, i + 1) = make_numeric_value (delay->num);
	}

      make_internal_attr ("*delay_type", condexp, 1);
    }

  /* For each delay possibility and delay slot, compute an eligibility
     attribute for non-annulled insns and for each type of annulled (annul
     if true and annul if false).  */
 for (delay = delays; delay; delay = delay->next)
   {
     for (i = 0; i < XVECLEN (delay->def, 1); i += 3)
       {
	 condexp = XVECEXP (delay->def, 1, i);
	 if (condexp == 0) condexp = false_rtx;
	 newexp = attr_rtx (IF_THEN_ELSE, condexp,
			    make_numeric_value (1), make_numeric_value (0));

	 p = attr_printf (sizeof ("*delay__") + MAX_DIGITS*2, "*delay_%d_%d",
			  delay->num, i / 3);
	 make_internal_attr (p, newexp, 1);

	 if (have_annul_true)
	   {
	     condexp = XVECEXP (delay->def, 1, i + 1);
	     if (condexp == 0) condexp = false_rtx;
	     newexp = attr_rtx (IF_THEN_ELSE, condexp,
				make_numeric_value (1),
				make_numeric_value (0));
	     p = attr_printf (sizeof ("*annul_true__") + MAX_DIGITS*2,
			      "*annul_true_%d_%d", delay->num, i / 3);
	     make_internal_attr (p, newexp, 1);
	   }

	 if (have_annul_false)
	   {
	     condexp = XVECEXP (delay->def, 1, i + 2);
	     if (condexp == 0) condexp = false_rtx;
	     newexp = attr_rtx (IF_THEN_ELSE, condexp,
				make_numeric_value (1),
				make_numeric_value (0));
	     p = attr_printf (sizeof ("*annul_false__") + MAX_DIGITS*2,
			      "*annul_false_%d_%d", delay->num, i / 3);
	     make_internal_attr (p, newexp, 1);
	   }
       }
   }
}

/* This function is given a left and right side expression and an operator.
   Each side is a conditional expression, each alternative of which has a
   numerical value.  The function returns another conditional expression
   which, for every possible set of condition values, returns a value that is
   the operator applied to the values of the two sides.

   Since this is called early, it must also support IF_THEN_ELSE.  */

static rtx
operate_exp (op, left, right)
     enum operator op;
     rtx left, right;
{
  int left_value, right_value;
  rtx newexp;
  int i;

  /* If left is a string, apply operator to it and the right side.  */
  if (GET_CODE (left) == CONST_STRING)
    {
      /* If right is also a string, just perform the operation.  */
      if (GET_CODE (right) == CONST_STRING)
	{
	  left_value = atoi (XSTR (left, 0));
	  right_value = atoi (XSTR (right, 0));
	  switch (op)
	    {
	    case PLUS_OP:
	      i = left_value + right_value;
	      break;

	    case MINUS_OP:
	      i = left_value - right_value;
	      break;

	    case POS_MINUS_OP:  /* The positive part of LEFT - RIGHT.  */
	      if (left_value > right_value)
		i = left_value - right_value;
	      else
		i = 0;
	      break;

	    case OR_OP:
	      i = left_value | right_value;
	      break;

	    case EQ_OP:
	      i = left_value == right_value;
	      break;

	    case RANGE_OP:
	      i = (left_value << (HOST_BITS_PER_INT / 2)) | right_value;
	      break;

	    case MAX_OP:
	      if (left_value > right_value)
		i = left_value;
	      else
		i = right_value;
	      break;

	    case MIN_OP:
	      if (left_value < right_value)
		i = left_value;
	      else
		i = right_value;
	      break;

	    default:
	      abort ();
	    }

	  return make_numeric_value (i);
	}
      else if (GET_CODE (right) == IF_THEN_ELSE)
	{
	  /* Apply recursively to all values within.  */
	  rtx newleft = operate_exp (op, left, XEXP (right, 1));
	  rtx newright = operate_exp (op, left, XEXP (right, 2));
	  if (rtx_equal_p (newleft, newright))
	    return newleft;
	  return attr_rtx (IF_THEN_ELSE, XEXP (right, 0), newleft, newright);
	}
      else if (GET_CODE (right) == COND)
	{
	  int allsame = 1;
	  rtx defval;

	  newexp = rtx_alloc (COND);
	  XVEC (newexp, 0) = rtvec_alloc (XVECLEN (right, 0));
	  defval = XEXP (newexp, 1) = operate_exp (op, left, XEXP (right, 1));

	  for (i = 0; i < XVECLEN (right, 0); i += 2)
	    {
	      XVECEXP (newexp, 0, i) = XVECEXP (right, 0, i);
	      XVECEXP (newexp, 0, i + 1)
		= operate_exp (op, left, XVECEXP (right, 0, i + 1));
	      if (! rtx_equal_p (XVECEXP (newexp, 0, i + 1),
				 defval))     
		allsame = 0;
	    }

	  /* If the resulting cond is trivial (all alternatives
	     give the same value), optimize it away.  */
	  if (allsame)
	    {
	      obstack_free (rtl_obstack, newexp);
	      return operate_exp (op, left, XEXP (right, 1));
	    }