genattrtab.c

gcc库的原代码,对编程有很大帮助.

  register RTX_CODE code;
  register char *format_ptr;

  /* No need to copy a permanent object.  */
  if (RTX_INTEGRATED_P (orig))
    return orig;

  code = GET_CODE (orig);

  switch (code)
    {
    case REG:
    case QUEUED:
    case CONST_INT:
    case CONST_DOUBLE:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
      return orig;
    }

  copy = rtx_alloc (code);
  PUT_MODE (copy, GET_MODE (orig));
  copy->in_struct = orig->in_struct;
  copy->volatil = orig->volatil;
  copy->unchanging = orig->unchanging;
  copy->integrated = orig->integrated;
  
  format_ptr = GET_RTX_FORMAT (GET_CODE (copy));

  for (i = 0; i < GET_RTX_LENGTH (GET_CODE (copy)); i++)
    {
      switch (*format_ptr++)
	{
	case 'e':
	  XEXP (copy, i) = XEXP (orig, i);
	  if (XEXP (orig, i) != NULL)
	    XEXP (copy, i) = attr_copy_rtx (XEXP (orig, i));
	  break;

	case 'E':
	case 'V':
	  XVEC (copy, i) = XVEC (orig, i);
	  if (XVEC (orig, i) != NULL)
	    {
	      XVEC (copy, i) = rtvec_alloc (XVECLEN (orig, i));
	      for (j = 0; j < XVECLEN (copy, i); j++)
		XVECEXP (copy, i, j) = attr_copy_rtx (XVECEXP (orig, i, j));
	    }
	  break;

	case 'n':
	case 'i':
	  XINT (copy, i) = XINT (orig, i);
	  break;

	case 'w':
	  XWINT (copy, i) = XWINT (orig, i);
	  break;

	case 's':
	case 'S':
	  XSTR (copy, i) = XSTR (orig, i);
	  break;

	default:
	  abort ();
	}
    }
  return copy;
}

/* Given a test expression for an attribute, ensure it is validly formed.
   IS_CONST indicates whether the expression is constant for each compiler
   run (a constant expression may not test any particular insn).

   Convert (eq_attr "att" "a1,a2") to (ior (eq_attr ... ) (eq_attrq ..))
   and (eq_attr "att" "!a1") to (not (eq_attr "att" "a1")).  Do the latter
   test first so that (eq_attr "att" "!a1,a2,a3") works as expected.

   Update the string address in EQ_ATTR expression to be the same used
   in the attribute (or `alternative_name') to speed up subsequent
   `find_attr' calls and eliminate most `strcmp' calls.

   Return the new expression, if any.   */

static rtx
check_attr_test (exp, is_const)
     rtx exp;
     int is_const;
{
  struct attr_desc *attr;
  struct attr_value *av;
  char *name_ptr, *p;
  rtx orexp, newexp;

  switch (GET_CODE (exp))
    {
    case EQ_ATTR:
      /* Handle negation test.  */
      if (XSTR (exp, 1)[0] == '!')
	return check_attr_test (attr_rtx (NOT,
					  attr_eq (XSTR (exp, 0),
						   &XSTR (exp, 1)[1])),
				is_const);

      else if (n_comma_elts (XSTR (exp, 1)) == 1)
	{
	  attr = find_attr (XSTR (exp, 0), 0);
	  if (attr == NULL)
	    {
	      if (! strcmp (XSTR (exp, 0), "alternative"))
		{
		  XSTR (exp, 0) = alternative_name;
		  /* This can't be simplified any further.  */
		  RTX_UNCHANGING_P (exp) = 1;
		  return exp;
		}
	      else
		fatal ("Unknown attribute `%s' in EQ_ATTR", XEXP (exp, 0));
	    }

	  if (is_const && ! attr->is_const)
	    fatal ("Constant expression uses insn attribute `%s' in EQ_ATTR",
		   XEXP (exp, 0));

	  /* Copy this just to make it permanent,
	     so expressions using it can be permanent too.  */
	  exp = attr_eq (XSTR (exp, 0), XSTR (exp, 1));

	  /* It shouldn't be possible to simplify the value given to a
	     constant attribute, so don't expand this until it's time to
	     write the test expression.  */	       
	  if (attr->is_const)
	    RTX_UNCHANGING_P (exp) = 1;

	  if (attr->is_numeric)
	    {
	      for (p = XSTR (exp, 1); *p; p++)
		if (*p < '0' || *p > '9')
		   fatal ("Attribute `%s' takes only numeric values", 
			  XEXP (exp, 0));
	    }
	  else
	    {
	      for (av = attr->first_value; av; av = av->next)
		if (GET_CODE (av->value) == CONST_STRING
		    && ! strcmp (XSTR (exp, 1), XSTR (av->value, 0)))
		  break;

	      if (av == NULL)
		fatal ("Unknown value `%s' for `%s' attribute",
		       XEXP (exp, 1), XEXP (exp, 0));
	    }
	}
      else
	{
	  /* Make an IOR tree of the possible values.  */
	  orexp = false_rtx;
	  name_ptr = XSTR (exp, 1);
	  while ((p = next_comma_elt (&name_ptr)) != NULL)
	    {
	      newexp = attr_eq (XSTR (exp, 0), p);
	      orexp = insert_right_side (IOR, orexp, newexp, -2, -2);
	    }

	  return check_attr_test (orexp, is_const);
	}
      break;

    case ATTR_FLAG:
      break;

    case CONST_INT:
      /* Either TRUE or FALSE.  */
      if (XWINT (exp, 0))
	return true_rtx;
      else
	return false_rtx;

    case IOR:
    case AND:
      XEXP (exp, 0) = check_attr_test (XEXP (exp, 0), is_const);
      XEXP (exp, 1) = check_attr_test (XEXP (exp, 1), is_const);
      break;

    case NOT:
      XEXP (exp, 0) = check_attr_test (XEXP (exp, 0), is_const);
      break;

    case MATCH_OPERAND:
      if (is_const)
	fatal ("RTL operator \"%s\" not valid in constant attribute test",
	       GET_RTX_NAME (MATCH_OPERAND));
      /* These cases can't be simplified.  */
      RTX_UNCHANGING_P (exp) = 1;
      break;

    case LE:  case LT:  case GT:  case GE:
    case LEU: case LTU: case GTU: case GEU:
    case NE:  case EQ:
      if (GET_CODE (XEXP (exp, 0)) == SYMBOL_REF
	  && GET_CODE (XEXP (exp, 1)) == SYMBOL_REF)
	exp = attr_rtx (GET_CODE (exp),
			attr_rtx (SYMBOL_REF, XSTR (XEXP (exp, 0), 0)),
			attr_rtx (SYMBOL_REF, XSTR (XEXP (exp, 1), 0)));
      /* These cases can't be simplified.  */
      RTX_UNCHANGING_P (exp) = 1;
      break;

    case SYMBOL_REF:
      if (is_const)
	{
	  /* These cases are valid for constant attributes, but can't be
	     simplified.  */
	  exp = attr_rtx (SYMBOL_REF, XSTR (exp, 0));
	  RTX_UNCHANGING_P (exp) = 1;
	  break;
	}
    default:
      fatal ("RTL operator \"%s\" not valid in attribute test",
	     GET_RTX_NAME (GET_CODE (exp)));
    }

  return exp;
}

/* Given an expression, ensure that it is validly formed and that all named
   attribute values are valid for the given attribute.  Issue a fatal error
   if not.  If no attribute is specified, assume a numeric attribute.

   Return a perhaps modified replacement expression for the value.  */

static rtx
check_attr_value (exp, attr)
     rtx exp;
     struct attr_desc *attr;
{
  struct attr_value *av;
  char *p;
  int i;

  switch (GET_CODE (exp))
    {
    case CONST_INT:
      if (attr && ! attr->is_numeric)
	fatal ("CONST_INT not valid for non-numeric `%s' attribute",
	       attr->name);

      if (INTVAL (exp) < 0)
	fatal ("Negative numeric value specified for `%s' attribute",
	       attr->name);

      break;

    case CONST_STRING:
      if (! strcmp (XSTR (exp, 0), "*"))
	break;

      if (attr == 0 || attr->is_numeric)
	{
	  p = XSTR (exp, 0);
	  if (attr && attr->negative_ok && *p == '-')
	    p++;
	  for (; *p; p++)
	    if (*p > '9' || *p < '0')
	      fatal ("Non-numeric value for numeric `%s' attribute",
		     attr ? attr->name : "internal");
	  break;
	}

      for (av = attr->first_value; av; av = av->next)
	if (GET_CODE (av->value) == CONST_STRING
	    && ! strcmp (XSTR (av->value, 0), XSTR (exp, 0)))
	  break;

      if (av == NULL)
	fatal ("Unknown value `%s' for `%s' attribute",
	       XSTR (exp, 0), attr ? attr->name : "internal");

      break;

    case IF_THEN_ELSE:
      XEXP (exp, 0) = check_attr_test (XEXP (exp, 0),
				       attr ? attr->is_const : 0);
      XEXP (exp, 1) = check_attr_value (XEXP (exp, 1), attr);
      XEXP (exp, 2) = check_attr_value (XEXP (exp, 2), attr);
      break;

    case COND:
      if (XVECLEN (exp, 0) % 2 != 0)
	fatal ("First operand of COND must have even length");

      for (i = 0; i < XVECLEN (exp, 0); i += 2)
	{
	  XVECEXP (exp, 0, i) = check_attr_test (XVECEXP (exp, 0, i),
						 attr ? attr->is_const : 0);
	  XVECEXP (exp, 0, i + 1)
	    = check_attr_value (XVECEXP (exp, 0, i + 1), attr);
	}

      XEXP (exp, 1) = check_attr_value (XEXP (exp, 1), attr);
      break;

    case SYMBOL_REF:
      if (attr && attr->is_const)
	/* A constant SYMBOL_REF is valid as a constant attribute test and
	   is expanded later by make_canonical into a COND.  */
	return attr_rtx (SYMBOL_REF, XSTR (exp, 0));
      /* Otherwise, fall through... */

    default:
      fatal ("Invalid operation `%s' for attribute value",
	     GET_RTX_NAME (GET_CODE (exp)));
    }

  return exp;
}

/* Given an SET_ATTR_ALTERNATIVE expression, convert to the canonical SET.
   It becomes a COND with each test being (eq_attr "alternative "n") */

static rtx
convert_set_attr_alternative (exp, num_alt, insn_code, insn_index)
     rtx exp;
     int num_alt;
     int insn_code, insn_index;
{
  rtx condexp;
  int i;

  if (XVECLEN (exp, 1) != num_alt)
    fatal ("Bad number of entries in SET_ATTR_ALTERNATIVE for insn %d",
	   insn_index);

  /* Make a COND with all tests but the last.  Select the last value via the
     default.  */
  condexp = rtx_alloc (COND);
  XVEC (condexp, 0) = rtvec_alloc ((num_alt - 1) * 2);

  for (i = 0; i < num_alt - 1; i++)
    {
      char *p;
      p = attr_numeral (i);

      XVECEXP (condexp, 0, 2 * i) = attr_eq (alternative_name, p);
#if 0
      /* Sharing this EQ_ATTR rtl causes trouble.  */   
      XVECEXP (condexp, 0, 2 * i) = rtx_alloc (EQ_ATTR);
      XSTR (XVECEXP (condexp, 0, 2 * i), 0) = alternative_name;
      XSTR (XVECEXP (condexp, 0, 2 * i), 1) = p;
#endif
      XVECEXP (condexp, 0, 2 * i + 1) = XVECEXP (exp, 1, i);
    }

  XEXP (condexp, 1) = XVECEXP (exp, 1, i);

  return attr_rtx (SET, attr_rtx (ATTR, XSTR (exp, 0)), condexp);
}

/* Given a SET_ATTR, convert to the appropriate SET.  If a comma-separated
   list of values is given, convert to SET_ATTR_ALTERNATIVE first.  */

static rtx
convert_set_attr (exp, num_alt, insn_code, insn_index)
     rtx exp;
     int num_alt;
     int insn_code, insn_index;
{
  rtx newexp;
  char *name_ptr;
  char *p;
  int n;

  /* See how many alternative specified.  */
  n = n_comma_elts (XSTR (exp, 1));
  if (n == 1)
    return attr_rtx (SET,
		     attr_rtx (ATTR, XSTR (exp, 0)),
		     attr_rtx (CONST_STRING, XSTR (exp, 1)));

  newexp = rtx_alloc (SET_ATTR_ALTERNATIVE);
  XSTR (newexp, 0) = XSTR (exp, 0);
  XVEC (newexp, 1) = rtvec_alloc (n);

  /* Process each comma-separated name.  */
  name_ptr = XSTR (exp, 1);
  n = 0;
  while ((p = next_comma_elt (&name_ptr)) != NULL)
    XVECEXP (newexp, 1, n++) = attr_rtx (CONST_STRING, p);

  return convert_set_attr_alternative (newexp, num_alt, insn_code, insn_index);
}

/* Scan all definitions, checking for validity.  Also, convert any SET_ATTR
   and SET_ATTR_ALTERNATIVE expressions to the corresponding SET
   expressions. */

static void
check_defs ()
{
  struct insn_def *id;
  struct attr_desc *attr;
  int i;
  rtx value;

  for (id = defs; id; id = id->next)
    {
      if (XVEC (id->def, id->vec_idx) == NULL)
	continue;

      for (i = 0; i < XVECLEN (id->def, id->vec_idx); i++)
	{
	  value = XVECEXP (id->def, id->vec_idx, i);
	  switch (GET_CODE (value))
	    {
	    case SET:
	      if (GET_CODE (XEXP (value, 0)) != ATTR)
		fatal ("Bad attribute set in pattern %d", id->insn_index);
	      break;