tree.c

GCC编译器源代码

     tree type, i;
{
  REAL_VALUE_TYPE d;
  REAL_VALUE_TYPE e;
  /* Some 386 compilers mishandle unsigned int to float conversions,
     so introduce a temporary variable E to avoid those bugs.  */

#ifdef REAL_ARITHMETIC
  if (! TREE_UNSIGNED (TREE_TYPE (i)))
    REAL_VALUE_FROM_INT (d, TREE_INT_CST_LOW (i), TREE_INT_CST_HIGH (i),
			 TYPE_MODE (type));
  else
    REAL_VALUE_FROM_UNSIGNED_INT (d, TREE_INT_CST_LOW (i),
				  TREE_INT_CST_HIGH (i), TYPE_MODE (type));
#else /* not REAL_ARITHMETIC */
  if (TREE_INT_CST_HIGH (i) < 0 && ! TREE_UNSIGNED (TREE_TYPE (i)))
    {
      d = (double) (~ TREE_INT_CST_HIGH (i));
      e = ((double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2))
	    * (double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)));
      d *= e;
      e = (double) (unsigned HOST_WIDE_INT) (~ TREE_INT_CST_LOW (i));
      d += e;
      d = (- d - 1.0);
    }
  else
    {
      d = (double) (unsigned HOST_WIDE_INT) TREE_INT_CST_HIGH (i);
      e = ((double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2))
	    * (double) ((HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)));
      d *= e;
      e = (double) (unsigned HOST_WIDE_INT) TREE_INT_CST_LOW (i);
      d += e;
    }
#endif /* not REAL_ARITHMETIC */
  return d;
}

/* This function can't be implemented if we can't do arithmetic
   on the float representation.  */

tree
build_real_from_int_cst (type, i)
     tree type;
     tree i;
{
  tree v;
  int overflow = TREE_OVERFLOW (i);
  REAL_VALUE_TYPE d;
  jmp_buf float_error;

  v = make_node (REAL_CST);
  TREE_TYPE (v) = type;

  if (setjmp (float_error))
    {
      d = dconst0;
      overflow = 1;
      goto got_it;
    }

  set_float_handler (float_error);

#ifdef REAL_ARITHMETIC
  d = real_value_from_int_cst (type, i);
#else
  d = REAL_VALUE_TRUNCATE (TYPE_MODE (type),
			   real_value_from_int_cst (type, i));
#endif

  /* Check for valid float value for this type on this target machine.  */

 got_it:
  set_float_handler (NULL_PTR);

#ifdef CHECK_FLOAT_VALUE
  CHECK_FLOAT_VALUE (TYPE_MODE (type), d, overflow);
#endif

  TREE_REAL_CST (v) = d;
  TREE_OVERFLOW (v) = TREE_CONSTANT_OVERFLOW (v) = overflow;
  return v;
}

#endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */

/* Return a newly constructed STRING_CST node whose value is
   the LEN characters at STR.
   The TREE_TYPE is not initialized.  */

tree
build_string (len, str)
     int len;
     char *str;
{
  /* Put the string in saveable_obstack since it will be placed in the RTL
     for an "asm" statement and will also be kept around a while if
     deferring constant output in varasm.c.  */

  register tree s = make_node (STRING_CST);
  TREE_STRING_LENGTH (s) = len;
  TREE_STRING_POINTER (s) = obstack_copy0 (saveable_obstack, str, len);
  return s;
}

/* Return a newly constructed COMPLEX_CST node whose value is
   specified by the real and imaginary parts REAL and IMAG.
   Both REAL and IMAG should be constant nodes.  TYPE, if specified,
   will be the type of the COMPLEX_CST; otherwise a new type will be made.  */

tree
build_complex (type, real, imag)
     tree type;
     tree real, imag;
{
  register tree t = make_node (COMPLEX_CST);

  TREE_REALPART (t) = real;
  TREE_IMAGPART (t) = imag;
  TREE_TYPE (t) = type ? type : build_complex_type (TREE_TYPE (real));
  TREE_OVERFLOW (t) = TREE_OVERFLOW (real) | TREE_OVERFLOW (imag);
  TREE_CONSTANT_OVERFLOW (t)
    = TREE_CONSTANT_OVERFLOW (real) | TREE_CONSTANT_OVERFLOW (imag);
  return t;
}

/* Build a newly constructed TREE_VEC node of length LEN.  */

tree
make_tree_vec (len)
     int len;
{
  register tree t;
  register int length = (len-1) * sizeof (tree) + sizeof (struct tree_vec);
  register struct obstack *obstack = current_obstack;
  register int i;

#ifdef GATHER_STATISTICS
  tree_node_counts[(int)vec_kind]++;
  tree_node_sizes[(int)vec_kind] += length;
#endif

  t = (tree) obstack_alloc (obstack, length);

  for (i = (length / sizeof (int)) - 1; i >= 0; i--)
    ((int *) t)[i] = 0;

  TREE_SET_CODE (t, TREE_VEC);
  TREE_VEC_LENGTH (t) = len;
  if (obstack == &permanent_obstack)
    TREE_PERMANENT (t) = 1;

  return t;
}

/* Return 1 if EXPR is the integer constant zero or a complex constant
   of zero.  */

int
integer_zerop (expr)
     tree expr;
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == INTEGER_CST
	   && ! TREE_CONSTANT_OVERFLOW (expr)
	   && TREE_INT_CST_LOW (expr) == 0
	   && TREE_INT_CST_HIGH (expr) == 0)
	  || (TREE_CODE (expr) == COMPLEX_CST
	      && integer_zerop (TREE_REALPART (expr))
	      && integer_zerop (TREE_IMAGPART (expr))));
}

/* Return 1 if EXPR is the integer constant one or the corresponding
   complex constant.  */

int
integer_onep (expr)
     tree expr;
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == INTEGER_CST
	   && ! TREE_CONSTANT_OVERFLOW (expr)
	   && TREE_INT_CST_LOW (expr) == 1
	   && TREE_INT_CST_HIGH (expr) == 0)
	  || (TREE_CODE (expr) == COMPLEX_CST
	      && integer_onep (TREE_REALPART (expr))
	      && integer_zerop (TREE_IMAGPART (expr))));
}

/* Return 1 if EXPR is an integer containing all 1's in as much precision as
   it contains.  Likewise for the corresponding complex constant.  */

int
integer_all_onesp (expr)
     tree expr;
{
  register int prec;
  register int uns;

  STRIP_NOPS (expr);

  if (TREE_CODE (expr) == COMPLEX_CST
      && integer_all_onesp (TREE_REALPART (expr))
      && integer_zerop (TREE_IMAGPART (expr)))
    return 1;

  else if (TREE_CODE (expr) != INTEGER_CST
	   || TREE_CONSTANT_OVERFLOW (expr))
    return 0;

  uns = TREE_UNSIGNED (TREE_TYPE (expr));
  if (!uns)
    return TREE_INT_CST_LOW (expr) == -1 && TREE_INT_CST_HIGH (expr) == -1;

  /* Note that using TYPE_PRECISION here is wrong.  We care about the
     actual bits, not the (arbitrary) range of the type.  */
  prec = GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (expr)));
  if (prec >= HOST_BITS_PER_WIDE_INT)
    {
      int high_value, shift_amount;

      shift_amount = prec - HOST_BITS_PER_WIDE_INT;

      if (shift_amount > HOST_BITS_PER_WIDE_INT)
	/* Can not handle precisions greater than twice the host int size.  */
	abort ();
      else if (shift_amount == HOST_BITS_PER_WIDE_INT)
	/* Shifting by the host word size is undefined according to the ANSI
	   standard, so we must handle this as a special case.  */
	high_value = -1;
      else
	high_value = ((HOST_WIDE_INT) 1 << shift_amount) - 1;

      return TREE_INT_CST_LOW (expr) == -1
	&& TREE_INT_CST_HIGH (expr) == high_value;
    }
  else
    return TREE_INT_CST_LOW (expr) == ((HOST_WIDE_INT) 1 << prec) - 1;
}

/* Return 1 if EXPR is an integer constant that is a power of 2 (i.e., has only
   one bit on).  */

int
integer_pow2p (expr)
     tree expr;
{
  int prec;
  HOST_WIDE_INT high, low;

  STRIP_NOPS (expr);

  if (TREE_CODE (expr) == COMPLEX_CST
      && integer_pow2p (TREE_REALPART (expr))
      && integer_zerop (TREE_IMAGPART (expr)))
    return 1;

  if (TREE_CODE (expr) != INTEGER_CST || TREE_CONSTANT_OVERFLOW (expr))
    return 0;

  prec = (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE
	  ? POINTER_SIZE : TYPE_PRECISION (TREE_TYPE (expr)));
  high = TREE_INT_CST_HIGH (expr);
  low = TREE_INT_CST_LOW (expr);

  /* First clear all bits that are beyond the type's precision in case
     we've been sign extended.  */

  if (prec == 2 * HOST_BITS_PER_WIDE_INT)
    ;
  else if (prec > HOST_BITS_PER_WIDE_INT)
    high &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
  else
    {
      high = 0;
      if (prec < HOST_BITS_PER_WIDE_INT)
	low &= ~((HOST_WIDE_INT) (-1) << prec);
    }

  if (high == 0 && low == 0)
    return 0;

  return ((high == 0 && (low & (low - 1)) == 0)
	  || (low == 0 && (high & (high - 1)) == 0));
}

/* Return the power of two represented by a tree node known to be a
   power of two.  */

int
tree_log2 (expr)
     tree expr;
{
  int prec;
  HOST_WIDE_INT high, low;

  STRIP_NOPS (expr);

  if (TREE_CODE (expr) == COMPLEX_CST)
    return tree_log2 (TREE_REALPART (expr));

  prec = (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE
	  ? POINTER_SIZE : TYPE_PRECISION (TREE_TYPE (expr)));

  high = TREE_INT_CST_HIGH (expr);
  low = TREE_INT_CST_LOW (expr);

  /* First clear all bits that are beyond the type's precision in case
     we've been sign extended.  */

  if (prec == 2 * HOST_BITS_PER_WIDE_INT)
    ;
  else if (prec > HOST_BITS_PER_WIDE_INT)
    high &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
  else
    {
      high = 0;
      if (prec < HOST_BITS_PER_WIDE_INT)
	low &= ~((HOST_WIDE_INT) (-1) << prec);
    }

  return (high != 0 ? HOST_BITS_PER_WIDE_INT + exact_log2 (high)
	  :  exact_log2 (low));
}

/* Return 1 if EXPR is the real constant zero.  */

int
real_zerop (expr)
     tree expr;
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == REAL_CST
	   && ! TREE_CONSTANT_OVERFLOW (expr)
	   && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst0))
	  || (TREE_CODE (expr) == COMPLEX_CST
	      && real_zerop (TREE_REALPART (expr))
	      && real_zerop (TREE_IMAGPART (expr))));
}

/* Return 1 if EXPR is the real constant one in real or complex form.  */

int
real_onep (expr)
     tree expr;
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == REAL_CST
	   && ! TREE_CONSTANT_OVERFLOW (expr)
	   && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst1))
	  || (TREE_CODE (expr) == COMPLEX_CST
	      && real_onep (TREE_REALPART (expr))
	      && real_zerop (TREE_IMAGPART (expr))));
}

/* Return 1 if EXPR is the real constant two.  */

int
real_twop (expr)
     tree expr;
{
  STRIP_NOPS (expr);

  return ((TREE_CODE (expr) == REAL_CST
	   && ! TREE_CONSTANT_OVERFLOW (expr)
	   && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst2))
	  || (TREE_CODE (expr) == COMPLEX_CST
	      && real_twop (TREE_REALPART (expr))
	      && real_zerop (TREE_IMAGPART (expr))));
}

/* Nonzero if EXP is a constant or a cast of a constant.  */
 
int
really_constant_p (exp)
     tree exp;
{
  /* This is not quite the same as STRIP_NOPS.  It does more.  */
  while (TREE_CODE (exp) == NOP_EXPR
	 || TREE_CODE (exp) == CONVERT_EXPR
	 || TREE_CODE (exp) == NON_LVALUE_EXPR)
    exp = TREE_OPERAND (exp, 0);
  return TREE_CONSTANT (exp);
}

/* Return first list element whose TREE_VALUE is ELEM.
   Return 0 if ELEM is not in LIST.  */

tree
value_member (elem, list)
     tree elem, list;
{
  while (list)
    {
      if (elem == TREE_VALUE (list))
	return list;
      list = TREE_CHAIN (list);
    }
  return NULL_TREE;
}

/* Return first list element whose TREE_PURPOSE is ELEM.
   Return 0 if ELEM is not in LIST.  */

tree
purpose_member (elem, list)
     tree elem, list;
{
  while (list)
    {
      if (elem == TREE_PURPOSE (list))
	return list;
      list = TREE_CHAIN (list);
    }
  return NULL_TREE;
}

/* Return first list element whose BINFO_TYPE is ELEM.
   Return 0 if ELEM is not in LIST.  */

tree
binfo_member (elem, list)
     tree elem, list;
{
  while (list)
    {
      if (elem == BINFO_TYPE (list))
	return list;
      list = TREE_CHAIN (list);
    }
  return NULL_TREE;
}

/* Return nonzero if ELEM is part of the chain CHAIN.  */

int
chain_member (elem, chain)
     tree elem, chain;
{
  while (chain)
    {
      if (elem == chain)
	return 1;
      chain = TREE_CHAIN (chain);
    }

  return 0;
}

/* Return nonzero if ELEM is equal to TREE_VALUE (CHAIN) for any piece of
   chain CHAIN.  */
/* ??? This function was added for machine specific attributes but is no
   longer used.  It could be deleted if we could confirm all front ends
   don't use it.  */

int
chain_member_value (elem, chain)
     tree elem, chain;
{
  while (chain)
    {
      if (elem == TREE_VALUE (chain))
	return 1;
      chain = TREE_CHAIN (chain);
    }

  return 0;
}

/* Return nonzero if ELEM is equal to TREE_PURPOSE (CHAIN)
   for any piece of chain CHAIN.  */
/* ??? This function was added for machine specific attributes but is no
   longer used.  It could be deleted if we could confirm all front ends