c-typeck.c

这是完整的gcc源代码

      if (t1 == 0 && t2 == 0)
	return 1;
      /* If one parmlist is shorter than the other,
	 they fail to match.  */
      if (t1 == 0 || t2 == 0)
	return 0;
      if (! comptypes (TREE_VALUE (t1), TREE_VALUE (t2)))
	return 0;
      t1 = TREE_CHAIN (t1);
      t2 = TREE_CHAIN (t2);
    }
}

/* Return 1 if PARMS specifies a fixed number of parameters
   and none of their types is affected by default promotions.  */

int
compparms1 (parms)
     tree parms;
{
  register tree t;
  for (t = parms; t; t = TREE_CHAIN (t))
    {
      register tree type = TREE_VALUE (t);

      if (TREE_CHAIN (t) == 0 && type != void_type_node)
	return 0;

      if (type == float_type_node)
	return 0;

      if (TREE_CODE (type) == INTEGER_TYPE
	  && TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node))
	return 0;
    }
  return 1;
}

/* Return an unsigned type the same as TYPE in other respects.  */

tree
unsigned_type (type)
     tree type;
{
  if (type == signed_char_type_node || type == char_type_node)
    return unsigned_char_type_node;
  if (type == integer_type_node)
    return unsigned_type_node;
  if (type == short_integer_type_node)
    return short_unsigned_type_node;
  if (type == long_integer_type_node)
    return long_unsigned_type_node;
  if (type == long_long_integer_type_node)
    return long_long_unsigned_type_node;
  return type;
}

/* Return a signed type the same as TYPE in other respects.  */

tree
signed_type (type)
     tree type;
{
  if (type == unsigned_char_type_node || type == char_type_node)
    return signed_char_type_node;
  if (type == unsigned_type_node)
    return integer_type_node;
  if (type == short_unsigned_type_node)
    return short_integer_type_node;
  if (type == long_unsigned_type_node)
    return long_integer_type_node;
  if (type == long_long_unsigned_type_node)
    return long_long_integer_type_node;
  return type;
}

/* Return a type the same as TYPE except unsigned or
   signed according to UNSIGNEDP.  */

tree
signed_or_unsigned_type (unsignedp, type)
     int unsignedp;
     tree type;
{
  if (TREE_CODE (type) != INTEGER_TYPE)
    return type;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (signed_char_type_node))
    return unsignedp ? unsigned_char_type_node : signed_char_type_node;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node)) 
    return unsignedp ? unsigned_type_node : integer_type_node;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (short_integer_type_node)) 
    return unsignedp ? short_unsigned_type_node : short_integer_type_node;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (long_integer_type_node)) 
    return unsignedp ? long_unsigned_type_node : long_integer_type_node;
  if (TYPE_PRECISION (type) == TYPE_PRECISION (long_long_integer_type_node)) 
    return (unsignedp ? long_long_unsigned_type_node
	    : long_long_integer_type_node);
  return type;
}

/* Return an integer type with BITS bits of precision,
   that is unsigned if UNSIGNEDP is nonzero, otherwise signed.  */

tree
type_for_size (bits, unsignedp)
     int bits;
     int unsignedp;
{
  if (bits <= TYPE_PRECISION (signed_char_type_node))
    return unsignedp ? unsigned_char_type_node : signed_char_type_node;

  if (bits <= TYPE_PRECISION (short_integer_type_node))
    return unsignedp ? short_unsigned_type_node : short_integer_type_node;

  if (bits <= TYPE_PRECISION (integer_type_node))
    return unsignedp ? unsigned_type_node : integer_type_node;

  if (bits <= TYPE_PRECISION (long_integer_type_node))
    return unsignedp ? long_unsigned_type_node : long_integer_type_node;

  if (bits <= TYPE_PRECISION (long_long_integer_type_node))
    return (unsignedp ? long_long_unsigned_type_node
	    : long_long_integer_type_node);

  return 0;
}

tree
get_floating_type (mode)
     enum machine_mode mode;
{
  if (mode == TYPE_MODE (float_type_node))
    return float_type_node;
  if (mode == TYPE_MODE (double_type_node))
    return double_type_node;
  if (mode == TYPE_MODE (long_double_type_node))
    return long_double_type_node;
  abort ();
}

tree
c_sizeof (type)
     tree type;
{
  enum tree_code code = TREE_CODE (type);

  if (code == FUNCTION_TYPE)
    {
      if (pedantic || warn_pointer_arith)
	warning ("sizeof applied to a function type");
      return build_int (1);
    }
  if (code == VOID_TYPE)
    {
      if (pedantic || warn_pointer_arith)
	warning ("sizeof applied to a void type");
      return build_int (1);
    }

  /* Convert in case a char is more than one unit.  */
  return convert_units (size_in_bytes (type), BITS_PER_UNIT,
			TYPE_PRECISION (char_type_node));
}

tree
c_sizeof_nowarn (type)
     tree type;
{
  enum tree_code code = TREE_CODE (type);

  if (code == FUNCTION_TYPE
      || code == VOID_TYPE)
    return build_int (1);

  /* Convert in case a char is more than one unit.  */
  return convert_units (size_in_bytes (type), BITS_PER_UNIT,
			TYPE_PRECISION (char_type_node));
}

/* Implement the __alignof keyword: Return the minimum required
   alignment of TYPE, measured in bytes.  */

tree
c_alignof (type)
     tree type;
{
  enum tree_code code = TREE_CODE (type);

  if (code == FUNCTION_TYPE)
    return build_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);

  if (code == VOID_TYPE)
    return build_int (1);

  return build_int (TYPE_ALIGN (type) / BITS_PER_UNIT);
}

/* Return either DECL or its known constant value (if it has one).  */

static tree
decl_constant_value (decl)
     tree decl;
{
  if (! TREE_PUBLIC (decl)
      /* Don't change a variable array bound or initial value to a constant
	 in a place where a variable is invalid.  */
      && current_function_decl != 0
      && ! pedantic
      && ! TREE_THIS_VOLATILE (decl)
      && DECL_INITIAL (decl) != 0
      && TREE_CODE (DECL_INITIAL (decl)) != ERROR_MARK
      /* This is invalid if initial value is not constant.
	 If it has either a function call, a memory reference,
	 or a variable, then re-evaluating it could give different results.  */
      && TREE_LITERAL (DECL_INITIAL (decl))
      /* Check for cases where this is sub-optimal, even though valid.  */
      && TREE_CODE (DECL_INITIAL (decl)) != CONSTRUCTOR
      && DECL_MODE (decl) != BLKmode)
    return DECL_INITIAL (decl);
  return decl;
}

/* Perform default promotions for C data used in expressions.
   Arrays and functions are converted to pointers;
   enumeral types or short or char, to int.
   In addition, manifest constants symbols are replaced by their values.  */

tree
default_conversion (exp)
     tree exp;
{
  register tree dt = TREE_TYPE (exp);
  register enum tree_code form = TREE_CODE (dt);

  if (TREE_CODE (exp) == CONST_DECL)
    exp = DECL_INITIAL (exp);
  /* Replace a nonvolatile const static variable with its value.  */
  else if (optimize
	   && TREE_CODE (exp) == VAR_DECL
	   && TREE_READONLY (exp))
    exp = decl_constant_value (exp);

  /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
     Strip such NOP_EXPRs, since EXP is being used in non-lvalue context.  */
  if (TREE_CODE (exp) == NOP_EXPR
      && TREE_TYPE (exp) == TREE_TYPE (TREE_OPERAND (exp, 0)))
    exp = TREE_OPERAND (exp, 0);

  if (form == ENUMERAL_TYPE
      || (form == INTEGER_TYPE
	  && (TYPE_PRECISION (dt)
	      < TYPE_PRECISION (integer_type_node))))
    {
      /* Traditionally, unsignedness is preserved in default promotions.  */
      if (flag_traditional && TREE_UNSIGNED (dt))
	return convert (unsigned_type_node, exp);
      return convert (integer_type_node, exp);
    }
  if (flag_traditional && dt == float_type_node)
    return convert (double_type_node, exp);
  if (form == VOID_TYPE)
    {
      error ("void value not ignored as it ought to be");
      return error_mark_node;
    }
  if (form == FUNCTION_TYPE)
    {
      return build_unary_op (ADDR_EXPR, exp, 0);
    }
  if (form == ARRAY_TYPE)
    {
      register tree adr;
      tree restype = TREE_TYPE (dt);
      tree ptrtype;

      if (TREE_CODE (exp) == INDIRECT_REF)
	return convert (TYPE_POINTER_TO (restype),
			TREE_OPERAND (exp, 0));

      if (TREE_CODE (exp) == COMPOUND_EXPR)
	{
	  tree op1 = default_conversion (TREE_OPERAND (exp, 1));
	  return build (COMPOUND_EXPR, TREE_TYPE (op1),
			TREE_OPERAND (exp, 0), op1);
	}

      if (!lvalue_p (exp)
	  && ! (TREE_CODE (exp) == CONSTRUCTOR && TREE_STATIC (exp)))
	{
	  error ("invalid use of non-lvalue array");
	  return error_mark_node;
	}

      if (TREE_READONLY (exp) || TREE_THIS_VOLATILE (exp))
	restype = c_build_type_variant (restype, TREE_READONLY (exp),
					TREE_THIS_VOLATILE (exp));

      ptrtype = build_pointer_type (restype);

      if (TREE_CODE (exp) == VAR_DECL)
	{
	  /* ??? This is not really quite correct
	     in that the type of the operand of ADDR_EXPR
	     is not the target type of the type of the ADDR_EXPR itself.
	     Question is, can this lossage be avoided?  */
	  adr = build (ADDR_EXPR, ptrtype, exp);
	  if (mark_addressable (exp) == 0)
	    return error_mark_node;
	  TREE_LITERAL (adr) = staticp (exp);
	  TREE_VOLATILE (adr) = 0;   /* Default would be, same as EXP.  */
	  return adr;
	}
      /* This way is better for a COMPONENT_REF since it can
	 simplify the offset for a component.  */
      adr = build_unary_op (ADDR_EXPR, exp, 1);
      return convert (ptrtype, adr);
    }
  return exp;
}

/* Make an expression to refer to the COMPONENT field of
   structure or union value DATUM.  COMPONENT is an IDENTIFIER_NODE.  */

tree
build_component_ref (datum, component)
     tree datum, component;
{
  register tree basename = datum;
  register tree basetype = TREE_TYPE (basename);
  register enum tree_code form = TREE_CODE (basetype);
  register tree field = NULL;
  register tree ref;

  /* First, see if there is a field or component with name COMPONENT. */

  if (form == RECORD_TYPE || form == UNION_TYPE)
    {
      if (TYPE_SIZE (basetype) == 0)
	{
	  incomplete_type_error (0, basetype);
	  return error_mark_node;
	}

      /* Look up component name in the structure type definition.  */

      for (field = TYPE_FIELDS (basetype); field; field = TREE_CHAIN (field))
	{
	  if (DECL_NAME (field) == component)
	    break;
	}

      if (!field)
	{
	  error (form == RECORD_TYPE
		 ? "structure has no member named `%s'"
		 : "union has no member named `%s'",
		 IDENTIFIER_POINTER (component));
	  return error_mark_node;
	}
      if (TREE_TYPE (field) == error_mark_node)
	return error_mark_node;

      ref = build (COMPONENT_REF, TREE_TYPE (field), basename, field);

      if (TREE_READONLY (basename) || TREE_READONLY (field))
	TREE_READONLY (ref) = 1;
      if (TREE_THIS_VOLATILE (basename) || TREE_VOLATILE (field))
	TREE_THIS_VOLATILE (ref) = 1;

      return ref;
    }
  else if (form != ERROR_MARK)
    error ("request for member `%s' in something not a structure or union",
	    IDENTIFIER_POINTER (component));

  return error_mark_node;
}

/* Given an expression PTR for a pointer, return an expression
   for the value pointed to.
   ERRORSTRING is the name of the operator to appear in error messages.  */

tree
build_indirect_ref (ptr, errorstring)
     tree ptr;
     char *errorstring;
{
  register tree pointer = default_conversion (ptr);
  register tree dt = TREE_TYPE (pointer);

  if (TREE_CODE (dt) == POINTER_TYPE)
    if (TREE_CODE (pointer) == ADDR_EXPR
	&& (TREE_TYPE (TREE_OPERAND (pointer, 0))
	    == TREE_TYPE (dt)))
      return TREE_OPERAND (pointer, 0);
    else
      {
	tree t = TREE_TYPE (dt);
	register tree ref = build (INDIRECT_REF,
				   TYPE_MAIN_VARIANT (t), pointer);

	if (TREE_CODE (t) == VOID_TYPE
	    || (TYPE_SIZE (t) == 0 && TREE_CODE (t) != ARRAY_TYPE))
	  {
	    error ("dereferencing pointer to incomplete type");
	    return error_mark_node;
	  }

	TREE_READONLY (ref) = TREE_READONLY (t);
	TREE_VOLATILE (ref) = TREE_VOLATILE (t) || TREE_VOLATILE (pointer);
	TREE_THIS_VOLATILE (ref) = TREE_VOLATILE (t);
	return ref;
      }
  else if (TREE_CODE (pointer) != ERROR_MARK)
    error ("invalid type argument of `%s'", errorstring);
  return error_mark_node;
}

/* This handles expressions of the form "a[i]", which denotes
   an array reference.

   This is logically equivalent in C to *(a+i), but we may do it differently.
   If A is a variable or a member, we generate a primitive ARRAY_REF.
   This avoids forcing the array out of registers, and can work on
   arrays that are not lvalues (for example, members of structures returned
   by functions).  */

tree
build_array_ref (array, index)
     tree array, index;
{