c-common.c

gcc库的原代码,对编程有很大帮助.

	      if (len > 4 && p[0] == '_' && p[1] == '_'
		  && p[len - 1] == '_' && p[len - 2] == '_')
		{
		  char *newp = (char *) alloca (len - 1);

		  strcpy (newp, &p[2]);
		  newp[len - 4] = '\0';
		  p = newp;
		}

	      /* Give this decl a type with the specified mode.
		 First check for the special modes.  */
	      if (! strcmp (p, "byte"))
		mode = byte_mode;
	      else if (!strcmp (p, "word"))
		mode = word_mode;
	      else if (! strcmp (p, "pointer"))
		mode = ptr_mode;
	      else
		for (j = 0; j < NUM_MACHINE_MODES; j++)
		  if (!strcmp (p, GET_MODE_NAME (j)))
		    mode = (enum machine_mode) j;

	      if (mode == VOIDmode)
		error ("unknown machine mode `%s'", p);
	      else if (0 == (typefm = type_for_mode (mode,
						     TREE_UNSIGNED (type))))
		error ("no data type for mode `%s'", p);
	      else
		{
		  TREE_TYPE (decl) = type = typefm;
		  DECL_SIZE (decl) = 0;
		  layout_decl (decl, 0);
		}
	    }
	  break;

	case A_SECTION:
#ifdef ASM_OUTPUT_SECTION_NAME
	  if ((TREE_CODE (decl) == FUNCTION_DECL
	       || TREE_CODE (decl) == VAR_DECL)
	      && TREE_CODE (TREE_VALUE (args)) == STRING_CST)
	    {
	      if (TREE_CODE (decl) == VAR_DECL 
		  && current_function_decl != NULL_TREE)
		error_with_decl (decl,
		  "section attribute cannot be specified for local variables");
	      /* The decl may have already been given a section attribute from
		 a previous declaration.  Ensure they match.  */
	      else if (DECL_SECTION_NAME (decl) != NULL_TREE
		       && strcmp (TREE_STRING_POINTER (DECL_SECTION_NAME (decl)),
				  TREE_STRING_POINTER (TREE_VALUE (args))) != 0)
		error_with_decl (node,
				 "section of `%s' conflicts with previous declaration");
	      else
		DECL_SECTION_NAME (decl) = TREE_VALUE (args);
	    }
	  else
	    error_with_decl (node,
			   "section attribute not allowed for `%s'");
#else
	  error_with_decl (node,
		  "section attributes are not supported for this target");
#endif
	  break;

	case A_ALIGNED:
	  {
	    tree align_expr
	      = args ? TREE_VALUE (args) : size_int (BIGGEST_ALIGNMENT);
	    int align;

	    /* Strip any NOPs of any kind.  */
	    while (TREE_CODE (align_expr) == NOP_EXPR
		   || TREE_CODE (align_expr) == CONVERT_EXPR
		   || TREE_CODE (align_expr) == NON_LVALUE_EXPR)
	      align_expr = TREE_OPERAND (align_expr, 0);
	  
	    if (TREE_CODE (align_expr) != INTEGER_CST)
	      {
		error ("requested alignment is not a constant");
		continue;
	      }

	    align = TREE_INT_CST_LOW (align_expr) * BITS_PER_UNIT;

	    if (exact_log2 (align) == -1)
	      error ("requested alignment is not a power of 2");
	    else if (is_type)
	      TYPE_ALIGN (type) = align;
	    else if (TREE_CODE (decl) != VAR_DECL
		     && TREE_CODE (decl) != FIELD_DECL)
	      error_with_decl (decl,
			       "alignment may not be specified for `%s'");
	    else
	      DECL_ALIGN (decl) = align;
	  }
	  break;

	case A_FORMAT:
	  {
	    tree format_type = TREE_VALUE (args);
	    tree format_num_expr = TREE_VALUE (TREE_CHAIN (args));
	    tree first_arg_num_expr
	      = TREE_VALUE (TREE_CHAIN (TREE_CHAIN (args)));
	    int format_num;
	    int first_arg_num;
	    int is_scan;
	    tree argument;
	    int arg_num;
	
	    if (TREE_CODE (decl) != FUNCTION_DECL)
	      {
		error_with_decl (decl,
			 "argument format specified for non-function `%s'");
		continue;
	      }
	
	    if (TREE_CODE (format_type) == IDENTIFIER_NODE
		&& (!strcmp (IDENTIFIER_POINTER (format_type), "printf")
		    || !strcmp (IDENTIFIER_POINTER (format_type),
				"__printf__")))
	      is_scan = 0;
	    else if (TREE_CODE (format_type) == IDENTIFIER_NODE
		     && (!strcmp (IDENTIFIER_POINTER (format_type), "scanf")
			 || !strcmp (IDENTIFIER_POINTER (format_type),
				     "__scanf__")))
	      is_scan = 1;
	    else
	      {
		error ("unrecognized format specifier for `%s'");
		continue;
	      }

	    /* Strip any conversions from the string index and first arg number
	       and verify they are constants.  */
	    while (TREE_CODE (format_num_expr) == NOP_EXPR
		   || TREE_CODE (format_num_expr) == CONVERT_EXPR
		   || TREE_CODE (format_num_expr) == NON_LVALUE_EXPR)
	      format_num_expr = TREE_OPERAND (format_num_expr, 0);

	    while (TREE_CODE (first_arg_num_expr) == NOP_EXPR
		   || TREE_CODE (first_arg_num_expr) == CONVERT_EXPR
		   || TREE_CODE (first_arg_num_expr) == NON_LVALUE_EXPR)
	      first_arg_num_expr = TREE_OPERAND (first_arg_num_expr, 0);

	    if (TREE_CODE (format_num_expr) != INTEGER_CST
		|| TREE_CODE (first_arg_num_expr) != INTEGER_CST)
	      {
		error ("format string has non-constant operand number");
		continue;
	      }

	    format_num = TREE_INT_CST_LOW (format_num_expr);
	    first_arg_num = TREE_INT_CST_LOW (first_arg_num_expr);
	    if (first_arg_num != 0 && first_arg_num <= format_num)
	      {
		error ("format string arg follows the args to be formatted");
		continue;
	      }

	    /* If a parameter list is specified, verify that the format_num
	       argument is actually a string, in case the format attribute
	       is in error.  */
	    argument = TYPE_ARG_TYPES (type);
	    if (argument)
	      {
		for (arg_num = 1; ; ++arg_num)
		  {
		    if (argument == 0 || arg_num == format_num)
		      break;
		    argument = TREE_CHAIN (argument);
		  }
		if (! argument
		    || TREE_CODE (TREE_VALUE (argument)) != POINTER_TYPE
		  || (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_VALUE (argument)))
		      != char_type_node))
		  {
		    error ("format string arg not a string type");
		    continue;
		  }
		if (first_arg_num != 0)
		  {
		    /* Verify that first_arg_num points to the last arg,
		       the ... */
		    while (argument)
		      arg_num++, argument = TREE_CHAIN (argument);
		  if (arg_num != first_arg_num)
		    {
		      error ("args to be formatted is not ...");
		      continue;
		    }
		  }
	      }

	    record_function_format (DECL_NAME (decl),
				    DECL_ASSEMBLER_NAME (decl),
				    is_scan, format_num, first_arg_num);
	    break;
	  }

	case A_WEAK:
	  declare_weak (decl);
	  break;

	case A_ALIAS:
	  if ((TREE_CODE (decl) == FUNCTION_DECL && DECL_INITIAL (decl))
	      || TREE_CODE (decl) != FUNCTION_DECL && ! DECL_EXTERNAL (decl))
	    error_with_decl (decl,
			     "`%s' defined both normally and as an alias");
	  else if (decl_function_context (decl) == 0)
	    {
	      tree id = get_identifier (TREE_STRING_POINTER
					(TREE_VALUE (args)));
	      if (TREE_CODE (decl) == FUNCTION_DECL)
		DECL_INITIAL (decl) = error_mark_node;
	      else
		DECL_EXTERNAL (decl) = 0;
	      assemble_alias (decl, id);
	    }
	  else
	    warning ("`%s' attribute ignored", IDENTIFIER_POINTER (name));
	  break;
	}
    }
}

/* Check a printf/fprintf/sprintf/scanf/fscanf/sscanf format against
   a parameter list.  */

#define T_I	&integer_type_node
#define T_L	&long_integer_type_node
#define T_LL	&long_long_integer_type_node
#define T_S	&short_integer_type_node
#define T_UI	&unsigned_type_node
#define T_UL	&long_unsigned_type_node
#define T_ULL	&long_long_unsigned_type_node
#define T_US	&short_unsigned_type_node
#define T_F	&float_type_node
#define T_D	&double_type_node
#define T_LD	&long_double_type_node
#define T_C	&char_type_node
#define T_V	&void_type_node
#define T_W	&wchar_type_node
#define T_ST    &sizetype

typedef struct {
  char *format_chars;
  int pointer_count;
  /* Type of argument if no length modifier is used.  */
  tree *nolen;
  /* Type of argument if length modifier for shortening is used.
     If NULL, then this modifier is not allowed.  */
  tree *hlen;
  /* Type of argument if length modifier `l' is used.
     If NULL, then this modifier is not allowed.  */
  tree *llen;
  /* Type of argument if length modifier `q' or `ll' is used.
     If NULL, then this modifier is not allowed.  */
  tree *qlen;
  /* Type of argument if length modifier `L' is used.
     If NULL, then this modifier is not allowed.  */
  tree *bigllen;
  /* List of other modifier characters allowed with these options.  */
  char *flag_chars;
} format_char_info;

static format_char_info print_char_table[] = {
  { "di",	0,	T_I,	T_I,	T_L,	T_LL,	T_LL,	"-wp0 +"	},
  { "oxX",	0,	T_UI,	T_UI,	T_UL,	T_ULL,	T_ULL,	"-wp0#"		},
  { "u",	0,	T_UI,	T_UI,	T_UL,	T_ULL,	T_ULL,	"-wp0"		},
/* Two GNU extensions.  */
  { "Z",	0,	T_ST,	NULL,	NULL,	NULL,	NULL,	"-wp0"		},
  { "m",	0,	T_V,	NULL,	NULL,	NULL,	NULL,	"-wp"		},
  { "feEgG",	0,	T_D,	NULL,	NULL,	NULL,	T_LD,	"-wp0 +#"	},
  { "c",	0,	T_I,	NULL,	T_W,	NULL,	NULL,	"-w"		},
  { "C",	0,	T_W,	NULL,	NULL,	NULL,	NULL,	"-w"		},
  { "s",	1,	T_C,	NULL,	T_W,	NULL,	NULL,	"-wp"		},
  { "S",	1,	T_W,	NULL,	NULL,	NULL,	NULL,	"-wp"		},
  { "p",	1,	T_V,	NULL,	NULL,	NULL,	NULL,	"-w"		},
  { "n",	1,	T_I,	T_S,	T_L,	T_LL,	NULL,	""		},
  { NULL }
};

static format_char_info scan_char_table[] = {
  { "di",	1,	T_I,	T_S,	T_L,	T_LL,	T_LL,	"*"	},
  { "ouxX",	1,	T_UI,	T_US,	T_UL,	T_ULL,	T_ULL,	"*"	},	
  { "efgEG",	1,	T_F,	NULL,	T_D,	NULL,	T_LD,	"*"	},
  { "sc",	1,	T_C,	NULL,	T_W,	NULL,	NULL,	"*a"	},
  { "[",	1,	T_C,	NULL,	NULL,	NULL,	NULL,	"*a"	},
  { "C",	1,	T_W,	NULL,	NULL,	NULL,	NULL,	"*"	},
  { "S",	1,	T_W,	NULL,	NULL,	NULL,	NULL,	"*"	},
  { "p",	2,	T_V,	NULL,	NULL,	NULL,	NULL,	"*"	},
  { "n",	1,	T_I,	T_S,	T_L,	T_LL,	NULL,	""	},
  { NULL }
};

typedef struct function_format_info {
  struct function_format_info *next;  /* next structure on the list */
  tree name;			/* identifier such as "printf" */
  tree assembler_name;		/* optional mangled identifier (for C++) */
  int is_scan;			/* TRUE if *scanf */
  int format_num;		/* number of format argument */
  int first_arg_num;		/* number of first arg (zero for varargs) */
} function_format_info;

static function_format_info *function_format_list = NULL;

static void check_format_info PROTO((function_format_info *, tree));

/* Initialize the table of functions to perform format checking on.
   The ANSI functions are always checked (whether <stdio.h> is
   included or not), since it is common to call printf without
   including <stdio.h>.  There shouldn't be a problem with this,
   since ANSI reserves these function names whether you include the
   header file or not.  In any case, the checking is harmless.  */

void
init_function_format_info ()
{
  record_function_format (get_identifier ("printf"), NULL_TREE, 0, 1, 2);
  record_function_format (get_identifier ("fprintf"), NULL_TREE, 0, 2, 3);
  record_function_format (get_identifier ("sprintf"), NULL_TREE, 0, 2, 3);
  record_function_format (get_identifier ("scanf"), NULL_TREE, 1, 1, 2);
  record_function_format (get_identifier ("fscanf"), NULL_TREE, 1, 2, 3);
  record_function_format (get_identifier ("sscanf"), NULL_TREE, 1, 2, 3);
  record_function_format (get_identifier ("vprintf"), NULL_TREE, 0, 1, 0);
  record_function_format (get_identifier ("vfprintf"), NULL_TREE, 0, 2, 0);
  record_function_format (get_identifier ("vsprintf"), NULL_TREE, 0, 2, 0);
}

/* Record information for argument format checking.  FUNCTION_IDENT is
   the identifier node for the name of the function to check (its decl
   need not exist yet).  IS_SCAN is true for scanf-type format checking;
   false indicates printf-style format checking.  FORMAT_NUM is the number
   of the argument which is the format control string (starting from 1).
   FIRST_ARG_NUM is the number of the first actual argument to check
   against teh format string, or zero if no checking is not be done
   (e.g. for varargs such as vfprintf).  */

void
record_function_format (name, assembler_name, is_scan,
			format_num, first_arg_num)
      tree name;
      tree assembler_name;
      int is_scan;
      int format_num;
      int first_arg_num;
{
  function_format_info *info;

  /* Re-use existing structure if it's there.  */

  for (info = function_format_list; info; info = info->next)
    {
      if (info->name == name && info->assembler_name == assembler_name)
	break;
    }
  if (! info)
    {
      info = (function_format_info *) xmalloc (sizeof (function_format_info));
      info->next = function_format_list;
      function_format_list = info;

      info->name = name;
      info->assembler_name = assembler_name;
    }

  info->is_scan = is_scan;
  info->format_num = format_num;
  info->first_arg_num = first_arg_num;
}

static char	tfaff[] = "too few arguments for format";

/* Check the argument list of a call to printf, scanf, etc.
   NAME is the function identifier.
   ASSEMBLER_NAME is the function's assembler identifier.
   (Either NAME or ASSEMBLER_NAME, but not both, may be NULL_TREE.)
   PARAMS is the list of argument values.  */

void
check_function_format (name, assembler_name, params)
     tree name;
     tree assembler_name;
     tree params;
{
  function_format_info *info;

  /* See if this function is a format function.  */
  for (info = function_format_list; info; info = info->next)
    {
      if (info->assembler_name
	  ? (info->assembler_name == assembler_name)
	  : (info->name == name))
	{
	  /* Yup; check it.  */
	  check_format_info (info, params);
	  break;
	}
    }
}

/* Check the argument list of a call to printf, scanf, etc.
   INFO points to the function_format_info structure.
   PARAMS is the list of argument values.  */

static void
check_format_info (info, params)
     function_format_info *info;
     tree params;
{
  int i;
  int arg_num;
  int suppressed, wide, precise;
  int length_char;
  int format_char;
  int format_length;
  tree format_tree;
  tree cur_param;
  tree cur_type;
  tree wanted_type;
  tree first_fillin_param;
  char *format_chars;
  format_char_info *fci;
  static char message[132];
  char flag_chars[8];
  int has_operand_number = 0;

  /* Skip to format argument.  If the argument isn't available, there's