Interpret integer

概要

• gcc-4.1.0/gcc/c-lex.cにて定義

引数

• const cpp_token *token
• unsigned int flags

実装

554 /* Interpret TOKEN, an integer with FLAGS as classified by cpplib.  */
555 static tree
556 interpret_integer (const cpp_token *token, unsigned int flags)
557 {
558   tree value, type;
559   enum integer_type_kind itk;
560   cpp_num integer;
561   cpp_options *options = cpp_get_options (parse_in);
562 
563   integer = cpp_interpret_integer (parse_in, token, flags);
564   integer = cpp_num_sign_extend (integer, options->precision);
565 
566   /* The type of a constant with a U suffix is straightforward.  */
567   if (flags & CPP_N_UNSIGNED)
568     itk = narrowest_unsigned_type (integer.low, integer.high, flags);
569   else
570     {
571       /* The type of a potentially-signed integer constant varies
572          depending on the base it's in, the standard in use, and the
573          length suffixes.  */
574       enum integer_type_kind itk_u
575         = narrowest_unsigned_type (integer.low, integer.high, flags);
576       enum integer_type_kind itk_s
577         = narrowest_signed_type (integer.low, integer.high, flags);
578 
579       /* In both C89 and C99, octal and hex constants may be signed or
580          unsigned, whichever fits tighter.  We do not warn about this
581          choice differing from the traditional choice, as the constant
582          is probably a bit pattern and either way will work.  */
583       if ((flags & CPP_N_RADIX) != CPP_N_DECIMAL)
584         itk = MIN (itk_u, itk_s);
585       else
586         {
587           /* In C99, decimal constants are always signed.
588              In C89, decimal constants that don't fit in long have
589              undefined behavior; we try to make them unsigned long.
590              In GCC's extended C89, that last is true of decimal
591              constants that don't fit in long long, too.  */
592 
593           itk = itk_s;
594           if (itk_s > itk_u && itk_s > itk_long)
595             {
596               if (!flag_isoc99)
597                 {
598                   if (itk_u < itk_unsigned_long)
599                     itk_u = itk_unsigned_long;
600                   itk = itk_u;
601                   warning (0, "this decimal constant is unsigned only in ISO C90");
602                 }
603               else
604                 warning (OPT_Wtraditional,
605                          "this decimal constant would be unsigned in ISO C90");
606             }
607         }
608     }
609 
610   if (itk == itk_none)
611     /* cpplib has already issued a warning for overflow.  */
612     type = ((flags & CPP_N_UNSIGNED)
613             ? widest_unsigned_literal_type_node
614             : widest_integer_literal_type_node);
615   else
616     type = integer_types[itk];
617 
618   if (itk > itk_unsigned_long
619       && (flags & CPP_N_WIDTH) != CPP_N_LARGE
620       && !in_system_header && !flag_isoc99)
621     pedwarn ("integer constant is too large for %qs type",
622              (flags & CPP_N_UNSIGNED) ? "unsigned long" : "long");
623 
624   value = build_int_cst_wide (type, integer.low, integer.high);
625 
626   /* Convert imaginary to a complex type.  */
627   if (flags & CPP_N_IMAGINARY)
628     value = build_complex (NULL_TREE, build_int_cst (type, 0), value);
629 
630   return value;
631 }

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