1 /* expr.c -operands, expressions-
2 Copyright (C) 1987, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 2000
3 Free Software Foundation, Inc.
5 This file is part of GAS, the GNU Assembler.
7 GAS is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GAS is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GAS; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 * This is really a branch office of as-read.c. I split it out to clearly
24 * distinguish the world of expressions from the world of statements.
25 * (It also gives smaller files to re-compile.)
26 * Here, "operand"s are of expressions, not instructions.
31 #define min(a, b) ((a) < (b) ? (a) : (b))
36 static void floating_constant
PARAMS ((expressionS
* expressionP
));
37 static valueT generic_bignum_to_int32
PARAMS ((void));
39 static valueT generic_bignum_to_int64
PARAMS ((void));
41 static void integer_constant
PARAMS ((int radix
, expressionS
* expressionP
));
42 static void mri_char_constant
PARAMS ((expressionS
*));
43 static void current_location
PARAMS ((expressionS
*));
44 static void clean_up_expression
PARAMS ((expressionS
* expressionP
));
45 static segT operand
PARAMS ((expressionS
*));
46 static operatorT
operator PARAMS ((void));
48 extern const char EXP_CHARS
[], FLT_CHARS
[];
50 /* We keep a mapping of expression symbols to file positions, so that
51 we can provide better error messages. */
53 struct expr_symbol_line
55 struct expr_symbol_line
*next
;
61 static struct expr_symbol_line
*expr_symbol_lines
;
63 /* Build a dummy symbol to hold a complex expression. This is how we
64 build expressions up out of other expressions. The symbol is put
65 into the fake section expr_section. */
68 make_expr_symbol (expressionP
)
69 expressionS
*expressionP
;
74 struct expr_symbol_line
*n
;
76 if (expressionP
->X_op
== O_symbol
77 && expressionP
->X_add_number
== 0)
78 return expressionP
->X_add_symbol
;
80 if (expressionP
->X_op
== O_big
)
82 /* This won't work, because the actual value is stored in
83 generic_floating_point_number or generic_bignum, and we are
84 going to lose it if we haven't already. */
85 if (expressionP
->X_add_number
> 0)
86 as_bad (_("bignum invalid; zero assumed"));
88 as_bad (_("floating point number invalid; zero assumed"));
89 zero
.X_op
= O_constant
;
90 zero
.X_add_number
= 0;
92 clean_up_expression (&zero
);
96 fake
= FAKE_LABEL_NAME
;
98 /* Putting constant symbols in absolute_section rather than
99 expr_section is convenient for the old a.out code, for which
100 S_GET_SEGMENT does not always retrieve the value put in by
102 symbolP
= symbol_create (fake
,
103 (expressionP
->X_op
== O_constant
106 0, &zero_address_frag
);
107 symbol_set_value_expression (symbolP
, expressionP
);
109 if (expressionP
->X_op
== O_constant
)
110 resolve_symbol_value (symbolP
, 1);
112 n
= (struct expr_symbol_line
*) xmalloc (sizeof *n
);
114 as_where (&n
->file
, &n
->line
);
115 n
->next
= expr_symbol_lines
;
116 expr_symbol_lines
= n
;
121 /* Return the file and line number for an expr symbol. Return
122 non-zero if something was found, 0 if no information is known for
126 expr_symbol_where (sym
, pfile
, pline
)
131 register struct expr_symbol_line
*l
;
133 for (l
= expr_symbol_lines
; l
!= NULL
; l
= l
->next
)
146 /* Utilities for building expressions.
147 Since complex expressions are recorded as symbols for use in other
148 expressions these return a symbolS * and not an expressionS *.
149 These explicitly do not take an "add_number" argument. */
150 /* ??? For completeness' sake one might want expr_build_symbol.
151 It would just return its argument. */
153 /* Build an expression for an unsigned constant.
154 The corresponding one for signed constants is missing because
155 there's currently no need for it. One could add an unsigned_p flag
156 but that seems more clumsy. */
159 expr_build_uconstant (value
)
165 e
.X_add_number
= value
;
167 return make_expr_symbol (&e
);
170 /* Build an expression for OP s1. */
173 expr_build_unary (op
, s1
)
182 return make_expr_symbol (&e
);
185 /* Build an expression for s1 OP s2. */
188 expr_build_binary (op
, s1
, s2
)
199 return make_expr_symbol (&e
);
202 /* Build an expression for the current location ('.'). */
209 current_location (&e
);
210 return make_expr_symbol (&e
);
214 * Build any floating-point literal here.
215 * Also build any bignum literal here.
218 /* Seems atof_machine can backscan through generic_bignum and hit whatever
219 happens to be loaded before it in memory. And its way too complicated
220 for me to fix right. Thus a hack. JF: Just make generic_bignum bigger,
221 and never write into the early words, thus they'll always be zero.
222 I hate Dean's floating-point code. Bleh. */
223 LITTLENUM_TYPE generic_bignum
[SIZE_OF_LARGE_NUMBER
+ 6];
224 FLONUM_TYPE generic_floating_point_number
=
226 &generic_bignum
[6], /* low (JF: Was 0) */
227 &generic_bignum
[SIZE_OF_LARGE_NUMBER
+ 6 - 1], /* high JF: (added +6) */
232 /* If nonzero, we've been asked to assemble nan, +inf or -inf */
233 int generic_floating_point_magic
;
236 floating_constant (expressionP
)
237 expressionS
*expressionP
;
239 /* input_line_pointer->*/
240 /* floating-point constant. */
243 error_code
= atof_generic (&input_line_pointer
, ".", EXP_CHARS
,
244 &generic_floating_point_number
);
248 if (error_code
== ERROR_EXPONENT_OVERFLOW
)
250 as_bad (_("bad floating-point constant: exponent overflow, probably assembling junk"));
254 as_bad (_("bad floating-point constant: unknown error code=%d."), error_code
);
257 expressionP
->X_op
= O_big
;
258 /* input_line_pointer->just after constant, */
259 /* which may point to whitespace. */
260 expressionP
->X_add_number
= -1;
264 generic_bignum_to_int32 ()
267 ((generic_bignum
[1] & LITTLENUM_MASK
) << LITTLENUM_NUMBER_OF_BITS
)
268 | (generic_bignum
[0] & LITTLENUM_MASK
);
269 number
&= 0xffffffff;
275 generic_bignum_to_int64 ()
278 ((((((((valueT
) generic_bignum
[3] & LITTLENUM_MASK
)
279 << LITTLENUM_NUMBER_OF_BITS
)
280 | ((valueT
) generic_bignum
[2] & LITTLENUM_MASK
))
281 << LITTLENUM_NUMBER_OF_BITS
)
282 | ((valueT
) generic_bignum
[1] & LITTLENUM_MASK
))
283 << LITTLENUM_NUMBER_OF_BITS
)
284 | ((valueT
) generic_bignum
[0] & LITTLENUM_MASK
));
290 integer_constant (radix
, expressionP
)
292 expressionS
*expressionP
;
294 char *start
; /* start of number. */
297 valueT number
; /* offset or (absolute) value */
298 short int digit
; /* value of next digit in current radix */
299 short int maxdig
= 0;/* highest permitted digit value. */
300 int too_many_digits
= 0; /* if we see >= this number of */
301 char *name
; /* points to name of symbol */
302 symbolS
*symbolP
; /* points to symbol */
304 int small
; /* true if fits in 32 bits. */
306 /* May be bignum, or may fit in 32 bits. */
307 /* Most numbers fit into 32 bits, and we want this case to be fast.
308 so we pretend it will fit into 32 bits. If, after making up a 32
309 bit number, we realise that we have scanned more digits than
310 comfortably fit into 32 bits, we re-scan the digits coding them
311 into a bignum. For decimal and octal numbers we are
312 conservative: Some numbers may be assumed bignums when in fact
313 they do fit into 32 bits. Numbers of any radix can have excess
314 leading zeros: We strive to recognise this and cast them back
315 into 32 bits. We must check that the bignum really is more than
316 32 bits, and change it back to a 32-bit number if it fits. The
317 number we are looking for is expected to be positive, but if it
318 fits into 32 bits as an unsigned number, we let it be a 32-bit
319 number. The cavalier approach is for speed in ordinary cases. */
320 /* This has been extended for 64 bits. We blindly assume that if
321 you're compiling in 64-bit mode, the target is a 64-bit machine.
322 This should be cleaned up. */
326 #else /* includes non-bfd case, mostly */
330 if ((NUMBERS_WITH_SUFFIX
|| flag_m68k_mri
) && radix
== 0)
334 /* In MRI mode, the number may have a suffix indicating the
335 radix. For that matter, it might actually be a floating
337 for (suffix
= input_line_pointer
;
338 isalnum ((unsigned char) *suffix
);
341 if (*suffix
== 'e' || *suffix
== 'E')
345 if (suffix
== input_line_pointer
)
353 if (islower ((unsigned char) c
))
359 else if (c
== 'O' || c
== 'Q')
363 else if (suffix
[1] == '.' || c
== 'E' || flt
)
365 floating_constant (expressionP
);
380 too_many_digits
= valuesize
+ 1;
384 too_many_digits
= (valuesize
+ 2) / 3 + 1;
388 too_many_digits
= (valuesize
+ 3) / 4 + 1;
392 too_many_digits
= (valuesize
+ 11) / 4; /* very rough */
395 start
= input_line_pointer
;
396 c
= *input_line_pointer
++;
398 (digit
= hex_value (c
)) < maxdig
;
399 c
= *input_line_pointer
++)
401 number
= number
* radix
+ digit
;
403 /* c contains character after number. */
404 /* input_line_pointer->char after c. */
405 small
= (input_line_pointer
- start
- 1) < too_many_digits
;
407 if (radix
== 16 && c
== '_')
409 /* This is literal of the form 0x333_0_12345678_1.
410 This example is equivalent to 0x00000333000000001234567800000001. */
412 int num_little_digits
= 0;
414 input_line_pointer
= start
; /*->1st digit. */
416 know (LITTLENUM_NUMBER_OF_BITS
== 16);
418 for (c
= '_'; c
== '_'; num_little_digits
+=2)
421 /* Convert one 64-bit word. */
424 for (c
= *input_line_pointer
++;
425 (digit
= hex_value (c
)) < maxdig
;
426 c
= *(input_line_pointer
++))
428 number
= number
* radix
+ digit
;
432 /* Check for 8 digit per word max. */
434 as_bad (_("A bignum with underscores may not have more than 8 hex digits in any word."));
436 /* Add this chunk to the bignum. Shift things down 2 little digits.*/
437 know (LITTLENUM_NUMBER_OF_BITS
== 16);
438 for (i
= min (num_little_digits
+ 1, SIZE_OF_LARGE_NUMBER
- 1); i
>= 2; i
--)
439 generic_bignum
[i
] = generic_bignum
[i
-2];
441 /* Add the new digits as the least significant new ones. */
442 generic_bignum
[0] = number
& 0xffffffff;
443 generic_bignum
[1] = number
>> 16;
446 /* Again, c is char after number, input_line_pointer->after c. */
448 if (num_little_digits
> SIZE_OF_LARGE_NUMBER
- 1)
449 num_little_digits
= SIZE_OF_LARGE_NUMBER
- 1;
451 assert (num_little_digits
>= 4);
453 if (num_little_digits
!= 8)
454 as_bad (_("A bignum with underscores must have exactly 4 words."));
456 /* We might have some leading zeros. These can be trimmed to give
457 * us a change to fit this constant into a small number.
459 while (generic_bignum
[num_little_digits
-1] == 0 && num_little_digits
> 1)
462 if (num_little_digits
<= 2)
464 /* will fit into 32 bits. */
465 number
= generic_bignum_to_int32 ();
469 else if (num_little_digits
<= 4)
471 /* Will fit into 64 bits. */
472 number
= generic_bignum_to_int64 ();
479 number
= num_little_digits
; /* number of littlenums in the bignum. */
485 * we saw a lot of digits. manufacture a bignum the hard way.
487 LITTLENUM_TYPE
*leader
; /*->high order littlenum of the bignum. */
488 LITTLENUM_TYPE
*pointer
; /*->littlenum we are frobbing now. */
491 leader
= generic_bignum
;
492 generic_bignum
[0] = 0;
493 generic_bignum
[1] = 0;
494 generic_bignum
[2] = 0;
495 generic_bignum
[3] = 0;
496 input_line_pointer
= start
; /*->1st digit. */
497 c
= *input_line_pointer
++;
499 (carry
= hex_value (c
)) < maxdig
;
500 c
= *input_line_pointer
++)
502 for (pointer
= generic_bignum
;
508 work
= carry
+ radix
* *pointer
;
509 *pointer
= work
& LITTLENUM_MASK
;
510 carry
= work
>> LITTLENUM_NUMBER_OF_BITS
;
514 if (leader
< generic_bignum
+ SIZE_OF_LARGE_NUMBER
- 1)
516 /* room to grow a longer bignum. */
521 /* again, c is char after number, */
522 /* input_line_pointer->after c. */
523 know (LITTLENUM_NUMBER_OF_BITS
== 16);
524 if (leader
< generic_bignum
+ 2)
526 /* will fit into 32 bits. */
527 number
= generic_bignum_to_int32 ();
531 else if (leader
< generic_bignum
+ 4)
533 /* Will fit into 64 bits. */
534 number
= generic_bignum_to_int64 ();
540 number
= leader
- generic_bignum
+ 1; /* number of littlenums in the bignum. */
544 if ((NUMBERS_WITH_SUFFIX
|| flag_m68k_mri
)
546 && input_line_pointer
- 1 == suffix
)
547 c
= *input_line_pointer
++;
552 * here with number, in correct radix. c is the next char.
553 * note that unlike un*x, we allow "011f" "0x9f" to
554 * both mean the same as the (conventional) "9f". this is simply easier
555 * than checking for strict canonical form. syntax sux!
558 if (LOCAL_LABELS_FB
&& c
== 'b')
561 * backward ref to local label.
562 * because it is backward, expect it to be defined.
564 /* Construct a local label. */
565 name
= fb_label_name ((int) number
, 0);
567 /* seen before, or symbol is defined: ok */
568 symbolP
= symbol_find (name
);
569 if ((symbolP
!= NULL
) && (S_IS_DEFINED (symbolP
)))
571 /* local labels are never absolute. don't waste time
572 checking absoluteness. */
573 know (SEG_NORMAL (S_GET_SEGMENT (symbolP
)));
575 expressionP
->X_op
= O_symbol
;
576 expressionP
->X_add_symbol
= symbolP
;
580 /* either not seen or not defined. */
581 /* @@ Should print out the original string instead of
582 the parsed number. */
583 as_bad (_("backw. ref to unknown label \"%d:\", 0 assumed."),
585 expressionP
->X_op
= O_constant
;
588 expressionP
->X_add_number
= 0;
590 else if (LOCAL_LABELS_FB
&& c
== 'f')
593 * forward reference. expect symbol to be undefined or
594 * unknown. undefined: seen it before. unknown: never seen
596 * construct a local label name, then an undefined symbol.
597 * don't create a xseg frag for it: caller may do that.
598 * just return it as never seen before.
600 name
= fb_label_name ((int) number
, 1);
601 symbolP
= symbol_find_or_make (name
);
602 /* we have no need to check symbol properties. */
603 #ifndef many_segments
604 /* since "know" puts its arg into a "string", we
605 can't have newlines in the argument. */
606 know (S_GET_SEGMENT (symbolP
) == undefined_section
|| S_GET_SEGMENT (symbolP
) == text_section
|| S_GET_SEGMENT (symbolP
) == data_section
);
608 expressionP
->X_op
= O_symbol
;
609 expressionP
->X_add_symbol
= symbolP
;
610 expressionP
->X_add_number
= 0;
612 else if (LOCAL_LABELS_DOLLAR
&& c
== '$')
614 /* If the dollar label is *currently* defined, then this is just
615 another reference to it. If it is not *currently* defined,
616 then this is a fresh instantiation of that number, so create
619 if (dollar_label_defined ((long) number
))
621 name
= dollar_label_name ((long) number
, 0);
622 symbolP
= symbol_find (name
);
623 know (symbolP
!= NULL
);
627 name
= dollar_label_name ((long) number
, 1);
628 symbolP
= symbol_find_or_make (name
);
631 expressionP
->X_op
= O_symbol
;
632 expressionP
->X_add_symbol
= symbolP
;
633 expressionP
->X_add_number
= 0;
637 expressionP
->X_op
= O_constant
;
638 #ifdef TARGET_WORD_SIZE
639 /* Sign extend NUMBER. */
640 number
|= (-(number
>> (TARGET_WORD_SIZE
- 1))) << (TARGET_WORD_SIZE
- 1);
642 expressionP
->X_add_number
= number
;
643 input_line_pointer
--; /* restore following character. */
644 } /* really just a number */
648 /* not a small number */
649 expressionP
->X_op
= O_big
;
650 expressionP
->X_add_number
= number
; /* number of littlenums */
651 input_line_pointer
--; /*->char following number. */
655 /* Parse an MRI multi character constant. */
658 mri_char_constant (expressionP
)
659 expressionS
*expressionP
;
663 if (*input_line_pointer
== '\''
664 && input_line_pointer
[1] != '\'')
666 expressionP
->X_op
= O_constant
;
667 expressionP
->X_add_number
= 0;
671 /* In order to get the correct byte ordering, we must build the
672 number in reverse. */
673 for (i
= SIZE_OF_LARGE_NUMBER
- 1; i
>= 0; i
--)
677 generic_bignum
[i
] = 0;
678 for (j
= 0; j
< CHARS_PER_LITTLENUM
; j
++)
680 if (*input_line_pointer
== '\'')
682 if (input_line_pointer
[1] != '\'')
684 ++input_line_pointer
;
686 generic_bignum
[i
] <<= 8;
687 generic_bignum
[i
] += *input_line_pointer
;
688 ++input_line_pointer
;
691 if (i
< SIZE_OF_LARGE_NUMBER
- 1)
693 /* If there is more than one littlenum, left justify the
694 last one to make it match the earlier ones. If there is
695 only one, we can just use the value directly. */
696 for (; j
< CHARS_PER_LITTLENUM
; j
++)
697 generic_bignum
[i
] <<= 8;
700 if (*input_line_pointer
== '\''
701 && input_line_pointer
[1] != '\'')
707 as_bad (_("Character constant too large"));
716 c
= SIZE_OF_LARGE_NUMBER
- i
;
717 for (j
= 0; j
< c
; j
++)
718 generic_bignum
[j
] = generic_bignum
[i
+ j
];
722 know (LITTLENUM_NUMBER_OF_BITS
== 16);
725 expressionP
->X_op
= O_big
;
726 expressionP
->X_add_number
= i
;
730 expressionP
->X_op
= O_constant
;
732 expressionP
->X_add_number
= generic_bignum
[0] & LITTLENUM_MASK
;
734 expressionP
->X_add_number
=
735 (((generic_bignum
[1] & LITTLENUM_MASK
)
736 << LITTLENUM_NUMBER_OF_BITS
)
737 | (generic_bignum
[0] & LITTLENUM_MASK
));
740 /* Skip the final closing quote. */
741 ++input_line_pointer
;
744 /* Return an expression representing the current location. This
745 handles the magic symbol `.'. */
748 current_location (expressionp
)
749 expressionS
*expressionp
;
751 if (now_seg
== absolute_section
)
753 expressionp
->X_op
= O_constant
;
754 expressionp
->X_add_number
= abs_section_offset
;
760 symbolp
= symbol_new (FAKE_LABEL_NAME
, now_seg
,
761 (valueT
) frag_now_fix (),
763 expressionp
->X_op
= O_symbol
;
764 expressionp
->X_add_symbol
= symbolp
;
765 expressionp
->X_add_number
= 0;
770 * Summary of operand().
772 * in: Input_line_pointer points to 1st char of operand, which may
775 * out: A expressionS.
776 * The operand may have been empty: in this case X_op == O_absent.
777 * Input_line_pointer->(next non-blank) char after operand.
781 operand (expressionP
)
782 expressionS
*expressionP
;
785 symbolS
*symbolP
; /* points to symbol */
786 char *name
; /* points to name of symbol */
789 /* All integers are regarded as unsigned unless they are negated.
790 This is because the only thing which cares whether a number is
791 unsigned is the code in emit_expr which extends constants into
792 bignums. It should only sign extend negative numbers, so that
793 something like ``.quad 0x80000000'' is not sign extended even
794 though it appears negative if valueT is 32 bits. */
795 expressionP
->X_unsigned
= 1;
797 /* digits, assume it is a bignum. */
799 SKIP_WHITESPACE (); /* leading whitespace is part of operand. */
800 c
= *input_line_pointer
++; /* input_line_pointer->past char in c. */
802 if (is_end_of_line
[(unsigned char) c
])
816 input_line_pointer
--;
818 integer_constant ((NUMBERS_WITH_SUFFIX
|| flag_m68k_mri
)
824 /* non-decimal radix */
826 if (NUMBERS_WITH_SUFFIX
|| flag_m68k_mri
)
830 /* Check for a hex constant. */
831 for (s
= input_line_pointer
; hex_p (*s
); s
++)
833 if (*s
== 'h' || *s
== 'H')
835 --input_line_pointer
;
836 integer_constant (0, expressionP
);
840 c
= *input_line_pointer
;
849 if (NUMBERS_WITH_SUFFIX
|| flag_m68k_mri
)
851 integer_constant (0, expressionP
);
857 if (c
&& strchr (FLT_CHARS
, c
))
859 input_line_pointer
++;
860 floating_constant (expressionP
);
861 expressionP
->X_add_number
=
862 - (isupper ((unsigned char) c
) ? tolower (c
) : c
);
866 /* The string was only zero */
867 expressionP
->X_op
= O_constant
;
868 expressionP
->X_add_number
= 0;
877 input_line_pointer
++;
878 integer_constant (16, expressionP
);
882 if (LOCAL_LABELS_FB
&& ! (flag_m68k_mri
|| NUMBERS_WITH_SUFFIX
))
884 /* This code used to check for '+' and '-' here, and, in
885 some conditions, fall through to call
886 integer_constant. However, that didn't make sense,
887 as integer_constant only accepts digits. */
888 /* Some of our code elsewhere does permit digits greater
889 than the expected base; for consistency, do the same
891 if (input_line_pointer
[1] < '0'
892 || input_line_pointer
[1] > '9')
894 /* Parse this as a back reference to label 0. */
895 input_line_pointer
--;
896 integer_constant (10, expressionP
);
899 /* Otherwise, parse this as a binary number. */
903 input_line_pointer
++;
904 if (flag_m68k_mri
|| NUMBERS_WITH_SUFFIX
)
906 integer_constant (2, expressionP
);
917 integer_constant ((flag_m68k_mri
|| NUMBERS_WITH_SUFFIX
)
925 /* If it says "0f" and it could possibly be a floating point
926 number, make it one. Otherwise, make it a local label,
927 and try to deal with parsing the rest later. */
928 if (!input_line_pointer
[1]
929 || (is_end_of_line
[0xff & input_line_pointer
[1]])
930 || strchr (FLT_CHARS
, 'f') == NULL
)
933 char *cp
= input_line_pointer
+ 1;
934 int r
= atof_generic (&cp
, ".", EXP_CHARS
,
935 &generic_floating_point_number
);
939 case ERROR_EXPONENT_OVERFLOW
:
940 if (*cp
== 'f' || *cp
== 'b')
941 /* looks like a difference expression */
943 else if (cp
== input_line_pointer
+ 1)
944 /* No characters has been accepted -- looks like
950 as_fatal (_("expr.c(operand): bad atof_generic return val %d"),
955 /* Okay, now we've sorted it out. We resume at one of these
956 two labels, depending on what we've decided we're probably
959 input_line_pointer
--;
960 integer_constant (10, expressionP
);
970 if (flag_m68k_mri
|| NUMBERS_WITH_SUFFIX
)
972 integer_constant (0, expressionP
);
982 input_line_pointer
++;
983 floating_constant (expressionP
);
984 expressionP
->X_add_number
=
985 - (isupper ((unsigned char) c
) ? tolower (c
) : c
);
989 if (LOCAL_LABELS_DOLLAR
)
991 integer_constant (10, expressionP
);
1001 #ifndef NEED_INDEX_OPERATOR
1004 /* didn't begin with digit & not a name */
1005 segment
= expression (expressionP
);
1006 /* Expression() will pass trailing whitespace */
1007 if ((c
== '(' && *input_line_pointer
!= ')')
1008 || (c
== '[' && *input_line_pointer
!= ']'))
1010 #ifdef RELAX_PAREN_GROUPING
1013 as_bad (_("Missing '%c' assumed"), c
== '(' ? ')' : ']');
1016 input_line_pointer
++;
1018 /* here with input_line_pointer->char after "(...)" */
1023 if (! flag_m68k_mri
|| *input_line_pointer
!= '\'')
1025 as_bad (_("EBCDIC constants are not supported"));
1028 if (! flag_m68k_mri
|| *input_line_pointer
!= '\'')
1030 ++input_line_pointer
;
1034 if (! flag_m68k_mri
)
1036 /* Warning: to conform to other people's assemblers NO
1037 ESCAPEMENT is permitted for a single quote. The next
1038 character, parity errors and all, is taken as the value
1039 of the operand. VERY KINKY. */
1040 expressionP
->X_op
= O_constant
;
1041 expressionP
->X_add_number
= *input_line_pointer
++;
1045 mri_char_constant (expressionP
);
1049 (void) operand (expressionP
);
1054 /* Double quote is the bitwise not operator in MRI mode. */
1055 if (! flag_m68k_mri
)
1060 /* ~ is permitted to start a label on the Delta. */
1061 if (is_name_beginner (c
))
1066 operand (expressionP
);
1067 if (expressionP
->X_op
== O_constant
)
1069 /* input_line_pointer -> char after operand */
1072 expressionP
->X_add_number
= - expressionP
->X_add_number
;
1073 /* Notice: '-' may overflow: no warning is given. This is
1074 compatible with other people's assemblers. Sigh. */
1075 expressionP
->X_unsigned
= 0;
1077 else if (c
== '~' || c
== '"')
1078 expressionP
->X_add_number
= ~ expressionP
->X_add_number
;
1080 expressionP
->X_add_number
= ! expressionP
->X_add_number
;
1082 else if (expressionP
->X_op
!= O_illegal
1083 && expressionP
->X_op
!= O_absent
)
1085 expressionP
->X_add_symbol
= make_expr_symbol (expressionP
);
1087 expressionP
->X_op
= O_uminus
;
1088 else if (c
== '~' || c
== '"')
1089 expressionP
->X_op
= O_bit_not
;
1091 expressionP
->X_op
= O_logical_not
;
1092 expressionP
->X_add_number
= 0;
1095 as_warn (_("Unary operator %c ignored because bad operand follows"),
1100 #if defined (DOLLAR_DOT) || defined (TC_M68K)
1102 /* $ is the program counter when in MRI mode, or when DOLLAR_DOT
1105 if (! flag_m68k_mri
)
1108 if (flag_m68k_mri
&& hex_p (*input_line_pointer
))
1110 /* In MRI mode, $ is also used as the prefix for a
1111 hexadecimal constant. */
1112 integer_constant (16, expressionP
);
1116 if (is_part_of_name (*input_line_pointer
))
1119 current_location (expressionP
);
1124 if (!is_part_of_name (*input_line_pointer
))
1126 current_location (expressionP
);
1129 else if ((strncasecmp (input_line_pointer
, "startof.", 8) == 0
1130 && ! is_part_of_name (input_line_pointer
[8]))
1131 || (strncasecmp (input_line_pointer
, "sizeof.", 7) == 0
1132 && ! is_part_of_name (input_line_pointer
[7])))
1136 start
= (input_line_pointer
[1] == 't'
1137 || input_line_pointer
[1] == 'T');
1138 input_line_pointer
+= start
? 8 : 7;
1140 if (*input_line_pointer
!= '(')
1141 as_bad (_("syntax error in .startof. or .sizeof."));
1146 ++input_line_pointer
;
1148 name
= input_line_pointer
;
1149 c
= get_symbol_end ();
1151 buf
= (char *) xmalloc (strlen (name
) + 10);
1153 sprintf (buf
, ".startof.%s", name
);
1155 sprintf (buf
, ".sizeof.%s", name
);
1156 symbolP
= symbol_make (buf
);
1159 expressionP
->X_op
= O_symbol
;
1160 expressionP
->X_add_symbol
= symbolP
;
1161 expressionP
->X_add_number
= 0;
1163 *input_line_pointer
= c
;
1165 if (*input_line_pointer
!= ')')
1166 as_bad (_("syntax error in .startof. or .sizeof."));
1168 ++input_line_pointer
;
1179 /* can't imagine any other kind of operand */
1180 expressionP
->X_op
= O_absent
;
1181 input_line_pointer
--;
1186 if (! flag_m68k_mri
)
1188 integer_constant (2, expressionP
);
1192 if (! flag_m68k_mri
)
1194 integer_constant (8, expressionP
);
1198 if (! flag_m68k_mri
)
1201 /* In MRI mode, this is a floating point constant represented
1202 using hexadecimal digits. */
1204 ++input_line_pointer
;
1205 integer_constant (16, expressionP
);
1209 if (! flag_m68k_mri
|| is_part_of_name (*input_line_pointer
))
1212 current_location (expressionP
);
1220 if (is_name_beginner (c
)) /* here if did not begin with a digit */
1223 * Identifier begins here.
1224 * This is kludged for speed, so code is repeated.
1227 name
= --input_line_pointer
;
1228 c
= get_symbol_end ();
1230 #ifdef md_parse_name
1231 /* This is a hook for the backend to parse certain names
1232 specially in certain contexts. If a name always has a
1233 specific value, it can often be handled by simply
1234 entering it in the symbol table. */
1235 if (md_parse_name (name
, expressionP
))
1237 *input_line_pointer
= c
;
1243 /* The MRI i960 assembler permits
1245 FIXME: This should use md_parse_name. */
1247 && (strcasecmp (name
, "sizeof") == 0
1248 || strcasecmp (name
, "startof") == 0))
1253 start
= (name
[1] == 't'
1256 *input_line_pointer
= c
;
1259 name
= input_line_pointer
;
1260 c
= get_symbol_end ();
1262 buf
= (char *) xmalloc (strlen (name
) + 10);
1264 sprintf (buf
, ".startof.%s", name
);
1266 sprintf (buf
, ".sizeof.%s", name
);
1267 symbolP
= symbol_make (buf
);
1270 expressionP
->X_op
= O_symbol
;
1271 expressionP
->X_add_symbol
= symbolP
;
1272 expressionP
->X_add_number
= 0;
1274 *input_line_pointer
= c
;
1281 symbolP
= symbol_find_or_make (name
);
1283 /* If we have an absolute symbol or a reg, then we know its
1285 segment
= S_GET_SEGMENT (symbolP
);
1286 if (segment
== absolute_section
)
1288 expressionP
->X_op
= O_constant
;
1289 expressionP
->X_add_number
= S_GET_VALUE (symbolP
);
1291 else if (segment
== reg_section
)
1293 expressionP
->X_op
= O_register
;
1294 expressionP
->X_add_number
= S_GET_VALUE (symbolP
);
1298 expressionP
->X_op
= O_symbol
;
1299 expressionP
->X_add_symbol
= symbolP
;
1300 expressionP
->X_add_number
= 0;
1302 *input_line_pointer
= c
;
1306 /* Let the target try to parse it. Success is indicated by changing
1307 the X_op field to something other than O_absent and pointing
1308 input_line_pointer passed the expression. If it can't parse the
1309 expression, X_op and input_line_pointer should be unchanged. */
1310 expressionP
->X_op
= O_absent
;
1311 --input_line_pointer
;
1312 md_operand (expressionP
);
1313 if (expressionP
->X_op
== O_absent
)
1315 ++input_line_pointer
;
1316 as_bad (_("Bad expression"));
1317 expressionP
->X_op
= O_constant
;
1318 expressionP
->X_add_number
= 0;
1325 * It is more 'efficient' to clean up the expressionS when they are created.
1326 * Doing it here saves lines of code.
1328 clean_up_expression (expressionP
);
1329 SKIP_WHITESPACE (); /*->1st char after operand. */
1330 know (*input_line_pointer
!= ' ');
1332 /* The PA port needs this information. */
1333 if (expressionP
->X_add_symbol
)
1334 symbol_mark_used (expressionP
->X_add_symbol
);
1336 switch (expressionP
->X_op
)
1339 return absolute_section
;
1341 return S_GET_SEGMENT (expressionP
->X_add_symbol
);
1347 /* Internal. Simplify a struct expression for use by expr() */
1350 * In: address of a expressionS.
1351 * The X_op field of the expressionS may only take certain values.
1352 * Elsewise we waste time special-case testing. Sigh. Ditto SEG_ABSENT.
1353 * Out: expressionS may have been modified:
1354 * 'foo-foo' symbol references cancelled to 0,
1355 * which changes X_op from O_subtract to O_constant.
1356 * Unused fields zeroed to help expr().
1360 clean_up_expression (expressionP
)
1361 expressionS
*expressionP
;
1363 switch (expressionP
->X_op
)
1367 expressionP
->X_add_number
= 0;
1372 expressionP
->X_add_symbol
= NULL
;
1377 expressionP
->X_op_symbol
= NULL
;
1380 if (expressionP
->X_op_symbol
== expressionP
->X_add_symbol
1381 || ((symbol_get_frag (expressionP
->X_op_symbol
)
1382 == symbol_get_frag (expressionP
->X_add_symbol
))
1383 && SEG_NORMAL (S_GET_SEGMENT (expressionP
->X_add_symbol
))
1384 && (S_GET_VALUE (expressionP
->X_op_symbol
)
1385 == S_GET_VALUE (expressionP
->X_add_symbol
))))
1387 addressT diff
= (S_GET_VALUE (expressionP
->X_add_symbol
)
1388 - S_GET_VALUE (expressionP
->X_op_symbol
));
1390 expressionP
->X_op
= O_constant
;
1391 expressionP
->X_add_symbol
= NULL
;
1392 expressionP
->X_op_symbol
= NULL
;
1393 expressionP
->X_add_number
+= diff
;
1401 /* Expression parser. */
1404 * We allow an empty expression, and just assume (absolute,0) silently.
1405 * Unary operators and parenthetical expressions are treated as operands.
1406 * As usual, Q==quantity==operand, O==operator, X==expression mnemonics.
1408 * We used to do a aho/ullman shift-reduce parser, but the logic got so
1409 * warped that I flushed it and wrote a recursive-descent parser instead.
1410 * Now things are stable, would anybody like to write a fast parser?
1411 * Most expressions are either register (which does not even reach here)
1412 * or 1 symbol. Then "symbol+constant" and "symbol-symbol" are common.
1413 * So I guess it doesn't really matter how inefficient more complex expressions
1416 * After expr(RANK,resultP) input_line_pointer->operator of rank <= RANK.
1417 * Also, we have consumed any leading or trailing spaces (operand does that)
1418 * and done all intervening operators.
1420 * This returns the segment of the result, which will be
1421 * absolute_section or the segment of a symbol.
1425 #define __ O_illegal
1427 static const operatorT op_encoding
[256] =
1428 { /* maps ASCII->operators */
1430 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
,
1431 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
,
1433 __
, O_bit_or_not
, __
, __
, __
, O_modulus
, O_bit_and
, __
,
1434 __
, __
, O_multiply
, O_add
, __
, O_subtract
, __
, O_divide
,
1435 __
, __
, __
, __
, __
, __
, __
, __
,
1436 __
, __
, __
, __
, O_lt
, __
, O_gt
, __
,
1437 __
, __
, __
, __
, __
, __
, __
, __
,
1438 __
, __
, __
, __
, __
, __
, __
, __
,
1439 __
, __
, __
, __
, __
, __
, __
, __
,
1441 #ifdef NEED_INDEX_OPERATOR
1446 __
, __
, O_bit_exclusive_or
, __
,
1447 __
, __
, __
, __
, __
, __
, __
, __
,
1448 __
, __
, __
, __
, __
, __
, __
, __
,
1449 __
, __
, __
, __
, __
, __
, __
, __
,
1450 __
, __
, __
, __
, O_bit_inclusive_or
, __
, __
, __
,
1452 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
,
1453 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
,
1454 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
,
1455 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
,
1456 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
,
1457 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
,
1458 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
,
1459 __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
, __
1465 * 0 operand, (expression)
1470 * 5 used for * / % in MRI mode
1475 static operator_rankT op_rank
[] =
1481 0, /* O_symbol_rva */
1486 9, /* O_logical_not */
1490 8, /* O_left_shift */
1491 8, /* O_right_shift */
1492 7, /* O_bit_inclusive_or */
1493 7, /* O_bit_or_not */
1494 7, /* O_bit_exclusive_or */
1504 3, /* O_logical_and */
1505 2, /* O_logical_or */
1525 /* Unfortunately, in MRI mode for the m68k, multiplication and
1526 division have lower precedence than the bit wise operators. This
1527 function sets the operator precedences correctly for the current
1528 mode. Also, MRI uses a different bit_not operator, and this fixes
1531 #define STANDARD_MUL_PRECEDENCE (7)
1532 #define MRI_MUL_PRECEDENCE (5)
1535 expr_set_precedence ()
1539 op_rank
[O_multiply
] = MRI_MUL_PRECEDENCE
;
1540 op_rank
[O_divide
] = MRI_MUL_PRECEDENCE
;
1541 op_rank
[O_modulus
] = MRI_MUL_PRECEDENCE
;
1545 op_rank
[O_multiply
] = STANDARD_MUL_PRECEDENCE
;
1546 op_rank
[O_divide
] = STANDARD_MUL_PRECEDENCE
;
1547 op_rank
[O_modulus
] = STANDARD_MUL_PRECEDENCE
;
1551 /* Initialize the expression parser. */
1556 expr_set_precedence ();
1558 /* Verify that X_op field is wide enough. */
1562 assert (e
.X_op
== O_max
);
1566 /* Return the encoding for the operator at INPUT_LINE_POINTER.
1567 Advance INPUT_LINE_POINTER to the last character in the operator
1568 (i.e., don't change it for a single character operator). */
1570 static inline operatorT
1576 c
= *input_line_pointer
& 0xff;
1578 if (is_end_of_line
[c
])
1584 return op_encoding
[c
];
1587 switch (input_line_pointer
[1])
1590 return op_encoding
[c
];
1601 ++input_line_pointer
;
1605 if (input_line_pointer
[1] != '=')
1606 return op_encoding
[c
];
1608 ++input_line_pointer
;
1612 switch (input_line_pointer
[1])
1615 return op_encoding
[c
];
1617 ret
= O_right_shift
;
1623 ++input_line_pointer
;
1627 /* We accept !! as equivalent to ^ for MRI compatibility. */
1628 if (input_line_pointer
[1] != '!')
1631 return O_bit_inclusive_or
;
1632 return op_encoding
[c
];
1634 ++input_line_pointer
;
1635 return O_bit_exclusive_or
;
1638 if (input_line_pointer
[1] != '|')
1639 return op_encoding
[c
];
1641 ++input_line_pointer
;
1642 return O_logical_or
;
1645 if (input_line_pointer
[1] != '&')
1646 return op_encoding
[c
];
1648 ++input_line_pointer
;
1649 return O_logical_and
;
1655 /* Parse an expression. */
1658 expr (rankarg
, resultP
)
1659 int rankarg
; /* Larger # is higher rank. */
1660 expressionS
*resultP
; /* Deliver result here. */
1662 operator_rankT rank
= (operator_rankT
) rankarg
;
1670 retval
= operand (resultP
);
1672 know (*input_line_pointer
!= ' '); /* Operand() gobbles spaces. */
1674 op_left
= operator ();
1675 while (op_left
!= O_illegal
&& op_rank
[(int) op_left
] > rank
)
1679 input_line_pointer
++; /*->after 1st character of operator. */
1681 rightseg
= expr (op_rank
[(int) op_left
], &right
);
1682 if (right
.X_op
== O_absent
)
1684 as_warn (_("missing operand; zero assumed"));
1685 right
.X_op
= O_constant
;
1686 right
.X_add_number
= 0;
1687 right
.X_add_symbol
= NULL
;
1688 right
.X_op_symbol
= NULL
;
1691 know (*input_line_pointer
!= ' ');
1693 if (op_left
== O_index
)
1695 if (*input_line_pointer
!= ']')
1696 as_bad ("missing right bracket");
1699 ++input_line_pointer
;
1704 if (retval
== undefined_section
)
1706 if (SEG_NORMAL (rightseg
))
1709 else if (! SEG_NORMAL (retval
))
1711 else if (SEG_NORMAL (rightseg
)
1712 && retval
!= rightseg
1714 && op_left
!= O_subtract
1717 as_bad (_("operation combines symbols in different segments"));
1719 op_right
= operator ();
1721 know (op_right
== O_illegal
|| op_rank
[(int) op_right
] <= op_rank
[(int) op_left
]);
1722 know ((int) op_left
>= (int) O_multiply
1723 && (int) op_left
<= (int) O_logical_or
);
1725 /* input_line_pointer->after right-hand quantity. */
1726 /* left-hand quantity in resultP */
1727 /* right-hand quantity in right. */
1728 /* operator in op_left. */
1730 if (resultP
->X_op
== O_big
)
1732 if (resultP
->X_add_number
> 0)
1733 as_warn (_("left operand is a bignum; integer 0 assumed"));
1735 as_warn (_("left operand is a float; integer 0 assumed"));
1736 resultP
->X_op
= O_constant
;
1737 resultP
->X_add_number
= 0;
1738 resultP
->X_add_symbol
= NULL
;
1739 resultP
->X_op_symbol
= NULL
;
1741 if (right
.X_op
== O_big
)
1743 if (right
.X_add_number
> 0)
1744 as_warn (_("right operand is a bignum; integer 0 assumed"));
1746 as_warn (_("right operand is a float; integer 0 assumed"));
1747 right
.X_op
= O_constant
;
1748 right
.X_add_number
= 0;
1749 right
.X_add_symbol
= NULL
;
1750 right
.X_op_symbol
= NULL
;
1753 /* Optimize common cases. */
1754 #ifdef md_optimize_expr
1755 if (md_optimize_expr (resultP
, op_left
, &right
))
1761 if (op_left
== O_add
&& right
.X_op
== O_constant
)
1764 resultP
->X_add_number
+= right
.X_add_number
;
1766 /* This case comes up in PIC code. */
1767 else if (op_left
== O_subtract
1768 && right
.X_op
== O_symbol
1769 && resultP
->X_op
== O_symbol
1770 && (symbol_get_frag (right
.X_add_symbol
)
1771 == symbol_get_frag (resultP
->X_add_symbol
))
1772 && SEG_NORMAL (S_GET_SEGMENT (right
.X_add_symbol
)))
1775 resultP
->X_add_number
-= right
.X_add_number
;
1776 resultP
->X_add_number
+= (S_GET_VALUE (resultP
->X_add_symbol
)
1777 - S_GET_VALUE (right
.X_add_symbol
));
1778 resultP
->X_op
= O_constant
;
1779 resultP
->X_add_symbol
= 0;
1781 else if (op_left
== O_subtract
&& right
.X_op
== O_constant
)
1784 resultP
->X_add_number
-= right
.X_add_number
;
1786 else if (op_left
== O_add
&& resultP
->X_op
== O_constant
)
1789 resultP
->X_op
= right
.X_op
;
1790 resultP
->X_add_symbol
= right
.X_add_symbol
;
1791 resultP
->X_op_symbol
= right
.X_op_symbol
;
1792 resultP
->X_add_number
+= right
.X_add_number
;
1795 else if (resultP
->X_op
== O_constant
&& right
.X_op
== O_constant
)
1797 /* Constant OP constant. */
1798 offsetT v
= right
.X_add_number
;
1799 if (v
== 0 && (op_left
== O_divide
|| op_left
== O_modulus
))
1801 as_warn (_("division by zero"));
1807 case O_multiply
: resultP
->X_add_number
*= v
; break;
1808 case O_divide
: resultP
->X_add_number
/= v
; break;
1809 case O_modulus
: resultP
->X_add_number
%= v
; break;
1810 case O_left_shift
: resultP
->X_add_number
<<= v
; break;
1812 /* We always use unsigned shifts, to avoid relying on
1813 characteristics of the compiler used to compile gas. */
1814 resultP
->X_add_number
=
1815 (offsetT
) ((valueT
) resultP
->X_add_number
>> (valueT
) v
);
1817 case O_bit_inclusive_or
: resultP
->X_add_number
|= v
; break;
1818 case O_bit_or_not
: resultP
->X_add_number
|= ~v
; break;
1819 case O_bit_exclusive_or
: resultP
->X_add_number
^= v
; break;
1820 case O_bit_and
: resultP
->X_add_number
&= v
; break;
1821 case O_add
: resultP
->X_add_number
+= v
; break;
1822 case O_subtract
: resultP
->X_add_number
-= v
; break;
1824 resultP
->X_add_number
=
1825 resultP
->X_add_number
== v
? ~ (offsetT
) 0 : 0;
1828 resultP
->X_add_number
=
1829 resultP
->X_add_number
!= v
? ~ (offsetT
) 0 : 0;
1832 resultP
->X_add_number
=
1833 resultP
->X_add_number
< v
? ~ (offsetT
) 0 : 0;
1836 resultP
->X_add_number
=
1837 resultP
->X_add_number
<= v
? ~ (offsetT
) 0 : 0;
1840 resultP
->X_add_number
=
1841 resultP
->X_add_number
>= v
? ~ (offsetT
) 0 : 0;
1844 resultP
->X_add_number
=
1845 resultP
->X_add_number
> v
? ~ (offsetT
) 0 : 0;
1848 resultP
->X_add_number
= resultP
->X_add_number
&& v
;
1851 resultP
->X_add_number
= resultP
->X_add_number
|| v
;
1855 else if (resultP
->X_op
== O_symbol
1856 && right
.X_op
== O_symbol
1857 && (op_left
== O_add
1858 || op_left
== O_subtract
1859 || (resultP
->X_add_number
== 0
1860 && right
.X_add_number
== 0)))
1862 /* Symbol OP symbol. */
1863 resultP
->X_op
= op_left
;
1864 resultP
->X_op_symbol
= right
.X_add_symbol
;
1865 if (op_left
== O_add
)
1866 resultP
->X_add_number
+= right
.X_add_number
;
1867 else if (op_left
== O_subtract
)
1868 resultP
->X_add_number
-= right
.X_add_number
;
1872 /* The general case. */
1873 resultP
->X_add_symbol
= make_expr_symbol (resultP
);
1874 resultP
->X_op_symbol
= make_expr_symbol (&right
);
1875 resultP
->X_op
= op_left
;
1876 resultP
->X_add_number
= 0;
1877 resultP
->X_unsigned
= 1;
1881 } /* While next operator is >= this rank. */
1883 /* The PA port needs this information. */
1884 if (resultP
->X_add_symbol
)
1885 symbol_mark_used (resultP
->X_add_symbol
);
1887 return resultP
->X_op
== O_constant
? absolute_section
: retval
;
1893 * This lives here because it belongs equally in expr.c & read.c.
1894 * Expr.c is just a branch office read.c anyway, and putting it
1895 * here lessens the crowd at read.c.
1897 * Assume input_line_pointer is at start of symbol name.
1898 * Advance input_line_pointer past symbol name.
1899 * Turn that character into a '\0', returning its former value.
1900 * This allows a string compare (RMS wants symbol names to be strings)
1901 * of the symbol name.
1902 * There will always be a char following symbol name, because all good
1903 * lines end in end-of-line.
1910 /* We accept \001 in a name in case this is being called with a
1911 constructed string. */
1912 if (is_name_beginner (c
= *input_line_pointer
++) || c
== '\001')
1914 while (is_part_of_name (c
= *input_line_pointer
++)
1917 if (is_name_ender (c
))
1918 c
= *input_line_pointer
++;
1920 *--input_line_pointer
= 0;
1926 get_single_number ()
1930 return exp
.X_add_number
;