xref: /dragonfly/contrib/binutils-2.27/gas/expr.c (revision 65cc0652)
1 /* expr.c -operands, expressions-
2    Copyright (C) 1987-2016 Free Software Foundation, Inc.
3 
4    This file is part of GAS, the GNU Assembler.
5 
6    GAS is free software; you can redistribute it and/or modify
7    it under the terms of the GNU General Public License as published by
8    the Free Software Foundation; either version 3, or (at your option)
9    any later version.
10 
11    GAS is distributed in the hope that it will be useful,
12    but WITHOUT ANY WARRANTY; without even the implied warranty of
13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14    GNU General Public License for more details.
15 
16    You should have received a copy of the GNU General Public License
17    along with GAS; see the file COPYING.  If not, write to the Free
18    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
19    02110-1301, USA.  */
20 
21 /* This is really a branch office of as-read.c. I split it out to clearly
22    distinguish the world of expressions from the world of statements.
23    (It also gives smaller files to re-compile.)
24    Here, "operand"s are of expressions, not instructions.  */
25 
26 #define min(a, b)       ((a) < (b) ? (a) : (b))
27 
28 #include "as.h"
29 #include "safe-ctype.h"
30 
31 #ifdef HAVE_LIMITS_H
32 #include <limits.h>
33 #endif
34 #ifndef CHAR_BIT
35 #define CHAR_BIT 8
36 #endif
37 
38 static void floating_constant (expressionS * expressionP);
39 static valueT generic_bignum_to_int32 (void);
40 #ifdef BFD64
41 static valueT generic_bignum_to_int64 (void);
42 #endif
43 static void integer_constant (int radix, expressionS * expressionP);
44 static void mri_char_constant (expressionS *);
45 static void clean_up_expression (expressionS * expressionP);
46 static segT operand (expressionS *, enum expr_mode);
47 static operatorT operatorf (int *);
48 
49 /* We keep a mapping of expression symbols to file positions, so that
50    we can provide better error messages.  */
51 
52 struct expr_symbol_line {
53   struct expr_symbol_line *next;
54   symbolS *sym;
55   const char *file;
56   unsigned int line;
57 };
58 
59 static struct expr_symbol_line *expr_symbol_lines;
60 
61 /* Build a dummy symbol to hold a complex expression.  This is how we
62    build expressions up out of other expressions.  The symbol is put
63    into the fake section expr_section.  */
64 
65 symbolS *
66 make_expr_symbol (expressionS *expressionP)
67 {
68   expressionS zero;
69   symbolS *symbolP;
70   struct expr_symbol_line *n;
71 
72   if (expressionP->X_op == O_symbol
73       && expressionP->X_add_number == 0)
74     return expressionP->X_add_symbol;
75 
76   if (expressionP->X_op == O_big)
77     {
78       /* This won't work, because the actual value is stored in
79 	 generic_floating_point_number or generic_bignum, and we are
80 	 going to lose it if we haven't already.  */
81       if (expressionP->X_add_number > 0)
82 	as_bad (_("bignum invalid"));
83       else
84 	as_bad (_("floating point number invalid"));
85       zero.X_op = O_constant;
86       zero.X_add_number = 0;
87       zero.X_unsigned = 0;
88       zero.X_extrabit = 0;
89       clean_up_expression (&zero);
90       expressionP = &zero;
91     }
92 
93   /* Putting constant symbols in absolute_section rather than
94      expr_section is convenient for the old a.out code, for which
95      S_GET_SEGMENT does not always retrieve the value put in by
96      S_SET_SEGMENT.  */
97   symbolP = symbol_create (FAKE_LABEL_NAME,
98 			   (expressionP->X_op == O_constant
99 			    ? absolute_section
100 			    : expressionP->X_op == O_register
101 			      ? reg_section
102 			      : expr_section),
103 			   0, &zero_address_frag);
104   symbol_set_value_expression (symbolP, expressionP);
105 
106   if (expressionP->X_op == O_constant)
107     resolve_symbol_value (symbolP);
108 
109   n = XNEW (struct expr_symbol_line);
110   n->sym = symbolP;
111   n->file = as_where (&n->line);
112   n->next = expr_symbol_lines;
113   expr_symbol_lines = n;
114 
115   return symbolP;
116 }
117 
118 /* Return the file and line number for an expr symbol.  Return
119    non-zero if something was found, 0 if no information is known for
120    the symbol.  */
121 
122 int
123 expr_symbol_where (symbolS *sym, const char **pfile, unsigned int *pline)
124 {
125   struct expr_symbol_line *l;
126 
127   for (l = expr_symbol_lines; l != NULL; l = l->next)
128     {
129       if (l->sym == sym)
130 	{
131 	  *pfile = l->file;
132 	  *pline = l->line;
133 	  return 1;
134 	}
135     }
136 
137   return 0;
138 }
139 
140 /* Utilities for building expressions.
141    Since complex expressions are recorded as symbols for use in other
142    expressions these return a symbolS * and not an expressionS *.
143    These explicitly do not take an "add_number" argument.  */
144 /* ??? For completeness' sake one might want expr_build_symbol.
145    It would just return its argument.  */
146 
147 /* Build an expression for an unsigned constant.
148    The corresponding one for signed constants is missing because
149    there's currently no need for it.  One could add an unsigned_p flag
150    but that seems more clumsy.  */
151 
152 symbolS *
153 expr_build_uconstant (offsetT value)
154 {
155   expressionS e;
156 
157   e.X_op = O_constant;
158   e.X_add_number = value;
159   e.X_unsigned = 1;
160   e.X_extrabit = 0;
161   return make_expr_symbol (&e);
162 }
163 
164 /* Build an expression for the current location ('.').  */
165 
166 symbolS *
167 expr_build_dot (void)
168 {
169   expressionS e;
170 
171   current_location (&e);
172   return symbol_clone_if_forward_ref (make_expr_symbol (&e));
173 }
174 
175 /* Build any floating-point literal here.
176    Also build any bignum literal here.  */
177 
178 /* Seems atof_machine can backscan through generic_bignum and hit whatever
179    happens to be loaded before it in memory.  And its way too complicated
180    for me to fix right.  Thus a hack.  JF:  Just make generic_bignum bigger,
181    and never write into the early words, thus they'll always be zero.
182    I hate Dean's floating-point code.  Bleh.  */
183 LITTLENUM_TYPE generic_bignum[SIZE_OF_LARGE_NUMBER + 6];
184 
185 FLONUM_TYPE generic_floating_point_number = {
186   &generic_bignum[6],		/* low.  (JF: Was 0)  */
187   &generic_bignum[SIZE_OF_LARGE_NUMBER + 6 - 1], /* high.  JF: (added +6)  */
188   0,				/* leader.  */
189   0,				/* exponent.  */
190   0				/* sign.  */
191 };
192 
193 
194 static void
195 floating_constant (expressionS *expressionP)
196 {
197   /* input_line_pointer -> floating-point constant.  */
198   int error_code;
199 
200   error_code = atof_generic (&input_line_pointer, ".", EXP_CHARS,
201 			     &generic_floating_point_number);
202 
203   if (error_code)
204     {
205       if (error_code == ERROR_EXPONENT_OVERFLOW)
206 	{
207 	  as_bad (_("bad floating-point constant: exponent overflow"));
208 	}
209       else
210 	{
211 	  as_bad (_("bad floating-point constant: unknown error code=%d"),
212 		  error_code);
213 	}
214     }
215   expressionP->X_op = O_big;
216   /* input_line_pointer -> just after constant, which may point to
217      whitespace.  */
218   expressionP->X_add_number = -1;
219 }
220 
221 static valueT
222 generic_bignum_to_int32 (void)
223 {
224   valueT number =
225 	   ((generic_bignum[1] & LITTLENUM_MASK) << LITTLENUM_NUMBER_OF_BITS)
226 	   | (generic_bignum[0] & LITTLENUM_MASK);
227   number &= 0xffffffff;
228   return number;
229 }
230 
231 #ifdef BFD64
232 static valueT
233 generic_bignum_to_int64 (void)
234 {
235   valueT number =
236     ((((((((valueT) generic_bignum[3] & LITTLENUM_MASK)
237 	  << LITTLENUM_NUMBER_OF_BITS)
238 	 | ((valueT) generic_bignum[2] & LITTLENUM_MASK))
239 	<< LITTLENUM_NUMBER_OF_BITS)
240        | ((valueT) generic_bignum[1] & LITTLENUM_MASK))
241       << LITTLENUM_NUMBER_OF_BITS)
242      | ((valueT) generic_bignum[0] & LITTLENUM_MASK));
243   return number;
244 }
245 #endif
246 
247 static void
248 integer_constant (int radix, expressionS *expressionP)
249 {
250   char *start;		/* Start of number.  */
251   char *suffix = NULL;
252   char c;
253   valueT number;	/* Offset or (absolute) value.  */
254   short int digit;	/* Value of next digit in current radix.  */
255   short int maxdig = 0;	/* Highest permitted digit value.  */
256   int too_many_digits = 0;	/* If we see >= this number of.  */
257   char *name;		/* Points to name of symbol.  */
258   symbolS *symbolP;	/* Points to symbol.  */
259 
260   int small;			/* True if fits in 32 bits.  */
261 
262   /* May be bignum, or may fit in 32 bits.  */
263   /* Most numbers fit into 32 bits, and we want this case to be fast.
264      so we pretend it will fit into 32 bits.  If, after making up a 32
265      bit number, we realise that we have scanned more digits than
266      comfortably fit into 32 bits, we re-scan the digits coding them
267      into a bignum.  For decimal and octal numbers we are
268      conservative: Some numbers may be assumed bignums when in fact
269      they do fit into 32 bits.  Numbers of any radix can have excess
270      leading zeros: We strive to recognise this and cast them back
271      into 32 bits.  We must check that the bignum really is more than
272      32 bits, and change it back to a 32-bit number if it fits.  The
273      number we are looking for is expected to be positive, but if it
274      fits into 32 bits as an unsigned number, we let it be a 32-bit
275      number.  The cavalier approach is for speed in ordinary cases.  */
276   /* This has been extended for 64 bits.  We blindly assume that if
277      you're compiling in 64-bit mode, the target is a 64-bit machine.
278      This should be cleaned up.  */
279 
280 #ifdef BFD64
281 #define valuesize 64
282 #else /* includes non-bfd case, mostly */
283 #define valuesize 32
284 #endif
285 
286   if (is_end_of_line[(unsigned char) *input_line_pointer])
287     {
288       expressionP->X_op = O_absent;
289       return;
290     }
291 
292   if ((NUMBERS_WITH_SUFFIX || flag_m68k_mri) && radix == 0)
293     {
294       int flt = 0;
295 
296       /* In MRI mode, the number may have a suffix indicating the
297 	 radix.  For that matter, it might actually be a floating
298 	 point constant.  */
299       for (suffix = input_line_pointer; ISALNUM (*suffix); suffix++)
300 	{
301 	  if (*suffix == 'e' || *suffix == 'E')
302 	    flt = 1;
303 	}
304 
305       if (suffix == input_line_pointer)
306 	{
307 	  radix = 10;
308 	  suffix = NULL;
309 	}
310       else
311 	{
312 	  c = *--suffix;
313 	  c = TOUPPER (c);
314 	  /* If we have both NUMBERS_WITH_SUFFIX and LOCAL_LABELS_FB,
315 	     we distinguish between 'B' and 'b'.  This is the case for
316 	     Z80.  */
317 	  if ((NUMBERS_WITH_SUFFIX && LOCAL_LABELS_FB ? *suffix : c) == 'B')
318 	    radix = 2;
319 	  else if (c == 'D')
320 	    radix = 10;
321 	  else if (c == 'O' || c == 'Q')
322 	    radix = 8;
323 	  else if (c == 'H')
324 	    radix = 16;
325 	  else if (suffix[1] == '.' || c == 'E' || flt)
326 	    {
327 	      floating_constant (expressionP);
328 	      return;
329 	    }
330 	  else
331 	    {
332 	      radix = 10;
333 	      suffix = NULL;
334 	    }
335 	}
336     }
337 
338   switch (radix)
339     {
340     case 2:
341       maxdig = 2;
342       too_many_digits = valuesize + 1;
343       break;
344     case 8:
345       maxdig = radix = 8;
346       too_many_digits = (valuesize + 2) / 3 + 1;
347       break;
348     case 16:
349       maxdig = radix = 16;
350       too_many_digits = (valuesize + 3) / 4 + 1;
351       break;
352     case 10:
353       maxdig = radix = 10;
354       too_many_digits = (valuesize + 11) / 4; /* Very rough.  */
355     }
356 #undef valuesize
357   start = input_line_pointer;
358   c = *input_line_pointer++;
359   for (number = 0;
360        (digit = hex_value (c)) < maxdig;
361        c = *input_line_pointer++)
362     {
363       number = number * radix + digit;
364     }
365   /* c contains character after number.  */
366   /* input_line_pointer->char after c.  */
367   small = (input_line_pointer - start - 1) < too_many_digits;
368 
369   if (radix == 16 && c == '_')
370     {
371       /* This is literal of the form 0x333_0_12345678_1.
372 	 This example is equivalent to 0x00000333000000001234567800000001.  */
373 
374       int num_little_digits = 0;
375       int i;
376       input_line_pointer = start;	/* -> 1st digit.  */
377 
378       know (LITTLENUM_NUMBER_OF_BITS == 16);
379 
380       for (c = '_'; c == '_'; num_little_digits += 2)
381 	{
382 
383 	  /* Convert one 64-bit word.  */
384 	  int ndigit = 0;
385 	  number = 0;
386 	  for (c = *input_line_pointer++;
387 	       (digit = hex_value (c)) < maxdig;
388 	       c = *(input_line_pointer++))
389 	    {
390 	      number = number * radix + digit;
391 	      ndigit++;
392 	    }
393 
394 	  /* Check for 8 digit per word max.  */
395 	  if (ndigit > 8)
396 	    as_bad (_("a bignum with underscores may not have more than 8 hex digits in any word"));
397 
398 	  /* Add this chunk to the bignum.
399 	     Shift things down 2 little digits.  */
400 	  know (LITTLENUM_NUMBER_OF_BITS == 16);
401 	  for (i = min (num_little_digits + 1, SIZE_OF_LARGE_NUMBER - 1);
402 	       i >= 2;
403 	       i--)
404 	    generic_bignum[i] = generic_bignum[i - 2];
405 
406 	  /* Add the new digits as the least significant new ones.  */
407 	  generic_bignum[0] = number & 0xffffffff;
408 	  generic_bignum[1] = number >> 16;
409 	}
410 
411       /* Again, c is char after number, input_line_pointer->after c.  */
412 
413       if (num_little_digits > SIZE_OF_LARGE_NUMBER - 1)
414 	num_little_digits = SIZE_OF_LARGE_NUMBER - 1;
415 
416       gas_assert (num_little_digits >= 4);
417 
418       if (num_little_digits != 8)
419 	as_bad (_("a bignum with underscores must have exactly 4 words"));
420 
421       /* We might have some leading zeros.  These can be trimmed to give
422 	 us a change to fit this constant into a small number.  */
423       while (generic_bignum[num_little_digits - 1] == 0
424 	     && num_little_digits > 1)
425 	num_little_digits--;
426 
427       if (num_little_digits <= 2)
428 	{
429 	  /* will fit into 32 bits.  */
430 	  number = generic_bignum_to_int32 ();
431 	  small = 1;
432 	}
433 #ifdef BFD64
434       else if (num_little_digits <= 4)
435 	{
436 	  /* Will fit into 64 bits.  */
437 	  number = generic_bignum_to_int64 ();
438 	  small = 1;
439 	}
440 #endif
441       else
442 	{
443 	  small = 0;
444 
445 	  /* Number of littlenums in the bignum.  */
446 	  number = num_little_digits;
447 	}
448     }
449   else if (!small)
450     {
451       /* We saw a lot of digits. manufacture a bignum the hard way.  */
452       LITTLENUM_TYPE *leader;	/* -> high order littlenum of the bignum.  */
453       LITTLENUM_TYPE *pointer;	/* -> littlenum we are frobbing now.  */
454       long carry;
455 
456       leader = generic_bignum;
457       generic_bignum[0] = 0;
458       generic_bignum[1] = 0;
459       generic_bignum[2] = 0;
460       generic_bignum[3] = 0;
461       input_line_pointer = start;	/* -> 1st digit.  */
462       c = *input_line_pointer++;
463       for (; (carry = hex_value (c)) < maxdig; c = *input_line_pointer++)
464 	{
465 	  for (pointer = generic_bignum; pointer <= leader; pointer++)
466 	    {
467 	      long work;
468 
469 	      work = carry + radix * *pointer;
470 	      *pointer = work & LITTLENUM_MASK;
471 	      carry = work >> LITTLENUM_NUMBER_OF_BITS;
472 	    }
473 	  if (carry)
474 	    {
475 	      if (leader < generic_bignum + SIZE_OF_LARGE_NUMBER - 1)
476 		{
477 		  /* Room to grow a longer bignum.  */
478 		  *++leader = carry;
479 		}
480 	    }
481 	}
482       /* Again, c is char after number.  */
483       /* input_line_pointer -> after c.  */
484       know (LITTLENUM_NUMBER_OF_BITS == 16);
485       if (leader < generic_bignum + 2)
486 	{
487 	  /* Will fit into 32 bits.  */
488 	  number = generic_bignum_to_int32 ();
489 	  small = 1;
490 	}
491 #ifdef BFD64
492       else if (leader < generic_bignum + 4)
493 	{
494 	  /* Will fit into 64 bits.  */
495 	  number = generic_bignum_to_int64 ();
496 	  small = 1;
497 	}
498 #endif
499       else
500 	{
501 	  /* Number of littlenums in the bignum.  */
502 	  number = leader - generic_bignum + 1;
503 	}
504     }
505 
506   if ((NUMBERS_WITH_SUFFIX || flag_m68k_mri)
507       && suffix != NULL
508       && input_line_pointer - 1 == suffix)
509     c = *input_line_pointer++;
510 
511 #ifndef tc_allow_U_suffix
512 #define tc_allow_U_suffix 1
513 #endif
514   /* PR 19910: Look for, and ignore, a U suffix to the number.  */
515   if (tc_allow_U_suffix && (c == 'U' || c == 'u'))
516     c = * input_line_pointer++;
517 
518   if (small)
519     {
520       /* Here with number, in correct radix. c is the next char.
521 	 Note that unlike un*x, we allow "011f" "0x9f" to both mean
522 	 the same as the (conventional) "9f".
523 	 This is simply easier than checking for strict canonical
524 	 form.  Syntax sux!  */
525 
526       if (LOCAL_LABELS_FB && c == 'b')
527 	{
528 	  /* Backward ref to local label.
529 	     Because it is backward, expect it to be defined.  */
530 	  /* Construct a local label.  */
531 	  name = fb_label_name ((int) number, 0);
532 
533 	  /* Seen before, or symbol is defined: OK.  */
534 	  symbolP = symbol_find (name);
535 	  if ((symbolP != NULL) && (S_IS_DEFINED (symbolP)))
536 	    {
537 	      /* Local labels are never absolute.  Don't waste time
538 		 checking absoluteness.  */
539 	      know (SEG_NORMAL (S_GET_SEGMENT (symbolP)));
540 
541 	      expressionP->X_op = O_symbol;
542 	      expressionP->X_add_symbol = symbolP;
543 	    }
544 	  else
545 	    {
546 	      /* Either not seen or not defined.  */
547 	      /* @@ Should print out the original string instead of
548 		 the parsed number.  */
549 	      as_bad (_("backward ref to unknown label \"%d:\""),
550 		      (int) number);
551 	      expressionP->X_op = O_constant;
552 	    }
553 
554 	  expressionP->X_add_number = 0;
555 	}			/* case 'b' */
556       else if (LOCAL_LABELS_FB && c == 'f')
557 	{
558 	  /* Forward reference.  Expect symbol to be undefined or
559 	     unknown.  undefined: seen it before.  unknown: never seen
560 	     it before.
561 
562 	     Construct a local label name, then an undefined symbol.
563 	     Don't create a xseg frag for it: caller may do that.
564 	     Just return it as never seen before.  */
565 	  name = fb_label_name ((int) number, 1);
566 	  symbolP = symbol_find_or_make (name);
567 	  /* We have no need to check symbol properties.  */
568 #ifndef many_segments
569 	  /* Since "know" puts its arg into a "string", we
570 	     can't have newlines in the argument.  */
571 	  know (S_GET_SEGMENT (symbolP) == undefined_section || S_GET_SEGMENT (symbolP) == text_section || S_GET_SEGMENT (symbolP) == data_section);
572 #endif
573 	  expressionP->X_op = O_symbol;
574 	  expressionP->X_add_symbol = symbolP;
575 	  expressionP->X_add_number = 0;
576 	}			/* case 'f' */
577       else if (LOCAL_LABELS_DOLLAR && c == '$')
578 	{
579 	  /* If the dollar label is *currently* defined, then this is just
580 	     another reference to it.  If it is not *currently* defined,
581 	     then this is a fresh instantiation of that number, so create
582 	     it.  */
583 
584 	  if (dollar_label_defined ((long) number))
585 	    {
586 	      name = dollar_label_name ((long) number, 0);
587 	      symbolP = symbol_find (name);
588 	      know (symbolP != NULL);
589 	    }
590 	  else
591 	    {
592 	      name = dollar_label_name ((long) number, 1);
593 	      symbolP = symbol_find_or_make (name);
594 	    }
595 
596 	  expressionP->X_op = O_symbol;
597 	  expressionP->X_add_symbol = symbolP;
598 	  expressionP->X_add_number = 0;
599 	}			/* case '$' */
600       else
601 	{
602 	  expressionP->X_op = O_constant;
603 	  expressionP->X_add_number = number;
604 	  input_line_pointer--;	/* Restore following character.  */
605 	}			/* Really just a number.  */
606     }
607   else
608     {
609       /* Not a small number.  */
610       expressionP->X_op = O_big;
611       expressionP->X_add_number = number;	/* Number of littlenums.  */
612       input_line_pointer--;	/* -> char following number.  */
613     }
614 }
615 
616 /* Parse an MRI multi character constant.  */
617 
618 static void
619 mri_char_constant (expressionS *expressionP)
620 {
621   int i;
622 
623   if (*input_line_pointer == '\''
624       && input_line_pointer[1] != '\'')
625     {
626       expressionP->X_op = O_constant;
627       expressionP->X_add_number = 0;
628       return;
629     }
630 
631   /* In order to get the correct byte ordering, we must build the
632      number in reverse.  */
633   for (i = SIZE_OF_LARGE_NUMBER - 1; i >= 0; i--)
634     {
635       int j;
636 
637       generic_bignum[i] = 0;
638       for (j = 0; j < CHARS_PER_LITTLENUM; j++)
639 	{
640 	  if (*input_line_pointer == '\'')
641 	    {
642 	      if (input_line_pointer[1] != '\'')
643 		break;
644 	      ++input_line_pointer;
645 	    }
646 	  generic_bignum[i] <<= 8;
647 	  generic_bignum[i] += *input_line_pointer;
648 	  ++input_line_pointer;
649 	}
650 
651       if (i < SIZE_OF_LARGE_NUMBER - 1)
652 	{
653 	  /* If there is more than one littlenum, left justify the
654 	     last one to make it match the earlier ones.  If there is
655 	     only one, we can just use the value directly.  */
656 	  for (; j < CHARS_PER_LITTLENUM; j++)
657 	    generic_bignum[i] <<= 8;
658 	}
659 
660       if (*input_line_pointer == '\''
661 	  && input_line_pointer[1] != '\'')
662 	break;
663     }
664 
665   if (i < 0)
666     {
667       as_bad (_("character constant too large"));
668       i = 0;
669     }
670 
671   if (i > 0)
672     {
673       int c;
674       int j;
675 
676       c = SIZE_OF_LARGE_NUMBER - i;
677       for (j = 0; j < c; j++)
678 	generic_bignum[j] = generic_bignum[i + j];
679       i = c;
680     }
681 
682   know (LITTLENUM_NUMBER_OF_BITS == 16);
683   if (i > 2)
684     {
685       expressionP->X_op = O_big;
686       expressionP->X_add_number = i;
687     }
688   else
689     {
690       expressionP->X_op = O_constant;
691       if (i < 2)
692 	expressionP->X_add_number = generic_bignum[0] & LITTLENUM_MASK;
693       else
694 	expressionP->X_add_number =
695 	  (((generic_bignum[1] & LITTLENUM_MASK)
696 	    << LITTLENUM_NUMBER_OF_BITS)
697 	   | (generic_bignum[0] & LITTLENUM_MASK));
698     }
699 
700   /* Skip the final closing quote.  */
701   ++input_line_pointer;
702 }
703 
704 /* Return an expression representing the current location.  This
705    handles the magic symbol `.'.  */
706 
707 void
708 current_location (expressionS *expressionp)
709 {
710   if (now_seg == absolute_section)
711     {
712       expressionp->X_op = O_constant;
713       expressionp->X_add_number = abs_section_offset;
714     }
715   else
716     {
717       expressionp->X_op = O_symbol;
718       expressionp->X_add_symbol = &dot_symbol;
719       expressionp->X_add_number = 0;
720     }
721 }
722 
723 /* In:	Input_line_pointer points to 1st char of operand, which may
724 	be a space.
725 
726    Out:	An expressionS.
727 	The operand may have been empty: in this case X_op == O_absent.
728 	Input_line_pointer->(next non-blank) char after operand.  */
729 
730 static segT
731 operand (expressionS *expressionP, enum expr_mode mode)
732 {
733   char c;
734   symbolS *symbolP;	/* Points to symbol.  */
735   char *name;		/* Points to name of symbol.  */
736   segT segment;
737 
738   /* All integers are regarded as unsigned unless they are negated.
739      This is because the only thing which cares whether a number is
740      unsigned is the code in emit_expr which extends constants into
741      bignums.  It should only sign extend negative numbers, so that
742      something like ``.quad 0x80000000'' is not sign extended even
743      though it appears negative if valueT is 32 bits.  */
744   expressionP->X_unsigned = 1;
745   expressionP->X_extrabit = 0;
746 
747   /* Digits, assume it is a bignum.  */
748 
749   SKIP_WHITESPACE ();		/* Leading whitespace is part of operand.  */
750   c = *input_line_pointer++;	/* input_line_pointer -> past char in c.  */
751 
752   if (is_end_of_line[(unsigned char) c])
753     goto eol;
754 
755   switch (c)
756     {
757     case '1':
758     case '2':
759     case '3':
760     case '4':
761     case '5':
762     case '6':
763     case '7':
764     case '8':
765     case '9':
766       input_line_pointer--;
767 
768       integer_constant ((NUMBERS_WITH_SUFFIX || flag_m68k_mri)
769 			? 0 : 10,
770 			expressionP);
771       break;
772 
773 #ifdef LITERAL_PREFIXDOLLAR_HEX
774     case '$':
775       /* $L is the start of a local label, not a hex constant.  */
776       if (* input_line_pointer == 'L')
777       goto isname;
778       integer_constant (16, expressionP);
779       break;
780 #endif
781 
782 #ifdef LITERAL_PREFIXPERCENT_BIN
783     case '%':
784       integer_constant (2, expressionP);
785       break;
786 #endif
787 
788     case '0':
789       /* Non-decimal radix.  */
790 
791       if (NUMBERS_WITH_SUFFIX || flag_m68k_mri)
792 	{
793 	  char *s;
794 
795 	  /* Check for a hex or float constant.  */
796 	  for (s = input_line_pointer; hex_p (*s); s++)
797 	    ;
798 	  if (*s == 'h' || *s == 'H' || *input_line_pointer == '.')
799 	    {
800 	      --input_line_pointer;
801 	      integer_constant (0, expressionP);
802 	      break;
803 	    }
804 	}
805       c = *input_line_pointer;
806       switch (c)
807 	{
808 	case 'o':
809 	case 'O':
810 	case 'q':
811 	case 'Q':
812 	case '8':
813 	case '9':
814 	  if (NUMBERS_WITH_SUFFIX || flag_m68k_mri)
815 	    {
816 	      integer_constant (0, expressionP);
817 	      break;
818 	    }
819 	  /* Fall through.  */
820 	default:
821 	default_case:
822 	  if (c && strchr (FLT_CHARS, c))
823 	    {
824 	      input_line_pointer++;
825 	      floating_constant (expressionP);
826 	      expressionP->X_add_number = - TOLOWER (c);
827 	    }
828 	  else
829 	    {
830 	      /* The string was only zero.  */
831 	      expressionP->X_op = O_constant;
832 	      expressionP->X_add_number = 0;
833 	    }
834 
835 	  break;
836 
837 	case 'x':
838 	case 'X':
839 	  if (flag_m68k_mri)
840 	    goto default_case;
841 	  input_line_pointer++;
842 	  integer_constant (16, expressionP);
843 	  break;
844 
845 	case 'b':
846 	  if (LOCAL_LABELS_FB && !flag_m68k_mri
847 	      && input_line_pointer[1] != '0'
848 	      && input_line_pointer[1] != '1')
849 	    {
850 	      /* Parse this as a back reference to label 0.  */
851 	      input_line_pointer--;
852 	      integer_constant (10, expressionP);
853 	      break;
854 	    }
855 	  /* Otherwise, parse this as a binary number.  */
856 	  /* Fall through.  */
857 	case 'B':
858 	  if (input_line_pointer[1] == '0'
859 	      || input_line_pointer[1] == '1')
860 	    {
861 	      input_line_pointer++;
862 	      integer_constant (2, expressionP);
863 	      break;
864 	    }
865 	  if (flag_m68k_mri || NUMBERS_WITH_SUFFIX)
866 	    input_line_pointer++;
867 	  goto default_case;
868 
869 	case '0':
870 	case '1':
871 	case '2':
872 	case '3':
873 	case '4':
874 	case '5':
875 	case '6':
876 	case '7':
877 	  integer_constant ((flag_m68k_mri || NUMBERS_WITH_SUFFIX)
878 			    ? 0 : 8,
879 			    expressionP);
880 	  break;
881 
882 	case 'f':
883 	  if (LOCAL_LABELS_FB)
884 	    {
885 	      int is_label = 1;
886 
887 	      /* If it says "0f" and it could possibly be a floating point
888 		 number, make it one.  Otherwise, make it a local label,
889 		 and try to deal with parsing the rest later.  */
890 	      if (!is_end_of_line[(unsigned char) input_line_pointer[1]]
891 		  && strchr (FLT_CHARS, 'f') != NULL)
892 		{
893 		  char *cp = input_line_pointer + 1;
894 
895 		  atof_generic (&cp, ".", EXP_CHARS,
896 				&generic_floating_point_number);
897 
898 		  /* Was nothing parsed, or does it look like an
899 		     expression?  */
900 		  is_label = (cp == input_line_pointer + 1
901 			      || (cp == input_line_pointer + 2
902 				  && (cp[-1] == '-' || cp[-1] == '+'))
903 			      || *cp == 'f'
904 			      || *cp == 'b');
905 		}
906 	      if (is_label)
907 		{
908 		  input_line_pointer--;
909 		  integer_constant (10, expressionP);
910 		  break;
911 		}
912 	    }
913 	  /* Fall through.  */
914 
915 	case 'd':
916 	case 'D':
917 	  if (flag_m68k_mri || NUMBERS_WITH_SUFFIX)
918 	    {
919 	      integer_constant (0, expressionP);
920 	      break;
921 	    }
922 	  /* Fall through.  */
923 	case 'F':
924 	case 'r':
925 	case 'e':
926 	case 'E':
927 	case 'g':
928 	case 'G':
929 	  input_line_pointer++;
930 	  floating_constant (expressionP);
931 	  expressionP->X_add_number = - TOLOWER (c);
932 	  break;
933 
934 	case '$':
935 	  if (LOCAL_LABELS_DOLLAR)
936 	    {
937 	      integer_constant (10, expressionP);
938 	      break;
939 	    }
940 	  else
941 	    goto default_case;
942 	}
943 
944       break;
945 
946 #ifndef NEED_INDEX_OPERATOR
947     case '[':
948 # ifdef md_need_index_operator
949       if (md_need_index_operator())
950 	goto de_fault;
951 # endif
952       /* FALLTHROUGH */
953 #endif
954     case '(':
955       /* Didn't begin with digit & not a name.  */
956       segment = expr (0, expressionP, mode);
957       /* expression () will pass trailing whitespace.  */
958       if ((c == '(' && *input_line_pointer != ')')
959 	  || (c == '[' && *input_line_pointer != ']'))
960 	{
961 	  if (* input_line_pointer)
962 	    as_bad (_("found '%c', expected: '%c'"),
963 		    * input_line_pointer, c == '(' ? ')' : ']');
964 	  else
965 	    as_bad (_("missing '%c'"), c == '(' ? ')' : ']');
966 	}
967       else
968 	input_line_pointer++;
969       SKIP_WHITESPACE ();
970       /* Here with input_line_pointer -> char after "(...)".  */
971       return segment;
972 
973 #ifdef TC_M68K
974     case 'E':
975       if (! flag_m68k_mri || *input_line_pointer != '\'')
976 	goto de_fault;
977       as_bad (_("EBCDIC constants are not supported"));
978       /* Fall through.  */
979     case 'A':
980       if (! flag_m68k_mri || *input_line_pointer != '\'')
981 	goto de_fault;
982       ++input_line_pointer;
983       /* Fall through.  */
984 #endif
985     case '\'':
986       if (! flag_m68k_mri)
987 	{
988 	  /* Warning: to conform to other people's assemblers NO
989 	     ESCAPEMENT is permitted for a single quote.  The next
990 	     character, parity errors and all, is taken as the value
991 	     of the operand.  VERY KINKY.  */
992 	  expressionP->X_op = O_constant;
993 	  expressionP->X_add_number = *input_line_pointer++;
994 	  break;
995 	}
996 
997       mri_char_constant (expressionP);
998       break;
999 
1000 #ifdef TC_M68K
1001     case '"':
1002       /* Double quote is the bitwise not operator in MRI mode.  */
1003       if (! flag_m68k_mri)
1004 	goto de_fault;
1005       /* Fall through.  */
1006 #endif
1007     case '~':
1008       /* '~' is permitted to start a label on the Delta.  */
1009       if (is_name_beginner (c))
1010 	goto isname;
1011     case '!':
1012     case '-':
1013     case '+':
1014       {
1015 #ifdef md_operator
1016       unary:
1017 #endif
1018 	operand (expressionP, mode);
1019 	if (expressionP->X_op == O_constant)
1020 	  {
1021 	    /* input_line_pointer -> char after operand.  */
1022 	    if (c == '-')
1023 	      {
1024 		expressionP->X_add_number
1025 		  = - (addressT) expressionP->X_add_number;
1026 		/* Notice: '-' may overflow: no warning is given.
1027 		   This is compatible with other people's
1028 		   assemblers.  Sigh.  */
1029 		expressionP->X_unsigned = 0;
1030 		if (expressionP->X_add_number)
1031 		  expressionP->X_extrabit ^= 1;
1032 	      }
1033 	    else if (c == '~' || c == '"')
1034 	      expressionP->X_add_number = ~ expressionP->X_add_number;
1035 	    else if (c == '!')
1036 	      expressionP->X_add_number = ! expressionP->X_add_number;
1037 	  }
1038 	else if (expressionP->X_op == O_big
1039 		 && expressionP->X_add_number <= 0
1040 		 && c == '-'
1041 		 && (generic_floating_point_number.sign == '+'
1042 		     || generic_floating_point_number.sign == 'P'))
1043 	  {
1044 	    /* Negative flonum (eg, -1.000e0).  */
1045 	    if (generic_floating_point_number.sign == '+')
1046 	      generic_floating_point_number.sign = '-';
1047 	    else
1048 	      generic_floating_point_number.sign = 'N';
1049 	  }
1050 	else if (expressionP->X_op == O_big
1051 		 && expressionP->X_add_number > 0)
1052 	  {
1053 	    int i;
1054 
1055 	    if (c == '~' || c == '-')
1056 	      {
1057 		for (i = 0; i < expressionP->X_add_number; ++i)
1058 		  generic_bignum[i] = ~generic_bignum[i];
1059 
1060 		/* Extend the bignum to at least the size of .octa.  */
1061 		if (expressionP->X_add_number < SIZE_OF_LARGE_NUMBER)
1062 		  {
1063 		    expressionP->X_add_number = SIZE_OF_LARGE_NUMBER;
1064 		    for (; i < expressionP->X_add_number; ++i)
1065 		      generic_bignum[i] = ~(LITTLENUM_TYPE) 0;
1066 		  }
1067 
1068 		if (c == '-')
1069 		  for (i = 0; i < expressionP->X_add_number; ++i)
1070 		    {
1071 		      generic_bignum[i] += 1;
1072 		      if (generic_bignum[i])
1073 			break;
1074 		    }
1075 	      }
1076 	    else if (c == '!')
1077 	      {
1078 		for (i = 0; i < expressionP->X_add_number; ++i)
1079 		  if (generic_bignum[i] != 0)
1080 		    break;
1081 		expressionP->X_add_number = i >= expressionP->X_add_number;
1082 		expressionP->X_op = O_constant;
1083 		expressionP->X_unsigned = 1;
1084 		expressionP->X_extrabit = 0;
1085 	      }
1086 	  }
1087 	else if (expressionP->X_op != O_illegal
1088 		 && expressionP->X_op != O_absent)
1089 	  {
1090 	    if (c != '+')
1091 	      {
1092 		expressionP->X_add_symbol = make_expr_symbol (expressionP);
1093 		if (c == '-')
1094 		  expressionP->X_op = O_uminus;
1095 		else if (c == '~' || c == '"')
1096 		  expressionP->X_op = O_bit_not;
1097 		else
1098 		  expressionP->X_op = O_logical_not;
1099 		expressionP->X_add_number = 0;
1100 	      }
1101 	  }
1102 	else
1103 	  as_warn (_("Unary operator %c ignored because bad operand follows"),
1104 		   c);
1105       }
1106       break;
1107 
1108 #if defined (DOLLAR_DOT) || defined (TC_M68K)
1109     case '$':
1110       /* '$' is the program counter when in MRI mode, or when
1111 	 DOLLAR_DOT is defined.  */
1112 #ifndef DOLLAR_DOT
1113       if (! flag_m68k_mri)
1114 	goto de_fault;
1115 #endif
1116       if (DOLLAR_AMBIGU && hex_p (*input_line_pointer))
1117 	{
1118 	  /* In MRI mode and on Z80, '$' is also used as the prefix
1119 	     for a hexadecimal constant.  */
1120 	  integer_constant (16, expressionP);
1121 	  break;
1122 	}
1123 
1124       if (is_part_of_name (*input_line_pointer))
1125 	goto isname;
1126 
1127       current_location (expressionP);
1128       break;
1129 #endif
1130 
1131     case '.':
1132       if (!is_part_of_name (*input_line_pointer))
1133 	{
1134 	  current_location (expressionP);
1135 	  break;
1136 	}
1137       else if ((strncasecmp (input_line_pointer, "startof.", 8) == 0
1138 		&& ! is_part_of_name (input_line_pointer[8]))
1139 	       || (strncasecmp (input_line_pointer, "sizeof.", 7) == 0
1140 		   && ! is_part_of_name (input_line_pointer[7])))
1141 	{
1142 	  int start;
1143 
1144 	  start = (input_line_pointer[1] == 't'
1145 		   || input_line_pointer[1] == 'T');
1146 	  input_line_pointer += start ? 8 : 7;
1147 	  SKIP_WHITESPACE ();
1148 	  if (*input_line_pointer != '(')
1149 	    as_bad (_("syntax error in .startof. or .sizeof."));
1150 	  else
1151 	    {
1152 	      char *buf;
1153 
1154 	      ++input_line_pointer;
1155 	      SKIP_WHITESPACE ();
1156 	      c = get_symbol_name (& name);
1157 
1158 	      buf = concat (start ? ".startof." : ".sizeof.", name,
1159 			    (char *) NULL);
1160 	      symbolP = symbol_make (buf);
1161 	      free (buf);
1162 
1163 	      expressionP->X_op = O_symbol;
1164 	      expressionP->X_add_symbol = symbolP;
1165 	      expressionP->X_add_number = 0;
1166 
1167 	      *input_line_pointer = c;
1168 	      SKIP_WHITESPACE_AFTER_NAME ();
1169 	      if (*input_line_pointer != ')')
1170 		as_bad (_("syntax error in .startof. or .sizeof."));
1171 	      else
1172 		++input_line_pointer;
1173 	    }
1174 	  break;
1175 	}
1176       else
1177 	{
1178 	  goto isname;
1179 	}
1180 
1181     case ',':
1182     eol:
1183       /* Can't imagine any other kind of operand.  */
1184       expressionP->X_op = O_absent;
1185       input_line_pointer--;
1186       break;
1187 
1188 #ifdef TC_M68K
1189     case '%':
1190       if (! flag_m68k_mri)
1191 	goto de_fault;
1192       integer_constant (2, expressionP);
1193       break;
1194 
1195     case '@':
1196       if (! flag_m68k_mri)
1197 	goto de_fault;
1198       integer_constant (8, expressionP);
1199       break;
1200 
1201     case ':':
1202       if (! flag_m68k_mri)
1203 	goto de_fault;
1204 
1205       /* In MRI mode, this is a floating point constant represented
1206 	 using hexadecimal digits.  */
1207 
1208       ++input_line_pointer;
1209       integer_constant (16, expressionP);
1210       break;
1211 
1212     case '*':
1213       if (! flag_m68k_mri || is_part_of_name (*input_line_pointer))
1214 	goto de_fault;
1215 
1216       current_location (expressionP);
1217       break;
1218 #endif
1219 
1220     default:
1221 #if defined(md_need_index_operator) || defined(TC_M68K)
1222     de_fault:
1223 #endif
1224       if (is_name_beginner (c) || c == '"')	/* Here if did not begin with a digit.  */
1225 	{
1226 	  /* Identifier begins here.
1227 	     This is kludged for speed, so code is repeated.  */
1228 	isname:
1229 	  -- input_line_pointer;
1230 	  c = get_symbol_name (&name);
1231 
1232 #ifdef md_operator
1233 	  {
1234 	    operatorT op = md_operator (name, 1, &c);
1235 
1236 	    switch (op)
1237 	      {
1238 	      case O_uminus:
1239 		restore_line_pointer (c);
1240 		c = '-';
1241 		goto unary;
1242 	      case O_bit_not:
1243 		restore_line_pointer (c);
1244 		c = '~';
1245 		goto unary;
1246 	      case O_logical_not:
1247 		restore_line_pointer (c);
1248 		c = '!';
1249 		goto unary;
1250 	      case O_illegal:
1251 		as_bad (_("invalid use of operator \"%s\""), name);
1252 		break;
1253 	      default:
1254 		break;
1255 	      }
1256 
1257 	    if (op != O_absent && op != O_illegal)
1258 	      {
1259 		restore_line_pointer (c);
1260 		expr (9, expressionP, mode);
1261 		expressionP->X_add_symbol = make_expr_symbol (expressionP);
1262 		expressionP->X_op_symbol = NULL;
1263 		expressionP->X_add_number = 0;
1264 		expressionP->X_op = op;
1265 		break;
1266 	      }
1267 	  }
1268 #endif
1269 
1270 #ifdef md_parse_name
1271 	  /* This is a hook for the backend to parse certain names
1272 	     specially in certain contexts.  If a name always has a
1273 	     specific value, it can often be handled by simply
1274 	     entering it in the symbol table.  */
1275 	  if (md_parse_name (name, expressionP, mode, &c))
1276 	    {
1277 	      restore_line_pointer (c);
1278 	      break;
1279 	    }
1280 #endif
1281 
1282 #ifdef TC_I960
1283 	  /* The MRI i960 assembler permits
1284 	         lda sizeof code,g13
1285 	     FIXME: This should use md_parse_name.  */
1286 	  if (flag_mri
1287 	      && (strcasecmp (name, "sizeof") == 0
1288 		  || strcasecmp (name, "startof") == 0))
1289 	    {
1290 	      int start;
1291 	      char *buf;
1292 
1293 	      start = (name[1] == 't'
1294 		       || name[1] == 'T');
1295 
1296 	      *input_line_pointer = c;
1297 	      SKIP_WHITESPACE_AFTER_NAME ();
1298 
1299 	      c = get_symbol_name (& name);
1300 
1301 	      buf = concat (start ? ".startof." : ".sizeof.", name,
1302 			    (char *) NULL);
1303 	      symbolP = symbol_make (buf);
1304 	      free (buf);
1305 
1306 	      expressionP->X_op = O_symbol;
1307 	      expressionP->X_add_symbol = symbolP;
1308 	      expressionP->X_add_number = 0;
1309 
1310 	      *input_line_pointer = c;
1311 	      SKIP_WHITESPACE_AFTER_NAME ();
1312 	      break;
1313 	    }
1314 #endif
1315 
1316 	  symbolP = symbol_find_or_make (name);
1317 
1318 	  /* If we have an absolute symbol or a reg, then we know its
1319 	     value now.  */
1320 	  segment = S_GET_SEGMENT (symbolP);
1321 	  if (mode != expr_defer
1322 	      && segment == absolute_section
1323 	      && !S_FORCE_RELOC (symbolP, 0))
1324 	    {
1325 	      expressionP->X_op = O_constant;
1326 	      expressionP->X_add_number = S_GET_VALUE (symbolP);
1327 	    }
1328 	  else if (mode != expr_defer && segment == reg_section)
1329 	    {
1330 	      expressionP->X_op = O_register;
1331 	      expressionP->X_add_number = S_GET_VALUE (symbolP);
1332 	    }
1333 	  else
1334 	    {
1335 	      expressionP->X_op = O_symbol;
1336 	      expressionP->X_add_symbol = symbolP;
1337 	      expressionP->X_add_number = 0;
1338 	    }
1339 
1340 	  restore_line_pointer (c);
1341 	}
1342       else
1343 	{
1344 	  /* Let the target try to parse it.  Success is indicated by changing
1345 	     the X_op field to something other than O_absent and pointing
1346 	     input_line_pointer past the expression.  If it can't parse the
1347 	     expression, X_op and input_line_pointer should be unchanged.  */
1348 	  expressionP->X_op = O_absent;
1349 	  --input_line_pointer;
1350 	  md_operand (expressionP);
1351 	  if (expressionP->X_op == O_absent)
1352 	    {
1353 	      ++input_line_pointer;
1354 	      as_bad (_("bad expression"));
1355 	      expressionP->X_op = O_constant;
1356 	      expressionP->X_add_number = 0;
1357 	    }
1358 	}
1359       break;
1360     }
1361 
1362   /* It is more 'efficient' to clean up the expressionS when they are
1363      created.  Doing it here saves lines of code.  */
1364   clean_up_expression (expressionP);
1365   SKIP_WHITESPACE ();		/* -> 1st char after operand.  */
1366   know (*input_line_pointer != ' ');
1367 
1368   /* The PA port needs this information.  */
1369   if (expressionP->X_add_symbol)
1370     symbol_mark_used (expressionP->X_add_symbol);
1371 
1372   if (mode != expr_defer)
1373     {
1374       expressionP->X_add_symbol
1375 	= symbol_clone_if_forward_ref (expressionP->X_add_symbol);
1376       expressionP->X_op_symbol
1377 	= symbol_clone_if_forward_ref (expressionP->X_op_symbol);
1378     }
1379 
1380   switch (expressionP->X_op)
1381     {
1382     default:
1383       return absolute_section;
1384     case O_symbol:
1385       return S_GET_SEGMENT (expressionP->X_add_symbol);
1386     case O_register:
1387       return reg_section;
1388     }
1389 }
1390 
1391 /* Internal.  Simplify a struct expression for use by expr ().  */
1392 
1393 /* In:	address of an expressionS.
1394 	The X_op field of the expressionS may only take certain values.
1395 	Elsewise we waste time special-case testing. Sigh. Ditto SEG_ABSENT.
1396 
1397    Out:	expressionS may have been modified:
1398 	Unused fields zeroed to help expr ().  */
1399 
1400 static void
1401 clean_up_expression (expressionS *expressionP)
1402 {
1403   switch (expressionP->X_op)
1404     {
1405     case O_illegal:
1406     case O_absent:
1407       expressionP->X_add_number = 0;
1408       /* Fall through.  */
1409     case O_big:
1410     case O_constant:
1411     case O_register:
1412       expressionP->X_add_symbol = NULL;
1413       /* Fall through.  */
1414     case O_symbol:
1415     case O_uminus:
1416     case O_bit_not:
1417       expressionP->X_op_symbol = NULL;
1418       break;
1419     default:
1420       break;
1421     }
1422 }
1423 
1424 /* Expression parser.  */
1425 
1426 /* We allow an empty expression, and just assume (absolute,0) silently.
1427    Unary operators and parenthetical expressions are treated as operands.
1428    As usual, Q==quantity==operand, O==operator, X==expression mnemonics.
1429 
1430    We used to do an aho/ullman shift-reduce parser, but the logic got so
1431    warped that I flushed it and wrote a recursive-descent parser instead.
1432    Now things are stable, would anybody like to write a fast parser?
1433    Most expressions are either register (which does not even reach here)
1434    or 1 symbol. Then "symbol+constant" and "symbol-symbol" are common.
1435    So I guess it doesn't really matter how inefficient more complex expressions
1436    are parsed.
1437 
1438    After expr(RANK,resultP) input_line_pointer->operator of rank <= RANK.
1439    Also, we have consumed any leading or trailing spaces (operand does that)
1440    and done all intervening operators.
1441 
1442    This returns the segment of the result, which will be
1443    absolute_section or the segment of a symbol.  */
1444 
1445 #undef __
1446 #define __ O_illegal
1447 #ifndef O_SINGLE_EQ
1448 #define O_SINGLE_EQ O_illegal
1449 #endif
1450 
1451 /* Maps ASCII -> operators.  */
1452 static const operatorT op_encoding[256] = {
1453   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1454   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1455 
1456   __, O_bit_or_not, __, __, __, O_modulus, O_bit_and, __,
1457   __, __, O_multiply, O_add, __, O_subtract, __, O_divide,
1458   __, __, __, __, __, __, __, __,
1459   __, __, __, __, O_lt, O_SINGLE_EQ, O_gt, __,
1460   __, __, __, __, __, __, __, __,
1461   __, __, __, __, __, __, __, __,
1462   __, __, __, __, __, __, __, __,
1463   __, __, __,
1464 #ifdef NEED_INDEX_OPERATOR
1465   O_index,
1466 #else
1467   __,
1468 #endif
1469   __, __, O_bit_exclusive_or, __,
1470   __, __, __, __, __, __, __, __,
1471   __, __, __, __, __, __, __, __,
1472   __, __, __, __, __, __, __, __,
1473   __, __, __, __, O_bit_inclusive_or, __, __, __,
1474 
1475   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1476   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1477   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1478   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1479   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1480   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1481   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1482   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __
1483 };
1484 
1485 /* Rank	Examples
1486    0	operand, (expression)
1487    1	||
1488    2	&&
1489    3	== <> < <= >= >
1490    4	+ -
1491    5	used for * / % in MRI mode
1492    6	& ^ ! |
1493    7	* / % << >>
1494    8	unary - unary ~
1495 */
1496 static operator_rankT op_rank[O_max] = {
1497   0,	/* O_illegal */
1498   0,	/* O_absent */
1499   0,	/* O_constant */
1500   0,	/* O_symbol */
1501   0,	/* O_symbol_rva */
1502   0,	/* O_register */
1503   0,	/* O_big */
1504   9,	/* O_uminus */
1505   9,	/* O_bit_not */
1506   9,	/* O_logical_not */
1507   8,	/* O_multiply */
1508   8,	/* O_divide */
1509   8,	/* O_modulus */
1510   8,	/* O_left_shift */
1511   8,	/* O_right_shift */
1512   7,	/* O_bit_inclusive_or */
1513   7,	/* O_bit_or_not */
1514   7,	/* O_bit_exclusive_or */
1515   7,	/* O_bit_and */
1516   5,	/* O_add */
1517   5,	/* O_subtract */
1518   4,	/* O_eq */
1519   4,	/* O_ne */
1520   4,	/* O_lt */
1521   4,	/* O_le */
1522   4,	/* O_ge */
1523   4,	/* O_gt */
1524   3,	/* O_logical_and */
1525   2,	/* O_logical_or */
1526   1,	/* O_index */
1527 };
1528 
1529 /* Unfortunately, in MRI mode for the m68k, multiplication and
1530    division have lower precedence than the bit wise operators.  This
1531    function sets the operator precedences correctly for the current
1532    mode.  Also, MRI uses a different bit_not operator, and this fixes
1533    that as well.  */
1534 
1535 #define STANDARD_MUL_PRECEDENCE 8
1536 #define MRI_MUL_PRECEDENCE 6
1537 
1538 void
1539 expr_set_precedence (void)
1540 {
1541   if (flag_m68k_mri)
1542     {
1543       op_rank[O_multiply] = MRI_MUL_PRECEDENCE;
1544       op_rank[O_divide] = MRI_MUL_PRECEDENCE;
1545       op_rank[O_modulus] = MRI_MUL_PRECEDENCE;
1546     }
1547   else
1548     {
1549       op_rank[O_multiply] = STANDARD_MUL_PRECEDENCE;
1550       op_rank[O_divide] = STANDARD_MUL_PRECEDENCE;
1551       op_rank[O_modulus] = STANDARD_MUL_PRECEDENCE;
1552     }
1553 }
1554 
1555 void
1556 expr_set_rank (operatorT op, operator_rankT rank)
1557 {
1558   gas_assert (op >= O_md1 && op < ARRAY_SIZE (op_rank));
1559   op_rank[op] = rank;
1560 }
1561 
1562 /* Initialize the expression parser.  */
1563 
1564 void
1565 expr_begin (void)
1566 {
1567   expr_set_precedence ();
1568 
1569   /* Verify that X_op field is wide enough.  */
1570   {
1571     expressionS e;
1572     e.X_op = O_max;
1573     gas_assert (e.X_op == O_max);
1574   }
1575 }
1576 
1577 /* Return the encoding for the operator at INPUT_LINE_POINTER, and
1578    sets NUM_CHARS to the number of characters in the operator.
1579    Does not advance INPUT_LINE_POINTER.  */
1580 
1581 static inline operatorT
1582 operatorf (int *num_chars)
1583 {
1584   int c;
1585   operatorT ret;
1586 
1587   c = *input_line_pointer & 0xff;
1588   *num_chars = 1;
1589 
1590   if (is_end_of_line[c])
1591     return O_illegal;
1592 
1593 #ifdef md_operator
1594   if (is_name_beginner (c))
1595     {
1596       char *name;
1597       char ec = get_symbol_name (& name);
1598 
1599       ret = md_operator (name, 2, &ec);
1600       switch (ret)
1601 	{
1602 	case O_absent:
1603 	  *input_line_pointer = ec;
1604 	  input_line_pointer = name;
1605 	  break;
1606 	case O_uminus:
1607 	case O_bit_not:
1608 	case O_logical_not:
1609 	  as_bad (_("invalid use of operator \"%s\""), name);
1610 	  ret = O_illegal;
1611 	  /* FALLTHROUGH */
1612 	default:
1613 	  *input_line_pointer = ec;
1614 	  *num_chars = input_line_pointer - name;
1615 	  input_line_pointer = name;
1616 	  return ret;
1617 	}
1618     }
1619 #endif
1620 
1621   switch (c)
1622     {
1623     default:
1624       ret = op_encoding[c];
1625 #ifdef md_operator
1626       if (ret == O_illegal)
1627 	{
1628 	  char *start = input_line_pointer;
1629 
1630 	  ret = md_operator (NULL, 2, NULL);
1631 	  if (ret != O_illegal)
1632 	    *num_chars = input_line_pointer - start;
1633 	  input_line_pointer = start;
1634 	}
1635 #endif
1636       return ret;
1637 
1638     case '+':
1639     case '-':
1640       return op_encoding[c];
1641 
1642     case '<':
1643       switch (input_line_pointer[1])
1644 	{
1645 	default:
1646 	  return op_encoding[c];
1647 	case '<':
1648 	  ret = O_left_shift;
1649 	  break;
1650 	case '>':
1651 	  ret = O_ne;
1652 	  break;
1653 	case '=':
1654 	  ret = O_le;
1655 	  break;
1656 	}
1657       *num_chars = 2;
1658       return ret;
1659 
1660     case '=':
1661       if (input_line_pointer[1] != '=')
1662 	return op_encoding[c];
1663 
1664       *num_chars = 2;
1665       return O_eq;
1666 
1667     case '>':
1668       switch (input_line_pointer[1])
1669 	{
1670 	default:
1671 	  return op_encoding[c];
1672 	case '>':
1673 	  ret = O_right_shift;
1674 	  break;
1675 	case '=':
1676 	  ret = O_ge;
1677 	  break;
1678 	}
1679       *num_chars = 2;
1680       return ret;
1681 
1682     case '!':
1683       switch (input_line_pointer[1])
1684 	{
1685 	case '!':
1686 	  /* We accept !! as equivalent to ^ for MRI compatibility. */
1687 	  *num_chars = 2;
1688 	  return O_bit_exclusive_or;
1689 	case '=':
1690 	  /* We accept != as equivalent to <>.  */
1691 	  *num_chars = 2;
1692 	  return O_ne;
1693 	default:
1694 	  if (flag_m68k_mri)
1695 	    return O_bit_inclusive_or;
1696 	  return op_encoding[c];
1697 	}
1698 
1699     case '|':
1700       if (input_line_pointer[1] != '|')
1701 	return op_encoding[c];
1702 
1703       *num_chars = 2;
1704       return O_logical_or;
1705 
1706     case '&':
1707       if (input_line_pointer[1] != '&')
1708 	return op_encoding[c];
1709 
1710       *num_chars = 2;
1711       return O_logical_and;
1712     }
1713 
1714   /* NOTREACHED  */
1715 }
1716 
1717 /* Implement "word-size + 1 bit" addition for
1718    {resultP->X_extrabit:resultP->X_add_number} + {rhs_highbit:amount}.  This
1719    is used so that the full range of unsigned word values and the full range of
1720    signed word values can be represented in an O_constant expression, which is
1721    useful e.g. for .sleb128 directives.  */
1722 
1723 void
1724 add_to_result (expressionS *resultP, offsetT amount, int rhs_highbit)
1725 {
1726   valueT ures = resultP->X_add_number;
1727   valueT uamount = amount;
1728 
1729   resultP->X_add_number += amount;
1730 
1731   resultP->X_extrabit ^= rhs_highbit;
1732 
1733   if (ures + uamount < ures)
1734     resultP->X_extrabit ^= 1;
1735 }
1736 
1737 /* Similarly, for subtraction.  */
1738 
1739 void
1740 subtract_from_result (expressionS *resultP, offsetT amount, int rhs_highbit)
1741 {
1742   valueT ures = resultP->X_add_number;
1743   valueT uamount = amount;
1744 
1745   resultP->X_add_number -= amount;
1746 
1747   resultP->X_extrabit ^= rhs_highbit;
1748 
1749   if (ures < uamount)
1750     resultP->X_extrabit ^= 1;
1751 }
1752 
1753 /* Parse an expression.  */
1754 
1755 segT
1756 expr (int rankarg,		/* Larger # is higher rank.  */
1757       expressionS *resultP,	/* Deliver result here.  */
1758       enum expr_mode mode	/* Controls behavior.  */)
1759 {
1760   operator_rankT rank = (operator_rankT) rankarg;
1761   segT retval;
1762   expressionS right;
1763   operatorT op_left;
1764   operatorT op_right;
1765   int op_chars;
1766 
1767   know (rankarg >= 0);
1768 
1769   /* Save the value of dot for the fixup code.  */
1770   if (rank == 0)
1771     {
1772       dot_value = frag_now_fix ();
1773       dot_frag = frag_now;
1774     }
1775 
1776   retval = operand (resultP, mode);
1777 
1778   /* operand () gobbles spaces.  */
1779   know (*input_line_pointer != ' ');
1780 
1781   op_left = operatorf (&op_chars);
1782   while (op_left != O_illegal && op_rank[(int) op_left] > rank)
1783     {
1784       segT rightseg;
1785       offsetT frag_off;
1786 
1787       input_line_pointer += op_chars;	/* -> after operator.  */
1788 
1789       right.X_md = 0;
1790       rightseg = expr (op_rank[(int) op_left], &right, mode);
1791       if (right.X_op == O_absent)
1792 	{
1793 	  as_warn (_("missing operand; zero assumed"));
1794 	  right.X_op = O_constant;
1795 	  right.X_add_number = 0;
1796 	  right.X_add_symbol = NULL;
1797 	  right.X_op_symbol = NULL;
1798 	}
1799 
1800       know (*input_line_pointer != ' ');
1801 
1802       if (op_left == O_index)
1803 	{
1804 	  if (*input_line_pointer != ']')
1805 	    as_bad ("missing right bracket");
1806 	  else
1807 	    {
1808 	      ++input_line_pointer;
1809 	      SKIP_WHITESPACE ();
1810 	    }
1811 	}
1812 
1813       op_right = operatorf (&op_chars);
1814 
1815       know (op_right == O_illegal || op_left == O_index
1816 	    || op_rank[(int) op_right] <= op_rank[(int) op_left]);
1817       know ((int) op_left >= (int) O_multiply);
1818 #ifndef md_operator
1819       know ((int) op_left <= (int) O_index);
1820 #else
1821       know ((int) op_left < (int) O_max);
1822 #endif
1823 
1824       /* input_line_pointer->after right-hand quantity.  */
1825       /* left-hand quantity in resultP.  */
1826       /* right-hand quantity in right.  */
1827       /* operator in op_left.  */
1828 
1829       if (resultP->X_op == O_big)
1830 	{
1831 	  if (resultP->X_add_number > 0)
1832 	    as_warn (_("left operand is a bignum; integer 0 assumed"));
1833 	  else
1834 	    as_warn (_("left operand is a float; integer 0 assumed"));
1835 	  resultP->X_op = O_constant;
1836 	  resultP->X_add_number = 0;
1837 	  resultP->X_add_symbol = NULL;
1838 	  resultP->X_op_symbol = NULL;
1839 	}
1840       if (right.X_op == O_big)
1841 	{
1842 	  if (right.X_add_number > 0)
1843 	    as_warn (_("right operand is a bignum; integer 0 assumed"));
1844 	  else
1845 	    as_warn (_("right operand is a float; integer 0 assumed"));
1846 	  right.X_op = O_constant;
1847 	  right.X_add_number = 0;
1848 	  right.X_add_symbol = NULL;
1849 	  right.X_op_symbol = NULL;
1850 	}
1851 
1852       /* Optimize common cases.  */
1853 #ifdef md_optimize_expr
1854       if (md_optimize_expr (resultP, op_left, &right))
1855 	{
1856 	  /* Skip.  */
1857 	  ;
1858 	}
1859       else
1860 #endif
1861 #ifndef md_register_arithmetic
1862 # define md_register_arithmetic 1
1863 #endif
1864       if (op_left == O_add && right.X_op == O_constant
1865 	  && (md_register_arithmetic || resultP->X_op != O_register))
1866 	{
1867 	  /* X + constant.  */
1868 	  add_to_result (resultP, right.X_add_number, right.X_extrabit);
1869 	}
1870       /* This case comes up in PIC code.  */
1871       else if (op_left == O_subtract
1872 	       && right.X_op == O_symbol
1873 	       && resultP->X_op == O_symbol
1874 	       && retval == rightseg
1875 #ifdef md_allow_local_subtract
1876 	       && md_allow_local_subtract (resultP, & right, rightseg)
1877 #endif
1878 	       && ((SEG_NORMAL (rightseg)
1879 		    && !S_FORCE_RELOC (resultP->X_add_symbol, 0)
1880 		    && !S_FORCE_RELOC (right.X_add_symbol, 0))
1881 		   || right.X_add_symbol == resultP->X_add_symbol)
1882 	       && frag_offset_fixed_p (symbol_get_frag (resultP->X_add_symbol),
1883 				       symbol_get_frag (right.X_add_symbol),
1884 				       &frag_off))
1885 	{
1886 	  offsetT symval_diff = S_GET_VALUE (resultP->X_add_symbol)
1887 				- S_GET_VALUE (right.X_add_symbol);
1888 	  subtract_from_result (resultP, right.X_add_number, right.X_extrabit);
1889 	  subtract_from_result (resultP, frag_off / OCTETS_PER_BYTE, 0);
1890 	  add_to_result (resultP, symval_diff, symval_diff < 0);
1891 	  resultP->X_op = O_constant;
1892 	  resultP->X_add_symbol = 0;
1893 	}
1894       else if (op_left == O_subtract && right.X_op == O_constant
1895 	       && (md_register_arithmetic || resultP->X_op != O_register))
1896 	{
1897 	  /* X - constant.  */
1898 	  subtract_from_result (resultP, right.X_add_number, right.X_extrabit);
1899 	}
1900       else if (op_left == O_add && resultP->X_op == O_constant
1901 	       && (md_register_arithmetic || right.X_op != O_register))
1902 	{
1903 	  /* Constant + X.  */
1904 	  resultP->X_op = right.X_op;
1905 	  resultP->X_add_symbol = right.X_add_symbol;
1906 	  resultP->X_op_symbol = right.X_op_symbol;
1907 	  add_to_result (resultP, right.X_add_number, right.X_extrabit);
1908 	  retval = rightseg;
1909 	}
1910       else if (resultP->X_op == O_constant && right.X_op == O_constant)
1911 	{
1912 	  /* Constant OP constant.  */
1913 	  offsetT v = right.X_add_number;
1914 	  if (v == 0 && (op_left == O_divide || op_left == O_modulus))
1915 	    {
1916 	      as_warn (_("division by zero"));
1917 	      v = 1;
1918 	    }
1919 	  if ((valueT) v >= sizeof(valueT) * CHAR_BIT
1920 	      && (op_left == O_left_shift || op_left == O_right_shift))
1921 	    {
1922 	      as_warn_value_out_of_range (_("shift count"), v, 0,
1923 					  sizeof(valueT) * CHAR_BIT - 1,
1924 					  NULL, 0);
1925 	      resultP->X_add_number = v = 0;
1926 	    }
1927 	  switch (op_left)
1928 	    {
1929 	    default:			goto general;
1930 	    case O_multiply:		resultP->X_add_number *= v; break;
1931 	    case O_divide:		resultP->X_add_number /= v; break;
1932 	    case O_modulus:		resultP->X_add_number %= v; break;
1933 	    case O_left_shift:		resultP->X_add_number <<= v; break;
1934 	    case O_right_shift:
1935 	      /* We always use unsigned shifts, to avoid relying on
1936 		 characteristics of the compiler used to compile gas.  */
1937 	      resultP->X_add_number =
1938 		(offsetT) ((valueT) resultP->X_add_number >> (valueT) v);
1939 	      break;
1940 	    case O_bit_inclusive_or:	resultP->X_add_number |= v; break;
1941 	    case O_bit_or_not:		resultP->X_add_number |= ~v; break;
1942 	    case O_bit_exclusive_or:	resultP->X_add_number ^= v; break;
1943 	    case O_bit_and:		resultP->X_add_number &= v; break;
1944 	      /* Constant + constant (O_add) is handled by the
1945 		 previous if statement for constant + X, so is omitted
1946 		 here.  */
1947 	    case O_subtract:
1948 	      subtract_from_result (resultP, v, 0);
1949 	      break;
1950 	    case O_eq:
1951 	      resultP->X_add_number =
1952 		resultP->X_add_number == v ? ~ (offsetT) 0 : 0;
1953 	      break;
1954 	    case O_ne:
1955 	      resultP->X_add_number =
1956 		resultP->X_add_number != v ? ~ (offsetT) 0 : 0;
1957 	      break;
1958 	    case O_lt:
1959 	      resultP->X_add_number =
1960 		resultP->X_add_number <  v ? ~ (offsetT) 0 : 0;
1961 	      break;
1962 	    case O_le:
1963 	      resultP->X_add_number =
1964 		resultP->X_add_number <= v ? ~ (offsetT) 0 : 0;
1965 	      break;
1966 	    case O_ge:
1967 	      resultP->X_add_number =
1968 		resultP->X_add_number >= v ? ~ (offsetT) 0 : 0;
1969 	      break;
1970 	    case O_gt:
1971 	      resultP->X_add_number =
1972 		resultP->X_add_number >  v ? ~ (offsetT) 0 : 0;
1973 	      break;
1974 	    case O_logical_and:
1975 	      resultP->X_add_number = resultP->X_add_number && v;
1976 	      break;
1977 	    case O_logical_or:
1978 	      resultP->X_add_number = resultP->X_add_number || v;
1979 	      break;
1980 	    }
1981 	}
1982       else if (resultP->X_op == O_symbol
1983 	       && right.X_op == O_symbol
1984 	       && (op_left == O_add
1985 		   || op_left == O_subtract
1986 		   || (resultP->X_add_number == 0
1987 		       && right.X_add_number == 0)))
1988 	{
1989 	  /* Symbol OP symbol.  */
1990 	  resultP->X_op = op_left;
1991 	  resultP->X_op_symbol = right.X_add_symbol;
1992 	  if (op_left == O_add)
1993 	    add_to_result (resultP, right.X_add_number, right.X_extrabit);
1994 	  else if (op_left == O_subtract)
1995 	    {
1996 	      subtract_from_result (resultP, right.X_add_number,
1997 				    right.X_extrabit);
1998 	      if (retval == rightseg
1999 		  && SEG_NORMAL (retval)
2000 		  && !S_FORCE_RELOC (resultP->X_add_symbol, 0)
2001 		  && !S_FORCE_RELOC (right.X_add_symbol, 0))
2002 		{
2003 		  retval = absolute_section;
2004 		  rightseg = absolute_section;
2005 		}
2006 	    }
2007 	}
2008       else
2009 	{
2010         general:
2011 	  /* The general case.  */
2012 	  resultP->X_add_symbol = make_expr_symbol (resultP);
2013 	  resultP->X_op_symbol = make_expr_symbol (&right);
2014 	  resultP->X_op = op_left;
2015 	  resultP->X_add_number = 0;
2016 	  resultP->X_unsigned = 1;
2017 	  resultP->X_extrabit = 0;
2018 	}
2019 
2020       if (retval != rightseg)
2021 	{
2022 	  if (retval == undefined_section)
2023 	    ;
2024 	  else if (rightseg == undefined_section)
2025 	    retval = rightseg;
2026 	  else if (retval == expr_section)
2027 	    ;
2028 	  else if (rightseg == expr_section)
2029 	    retval = rightseg;
2030 	  else if (retval == reg_section)
2031 	    ;
2032 	  else if (rightseg == reg_section)
2033 	    retval = rightseg;
2034 	  else if (rightseg == absolute_section)
2035 	    ;
2036 	  else if (retval == absolute_section)
2037 	    retval = rightseg;
2038 #ifdef DIFF_EXPR_OK
2039 	  else if (op_left == O_subtract)
2040 	    ;
2041 #endif
2042 	  else
2043 	    as_bad (_("operation combines symbols in different segments"));
2044 	}
2045 
2046       op_left = op_right;
2047     }				/* While next operator is >= this rank.  */
2048 
2049   /* The PA port needs this information.  */
2050   if (resultP->X_add_symbol)
2051     symbol_mark_used (resultP->X_add_symbol);
2052 
2053   if (rank == 0 && mode == expr_evaluate)
2054     resolve_expression (resultP);
2055 
2056   return resultP->X_op == O_constant ? absolute_section : retval;
2057 }
2058 
2059 /* Resolve an expression without changing any symbols/sub-expressions
2060    used.  */
2061 
2062 int
2063 resolve_expression (expressionS *expressionP)
2064 {
2065   /* Help out with CSE.  */
2066   valueT final_val = expressionP->X_add_number;
2067   symbolS *add_symbol = expressionP->X_add_symbol;
2068   symbolS *orig_add_symbol = add_symbol;
2069   symbolS *op_symbol = expressionP->X_op_symbol;
2070   operatorT op = expressionP->X_op;
2071   valueT left, right;
2072   segT seg_left, seg_right;
2073   fragS *frag_left, *frag_right;
2074   offsetT frag_off;
2075 
2076   switch (op)
2077     {
2078     default:
2079       return 0;
2080 
2081     case O_constant:
2082     case O_register:
2083       left = 0;
2084       break;
2085 
2086     case O_symbol:
2087     case O_symbol_rva:
2088       if (!snapshot_symbol (&add_symbol, &left, &seg_left, &frag_left))
2089 	return 0;
2090 
2091       break;
2092 
2093     case O_uminus:
2094     case O_bit_not:
2095     case O_logical_not:
2096       if (!snapshot_symbol (&add_symbol, &left, &seg_left, &frag_left))
2097 	return 0;
2098 
2099       if (seg_left != absolute_section)
2100 	return 0;
2101 
2102       if (op == O_logical_not)
2103 	left = !left;
2104       else if (op == O_uminus)
2105 	left = -left;
2106       else
2107 	left = ~left;
2108       op = O_constant;
2109       break;
2110 
2111     case O_multiply:
2112     case O_divide:
2113     case O_modulus:
2114     case O_left_shift:
2115     case O_right_shift:
2116     case O_bit_inclusive_or:
2117     case O_bit_or_not:
2118     case O_bit_exclusive_or:
2119     case O_bit_and:
2120     case O_add:
2121     case O_subtract:
2122     case O_eq:
2123     case O_ne:
2124     case O_lt:
2125     case O_le:
2126     case O_ge:
2127     case O_gt:
2128     case O_logical_and:
2129     case O_logical_or:
2130       if (!snapshot_symbol (&add_symbol, &left, &seg_left, &frag_left)
2131 	  || !snapshot_symbol (&op_symbol, &right, &seg_right, &frag_right))
2132 	return 0;
2133 
2134       /* Simplify addition or subtraction of a constant by folding the
2135 	 constant into X_add_number.  */
2136       if (op == O_add)
2137 	{
2138 	  if (seg_right == absolute_section)
2139 	    {
2140 	      final_val += right;
2141 	      op = O_symbol;
2142 	      break;
2143 	    }
2144 	  else if (seg_left == absolute_section)
2145 	    {
2146 	      final_val += left;
2147 	      left = right;
2148 	      seg_left = seg_right;
2149 	      add_symbol = op_symbol;
2150 	      orig_add_symbol = expressionP->X_op_symbol;
2151 	      op = O_symbol;
2152 	      break;
2153 	    }
2154 	}
2155       else if (op == O_subtract)
2156 	{
2157 	  if (seg_right == absolute_section)
2158 	    {
2159 	      final_val -= right;
2160 	      op = O_symbol;
2161 	      break;
2162 	    }
2163 	}
2164 
2165       /* Equality and non-equality tests are permitted on anything.
2166 	 Subtraction, and other comparison operators are permitted if
2167 	 both operands are in the same section.
2168 	 Shifts by constant zero are permitted on anything.
2169 	 Multiplies, bit-ors, and bit-ands with constant zero are
2170 	 permitted on anything.
2171 	 Multiplies and divides by constant one are permitted on
2172 	 anything.
2173 	 Binary operations with both operands being the same register
2174 	 or undefined symbol are permitted if the result doesn't depend
2175 	 on the input value.
2176 	 Otherwise, both operands must be absolute.  We already handled
2177 	 the case of addition or subtraction of a constant above.  */
2178       frag_off = 0;
2179       if (!(seg_left == absolute_section
2180 	       && seg_right == absolute_section)
2181 	  && !(op == O_eq || op == O_ne)
2182 	  && !((op == O_subtract
2183 		|| op == O_lt || op == O_le || op == O_ge || op == O_gt)
2184 	       && seg_left == seg_right
2185 	       && (finalize_syms
2186 		   || frag_offset_fixed_p (frag_left, frag_right, &frag_off))
2187 	       && (seg_left != reg_section || left == right)
2188 	       && (seg_left != undefined_section || add_symbol == op_symbol)))
2189 	{
2190 	  if ((seg_left == absolute_section && left == 0)
2191 	      || (seg_right == absolute_section && right == 0))
2192 	    {
2193 	      if (op == O_bit_exclusive_or || op == O_bit_inclusive_or)
2194 		{
2195 		  if (!(seg_right == absolute_section && right == 0))
2196 		    {
2197 		      seg_left = seg_right;
2198 		      left = right;
2199 		      add_symbol = op_symbol;
2200 		      orig_add_symbol = expressionP->X_op_symbol;
2201 		    }
2202 		  op = O_symbol;
2203 		  break;
2204 		}
2205 	      else if (op == O_left_shift || op == O_right_shift)
2206 		{
2207 		  if (!(seg_left == absolute_section && left == 0))
2208 		    {
2209 		      op = O_symbol;
2210 		      break;
2211 		    }
2212 		}
2213 	      else if (op != O_multiply
2214 		       && op != O_bit_or_not && op != O_bit_and)
2215 	        return 0;
2216 	    }
2217 	  else if (op == O_multiply
2218 		   && seg_left == absolute_section && left == 1)
2219 	    {
2220 	      seg_left = seg_right;
2221 	      left = right;
2222 	      add_symbol = op_symbol;
2223 	      orig_add_symbol = expressionP->X_op_symbol;
2224 	      op = O_symbol;
2225 	      break;
2226 	    }
2227 	  else if ((op == O_multiply || op == O_divide)
2228 		   && seg_right == absolute_section && right == 1)
2229 	    {
2230 	      op = O_symbol;
2231 	      break;
2232 	    }
2233 	  else if (!(left == right
2234 		     && ((seg_left == reg_section && seg_right == reg_section)
2235 			 || (seg_left == undefined_section
2236 			     && seg_right == undefined_section
2237 			     && add_symbol == op_symbol))))
2238 	    return 0;
2239 	  else if (op == O_bit_and || op == O_bit_inclusive_or)
2240 	    {
2241 	      op = O_symbol;
2242 	      break;
2243 	    }
2244 	  else if (op != O_bit_exclusive_or && op != O_bit_or_not)
2245 	    return 0;
2246 	}
2247 
2248       right += frag_off / OCTETS_PER_BYTE;
2249       switch (op)
2250 	{
2251 	case O_add:			left += right; break;
2252 	case O_subtract:		left -= right; break;
2253 	case O_multiply:		left *= right; break;
2254 	case O_divide:
2255 	  if (right == 0)
2256 	    return 0;
2257 	  left = (offsetT) left / (offsetT) right;
2258 	  break;
2259 	case O_modulus:
2260 	  if (right == 0)
2261 	    return 0;
2262 	  left = (offsetT) left % (offsetT) right;
2263 	  break;
2264 	case O_left_shift:		left <<= right; break;
2265 	case O_right_shift:		left >>= right; break;
2266 	case O_bit_inclusive_or:	left |= right; break;
2267 	case O_bit_or_not:		left |= ~right; break;
2268 	case O_bit_exclusive_or:	left ^= right; break;
2269 	case O_bit_and:			left &= right; break;
2270 	case O_eq:
2271 	case O_ne:
2272 	  left = (left == right
2273 		  && seg_left == seg_right
2274 		  && (finalize_syms || frag_left == frag_right)
2275 		  && (seg_left != undefined_section
2276 		      || add_symbol == op_symbol)
2277 		  ? ~ (valueT) 0 : 0);
2278 	  if (op == O_ne)
2279 	    left = ~left;
2280 	  break;
2281 	case O_lt:
2282 	  left = (offsetT) left <  (offsetT) right ? ~ (valueT) 0 : 0;
2283 	  break;
2284 	case O_le:
2285 	  left = (offsetT) left <= (offsetT) right ? ~ (valueT) 0 : 0;
2286 	  break;
2287 	case O_ge:
2288 	  left = (offsetT) left >= (offsetT) right ? ~ (valueT) 0 : 0;
2289 	  break;
2290 	case O_gt:
2291 	  left = (offsetT) left >  (offsetT) right ? ~ (valueT) 0 : 0;
2292 	  break;
2293 	case O_logical_and:	left = left && right; break;
2294 	case O_logical_or:	left = left || right; break;
2295 	default:		abort ();
2296 	}
2297 
2298       op = O_constant;
2299       break;
2300     }
2301 
2302   if (op == O_symbol)
2303     {
2304       if (seg_left == absolute_section)
2305 	op = O_constant;
2306       else if (seg_left == reg_section && final_val == 0)
2307 	op = O_register;
2308       else if (!symbol_same_p (add_symbol, orig_add_symbol))
2309 	final_val += left;
2310       expressionP->X_add_symbol = add_symbol;
2311     }
2312   expressionP->X_op = op;
2313 
2314   if (op == O_constant || op == O_register)
2315     final_val += left;
2316   expressionP->X_add_number = final_val;
2317 
2318   return 1;
2319 }
2320 
2321 /* This lives here because it belongs equally in expr.c & read.c.
2322    expr.c is just a branch office read.c anyway, and putting it
2323    here lessens the crowd at read.c.
2324 
2325    Assume input_line_pointer is at start of symbol name, or the
2326     start of a double quote enclosed symbol name.
2327    Advance input_line_pointer past symbol name.
2328    Turn that character into a '\0', returning its former value,
2329     which may be the closing double quote.
2330    This allows a string compare (RMS wants symbol names to be strings)
2331     of the symbol name.
2332    There will always be a char following symbol name, because all good
2333    lines end in end-of-line.  */
2334 
2335 char
2336 get_symbol_name (char ** ilp_return)
2337 {
2338   char c;
2339 
2340   * ilp_return = input_line_pointer;
2341   /* We accept \001 in a name in case this is being called with a
2342      constructed string.  */
2343   if (is_name_beginner (c = *input_line_pointer++) || c == '\001')
2344     {
2345       while (is_part_of_name (c = *input_line_pointer++)
2346 	     || c == '\001')
2347 	;
2348       if (is_name_ender (c))
2349 	c = *input_line_pointer++;
2350     }
2351   else if (c == '"')
2352     {
2353       bfd_boolean backslash_seen;
2354 
2355       * ilp_return = input_line_pointer;
2356       do
2357 	{
2358 	  backslash_seen = c == '\\';
2359 	  c = * input_line_pointer ++;
2360 	}
2361       while (c != 0 && (c != '"' || backslash_seen));
2362 
2363       if (c == 0)
2364 	as_warn (_("missing closing '\"'"));
2365     }
2366   *--input_line_pointer = 0;
2367   return c;
2368 }
2369 
2370 /* Replace the NUL character pointed to by input_line_pointer
2371    with C.  If C is \" then advance past it.  Return the character
2372    now pointed to by input_line_pointer.  */
2373 
2374 char
2375 restore_line_pointer (char c)
2376 {
2377   * input_line_pointer = c;
2378   if (c == '"')
2379     c = * ++ input_line_pointer;
2380   return c;
2381 }
2382 
2383 unsigned int
2384 get_single_number (void)
2385 {
2386   expressionS exp;
2387   operand (&exp, expr_normal);
2388   return exp.X_add_number;
2389 }
2390