Coverage Report

Created: 2024-05-21 06:29

/src/binutils-gdb/gas/frags.c
Line
Count
Source (jump to first uncovered line)
1
/* frags.c - manage frags -
2
   Copyright (C) 1987-2024 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
#include "as.h"
22
#include "subsegs.h"
23
#include "obstack.h"
24
25
extern fragS zero_address_frag;
26
extern fragS predefined_address_frag;
27
28
static int totalfrags;
29
30
int
31
get_frag_count (void)
32
0
{
33
0
  return totalfrags;
34
0
}
35
36
void
37
clear_frag_count (void)
38
0
{
39
0
  totalfrags = 0;
40
0
}
41

42
/* Initialization for frag routines.  */
43
44
void
45
frag_init (void)
46
736
{
47
736
  zero_address_frag.fr_type = rs_fill;
48
736
  predefined_address_frag.fr_type = rs_fill;
49
736
}
50

51
/* Check that we're not trying to assemble into a section that can't
52
   allocate frags (currently, this is only possible in the absolute
53
   section), or into an mri common.  */
54
55
static void
56
frag_alloc_check (const struct obstack *ob)
57
2.54M
{
58
2.54M
  if (ob->chunk_size == 0)
59
0
    {
60
0
      as_bad (_("attempt to allocate data in absolute section"));
61
0
      subseg_set (text_section, 0);
62
0
    }
63
64
2.54M
  if (mri_common_symbol != NULL)
65
0
    {
66
0
      as_bad (_("attempt to allocate data in common section"));
67
0
      mri_common_symbol = NULL;
68
0
    }
69
2.54M
}
70
71
/* Allocate a frag on the specified obstack.
72
   Call this routine from everywhere else, so that all the weird alignment
73
   hackery can be done in just one place.  */
74
75
fragS *
76
frag_alloc (struct obstack *ob)
77
225k
{
78
225k
  fragS *ptr;
79
225k
  int oalign;
80
81
225k
  (void) obstack_alloc (ob, 0);
82
225k
  oalign = obstack_alignment_mask (ob);
83
225k
  obstack_alignment_mask (ob) = 0;
84
225k
  ptr = (fragS *) obstack_alloc (ob, SIZEOF_STRUCT_FRAG);
85
225k
  obstack_alignment_mask (ob) = oalign;
86
225k
  memset (ptr, 0, SIZEOF_STRUCT_FRAG);
87
225k
  totalfrags++;
88
225k
  return ptr;
89
225k
}
90

91
/* Try to augment current frag by nchars chars.
92
   If there is no room, close off the current frag with a ".fill 0"
93
   and begin a new frag.  Then loop until the new frag has at least
94
   nchars chars available.  Does not set up any fields in frag_now.  */
95
96
void
97
frag_grow (size_t nchars)
98
1.13M
{
99
1.13M
  if (obstack_room (&frchain_now->frch_obstack) < nchars)
100
322
    {
101
322
      size_t oldc;
102
322
      size_t newc;
103
104
      /* Try to allocate a bit more than needed right now.  But don't do
105
         this if we would waste too much memory.  Especially necessary
106
         for extremely big (like 2GB initialized) frags.  */
107
322
      if (nchars < 0x10000)
108
322
        newc = 2 * nchars;
109
0
      else
110
0
        newc = nchars + 0x10000;
111
322
      newc += SIZEOF_STRUCT_FRAG;
112
113
      /* Check for possible overflow.  */
114
322
      if (newc < nchars)
115
0
  as_fatal (ngettext ("can't extend frag %lu char",
116
0
          "can't extend frag %lu chars",
117
0
          (unsigned long) nchars),
118
0
      (unsigned long) nchars);
119
120
      /* Force to allocate at least NEWC bytes, but not less than the
121
         default.  */
122
322
      oldc = obstack_chunk_size (&frchain_now->frch_obstack);
123
322
      if (newc > oldc)
124
275
  obstack_chunk_size (&frchain_now->frch_obstack) = newc;
125
126
113k
      while (obstack_room (&frchain_now->frch_obstack) < nchars)
127
112k
        {
128
          /* Not enough room in this frag.  Close it and start a new one.
129
             This must be done in a loop because the created frag may not
130
             be big enough if the current obstack chunk is used.  */
131
112k
          frag_wane (frag_now);
132
112k
          frag_new (0);
133
112k
        }
134
135
      /* Restore the old chunk size.  */
136
322
      obstack_chunk_size (&frchain_now->frch_obstack) = oldc;
137
322
    }
138
1.13M
}
139

140
/* Call this to close off a completed frag, and start up a new (empty)
141
   frag, in the same subsegment as the old frag.
142
   [frchain_now remains the same but frag_now is updated.]
143
   Because this calculates the correct value of fr_fix by
144
   looking at the obstack 'frags', it needs to know how many
145
   characters at the end of the old frag belong to the maximal
146
   variable part;  The rest must belong to fr_fix.
147
   It doesn't actually set up the old frag's fr_var.  You may have
148
   set fr_var == 1, but allocated 10 chars to the end of the frag;
149
   In this case you pass old_frags_var_max_size == 10.
150
   In fact, you may use fr_var for something totally unrelated to the
151
   size of the variable part of the frag;  None of the generic frag
152
   handling code makes use of fr_var.
153
154
   Make a new frag, initialising some components. Link new frag at end
155
   of frchain_now.  */
156
157
void
158
frag_new (size_t old_frags_var_max_size
159
    /* Number of chars (already allocated on obstack frags) in
160
       variable_length part of frag.  */)
161
217k
{
162
217k
  fragS *former_last_fragP;
163
217k
  frchainS *frchP;
164
165
217k
  gas_assert (frchain_now->frch_last == frag_now);
166
167
  /* Fix up old frag's fr_fix.  */
168
217k
  frag_now->fr_fix = frag_now_fix_octets ();
169
217k
  gas_assert (frag_now->fr_fix >= old_frags_var_max_size
170
217k
        || now_seg == absolute_section);
171
217k
  frag_now->fr_fix -= old_frags_var_max_size;
172
  /* Make sure its type is valid.  */
173
217k
  gas_assert (frag_now->fr_type != 0);
174
175
  /* This will align the obstack so the next struct we allocate on it
176
     will begin at a correct boundary.  */
177
217k
  obstack_finish (&frchain_now->frch_obstack);
178
217k
  frchP = frchain_now;
179
217k
  know (frchP);
180
217k
  former_last_fragP = frchP->frch_last;
181
217k
  gas_assert (former_last_fragP != 0);
182
217k
  gas_assert (former_last_fragP == frag_now);
183
217k
  frag_now = frag_alloc (&frchP->frch_obstack);
184
185
217k
  frag_now->fr_file = as_where (&frag_now->fr_line);
186
187
  /* Generally, frag_now->points to an address rounded up to next
188
     alignment.  However, characters will add to obstack frags
189
     IMMEDIATELY after the struct frag, even if they are not starting
190
     at an alignment address.  */
191
217k
  former_last_fragP->fr_next = frag_now;
192
217k
  frchP->frch_last = frag_now;
193
194
217k
#ifndef NO_LISTING
195
217k
  {
196
217k
    extern struct list_info_struct *listing_tail;
197
217k
    frag_now->line = listing_tail;
198
217k
  }
199
217k
#endif
200
201
217k
  gas_assert (frchain_now->frch_last == frag_now);
202
203
217k
  frag_now->fr_next = NULL;
204
217k
}
205

206
/* Start a new frag unless we have n more chars of room in the current frag.
207
   Close off the old frag with a .fill 0.
208
209
   Return the address of the 1st char to write into. Advance
210
   frag_now_growth past the new chars.  */
211
212
char *
213
frag_more (size_t nchars)
214
852k
{
215
852k
  char *retval;
216
217
852k
  frag_alloc_check (&frchain_now->frch_obstack);
218
852k
  frag_grow (nchars);
219
852k
  retval = obstack_next_free (&frchain_now->frch_obstack);
220
852k
  obstack_blank_fast (&frchain_now->frch_obstack, nchars);
221
852k
  return retval;
222
852k
}
223

224
/* Close the current frag, setting its fields for a relaxable frag.  Start a
225
   new frag.  */
226
227
static void
228
frag_var_init (relax_stateT type, size_t max_chars, size_t var,
229
         relax_substateT subtype, symbolS *symbol, offsetT offset,
230
               char *opcode)
231
104k
{
232
104k
  frag_now->fr_var = var;
233
104k
  frag_now->fr_type = type;
234
104k
  frag_now->fr_subtype = subtype;
235
104k
  frag_now->fr_symbol = symbol;
236
104k
  frag_now->fr_offset = offset;
237
104k
  frag_now->fr_opcode = opcode;
238
#ifdef USING_CGEN
239
  frag_now->fr_cgen.insn = 0;
240
  frag_now->fr_cgen.opindex = 0;
241
  frag_now->fr_cgen.opinfo = 0;
242
#endif
243
104k
#ifdef TC_FRAG_INIT
244
104k
  TC_FRAG_INIT (frag_now, max_chars);
245
104k
#endif
246
104k
  frag_now->fr_file = as_where (&frag_now->fr_line);
247
248
104k
  frag_new (max_chars);
249
104k
}
250
251
/* Start a new frag unless we have max_chars more chars of room in the
252
   current frag.  Close off the old frag with a .fill 0.
253
254
   Set up a machine_dependent relaxable frag, then start a new frag.
255
   Return the address of the 1st char of the var part of the old frag
256
   to write into.  */
257
258
char *
259
frag_var (relax_stateT type, size_t max_chars, size_t var,
260
    relax_substateT subtype, symbolS *symbol, offsetT offset,
261
    char *opcode)
262
104k
{
263
104k
  char *retval;
264
265
104k
  frag_grow (max_chars);
266
104k
  retval = obstack_next_free (&frchain_now->frch_obstack);
267
104k
  obstack_blank_fast (&frchain_now->frch_obstack, max_chars);
268
104k
  frag_var_init (type, max_chars, var, subtype, symbol, offset, opcode);
269
104k
  return retval;
270
104k
}
271

272
/* OVE: This variant of frag_var assumes that space for the tail has been
273
  allocated by caller.
274
  No call to frag_grow is done.  */
275
276
char *
277
frag_variant (relax_stateT type, size_t max_chars, size_t var,
278
        relax_substateT subtype, symbolS *symbol, offsetT offset,
279
        char *opcode)
280
0
{
281
0
  char *retval;
282
283
0
  retval = obstack_next_free (&frchain_now->frch_obstack);
284
0
  frag_var_init (type, max_chars, var, subtype, symbol, offset, opcode);
285
286
0
  return retval;
287
0
}
288

289
/* Reduce the variable end of a frag to a harmless state.  */
290
291
void
292
frag_wane (fragS *fragP)
293
113k
{
294
113k
  fragP->fr_type = rs_fill;
295
113k
  fragP->fr_offset = 0;
296
113k
  fragP->fr_var = 0;
297
113k
}
298

299
/* Return the number of bytes by which the current frag can be grown.  */
300
301
size_t
302
frag_room (void)
303
0
{
304
0
  return obstack_room (&frchain_now->frch_obstack);
305
0
}
306

307
/* Make an alignment frag.  The size of this frag will be adjusted to
308
   force the next frag to have the appropriate alignment.  ALIGNMENT
309
   is the power of two to which to align.  FILL_CHARACTER is the
310
   character to use to fill in any bytes which are skipped.  MAX is
311
   the maximum number of characters to skip when doing the alignment,
312
   or 0 if there is no maximum.  */
313
314
void
315
frag_align (int alignment, int fill_character, int max)
316
34.1k
{
317
34.1k
  if (now_seg == absolute_section)
318
6.31k
    {
319
6.31k
      addressT new_off;
320
6.31k
      addressT mask;
321
322
6.31k
      mask = (~(addressT) 0) << alignment;
323
6.31k
      new_off = (abs_section_offset + ~mask) & mask;
324
6.31k
      if (max == 0 || new_off - abs_section_offset <= (addressT) max)
325
6.31k
  abs_section_offset = new_off;
326
6.31k
    }
327
27.7k
  else
328
27.7k
    {
329
27.7k
      char *p;
330
331
27.7k
      p = frag_var (rs_align, 1, 1, (relax_substateT) max,
332
27.7k
        (symbolS *) 0, (offsetT) alignment, (char *) 0);
333
27.7k
      *p = fill_character;
334
27.7k
    }
335
34.1k
}
336
337
/* Make an alignment frag like frag_align, but fill with a repeating
338
   pattern rather than a single byte.  ALIGNMENT is the power of two
339
   to which to align.  FILL_PATTERN is the fill pattern to repeat in
340
   the bytes which are skipped.  N_FILL is the number of bytes in
341
   FILL_PATTERN.  MAX is the maximum number of characters to skip when
342
   doing the alignment, or 0 if there is no maximum.  */
343
344
void
345
frag_align_pattern (int alignment, const char *fill_pattern,
346
        size_t n_fill, int max)
347
0
{
348
0
  char *p;
349
350
0
  p = frag_var (rs_align, n_fill, n_fill, (relax_substateT) max,
351
0
    (symbolS *) 0, (offsetT) alignment, (char *) 0);
352
0
  memcpy (p, fill_pattern, n_fill);
353
0
}
354
355
/* The NOP_OPCODE is for the alignment fill value.  Fill it with a nop
356
   instruction so that the disassembler does not choke on it.  */
357
#ifndef NOP_OPCODE
358
#define NOP_OPCODE 0x00
359
#endif
360
361
/* Use this to restrict the amount of memory allocated for representing
362
   the alignment code.  Needs to be large enough to hold any fixed sized
363
   prologue plus the replicating portion.  */
364
#ifndef MAX_MEM_FOR_RS_ALIGN_CODE
365
  /* Assume that if HANDLE_ALIGN is not defined then no special action
366
     is required to code fill, which means that we get just repeat the
367
     one NOP_OPCODE byte.  */
368
# ifndef HANDLE_ALIGN
369
#  define MAX_MEM_FOR_RS_ALIGN_CODE  1
370
# else
371
#  define MAX_MEM_FOR_RS_ALIGN_CODE  (((size_t) 1 << alignment) - 1)
372
# endif
373
#endif
374
375
void
376
frag_align_code (int alignment, int max)
377
330
{
378
330
  char *p;
379
380
330
  p = frag_var (rs_align_code, MAX_MEM_FOR_RS_ALIGN_CODE, 1,
381
330
    (relax_substateT) max, (symbolS *) 0,
382
330
    (offsetT) alignment, (char *) 0);
383
330
  *p = NOP_OPCODE;
384
330
}
385
386
addressT
387
frag_now_fix_octets (void)
388
21.2M
{
389
21.2M
  if (now_seg == absolute_section)
390
2.81M
    return abs_section_offset;
391
392
18.4M
  return ((char *) obstack_next_free (&frchain_now->frch_obstack)
393
18.4M
    - frag_now->fr_literal);
394
21.2M
}
395
396
addressT
397
frag_now_fix (void)
398
21.0M
{
399
  /* Symbols whose section has SEC_ELF_OCTETS set,
400
     resolve to octets instead of target bytes.  */
401
21.0M
  if (now_seg->flags & SEC_OCTETS)
402
50.1k
    return frag_now_fix_octets ();
403
20.9M
  else
404
20.9M
    return frag_now_fix_octets () / OCTETS_PER_BYTE;
405
21.0M
}
406
407
void
408
frag_append_1_char (int datum)
409
1.69M
{
410
1.69M
  frag_alloc_check (&frchain_now->frch_obstack);
411
1.69M
  if (obstack_room (&frchain_now->frch_obstack) <= 1)
412
286
    {
413
286
      frag_wane (frag_now);
414
286
      frag_new (0);
415
286
    }
416
1.69M
  obstack_1grow (&frchain_now->frch_obstack, datum);
417
1.69M
}
418
419
/* Return TRUE if FRAG1 and FRAG2 have a fixed relationship between
420
   their start addresses.  Set OFFSET to the difference in address
421
   not already accounted for in the frag FR_ADDRESS.  */
422
423
bool
424
frag_offset_fixed_p (const fragS *frag1, const fragS *frag2, offsetT *offset)
425
5.08k
{
426
5.08k
  const fragS *frag;
427
5.08k
  offsetT off;
428
429
  /* Start with offset initialised to difference between the two frags.
430
     Prior to assigning frag addresses this will be zero.  */
431
5.08k
  off = frag1->fr_address - frag2->fr_address;
432
5.08k
  if (frag1 == frag2)
433
4.85k
    {
434
4.85k
      *offset = off;
435
4.85k
      return true;
436
4.85k
    }
437
438
  /* Maybe frag2 is after frag1.  */
439
227
  frag = frag1;
440
16.9k
  while (frag->fr_type == rs_fill)
441
16.9k
    {
442
16.9k
      off += frag->fr_fix + frag->fr_offset * frag->fr_var;
443
16.9k
      frag = frag->fr_next;
444
16.9k
      if (frag == NULL)
445
0
  break;
446
16.9k
      if (frag == frag2)
447
205
  {
448
205
    *offset = off;
449
205
    return true;
450
205
  }
451
16.9k
    }
452
453
  /* Maybe frag1 is after frag2.  */
454
22
  off = frag1->fr_address - frag2->fr_address;
455
22
  frag = frag2;
456
132
  while (frag->fr_type == rs_fill)
457
110
    {
458
110
      off -= frag->fr_fix + frag->fr_offset * frag->fr_var;
459
110
      frag = frag->fr_next;
460
110
      if (frag == NULL)
461
0
  break;
462
110
      if (frag == frag1)
463
0
  {
464
0
    *offset = off;
465
0
    return true;
466
0
  }
467
110
    }
468
469
22
  return false;
470
22
}
471
472
/* Return TRUE if FRAG2 follows FRAG1 with a fixed relationship
473
   between the two assuming alignment frags do nothing.  Set OFFSET to
474
   the difference in address not already accounted for in the frag
475
   FR_ADDRESS.  */
476
477
bool
478
frag_offset_ignore_align_p (const fragS *frag1, const fragS *frag2,
479
          offsetT *offset)
480
614k
{
481
614k
  const fragS *frag;
482
614k
  offsetT off;
483
484
  /* Start with offset initialised to difference between the two frags.
485
     Prior to assigning frag addresses this will be zero.  */
486
614k
  off = frag1->fr_address - frag2->fr_address;
487
614k
  if (frag1 == frag2)
488
596k
    {
489
596k
      *offset = off;
490
596k
      return true;
491
596k
    }
492
493
18.2k
  frag = frag1;
494
18.2k
  while (frag->fr_type == rs_fill
495
18.2k
   || frag->fr_type == rs_align
496
18.2k
   || frag->fr_type == rs_align_code
497
18.2k
   || frag->fr_type == rs_align_test)
498
18.2k
    {
499
18.2k
      if (frag->fr_type == rs_fill)
500
18.2k
  off += frag->fr_fix + frag->fr_offset * frag->fr_var;
501
18.2k
      frag = frag->fr_next;
502
18.2k
      if (frag == NULL)
503
0
  break;
504
18.2k
      if (frag == frag2)
505
18.2k
  {
506
18.2k
    *offset = off;
507
18.2k
    return true;
508
18.2k
  }
509
18.2k
    }
510
511
0
  return false;
512
18.2k
}
513
514
/* Return TRUE if we can determine whether FRAG2 OFF2 appears after
515
   (strict >, not >=) FRAG1 OFF1, assuming it is not before.  Set
516
   *OFFSET so that resolve_expression will resolve an O_gt operation
517
   between them to false (0) if they are guaranteed to be at the same
518
   location, or to true (-1) if they are guaranteed to be at different
519
   locations.  Return FALSE conservatively, e.g. if neither result can
520
   be guaranteed (yet).
521
522
   They are known to be in the same segment, and not the same frag
523
   (this is a fallback for frag_offset_fixed_p, that always takes care
524
   of this case), and it is expected (from the uses this is designed
525
   to simplify, namely location view increments) that frag2 is
526
   reachable from frag1 following the fr_next links, rather than the
527
   other way round.  */
528
529
bool
530
frag_gtoffset_p (valueT off2, const fragS *frag2,
531
     valueT off1, const fragS *frag1, offsetT *offset)
532
0
{
533
  /* Insanity check.  */
534
0
  if (frag2 == frag1 || off1 > frag1->fr_fix)
535
0
    return false;
536
537
  /* If the first symbol offset is at the end of the first frag and
538
     the second symbol offset at the beginning of the second frag then
539
     it is possible they are at the same address.  Go looking for a
540
     non-zero fr_fix in any frag between these frags.  If found then
541
     we can say the O_gt result will be true.  If no such frag is
542
     found we assume that frag1 or any of the following frags might
543
     have a variable tail and thus the answer is unknown.  This isn't
544
     strictly true; some frags don't have a variable tail, but it
545
     doesn't seem worth optimizing for those cases.  */
546
0
  const fragS *frag = frag1;
547
0
  offsetT delta = off2 - off1;
548
0
  for (;;)
549
0
    {
550
0
      delta += frag->fr_fix;
551
0
      frag = frag->fr_next;
552
0
      if (frag == frag2)
553
0
  {
554
0
    if (delta == 0)
555
0
      return false;
556
0
    break;
557
0
  }
558
      /* If we run off the end of the frag chain then we have a case
559
   where frag2 is not after frag1, ie. an O_gt expression not
560
   created for .loc view.  */
561
0
      if (frag == NULL)
562
0
  return false;
563
0
    }
564
565
0
  *offset = (off2 - off1 - delta) * OCTETS_PER_BYTE;
566
0
  return true;
567
0
}