aboutsummaryrefslogtreecommitdiff
path: root/gas/frags.c
blob: adb9b1986301f9fd3a3f3f9888d69aacd044b04c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
/* frags.c - manage frags -
   Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2003, 2004, 2005, 2006
   Free Software Foundation, Inc.

   This file is part of GAS, the GNU Assembler.

   GAS is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   GAS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GAS; see the file COPYING.  If not, write to the Free
   Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
   02110-1301, USA.  */

#include "as.h"
#include "subsegs.h"
#include "obstack.h"

extern fragS zero_address_frag;
extern fragS bss_address_frag;

/* Initialization for frag routines.  */

void
frag_init (void)
{
  zero_address_frag.fr_type = rs_fill;
  bss_address_frag.fr_type = rs_fill;
}

/* Check that we're not trying to assemble into a section that can't
   allocate frags (currently, this is only possible in the absolute
   section), or into an mri common.  */

static void
frag_alloc_check (const struct obstack *ob)
{
  if (ob->chunk_size == 0)
    {
      as_bad (_("attempt to allocate data in absolute section"));
      subseg_set (text_section, 0);
    }

  if (mri_common_symbol != NULL)
    {
      as_bad (_("attempt to allocate data in common section"));
      mri_common_symbol = NULL;
    }
}

/* Allocate a frag on the specified obstack.
   Call this routine from everywhere else, so that all the weird alignment
   hackery can be done in just one place.  */

fragS *
frag_alloc (struct obstack *ob)
{
  fragS *ptr;
  int oalign;

  (void) obstack_alloc (ob, 0);
  oalign = obstack_alignment_mask (ob);
  obstack_alignment_mask (ob) = 0;
  ptr = (fragS *) obstack_alloc (ob, SIZEOF_STRUCT_FRAG);
  obstack_alignment_mask (ob) = oalign;
  memset (ptr, 0, SIZEOF_STRUCT_FRAG);
  return ptr;
}

/* Try to augment current frag by nchars chars.
   If there is no room, close of the current frag with a ".fill 0"
   and begin a new frag. Unless the new frag has nchars chars available
   do not return. Do not set up any fields of *now_frag.  */

void
frag_grow (unsigned int nchars)
{
  if (obstack_room (&frchain_now->frch_obstack) < nchars)
    {
      unsigned int n;
      long oldc;

      frag_wane (frag_now);
      frag_new (0);
      oldc = frchain_now->frch_obstack.chunk_size;
      /* Try to allocate a bit more than needed right now.  But don't do
         this if we would waste too much memory.  Especially necessary
	 for extremely big (like 2GB initialized) frags.  */
      if (nchars < 0x10000)
	frchain_now->frch_obstack.chunk_size = 2 * nchars;
      else
        frchain_now->frch_obstack.chunk_size = nchars + 0x10000;
      frchain_now->frch_obstack.chunk_size += SIZEOF_STRUCT_FRAG;
      if (frchain_now->frch_obstack.chunk_size > 0)
	while ((n = obstack_room (&frchain_now->frch_obstack)) < nchars
	       && (unsigned long) frchain_now->frch_obstack.chunk_size > nchars)
	  {
	    frag_wane (frag_now);
	    frag_new (0);
	  }
      frchain_now->frch_obstack.chunk_size = oldc;
    }
  if (obstack_room (&frchain_now->frch_obstack) < nchars)
    as_fatal (_("can't extend frag %u chars"), nchars);
}

/* Call this to close off a completed frag, and start up a new (empty)
   frag, in the same subsegment as the old frag.
   [frchain_now remains the same but frag_now is updated.]
   Because this calculates the correct value of fr_fix by
   looking at the obstack 'frags', it needs to know how many
   characters at the end of the old frag belong to the maximal
   variable part;  The rest must belong to fr_fix.
   It doesn't actually set up the old frag's fr_var.  You may have
   set fr_var == 1, but allocated 10 chars to the end of the frag;
   In this case you pass old_frags_var_max_size == 10.
   In fact, you may use fr_var for something totally unrelated to the
   size of the variable part of the frag;  None of the generic frag
   handling code makes use of fr_var.

   Make a new frag, initialising some components. Link new frag at end
   of frchain_now.  */

void
frag_new (int old_frags_var_max_size
	  /* Number of chars (already allocated on obstack frags) in
	     variable_length part of frag.  */)
{
  fragS *former_last_fragP;
  frchainS *frchP;

  assert (frchain_now->frch_last == frag_now);

  /* Fix up old frag's fr_fix.  */
  frag_now->fr_fix = frag_now_fix_octets () - old_frags_var_max_size;
  /* Make sure its type is valid.  */
  assert (frag_now->fr_type != 0);

  /* This will align the obstack so the next struct we allocate on it
     will begin at a correct boundary.  */
  obstack_finish (&frchain_now->frch_obstack);
  frchP = frchain_now;
  know (frchP);
  former_last_fragP = frchP->frch_last;
  assert (former_last_fragP != 0);
  assert (former_last_fragP == frag_now);
  frag_now = frag_alloc (&frchP->frch_obstack);

  as_where (&frag_now->fr_file, &frag_now->fr_line);

  /* Generally, frag_now->points to an address rounded up to next
     alignment.  However, characters will add to obstack frags
     IMMEDIATELY after the struct frag, even if they are not starting
     at an alignment address.  */
  former_last_fragP->fr_next = frag_now;
  frchP->frch_last = frag_now;

#ifndef NO_LISTING
  {
    extern struct list_info_struct *listing_tail;
    frag_now->line = listing_tail;
  }
#endif

  assert (frchain_now->frch_last == frag_now);

  frag_now->fr_next = NULL;
}

/* Start a new frag unless we have n more chars of room in the current frag.
   Close off the old frag with a .fill 0.

   Return the address of the 1st char to write into. Advance
   frag_now_growth past the new chars.  */

char *
frag_more (int nchars)
{
  register char *retval;

  frag_alloc_check (&frchain_now->frch_obstack);
  frag_grow (nchars);
  retval = obstack_next_free (&frchain_now->frch_obstack);
  obstack_blank_fast (&frchain_now->frch_obstack, nchars);
  return (retval);
}

/* Start a new frag unless we have max_chars more chars of room in the
   current frag.  Close off the old frag with a .fill 0.

   Set up a machine_dependent relaxable frag, then start a new frag.
   Return the address of the 1st char of the var part of the old frag
   to write into.  */

char *
frag_var (relax_stateT type, int max_chars, int var, relax_substateT subtype,
	  symbolS *symbol, offsetT offset, char *opcode)
{
  register char *retval;

  frag_grow (max_chars);
  retval = obstack_next_free (&frchain_now->frch_obstack);
  obstack_blank_fast (&frchain_now->frch_obstack, max_chars);
  frag_now->fr_var = var;
  frag_now->fr_type = type;
  frag_now->fr_subtype = subtype;
  frag_now->fr_symbol = symbol;
  frag_now->fr_offset = offset;
  frag_now->fr_opcode = opcode;
#ifdef USING_CGEN
  frag_now->fr_cgen.insn = 0;
  frag_now->fr_cgen.opindex = 0;
  frag_now->fr_cgen.opinfo = 0;
#endif
#ifdef TC_FRAG_INIT
  TC_FRAG_INIT (frag_now);
#endif
  as_where (&frag_now->fr_file, &frag_now->fr_line);
  frag_new (max_chars);
  return (retval);
}

/* OVE: This variant of frag_var assumes that space for the tail has been
	allocated by caller.
	No call to frag_grow is done.  */

char *
frag_variant (relax_stateT type, int max_chars, int var,
	      relax_substateT subtype, symbolS *symbol, offsetT offset,
	      char *opcode)
{
  register char *retval;

  retval = obstack_next_free (&frchain_now->frch_obstack);
  frag_now->fr_var = var;
  frag_now->fr_type = type;
  frag_now->fr_subtype = subtype;
  frag_now->fr_symbol = symbol;
  frag_now->fr_offset = offset;
  frag_now->fr_opcode = opcode;
#ifdef USING_CGEN
  frag_now->fr_cgen.insn = 0;
  frag_now->fr_cgen.opindex = 0;
  frag_now->fr_cgen.opinfo = 0;
#endif
#ifdef TC_FRAG_INIT
  TC_FRAG_INIT (frag_now);
#endif
  as_where (&frag_now->fr_file, &frag_now->fr_line);
  frag_new (max_chars);
  return (retval);
}

/* Reduce the variable end of a frag to a harmless state.  */

void
frag_wane (register fragS *fragP)
{
  fragP->fr_type = rs_fill;
  fragP->fr_offset = 0;
  fragP->fr_var = 0;
}

/* Return the number of bytes by which the current frag can be grown.  */

int
frag_room (void)
{
  return obstack_room (&frchain_now->frch_obstack);
}

/* Make an alignment frag.  The size of this frag will be adjusted to
   force the next frag to have the appropriate alignment.  ALIGNMENT
   is the power of two to which to align.  FILL_CHARACTER is the
   character to use to fill in any bytes which are skipped.  MAX is
   the maximum number of characters to skip when doing the alignment,
   or 0 if there is no maximum.  */

void
frag_align (int alignment, int fill_character, int max)
{
  if (now_seg == absolute_section)
    {
      addressT new_off;
      addressT mask;

      mask = (~(addressT) 0) << alignment;
      new_off = (abs_section_offset + ~mask) & mask;
      if (max == 0 || new_off - abs_section_offset <= (addressT) max)
	abs_section_offset = new_off;
    }
  else
    {
      char *p;

      p = frag_var (rs_align, 1, 1, (relax_substateT) max,
		    (symbolS *) 0, (offsetT) alignment, (char *) 0);
      *p = fill_character;
    }
}

/* Make an alignment frag like frag_align, but fill with a repeating
   pattern rather than a single byte.  ALIGNMENT is the power of two
   to which to align.  FILL_PATTERN is the fill pattern to repeat in
   the bytes which are skipped.  N_FILL is the number of bytes in
   FILL_PATTERN.  MAX is the maximum number of characters to skip when
   doing the alignment, or 0 if there is no maximum.  */

void
frag_align_pattern (int alignment, const char *fill_pattern,
		    int n_fill, int max)
{
  char *p;

  p = frag_var (rs_align, n_fill, n_fill, (relax_substateT) max,
		(symbolS *) 0, (offsetT) alignment, (char *) 0);
  memcpy (p, fill_pattern, n_fill);
}

/* The NOP_OPCODE is for the alignment fill value.  Fill it with a nop
   instruction so that the disassembler does not choke on it.  */
#ifndef NOP_OPCODE
#define NOP_OPCODE 0x00
#endif

/* Use this to restrict the amount of memory allocated for representing
   the alignment code.  Needs to be large enough to hold any fixed sized
   prologue plus the replicating portion.  */
#ifndef MAX_MEM_FOR_RS_ALIGN_CODE
  /* Assume that if HANDLE_ALIGN is not defined then no special action
     is required to code fill, which means that we get just repeat the
     one NOP_OPCODE byte.  */
# ifndef HANDLE_ALIGN
#  define MAX_MEM_FOR_RS_ALIGN_CODE  1
# else
#  define MAX_MEM_FOR_RS_ALIGN_CODE  ((1 << alignment) - 1)
# endif
#endif

void
frag_align_code (int alignment, int max)
{
  char *p;

  p = frag_var (rs_align_code, MAX_MEM_FOR_RS_ALIGN_CODE, 1,
		(relax_substateT) max, (symbolS *) 0,
		(offsetT) alignment, (char *) 0);
  *p = NOP_OPCODE;
}

addressT
frag_now_fix_octets (void)
{
  if (now_seg == absolute_section)
    return abs_section_offset;

  return ((char *) obstack_next_free (&frchain_now->frch_obstack)
	  - frag_now->fr_literal);
}

addressT
frag_now_fix (void)
{
  return frag_now_fix_octets () / OCTETS_PER_BYTE;
}

void
frag_append_1_char (int datum)
{
  frag_alloc_check (&frchain_now->frch_obstack);
  if (obstack_room (&frchain_now->frch_obstack) <= 1)
    {
      frag_wane (frag_now);
      frag_new (0);
    }
  obstack_1grow (&frchain_now->frch_obstack, datum);
}

/* Return TRUE if FRAG1 and FRAG2 have a fixed relationship between
   their start addresses.  Set OFFSET to the difference in address
   not already accounted for in the frag FR_ADDRESS.  */

bfd_boolean
frag_offset_fixed_p (const fragS *frag1, const fragS *frag2, bfd_vma *offset)
{
  const fragS *frag;
  bfd_vma off;

  /* Start with offset initialised to difference between the two frags.
     Prior to assigning frag addresses this will be zero.  */
  off = frag1->fr_address - frag2->fr_address;
  if (frag1 == frag2)
    {
      *offset = off;
      return TRUE;
    }

  /* Maybe frag2 is after frag1.  */
  frag = frag1;
  while (frag->fr_type == rs_fill)
    {
      off += frag->fr_fix + frag->fr_offset * frag->fr_var;
      frag = frag->fr_next;
      if (frag == NULL)
	break;
      if (frag == frag2)
	{
	  *offset = off;
	  return TRUE;
	}
    }

  /* Maybe frag1 is after frag2.  */
  off = frag1->fr_address - frag2->fr_address;
  frag = frag2;
  while (frag->fr_type == rs_fill)
    {
      off -= frag->fr_fix + frag->fr_offset * frag->fr_var;
      frag = frag->fr_next;
      if (frag == NULL)
	break;
      if (frag == frag1)
	{
	  *offset = off;
	  return TRUE;
	}
    }

  return FALSE;
}