1 /* subsegs.c - subsegments -
2 Copyright (C) 1987-2014 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 /* Segments & sub-segments. */
22
23 #include "as.h"
24
25 #include "subsegs.h"
26 #include "obstack.h"
27
28 frchainS *frchain_now;
29
30 static struct obstack frchains;
31
32 static fragS dummy_frag;
33
34
35 void
subsegs_begin(void)36 subsegs_begin (void)
37 {
38 obstack_begin (&frchains, chunksize);
39 #if __GNUC__ >= 2
40 obstack_alignment_mask (&frchains) = __alignof__ (frchainS) - 1;
41 #endif
42
43 frchain_now = NULL; /* Warn new_subseg() that we are booting. */
44 frag_now = &dummy_frag;
45 }
46
47 /*
48 * subseg_change()
49 *
50 * Change the subsegment we are in, BUT DO NOT MAKE A NEW FRAG for the
51 * subsegment. If we are already in the correct subsegment, change nothing.
52 * This is used eg as a worker for subseg_set [which does make a new frag_now]
53 * and for changing segments after we have read the source. We construct eg
54 * fixSs even after the source file is read, so we do have to keep the
55 * segment context correct.
56 */
57 void
subseg_change(segT seg,int subseg)58 subseg_change (segT seg, int subseg)
59 {
60 segment_info_type *seginfo = seg_info (seg);
61 now_seg = seg;
62 now_subseg = subseg;
63
64 if (! seginfo)
65 {
66 seginfo = (segment_info_type *) xcalloc (1, sizeof (*seginfo));
67 seginfo->bfd_section = seg;
68 bfd_set_section_userdata (stdoutput, seg, seginfo);
69 }
70 }
71
72 static void
subseg_set_rest(segT seg,subsegT subseg)73 subseg_set_rest (segT seg, subsegT subseg)
74 {
75 frchainS *frcP; /* crawl frchain chain */
76 frchainS **lastPP; /* address of last pointer */
77 frchainS *newP; /* address of new frchain */
78 segment_info_type *seginfo;
79
80 mri_common_symbol = NULL;
81
82 if (frag_now && frchain_now)
83 frchain_now->frch_frag_now = frag_now;
84
85 gas_assert (frchain_now == 0
86 || frchain_now->frch_last == frag_now);
87
88 subseg_change (seg, (int) subseg);
89
90 seginfo = seg_info (seg);
91
92 /* Attempt to find or make a frchain for that subsection.
93 We keep the list sorted by subsection number. */
94 for (frcP = *(lastPP = &seginfo->frchainP);
95 frcP != NULL;
96 frcP = *(lastPP = &frcP->frch_next))
97 if (frcP->frch_subseg >= subseg)
98 break;
99
100 if (frcP == NULL || frcP->frch_subseg != subseg)
101 {
102 /* This should be the only code that creates a frchainS. */
103
104 newP = (frchainS *) obstack_alloc (&frchains, sizeof (frchainS));
105 newP->frch_subseg = subseg;
106 newP->fix_root = NULL;
107 newP->fix_tail = NULL;
108 obstack_begin (&newP->frch_obstack, chunksize);
109 #if __GNUC__ >= 2
110 obstack_alignment_mask (&newP->frch_obstack) = __alignof__ (fragS) - 1;
111 #endif
112 newP->frch_frag_now = frag_alloc (&newP->frch_obstack);
113 newP->frch_frag_now->fr_type = rs_fill;
114 newP->frch_cfi_data = NULL;
115
116 newP->frch_root = newP->frch_last = newP->frch_frag_now;
117
118 *lastPP = newP;
119 newP->frch_next = frcP;
120 frcP = newP;
121 }
122
123 frchain_now = frcP;
124 frag_now = frcP->frch_frag_now;
125
126 gas_assert (frchain_now->frch_last == frag_now);
127 }
128
129 /*
130 * subseg_set(segT, subsegT)
131 *
132 * If you attempt to change to the current subsegment, nothing happens.
133 *
134 * In: segT, subsegT code for new subsegment.
135 * frag_now -> incomplete frag for current subsegment.
136 * If frag_now==NULL, then there is no old, incomplete frag, so
137 * the old frag is not closed off.
138 *
139 * Out: now_subseg, now_seg updated.
140 * Frchain_now points to the (possibly new) struct frchain for this
141 * sub-segment.
142 */
143
144 segT
subseg_get(const char * segname,int force_new)145 subseg_get (const char *segname, int force_new)
146 {
147 segT secptr;
148 segment_info_type *seginfo;
149 const char *now_seg_name = (now_seg
150 ? bfd_get_section_name (stdoutput, now_seg)
151 : 0);
152
153 if (!force_new
154 && now_seg_name
155 && (now_seg_name == segname
156 || !strcmp (now_seg_name, segname)))
157 return now_seg;
158
159 if (!force_new)
160 secptr = bfd_make_section_old_way (stdoutput, segname);
161 else
162 secptr = bfd_make_section_anyway (stdoutput, segname);
163
164 seginfo = seg_info (secptr);
165 if (! seginfo)
166 {
167 secptr->output_section = secptr;
168 seginfo = (segment_info_type *) xcalloc (1, sizeof (*seginfo));
169 seginfo->bfd_section = secptr;
170 bfd_set_section_userdata (stdoutput, secptr, seginfo);
171 }
172 return secptr;
173 }
174
175 segT
subseg_new(const char * segname,subsegT subseg)176 subseg_new (const char *segname, subsegT subseg)
177 {
178 segT secptr;
179
180 secptr = subseg_get (segname, 0);
181 subseg_set_rest (secptr, subseg);
182 return secptr;
183 }
184
185 /* Like subseg_new, except a new section is always created, even if
186 a section with that name already exists. */
187 segT
subseg_force_new(const char * segname,subsegT subseg)188 subseg_force_new (const char *segname, subsegT subseg)
189 {
190 segT secptr;
191
192 secptr = subseg_get (segname, 1);
193 subseg_set_rest (secptr, subseg);
194 return secptr;
195 }
196
197 void
subseg_set(segT secptr,subsegT subseg)198 subseg_set (segT secptr, subsegT subseg)
199 {
200 if (! (secptr == now_seg && subseg == now_subseg))
201 subseg_set_rest (secptr, subseg);
202 mri_common_symbol = NULL;
203 }
204
205 #ifndef obj_sec_sym_ok_for_reloc
206 #define obj_sec_sym_ok_for_reloc(SEC) 0
207 #endif
208
209 symbolS *
section_symbol(segT sec)210 section_symbol (segT sec)
211 {
212 segment_info_type *seginfo = seg_info (sec);
213 symbolS *s;
214
215 if (seginfo == 0)
216 abort ();
217 if (seginfo->sym)
218 return seginfo->sym;
219
220 #ifndef EMIT_SECTION_SYMBOLS
221 #define EMIT_SECTION_SYMBOLS 1
222 #endif
223
224 if (! EMIT_SECTION_SYMBOLS || symbol_table_frozen)
225 {
226 /* Here we know it won't be going into the symbol table. */
227 s = symbol_create (sec->symbol->name, sec, 0, &zero_address_frag);
228 }
229 else
230 {
231 segT seg;
232 s = symbol_find (sec->symbol->name);
233 /* We have to make sure it is the right symbol when we
234 have multiple sections with the same section name. */
235 if (s == NULL
236 || ((seg = S_GET_SEGMENT (s)) != sec
237 && seg != undefined_section))
238 s = symbol_new (sec->symbol->name, sec, 0, &zero_address_frag);
239 else if (seg == undefined_section)
240 {
241 S_SET_SEGMENT (s, sec);
242 symbol_set_frag (s, &zero_address_frag);
243 }
244 }
245
246 S_CLEAR_EXTERNAL (s);
247
248 /* Use the BFD section symbol, if possible. */
249 if (obj_sec_sym_ok_for_reloc (sec))
250 symbol_set_bfdsym (s, sec->symbol);
251 else
252 symbol_get_bfdsym (s)->flags |= BSF_SECTION_SYM;
253
254 seginfo->sym = s;
255 return s;
256 }
257
258 /* Return whether the specified segment is thought to hold text. */
259
260 int
subseg_text_p(segT sec)261 subseg_text_p (segT sec)
262 {
263 return (bfd_get_section_flags (stdoutput, sec) & SEC_CODE) != 0;
264 }
265
266 /* Return non zero if SEC has at least one byte of data. It is
267 possible that we'll return zero even on a non-empty section because
268 we don't know all the fragment types, and it is possible that an
269 fr_fix == 0 one still contributes data. Think of this as
270 seg_definitely_not_empty_p. */
271
272 int
seg_not_empty_p(segT sec ATTRIBUTE_UNUSED)273 seg_not_empty_p (segT sec ATTRIBUTE_UNUSED)
274 {
275 segment_info_type *seginfo = seg_info (sec);
276 frchainS *chain;
277 fragS *frag;
278
279 if (!seginfo)
280 return 0;
281
282 for (chain = seginfo->frchainP; chain; chain = chain->frch_next)
283 {
284 for (frag = chain->frch_root; frag; frag = frag->fr_next)
285 if (frag->fr_fix)
286 return 1;
287 if (obstack_next_free (&chain->frch_obstack)
288 != chain->frch_last->fr_literal)
289 return 1;
290 }
291 return 0;
292 }
293
294 void
subsegs_print_statistics(FILE * file)295 subsegs_print_statistics (FILE *file)
296 {
297 frchainS *frchp;
298 asection *s;
299
300 fprintf (file, "frag chains:\n");
301 for (s = stdoutput->sections; s; s = s->next)
302 {
303 segment_info_type *seginfo;
304
305 /* Skip gas-internal sections. */
306 if (segment_name (s)[0] == '*')
307 continue;
308
309 seginfo = seg_info (s);
310 if (!seginfo)
311 continue;
312
313 for (frchp = seginfo->frchainP; frchp; frchp = frchp->frch_next)
314 {
315 int count = 0;
316 fragS *fragp;
317
318 for (fragp = frchp->frch_root; fragp; fragp = fragp->fr_next)
319 count++;
320
321 fprintf (file, "\n");
322 fprintf (file, "\t%p %-10s\t%10d frags\n", (void *) frchp,
323 segment_name (s), count);
324 }
325 }
326 }
327
328 /* end of subsegs.c */
329