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[binutils.git] / gas / subsegs.c
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1 /* subsegs.c - subsegments -
2 Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 Free Software Foundation, Inc.
6 This file is part of GAS, the GNU Assembler.
8 GAS is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
11 any later version.
13 GAS is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GAS; see the file COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
21 02110-1301, USA. */
23 /* Segments & sub-segments. */
25 #include "as.h"
27 #include "subsegs.h"
28 #include "obstack.h"
30 frchainS *frchain_now;
32 static struct obstack frchains;
34 static fragS dummy_frag;
37 void
38 subsegs_begin (void)
40 obstack_begin (&frchains, chunksize);
41 #if __GNUC__ >= 2
42 obstack_alignment_mask (&frchains) = __alignof__ (frchainS) - 1;
43 #endif
45 frchain_now = NULL; /* Warn new_subseg() that we are booting. */
46 frag_now = &dummy_frag;
50 * subseg_change()
52 * Change the subsegment we are in, BUT DO NOT MAKE A NEW FRAG for the
53 * subsegment. If we are already in the correct subsegment, change nothing.
54 * This is used eg as a worker for subseg_set [which does make a new frag_now]
55 * and for changing segments after we have read the source. We construct eg
56 * fixSs even after the source file is read, so we do have to keep the
57 * segment context correct.
59 void
60 subseg_change (register segT seg, register int subseg)
62 segment_info_type *seginfo = seg_info (seg);
63 now_seg = seg;
64 now_subseg = subseg;
66 if (! seginfo)
68 seginfo = xcalloc (1, sizeof (*seginfo));
69 seginfo->bfd_section = seg;
70 bfd_set_section_userdata (stdoutput, seg, seginfo);
74 static void
75 subseg_set_rest (segT seg, subsegT subseg)
77 frchainS *frcP; /* crawl frchain chain */
78 frchainS **lastPP; /* address of last pointer */
79 frchainS *newP; /* address of new frchain */
80 segment_info_type *seginfo;
82 mri_common_symbol = NULL;
84 if (frag_now && frchain_now)
85 frchain_now->frch_frag_now = frag_now;
87 assert (frchain_now == 0
88 || frchain_now->frch_last == frag_now);
90 subseg_change (seg, (int) subseg);
92 seginfo = seg_info (seg);
94 /* Attempt to find or make a frchain for that subsection.
95 We keep the list sorted by subsection number. */
96 for (frcP = *(lastPP = &seginfo->frchainP);
97 frcP != NULL;
98 frcP = *(lastPP = &frcP->frch_next))
99 if (frcP->frch_subseg >= subseg)
100 break;
102 if (frcP == NULL || frcP->frch_subseg != subseg)
104 /* This should be the only code that creates a frchainS. */
106 newP = obstack_alloc (&frchains, sizeof (frchainS));
107 newP->frch_subseg = subseg;
108 newP->fix_root = NULL;
109 newP->fix_tail = NULL;
110 obstack_begin (&newP->frch_obstack, chunksize);
111 #if __GNUC__ >= 2
112 obstack_alignment_mask (&newP->frch_obstack) = __alignof__ (fragS) - 1;
113 #endif
114 newP->frch_frag_now = frag_alloc (&newP->frch_obstack);
115 newP->frch_frag_now->fr_type = rs_fill;
116 newP->frch_cfi_data = NULL;
118 newP->frch_root = newP->frch_last = newP->frch_frag_now;
120 *lastPP = newP;
121 newP->frch_next = frcP;
122 frcP = newP;
125 frchain_now = frcP;
126 frag_now = frcP->frch_frag_now;
128 assert (frchain_now->frch_last == frag_now);
132 * subseg_set(segT, subsegT)
134 * If you attempt to change to the current subsegment, nothing happens.
136 * In: segT, subsegT code for new subsegment.
137 * frag_now -> incomplete frag for current subsegment.
138 * If frag_now==NULL, then there is no old, incomplete frag, so
139 * the old frag is not closed off.
141 * Out: now_subseg, now_seg updated.
142 * Frchain_now points to the (possibly new) struct frchain for this
143 * sub-segment.
146 segT
147 subseg_get (const char *segname, int force_new)
149 segT secptr;
150 segment_info_type *seginfo;
151 const char *now_seg_name = (now_seg
152 ? bfd_get_section_name (stdoutput, now_seg)
153 : 0);
155 if (!force_new
156 && now_seg_name
157 && (now_seg_name == segname
158 || !strcmp (now_seg_name, segname)))
159 return now_seg;
161 if (!force_new)
162 secptr = bfd_make_section_old_way (stdoutput, segname);
163 else
164 secptr = bfd_make_section_anyway (stdoutput, segname);
166 seginfo = seg_info (secptr);
167 if (! seginfo)
169 secptr->output_section = secptr;
170 seginfo = xcalloc (1, sizeof (*seginfo));
171 seginfo->bfd_section = secptr;
172 bfd_set_section_userdata (stdoutput, secptr, seginfo);
174 return secptr;
177 segT
178 subseg_new (const char *segname, subsegT subseg)
180 segT secptr;
182 secptr = subseg_get (segname, 0);
183 subseg_set_rest (secptr, subseg);
184 return secptr;
187 /* Like subseg_new, except a new section is always created, even if
188 a section with that name already exists. */
189 segT
190 subseg_force_new (const char *segname, subsegT subseg)
192 segT secptr;
194 secptr = subseg_get (segname, 1);
195 subseg_set_rest (secptr, subseg);
196 return secptr;
199 void
200 subseg_set (segT secptr, subsegT subseg)
202 if (! (secptr == now_seg && subseg == now_subseg))
203 subseg_set_rest (secptr, subseg);
204 mri_common_symbol = NULL;
207 #ifndef obj_sec_sym_ok_for_reloc
208 #define obj_sec_sym_ok_for_reloc(SEC) 0
209 #endif
211 symbolS *
212 section_symbol (segT sec)
214 segment_info_type *seginfo = seg_info (sec);
215 symbolS *s;
217 if (seginfo == 0)
218 abort ();
219 if (seginfo->sym)
220 return seginfo->sym;
222 #ifndef EMIT_SECTION_SYMBOLS
223 #define EMIT_SECTION_SYMBOLS 1
224 #endif
226 if (! EMIT_SECTION_SYMBOLS || symbol_table_frozen)
228 /* Here we know it won't be going into the symbol table. */
229 s = symbol_create (sec->symbol->name, sec, 0, &zero_address_frag);
231 else
233 segT seg;
234 s = symbol_find (sec->symbol->name);
235 /* We have to make sure it is the right symbol when we
236 have multiple sections with the same section name. */
237 if (s == NULL
238 || ((seg = S_GET_SEGMENT (s)) != sec
239 && seg != undefined_section))
240 s = symbol_new (sec->symbol->name, sec, 0, &zero_address_frag);
241 else if (seg == undefined_section)
243 S_SET_SEGMENT (s, sec);
244 symbol_set_frag (s, &zero_address_frag);
248 S_CLEAR_EXTERNAL (s);
250 /* Use the BFD section symbol, if possible. */
251 if (obj_sec_sym_ok_for_reloc (sec))
252 symbol_set_bfdsym (s, sec->symbol);
253 else
254 symbol_get_bfdsym (s)->flags |= BSF_SECTION_SYM;
256 seginfo->sym = s;
257 return s;
260 /* Return whether the specified segment is thought to hold text. */
263 subseg_text_p (segT sec)
265 return (bfd_get_section_flags (stdoutput, sec) & SEC_CODE) != 0;
268 /* Return non zero if SEC has at least one byte of data. It is
269 possible that we'll return zero even on a non-empty section because
270 we don't know all the fragment types, and it is possible that an
271 fr_fix == 0 one still contributes data. Think of this as
272 seg_definitely_not_empty_p. */
275 seg_not_empty_p (segT sec ATTRIBUTE_UNUSED)
277 segment_info_type *seginfo = seg_info (sec);
278 frchainS *chain;
279 fragS *frag;
281 if (!seginfo)
282 return 0;
284 for (chain = seginfo->frchainP; chain; chain = chain->frch_next)
286 for (frag = chain->frch_root; frag; frag = frag->fr_next)
287 if (frag->fr_fix)
288 return 1;
289 if (obstack_next_free (&chain->frch_obstack)
290 != chain->frch_last->fr_literal)
291 return 1;
293 return 0;
296 void
297 subsegs_print_statistics (FILE *file)
299 frchainS *frchp;
300 asection *s;
302 fprintf (file, "frag chains:\n");
303 for (s = stdoutput->sections; s; s = s->next)
305 segment_info_type *seginfo;
307 /* Skip gas-internal sections. */
308 if (segment_name (s)[0] == '*')
309 continue;
311 seginfo = seg_info (s);
312 if (!seginfo)
313 continue;
315 for (frchp = seginfo->frchainP; frchp; frchp = frchp->frch_next)
317 int count = 0;
318 fragS *fragp;
320 for (fragp = frchp->frch_root; fragp; fragp = fragp->fr_next)
321 count++;
323 fprintf (file, "\n");
324 fprintf (file, "\t%p %-10s\t%10d frags\n", (void *) frchp,
325 segment_name (s), count);
330 /* end of subsegs.c */