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. 5 6 This file is part of GAS, the GNU Assembler. 7 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 2, or (at your option) 11 any later version. 12 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. 17 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. */ 22 23/* Segments & sub-segments. */ 24 25#include "as.h" 26 27#include "subsegs.h" 28#include "obstack.h" 29 30frchainS *frchain_now; 31 32static struct obstack frchains; 33 34static fragS dummy_frag; 35 36 37void 38subsegs_begin (void) 39{ 40 obstack_begin (&frchains, chunksize); 41#if __GNUC__ >= 2 42 obstack_alignment_mask (&frchains) = __alignof__ (frchainS) - 1; 43#endif 44 45 frchain_now = NULL; /* Warn new_subseg() that we are booting. */ 46 frag_now = &dummy_frag; 47} 48 49/* 50 * subseg_change() 51 * 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. 58 */ 59void 60subseg_change (register segT seg, register int subseg) 61{ 62 segment_info_type *seginfo = seg_info (seg); 63 now_seg = seg; 64 now_subseg = subseg; 65 66 if (! seginfo) 67 { 68 seginfo = xcalloc (1, sizeof (*seginfo)); 69 seginfo->bfd_section = seg; 70 (void) bfd_set_section_userdata (stdoutput, seg, seginfo); 71 } 72} 73 74static void 75subseg_set_rest (segT seg, subsegT subseg) 76{ 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; 81 82 mri_common_symbol = NULL; 83 84 if (frag_now && frchain_now) 85 frchain_now->frch_frag_now = frag_now; 86 87 assert (frchain_now == 0 88 || frchain_now->frch_last == frag_now); 89 90 subseg_change (seg, (int) subseg); 91 92 seginfo = seg_info (seg); 93 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; 101 102 if (frcP == NULL || frcP->frch_subseg != subseg) 103 { 104 /* This should be the only code that creates a frchainS. */ 105 106 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; 117 118 newP->frch_root = newP->frch_last = newP->frch_frag_now; 119 120 *lastPP = newP; 121 newP->frch_next = frcP; 122 frcP = newP; 123 } 124 125 frchain_now = frcP; 126 frag_now = frcP->frch_frag_now; 127 128 assert (frchain_now->frch_last == frag_now); 129} 130 131/* 132 * subseg_set(segT, subsegT) 133 * 134 * If you attempt to change to the current subsegment, nothing happens. 135 * 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. 140 * 141 * Out: now_subseg, now_seg updated. 142 * Frchain_now points to the (possibly new) struct frchain for this 143 * sub-segment. 144 */ 145 146segT 147subseg_get (const char *segname, int force_new) 148{ 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); 154 155 if (!force_new 156 && now_seg_name 157 && (now_seg_name == segname 158 || !strcmp (now_seg_name, segname))) 159 return now_seg; 160 161 if (!force_new) 162 secptr = bfd_make_section_old_way (stdoutput, segname); 163 else 164 secptr = bfd_make_section_anyway (stdoutput, segname); 165 166 seginfo = seg_info (secptr); 167 if (! seginfo) 168 { 169 secptr->output_section = secptr; 170 seginfo = xcalloc (1, sizeof (*seginfo)); 171 seginfo->bfd_section = secptr; 172 (void) bfd_set_section_userdata (stdoutput, secptr, seginfo); 173 } 174 return secptr; 175} 176 177segT 178subseg_new (const char *segname, subsegT subseg) 179{ 180 segT secptr; 181 182 secptr = subseg_get (segname, 0); 183 subseg_set_rest (secptr, subseg); 184 return secptr; 185} 186 187/* Like subseg_new, except a new section is always created, even if 188 a section with that name already exists. */ 189segT 190subseg_force_new (const char *segname, subsegT subseg) 191{ 192 segT secptr; 193 194 secptr = subseg_get (segname, 1); 195 subseg_set_rest (secptr, subseg); 196 return secptr; 197} 198 199void 200subseg_set (segT secptr, subsegT subseg) 201{ 202 if (! (secptr == now_seg && subseg == now_subseg)) 203 subseg_set_rest (secptr, subseg); 204 mri_common_symbol = NULL; 205} 206 207#ifndef obj_sec_sym_ok_for_reloc 208#define obj_sec_sym_ok_for_reloc(SEC) 0 209#endif 210 211symbolS * 212section_symbol (segT sec) 213{ 214 segment_info_type *seginfo = seg_info (sec); 215 symbolS *s; 216 217 if (seginfo == 0) 218 abort (); 219 if (seginfo->sym) 220 return seginfo->sym; 221 222#ifndef EMIT_SECTION_SYMBOLS 223#define EMIT_SECTION_SYMBOLS 1 224#endif 225 226 if (! EMIT_SECTION_SYMBOLS || symbol_table_frozen) 227 { 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); 230 } 231 else 232 { 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) 242 { 243 S_SET_SEGMENT (s, sec); 244 symbol_set_frag (s, &zero_address_frag); 245 } 246 } 247 248 S_CLEAR_EXTERNAL (s); 249 250 /* 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; 255 256 seginfo->sym = s; 257 return s; 258} 259 260/* Return whether the specified segment is thought to hold text. */ 261 262int 263subseg_text_p (segT sec) 264{ 265 return (bfd_get_section_flags (stdoutput, sec) & SEC_CODE) != 0; 266} 267 268/* 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. */ 273 274int 275seg_not_empty_p (segT sec ATTRIBUTE_UNUSED) 276{ 277 segment_info_type *seginfo = seg_info (sec); 278 frchainS *chain; 279 fragS *frag; 280 281 if (!seginfo) 282 return 0; 283 284 for (chain = seginfo->frchainP; chain; chain = chain->frch_next) 285 { 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; 292 } 293 return 0; 294} 295 296void 297subsegs_print_statistics (FILE *file) 298{ 299 frchainS *frchp; 300 asection *s; 301 302 fprintf (file, "frag chains:\n"); 303 for (s = stdoutput->sections; s; s = s->next) 304 { 305 segment_info_type *seginfo; 306 307 /* Skip gas-internal sections. */ 308 if (segment_name (s)[0] == '*') 309 continue; 310 311 seginfo = seg_info (s); 312 if (!seginfo) 313 continue; 314 315 for (frchp = seginfo->frchainP; frchp; frchp = frchp->frch_next) 316 { 317 int count = 0; 318 fragS *fragp; 319 320 for (fragp = frchp->frch_root; fragp; fragp = fragp->fr_next) 321 count++; 322 323 fprintf (file, "\n"); 324 fprintf (file, "\t%p %-10s\t%10d frags\n", (void *) frchp, 325 segment_name (s), count); 326 } 327 } 328} 329 330/* end of subsegs.c */ 331