1 /* subsegs.c - subsegments - 2 Copyright (C) 1987-2016 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 37 subsegs_begin (void) 38 { 39 obstack_begin (&frchains, chunksize); 40 #if __GNUC__ >= 2 41 obstack_alignment_mask (&frchains) = __alignof__ (frchainS) - 1; 42 #endif 43 44 frchain_now = NULL; /* Warn new_subseg() that we are booting. */ 45 frag_now = &dummy_frag; 46 } 47 48 /* 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 */ 59 void 60 subseg_change (segT seg, 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 = XCNEW (segment_info_type); 69 seginfo->bfd_section = seg; 70 bfd_set_section_userdata (stdoutput, seg, seginfo); 71 } 72 } 73 74 static void 76 subseg_set_rest (segT seg, subsegT subseg) 77 { 78 frchainS *frcP; /* crawl frchain chain */ 79 frchainS **lastPP; /* address of last pointer */ 80 frchainS *newP; /* address of new frchain */ 81 segment_info_type *seginfo; 82 83 mri_common_symbol = NULL; 84 85 if (frag_now && frchain_now) 86 frchain_now->frch_frag_now = frag_now; 87 88 gas_assert (frchain_now == 0 89 || frchain_now->frch_last == frag_now); 90 91 subseg_change (seg, (int) subseg); 92 93 seginfo = seg_info (seg); 94 95 /* Attempt to find or make a frchain for that subsection. 96 We keep the list sorted by subsection number. */ 97 for (frcP = *(lastPP = &seginfo->frchainP); 98 frcP != NULL; 99 frcP = *(lastPP = &frcP->frch_next)) 100 if (frcP->frch_subseg >= subseg) 101 break; 102 103 if (frcP == NULL || frcP->frch_subseg != subseg) 104 { 105 /* This should be the only code that creates a frchainS. */ 106 107 newP = (frchainS *) obstack_alloc (&frchains, sizeof (frchainS)); 108 newP->frch_subseg = subseg; 109 newP->fix_root = NULL; 110 newP->fix_tail = NULL; 111 obstack_begin (&newP->frch_obstack, chunksize); 112 #if __GNUC__ >= 2 113 obstack_alignment_mask (&newP->frch_obstack) = __alignof__ (fragS) - 1; 114 #endif 115 newP->frch_frag_now = frag_alloc (&newP->frch_obstack); 116 newP->frch_frag_now->fr_type = rs_fill; 117 newP->frch_cfi_data = NULL; 118 119 newP->frch_root = newP->frch_last = newP->frch_frag_now; 120 121 *lastPP = newP; 122 newP->frch_next = frcP; 123 frcP = newP; 124 } 125 126 frchain_now = frcP; 127 frag_now = frcP->frch_frag_now; 128 129 gas_assert (frchain_now->frch_last == frag_now); 130 } 131 132 /* 133 * subseg_set(segT, subsegT) 134 * 135 * If you attempt to change to the current subsegment, nothing happens. 136 * 137 * In: segT, subsegT code for new subsegment. 138 * frag_now -> incomplete frag for current subsegment. 139 * If frag_now==NULL, then there is no old, incomplete frag, so 140 * the old frag is not closed off. 141 * 142 * Out: now_subseg, now_seg updated. 143 * Frchain_now points to the (possibly new) struct frchain for this 144 * sub-segment. 145 */ 146 147 segT 148 subseg_get (const char *segname, int force_new) 149 { 150 segT secptr; 151 segment_info_type *seginfo; 152 const char *now_seg_name = (now_seg 153 ? bfd_get_section_name (stdoutput, now_seg) 154 : 0); 155 156 if (!force_new 157 && now_seg_name 158 && (now_seg_name == segname 159 || !strcmp (now_seg_name, segname))) 160 return now_seg; 161 162 if (!force_new) 163 secptr = bfd_make_section_old_way (stdoutput, segname); 164 else 165 secptr = bfd_make_section_anyway (stdoutput, segname); 166 167 seginfo = seg_info (secptr); 168 if (! seginfo) 169 { 170 secptr->output_section = secptr; 171 seginfo = XCNEW (segment_info_type); 172 seginfo->bfd_section = secptr; 173 bfd_set_section_userdata (stdoutput, secptr, seginfo); 174 } 175 return secptr; 176 } 177 178 segT 179 subseg_new (const char *segname, subsegT subseg) 180 { 181 segT secptr; 182 183 secptr = subseg_get (segname, 0); 184 subseg_set_rest (secptr, subseg); 185 return secptr; 186 } 187 188 /* Like subseg_new, except a new section is always created, even if 189 a section with that name already exists. */ 190 segT 191 subseg_force_new (const char *segname, subsegT subseg) 192 { 193 segT secptr; 194 195 secptr = subseg_get (segname, 1); 196 subseg_set_rest (secptr, subseg); 197 return secptr; 198 } 199 200 void 201 subseg_set (segT secptr, subsegT subseg) 202 { 203 if (! (secptr == now_seg && subseg == now_subseg)) 204 subseg_set_rest (secptr, subseg); 205 mri_common_symbol = NULL; 206 } 207 208 #ifndef obj_sec_sym_ok_for_reloc 209 #define obj_sec_sym_ok_for_reloc(SEC) 0 210 #endif 211 212 symbolS * 213 section_symbol (segT sec) 214 { 215 segment_info_type *seginfo = seg_info (sec); 216 symbolS *s; 217 218 if (seginfo == 0) 219 abort (); 220 if (seginfo->sym) 221 return seginfo->sym; 222 223 #ifndef EMIT_SECTION_SYMBOLS 224 #define EMIT_SECTION_SYMBOLS 1 225 #endif 226 227 if (! EMIT_SECTION_SYMBOLS || symbol_table_frozen) 228 { 229 /* Here we know it won't be going into the symbol table. */ 230 s = symbol_create (sec->symbol->name, sec, 0, &zero_address_frag); 231 } 232 else 233 { 234 segT seg; 235 s = symbol_find (sec->symbol->name); 236 /* We have to make sure it is the right symbol when we 237 have multiple sections with the same section name. */ 238 if (s == NULL 239 || ((seg = S_GET_SEGMENT (s)) != sec 240 && seg != undefined_section)) 241 s = symbol_new (sec->symbol->name, sec, 0, &zero_address_frag); 242 else if (seg == undefined_section) 243 { 244 S_SET_SEGMENT (s, sec); 245 symbol_set_frag (s, &zero_address_frag); 246 } 247 } 248 249 S_CLEAR_EXTERNAL (s); 250 251 /* Use the BFD section symbol, if possible. */ 252 if (obj_sec_sym_ok_for_reloc (sec)) 253 symbol_set_bfdsym (s, sec->symbol); 254 else 255 symbol_get_bfdsym (s)->flags |= BSF_SECTION_SYM; 256 257 seginfo->sym = s; 258 return s; 259 } 260 261 /* Return whether the specified segment is thought to hold text. */ 262 263 int 264 subseg_text_p (segT sec) 265 { 266 return (bfd_get_section_flags (stdoutput, sec) & SEC_CODE) != 0; 267 } 268 269 /* Return non zero if SEC has at least one byte of data. It is 270 possible that we'll return zero even on a non-empty section because 271 we don't know all the fragment types, and it is possible that an 272 fr_fix == 0 one still contributes data. Think of this as 273 seg_definitely_not_empty_p. */ 274 275 int 276 seg_not_empty_p (segT sec ATTRIBUTE_UNUSED) 277 { 278 segment_info_type *seginfo = seg_info (sec); 279 frchainS *chain; 280 fragS *frag; 281 282 if (!seginfo) 283 return 0; 284 285 for (chain = seginfo->frchainP; chain; chain = chain->frch_next) 286 { 287 for (frag = chain->frch_root; frag; frag = frag->fr_next) 288 if (frag->fr_fix) 289 return 1; 290 if (obstack_next_free (&chain->frch_obstack) 291 != chain->frch_last->fr_literal) 292 return 1; 293 } 294 return 0; 295 } 296 297 void 298 subsegs_print_statistics (FILE *file) 299 { 300 frchainS *frchp; 301 asection *s; 302 303 fprintf (file, "frag chains:\n"); 304 for (s = stdoutput->sections; s; s = s->next) 305 { 306 segment_info_type *seginfo; 307 308 /* Skip gas-internal sections. */ 309 if (segment_name (s)[0] == '*') 310 continue; 311 312 seginfo = seg_info (s); 313 if (!seginfo) 314 continue; 315 316 for (frchp = seginfo->frchainP; frchp; frchp = frchp->frch_next) 317 { 318 int count = 0; 319 fragS *fragp; 320 321 for (fragp = frchp->frch_root; fragp; fragp = fragp->fr_next) 322 count++; 323 324 fprintf (file, "\n"); 325 fprintf (file, "\t%p %-10s\t%10d frags\n", (void *) frchp, 326 segment_name (s), count); 327 } 328 } 329 } 330 331 /* end of subsegs.c */ 332
