1 /* subsegs.c - subsegments - 2 Copyright (C) 1987-2020 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 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 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 = XCNEW (segment_info_type); 67 seginfo->bfd_section = seg; 68 bfd_set_section_userdata (seg, seginfo); 69 } 70 } 71 72 static void 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 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 ? bfd_section_name (now_seg) : 0; 150 151 if (!force_new 152 && now_seg_name 153 && (now_seg_name == segname 154 || !strcmp (now_seg_name, segname))) 155 return now_seg; 156 157 if (!force_new) 158 secptr = bfd_make_section_old_way (stdoutput, segname); 159 else 160 secptr = bfd_make_section_anyway (stdoutput, segname); 161 162 seginfo = seg_info (secptr); 163 if (! seginfo) 164 { 165 secptr->output_section = secptr; 166 seginfo = XCNEW (segment_info_type); 167 seginfo->bfd_section = secptr; 168 bfd_set_section_userdata (secptr, seginfo); 169 } 170 return secptr; 171 } 172 173 segT 174 subseg_new (const char *segname, subsegT subseg) 175 { 176 segT secptr; 177 178 secptr = subseg_get (segname, 0); 179 subseg_set_rest (secptr, subseg); 180 return secptr; 181 } 182 183 /* Like subseg_new, except a new section is always created, even if 184 a section with that name already exists. */ 185 segT 186 subseg_force_new (const char *segname, subsegT subseg) 187 { 188 segT secptr; 189 190 secptr = subseg_get (segname, 1); 191 subseg_set_rest (secptr, subseg); 192 return secptr; 193 } 194 195 void 196 subseg_set (segT secptr, subsegT subseg) 197 { 198 if (! (secptr == now_seg && subseg == now_subseg)) 199 subseg_set_rest (secptr, subseg); 200 mri_common_symbol = NULL; 201 } 202 203 #ifndef obj_sec_sym_ok_for_reloc 204 #define obj_sec_sym_ok_for_reloc(SEC) 0 205 #endif 206 207 symbolS * 208 section_symbol (segT sec) 209 { 210 segment_info_type *seginfo = seg_info (sec); 211 symbolS *s; 212 213 if (seginfo == 0) 214 abort (); 215 if (seginfo->sym) 216 return seginfo->sym; 217 218 #ifndef EMIT_SECTION_SYMBOLS 219 #define EMIT_SECTION_SYMBOLS 1 220 #endif 221 222 if (! EMIT_SECTION_SYMBOLS || symbol_table_frozen) 223 { 224 /* Here we know it won't be going into the symbol table. */ 225 s = symbol_create (sec->symbol->name, sec, 0, &zero_address_frag); 226 } 227 else 228 { 229 segT seg; 230 s = symbol_find (sec->symbol->name); 231 /* We have to make sure it is the right symbol when we 232 have multiple sections with the same section name. */ 233 if (s == NULL 234 || ((seg = S_GET_SEGMENT (s)) != sec 235 && seg != undefined_section)) 236 s = symbol_new (sec->symbol->name, sec, 0, &zero_address_frag); 237 else if (seg == undefined_section) 238 { 239 S_SET_SEGMENT (s, sec); 240 symbol_set_frag (s, &zero_address_frag); 241 } 242 } 243 244 S_CLEAR_EXTERNAL (s); 245 246 /* Use the BFD section symbol, if possible. */ 247 if (obj_sec_sym_ok_for_reloc (sec)) 248 symbol_set_bfdsym (s, sec->symbol); 249 else 250 symbol_get_bfdsym (s)->flags |= BSF_SECTION_SYM; 251 252 seginfo->sym = s; 253 return s; 254 } 255 256 /* Return whether the specified segment is thought to hold text. */ 257 258 int 259 subseg_text_p (segT sec) 260 { 261 return (bfd_section_flags (sec) & SEC_CODE) != 0; 262 } 263 264 /* Return non zero if SEC has at least one byte of data. It is 265 possible that we'll return zero even on a non-empty section because 266 we don't know all the fragment types, and it is possible that an 267 fr_fix == 0 one still contributes data. Think of this as 268 seg_definitely_not_empty_p. */ 269 270 int 271 seg_not_empty_p (segT sec ATTRIBUTE_UNUSED) 272 { 273 segment_info_type *seginfo = seg_info (sec); 274 frchainS *chain; 275 fragS *frag; 276 277 if (!seginfo) 278 return 0; 279 280 for (chain = seginfo->frchainP; chain; chain = chain->frch_next) 281 { 282 for (frag = chain->frch_root; frag; frag = frag->fr_next) 283 if (frag->fr_fix) 284 return 1; 285 if (obstack_next_free (&chain->frch_obstack) 286 != chain->frch_last->fr_literal) 287 return 1; 288 } 289 return 0; 290 } 291 292 void 293 subsegs_print_statistics (FILE *file) 294 { 295 frchainS *frchp; 296 asection *s; 297 298 /* PR 20897 - check to see if the output bfd was actually created. */ 299 if (stdoutput == NULL) 300 return; 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