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 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 (stdoutput, 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 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 = XCNEW (segment_info_type); 169 seginfo->bfd_section = secptr; 170 bfd_set_section_userdata (stdoutput, secptr, seginfo); 171 } 172 return secptr; 173 } 174 175 segT 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 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 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 * 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 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 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 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