| 1 | /* subsegs.c - subsegments - |
| 2 | Copyright (C) 1987-2018 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 | \f |
| 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 | \f |
| 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 | \f |
| 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 | /* PR 20897 - check to see if the output bfd was actually created. */ |
| 301 | if (stdoutput == NULL) |
| 302 | return; |
| 303 | |
| 304 | fprintf (file, "frag chains:\n"); |
| 305 | for (s = stdoutput->sections; s; s = s->next) |
| 306 | { |
| 307 | segment_info_type *seginfo; |
| 308 | |
| 309 | /* Skip gas-internal sections. */ |
| 310 | if (segment_name (s)[0] == '*') |
| 311 | continue; |
| 312 | |
| 313 | seginfo = seg_info (s); |
| 314 | if (!seginfo) |
| 315 | continue; |
| 316 | |
| 317 | for (frchp = seginfo->frchainP; frchp; frchp = frchp->frch_next) |
| 318 | { |
| 319 | int count = 0; |
| 320 | fragS *fragp; |
| 321 | |
| 322 | for (fragp = frchp->frch_root; fragp; fragp = fragp->fr_next) |
| 323 | count++; |
| 324 | |
| 325 | fprintf (file, "\n"); |
| 326 | fprintf (file, "\t%p %-10s\t%10d frags\n", (void *) frchp, |
| 327 | segment_name (s), count); |
| 328 | } |
| 329 | } |
| 330 | } |
| 331 | |
| 332 | /* end of subsegs.c */ |