gcc/lto/lto-object.cc

   1 /* LTO routines to use object files.
   2    Copyright (C) 2010-2023 Free Software Foundation, Inc.
   3    Written by Ian Lance Taylor, Google.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "diagnostic-core.h"
  26 #include "lto.h"
  27 #include "lto-section-names.h"
  28 #include "simple-object.h"
  29
  30 /* An LTO file wrapped around an simple_object.  */
  31
  32 struct lto_simple_object
  33 {
  34   /* The base information.  */
  35   lto_file base;
  36
  37   /* The system file descriptor.  */
  38   int fd;
  39
  40   /* The simple_object if we are reading the file.  */
  41   simple_object_read *sobj_r;
  42
  43   /* The simple_object if we are writing the file.  */
  44   simple_object_write *sobj_w;
  45
  46   /* The currently active section.  */
  47   simple_object_write_section *section;
  48 };
  49
  50 /* Saved simple_object attributes.  FIXME: Once set, this is never
  51    cleared.  */
  52
  53 static simple_object_attributes *saved_attributes;
  54
  55 /* Initialize FILE, an LTO file object for FILENAME.  */
  56
  57 static void
  58 lto_file_init (lto_file *file, const char *filename, off_t offset)
  59 {
  60   file->filename = filename;
  61   file->offset = offset;
  62 }
  63
  64 /* Open the file FILENAME.  It WRITABLE is true, the file is opened
  65    for write and, if necessary, created.  Otherwise, the file is
  66    opened for reading.  Returns the opened file.  */
  67
  68 lto_file *
  69 lto_obj_file_open (const char *filename, bool writable)
  70 {
  71   const char *offset_p;
  72   long loffset;
  73   int consumed;
  74   char *fname;
  75   off_t offset;
  76   struct lto_simple_object *lo;
  77   const char *errmsg;
  78   int err;
  79
  80   offset_p = strrchr (filename, '@');
  81   if (offset_p != NULL
  82       && offset_p != filename
  83       && sscanf (offset_p, "@%li%n", &loffset, &consumed) >= 1
  84       && strlen (offset_p) == (unsigned int) consumed)
  85     {
  86       fname = XNEWVEC (char, offset_p - filename + 1);
  87       memcpy (fname, filename, offset_p - filename);
  88       fname[offset_p - filename] = '\0';
  89       offset = (off_t) loffset;
  90     }
  91   else
  92     {
  93       fname = xstrdup (filename);
  94       offset = 0;
  95     }
  96
  97   lo = XCNEW (struct lto_simple_object);
  98   lto_file_init ((lto_file *) lo, fname, offset);
  99
 100   lo->fd = open (fname,
 101                  (writable
 102                   ? O_WRONLY | O_CREAT | O_BINARY
 103                   : O_RDONLY | O_BINARY),
 104                  0666);
 105   if (lo->fd == -1)
 106     fatal_error (input_location, "open %s failed: %s", fname, xstrerror (errno));
 107
 108   if (!writable)
 109     {
 110       simple_object_attributes *attrs;
 111
 112       lo->sobj_r = simple_object_start_read (lo->fd, offset, LTO_SEGMENT_NAME,
 113                                              &errmsg, &err);
 114       if (lo->sobj_r == NULL)
 115         goto fail_errmsg;
 116
 117       attrs = simple_object_fetch_attributes (lo->sobj_r, &errmsg, &err);
 118       if (attrs == NULL)
 119         goto fail_errmsg;
 120
 121       if (saved_attributes == NULL)
 122         saved_attributes = attrs;
 123       else
 124         {
 125           errmsg = simple_object_attributes_merge (saved_attributes, attrs,
 126                                                    &err);
 127           if (errmsg != NULL)
 128             {
 129               free (attrs);
 130               goto fail_errmsg;
 131             }
 132         }
 133     }
 134   else
 135     {
 136       gcc_assert (saved_attributes != NULL);
 137       lo->sobj_w = simple_object_start_write (saved_attributes,
 138                                               LTO_SEGMENT_NAME,
 139                                               &errmsg, &err);
 140       if (lo->sobj_w == NULL)
 141         goto fail_errmsg;
 142     }
 143
 144   return &lo->base;
 145
 146 fail_errmsg:
 147   if (err == 0)
 148     error ("%s: %s", fname, errmsg);
 149   else
 150     error ("%s: %s: %s", fname, errmsg, xstrerror (err));
 151
 152   if (lo->fd != -1)
 153     lto_obj_file_close ((lto_file *) lo);
 154   free (lo);
 155   return NULL;
 156 }
 157
 158
 159 /* Close FILE.  If FILE was opened for writing, it is written out
 160    now.  */
 161
 162 void
 163 lto_obj_file_close (lto_file *file)
 164 {
 165   struct lto_simple_object *lo = (struct lto_simple_object *) file;
 166
 167   if (lo->sobj_r != NULL)
 168     simple_object_release_read (lo->sobj_r);
 169   else if (lo->sobj_w != NULL)
 170     {
 171       const char *errmsg;
 172       int err;
 173
 174       gcc_assert (lo->base.offset == 0);
 175
 176       errmsg = simple_object_write_to_file (lo->sobj_w, lo->fd, &err);
 177       if (errmsg != NULL)
 178         {
 179           if (err == 0)
 180             fatal_error (input_location, "%s", errmsg);
 181           else
 182             fatal_error (input_location, "%s: %s", errmsg, xstrerror (err));
 183         }
 184
 185       simple_object_release_write (lo->sobj_w);
 186     }
 187
 188   if (lo->fd != -1)
 189     {
 190       if (close (lo->fd) < 0)
 191         fatal_error (input_location, "close: %s", xstrerror (errno));
 192     }
 193 }
 194
 195 /* This is passed to lto_obj_add_section.  */
 196
 197 struct lto_obj_add_section_data
 198 {
 199   /* The hash table of sections.  */
 200   htab_t section_hash_table;
 201   /* The offset of this file.  */
 202   off_t base_offset;
 203   /* List in linker order */
 204   struct lto_section_list *list;
 205 };
 206
 207 /* This is called for each section in the file.  */
 208
 209 static int
 210 lto_obj_add_section (void *data, const char *name, off_t offset,
 211                      off_t length)
 212 {
 213   struct lto_obj_add_section_data *loasd =
 214     (struct lto_obj_add_section_data *) data;
 215   htab_t section_hash_table = (htab_t) loasd->section_hash_table;
 216   char *new_name;
 217   struct lto_section_slot s_slot;
 218   void **slot;
 219   struct lto_section_list *list = loasd->list;
 220
 221   if (strncmp (name, section_name_prefix, strlen (section_name_prefix)))
 222     return 1;
 223
 224   new_name = xstrdup (name);
 225   s_slot.name = new_name;
 226   slot = htab_find_slot (section_hash_table, &s_slot, INSERT);
 227   if (*slot == NULL)
 228     {
 229       struct lto_section_slot *new_slot = XCNEW (struct lto_section_slot);
 230
 231       new_slot->name = new_name;
 232       new_slot->start = loasd->base_offset + offset;
 233       new_slot->len = length;
 234       *slot = new_slot;
 235
 236       if (list != NULL)
 237         {
 238           if (!list->first)
 239             list->first = new_slot;
 240           if (list->last)
 241             list->last->next = new_slot;
 242           list->last = new_slot;
 243         }
 244     }
 245   else
 246     {
 247       error ("two or more sections for %s", new_name);
 248       return 0;
 249     }
 250
 251   return 1;
 252 }
 253
 254 /* Build a hash table whose key is the section name and whose data is
 255    the start and size of each section in the .o file.  */
 256
 257 htab_t
 258 lto_obj_build_section_table (lto_file *lto_file, struct lto_section_list *list)
 259 {
 260   struct lto_simple_object *lo = (struct lto_simple_object *) lto_file;
 261   htab_t section_hash_table;
 262   struct lto_obj_add_section_data loasd;
 263   const char *errmsg;
 264   int err;
 265
 266   section_hash_table = lto_obj_create_section_hash_table ();
 267
 268   gcc_assert (lo->sobj_r != NULL && lo->sobj_w == NULL);
 269   loasd.section_hash_table = section_hash_table;
 270   loasd.base_offset = lo->base.offset;
 271   loasd.list = list;
 272   errmsg = simple_object_find_sections (lo->sobj_r, lto_obj_add_section,
 273                                         &loasd, &err);
 274   if (errmsg != NULL)
 275     {
 276       if (err == 0)
 277         error ("%s", errmsg);
 278       else
 279         error ("%s: %s", errmsg, xstrerror (err));
 280       htab_delete (section_hash_table);
 281       return NULL;
 282     }
 283
 284   return section_hash_table;
 285 }
 286
 287 /* The current output file.  */
 288
 289 static lto_file *current_out_file;
 290
 291 /* Set the current output file.  Return the old one.  */
 292
 293 lto_file *
 294 lto_set_current_out_file (lto_file *file)
 295 {
 296   lto_file *old_file;
 297
 298   old_file = current_out_file;
 299   current_out_file = file;
 300   return old_file;
 301 }
 302
 303 /* Return the current output file.  */
 304
 305 lto_file *
 306 lto_get_current_out_file (void)
 307 {
 308   return current_out_file;
 309 }
 310
 311 /* Begin writing a new section named NAME in the current output
 312    file.  */
 313
 314 void
 315 lto_obj_begin_section (const char *name)
 316 {
 317   struct lto_simple_object *lo;
 318   int align;
 319   const char *errmsg;
 320   int err;
 321
 322   lo = (struct lto_simple_object *) current_out_file;
 323   gcc_assert (lo != NULL
 324               && lo->sobj_r == NULL
 325               && lo->sobj_w != NULL
 326               && lo->section == NULL);
 327
 328   align = ceil_log2 (POINTER_SIZE_UNITS);
 329   lo->section = simple_object_write_create_section (lo->sobj_w, name, align,
 330                                                     &errmsg, &err);
 331   if (lo->section == NULL)
 332     {
 333       if (err == 0)
 334         fatal_error (input_location, "%s", errmsg);
 335       else
 336         fatal_error (input_location, "%s: %s", errmsg, xstrerror (errno));
 337     }
 338 }
 339
 340 /* Add data to a section.  BLOCK is a pointer to memory containing
 341    DATA.  */
 342
 343 void
 344 lto_obj_append_data (const void *data, size_t len, void *)
 345 {
 346   struct lto_simple_object *lo;
 347   const char *errmsg;
 348   int err;
 349
 350   lo = (struct lto_simple_object *) current_out_file;
 351   gcc_assert (lo != NULL && lo->section != NULL);
 352
 353   errmsg = simple_object_write_add_data (lo->sobj_w, lo->section, data, len,
 354                                          1, &err);
 355   if (errmsg != NULL)
 356     {
 357       if (err == 0)
 358         fatal_error (input_location, "%s", errmsg);
 359       else
 360         fatal_error (input_location, "%s: %s", errmsg, xstrerror (errno));
 361     }
 362 }
 363
 364 /* Stop writing to the current output section.  */
 365
 366 void
 367 lto_obj_end_section (void)
 368 {
 369   struct lto_simple_object *lo;
 370
 371   lo = (struct lto_simple_object *) current_out_file;
 372   gcc_assert (lo != NULL && lo->section != NULL);
 373   lo->section = NULL;
 374 }