gcc/lto/lto-object.c

   1 /* LTO routines to use object files.
   2    Copyright (C) 2010-2017 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     {
 107       error ("open %s failed: %s", fname, xstrerror (errno));
 108       goto fail;
 109     }
 110
 111   if (!writable)
 112     {
 113       simple_object_attributes *attrs;
 114
 115       lo->sobj_r = simple_object_start_read (lo->fd, offset, LTO_SEGMENT_NAME,
 116                                              &errmsg, &err);
 117       if (lo->sobj_r == NULL)
 118         goto fail_errmsg;
 119
 120       attrs = simple_object_fetch_attributes (lo->sobj_r, &errmsg, &err);
 121       if (attrs == NULL)
 122         goto fail_errmsg;
 123
 124       if (saved_attributes == NULL)
 125         saved_attributes = attrs;
 126       else
 127         {
 128           errmsg = simple_object_attributes_merge (saved_attributes, attrs,
 129                                                    &err);
 130           if (errmsg != NULL)
 131             {
 132               free (attrs);
 133               goto fail_errmsg;
 134             }
 135         }
 136     }
 137   else
 138     {
 139       gcc_assert (saved_attributes != NULL);
 140       lo->sobj_w = simple_object_start_write (saved_attributes,
 141                                               LTO_SEGMENT_NAME,
 142                                               &errmsg, &err);
 143       if (lo->sobj_w == NULL)
 144         goto fail_errmsg;
 145     }
 146
 147   return &lo->base;
 148
 149  fail_errmsg:
 150   if (err == 0)
 151     error ("%s: %s", fname, errmsg);
 152   else
 153     error ("%s: %s: %s", fname, errmsg, xstrerror (err));
 154
 155  fail:
 156   if (lo->fd != -1)
 157     lto_obj_file_close ((lto_file *) lo);
 158   free (lo);
 159   return NULL;
 160 }
 161
 162
 163 /* Close FILE.  If FILE was opened for writing, it is written out
 164    now.  */
 165
 166 void
 167 lto_obj_file_close (lto_file *file)
 168 {
 169   struct lto_simple_object *lo = (struct lto_simple_object *) file;
 170
 171   if (lo->sobj_r != NULL)
 172     simple_object_release_read (lo->sobj_r);
 173   else if (lo->sobj_w != NULL)
 174     {
 175       const char *errmsg;
 176       int err;
 177
 178       gcc_assert (lo->base.offset == 0);
 179
 180       errmsg = simple_object_write_to_file (lo->sobj_w, lo->fd, &err);
 181       if (errmsg != NULL)
 182         {
 183           if (err == 0)
 184             fatal_error (input_location, "%s", errmsg);
 185           else
 186             fatal_error (input_location, "%s: %s", errmsg, xstrerror (err));
 187         }
 188
 189       simple_object_release_write (lo->sobj_w);
 190     }
 191
 192   if (lo->fd != -1)
 193     {
 194       if (close (lo->fd) < 0)
 195         fatal_error (input_location, "close: %s", xstrerror (errno));
 196     }
 197 }
 198
 199 /* This is passed to lto_obj_add_section.  */
 200
 201 struct lto_obj_add_section_data
 202 {
 203   /* The hash table of sections.  */
 204   htab_t section_hash_table;
 205   /* The offset of this file.  */
 206   off_t base_offset;
 207   /* List in linker order */
 208   struct lto_section_list *list;
 209 };
 210
 211 /* This is called for each section in the file.  */
 212
 213 static int
 214 lto_obj_add_section (void *data, const char *name, off_t offset,
 215                      off_t length)
 216 {
 217   struct lto_obj_add_section_data *loasd =
 218     (struct lto_obj_add_section_data *) data;
 219   htab_t section_hash_table = (htab_t) loasd->section_hash_table;
 220   char *new_name;
 221   struct lto_section_slot s_slot;
 222   void **slot;
 223   struct lto_section_list *list = loasd->list;
 224
 225   if (strncmp (name, section_name_prefix, strlen (section_name_prefix)))
 226     return 1;
 227
 228   new_name = xstrdup (name);
 229   s_slot.name = new_name;
 230   slot = htab_find_slot (section_hash_table, &s_slot, INSERT);
 231   if (*slot == NULL)
 232     {
 233       struct lto_section_slot *new_slot = XCNEW (struct lto_section_slot);
 234
 235       new_slot->name = new_name;
 236       new_slot->start = loasd->base_offset + offset;
 237       new_slot->len = length;
 238       *slot = new_slot;
 239
 240       if (list != NULL)
 241         {
 242           if (!list->first)
 243             list->first = new_slot;
 244           if (list->last)
 245             list->last->next = new_slot;
 246           list->last = new_slot;
 247         }
 248     }
 249   else
 250     {
 251       error ("two or more sections for %s", new_name);
 252       return 0;
 253     }
 254
 255   return 1;
 256 }
 257
 258 /* Build a hash table whose key is the section name and whose data is
 259    the start and size of each section in the .o file.  */
 260
 261 htab_t
 262 lto_obj_build_section_table (lto_file *lto_file, struct lto_section_list *list)
 263 {
 264   struct lto_simple_object *lo = (struct lto_simple_object *) lto_file;
 265   htab_t section_hash_table;
 266   struct lto_obj_add_section_data loasd;
 267   const char *errmsg;
 268   int err;
 269
 270   section_hash_table = lto_obj_create_section_hash_table ();
 271
 272   gcc_assert (lo->sobj_r != NULL && lo->sobj_w == NULL);
 273   loasd.section_hash_table = section_hash_table;
 274   loasd.base_offset = lo->base.offset;
 275   loasd.list = list;
 276   errmsg = simple_object_find_sections (lo->sobj_r, lto_obj_add_section,
 277                                         &loasd, &err);
 278   if (errmsg != NULL)
 279     {
 280       if (err == 0)
 281         error ("%s", errmsg);
 282       else
 283         error ("%s: %s", errmsg, xstrerror (err));
 284       htab_delete (section_hash_table);
 285       return NULL;
 286     }
 287
 288   return section_hash_table;
 289 }
 290
 291 /* The current output file.  */
 292
 293 static lto_file *current_out_file;
 294
 295 /* Set the current output file.  Return the old one.  */
 296
 297 lto_file *
 298 lto_set_current_out_file (lto_file *file)
 299 {
 300   lto_file *old_file;
 301
 302   old_file = current_out_file;
 303   current_out_file = file;
 304   return old_file;
 305 }
 306
 307 /* Return the current output file.  */
 308
 309 lto_file *
 310 lto_get_current_out_file (void)
 311 {
 312   return current_out_file;
 313 }
 314
 315 /* Begin writing a new section named NAME in the current output
 316    file.  */
 317
 318 void
 319 lto_obj_begin_section (const char *name)
 320 {
 321   struct lto_simple_object *lo;
 322   int align;
 323   const char *errmsg;
 324   int err;
 325
 326   lo = (struct lto_simple_object *) current_out_file;
 327   gcc_assert (lo != NULL
 328               && lo->sobj_r == NULL
 329               && lo->sobj_w != NULL
 330               && lo->section == NULL);
 331
 332   align = ceil_log2 (POINTER_SIZE_UNITS);
 333   lo->section = simple_object_write_create_section (lo->sobj_w, name, align,
 334                                                     &errmsg, &err);
 335   if (lo->section == NULL)
 336     {
 337       if (err == 0)
 338         fatal_error (input_location, "%s", errmsg);
 339       else
 340         fatal_error (input_location, "%s: %s", errmsg, xstrerror (errno));
 341     }
 342 }
 343
 344 /* Add data to a section.  BLOCK is a pointer to memory containing
 345    DATA.  */
 346
 347 void
 348 lto_obj_append_data (const void *data, size_t len, void *)
 349 {
 350   struct lto_simple_object *lo;
 351   const char *errmsg;
 352   int err;
 353
 354   lo = (struct lto_simple_object *) current_out_file;
 355   gcc_assert (lo != NULL && lo->section != NULL);
 356
 357   errmsg = simple_object_write_add_data (lo->sobj_w, lo->section, data, len,
 358                                          1, &err);
 359   if (errmsg != NULL)
 360     {
 361       if (err == 0)
 362         fatal_error (input_location, "%s", errmsg);
 363       else
 364         fatal_error (input_location, "%s: %s", errmsg, xstrerror (errno));
 365     }
 366 }
 367
 368 /* Stop writing to the current output section.  */
 369
 370 void
 371 lto_obj_end_section (void)
 372 {
 373   struct lto_simple_object *lo;
 374
 375   lo = (struct lto_simple_object *) current_out_file;
 376   gcc_assert (lo != NULL && lo->section != NULL);
 377   lo->section = NULL;
 378 }