gcc/c-family/c-pch.c

   1 /* Precompiled header implementation for the C languages.
   2    Copyright (C) 2000-2014 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC 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 GCC 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 GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "version.h"
  24 #include "cpplib.h"
  25 #include "tree.h"
  26 #include "flags.h"
  27 #include "c-common.h"
  28 #include "debug.h"
  29 #include "c-pragma.h"
  30 #include "ggc.h"
  31 #include "langhooks.h"
  32 #include "hosthooks.h"
  33 #include "target.h"
  34 #include "opts.h"
  35 #include "timevar.h"
  36
  37 /* This is a list of flag variables that must match exactly, and their
  38    names for the error message.  The possible values for *flag_var must
  39    fit in a 'signed char'.  */
  40
  41 static const struct c_pch_matching
  42 {
  43   int *flag_var;
  44   const char *flag_name;
  45 } pch_matching[] = {
  46   { &flag_exceptions, "-fexceptions" },
  47 };
  48
  49 enum {
  50   MATCH_SIZE = ARRAY_SIZE (pch_matching)
  51 };
  52
  53 /* The value of the checksum in the dummy compiler that is actually
  54    checksummed.  That compiler should never be run.  */
  55 static const char no_checksum[16] = { 0 };
  56
  57 /* Information about flags and suchlike that affect PCH validity.
  58
  59    Before this structure is read, both an initial 8-character identification
  60    string, and a 16-byte checksum, have been read and validated.  */
  61
  62 struct c_pch_validity
  63 {
  64   unsigned char debug_info_type;
  65   signed char match[MATCH_SIZE];
  66   void (*pch_init) (void);
  67   size_t target_data_length;
  68 };
  69
  70 #define IDENT_LENGTH 8
  71
  72 /* The file we'll be writing the PCH to.  */
  73 static FILE *pch_outfile;
  74
  75 static const char *get_ident (void);
  76
  77 /* Compute an appropriate 8-byte magic number for the PCH file, so that
  78    utilities like file(1) can identify it, and so that GCC can quickly
  79    ignore non-PCH files and PCH files that are of a completely different
  80    format.  */
  81
  82 static const char *
  83 get_ident (void)
  84 {
  85   static char result[IDENT_LENGTH];
  86   static const char templ[] = "gpch.014";
  87   static const char c_language_chars[] = "Co+O";
  88
  89   memcpy (result, templ, IDENT_LENGTH);
  90   result[4] = c_language_chars[c_language];
  91
  92   return result;
  93 }
  94
  95 /* Whether preprocessor state should be saved by pch_init.  */
  96
  97 static bool pch_ready_to_save_cpp_state = false;
  98
  99 /* Prepare to write a PCH file, if one is being written.  This is
 100    called at the start of compilation.  */
 101
 102 void
 103 pch_init (void)
 104 {
 105   FILE *f;
 106   struct c_pch_validity v;
 107   void *target_validity;
 108   static const char partial_pch[] = "gpcWrite";
 109
 110   if (!pch_file)
 111     return;
 112
 113   f = fopen (pch_file, "w+b");
 114   if (f == NULL)
 115     fatal_error ("can%'t create precompiled header %s: %m", pch_file);
 116   pch_outfile = f;
 117
 118   gcc_assert (memcmp (executable_checksum, no_checksum, 16) != 0);
 119
 120   memset (&v, '\0', sizeof (v));
 121   v.debug_info_type = write_symbols;
 122   {
 123     size_t i;
 124     for (i = 0; i < MATCH_SIZE; i++)
 125       {
 126         v.match[i] = *pch_matching[i].flag_var;
 127         gcc_assert (v.match[i] == *pch_matching[i].flag_var);
 128       }
 129   }
 130   v.pch_init = &pch_init;
 131   target_validity = targetm.get_pch_validity (&v.target_data_length);
 132
 133   if (fwrite (partial_pch, IDENT_LENGTH, 1, f) != 1
 134       || fwrite (executable_checksum, 16, 1, f) != 1
 135       || fwrite (&v, sizeof (v), 1, f) != 1
 136       || fwrite (target_validity, v.target_data_length, 1, f) != 1)
 137     fatal_error ("can%'t write to %s: %m", pch_file);
 138
 139   /* Let the debugging format deal with the PCHness.  */
 140   (*debug_hooks->handle_pch) (0);
 141
 142   if (pch_ready_to_save_cpp_state)
 143     pch_cpp_save_state ();
 144
 145   XDELETE (target_validity);
 146 }
 147
 148 /* Whether preprocessor state has been saved in a PCH file.  */
 149
 150 static bool pch_cpp_state_saved = false;
 151
 152 /* Save preprocessor state in a PCH file, after implicitly included
 153    headers have been read.  If the PCH file has not yet been opened,
 154    record that state should be saved when it is opened.  */
 155
 156 void
 157 pch_cpp_save_state (void)
 158 {
 159   if (!pch_cpp_state_saved)
 160     {
 161       if (pch_outfile)
 162         {
 163           cpp_save_state (parse_in, pch_outfile);
 164           pch_cpp_state_saved = true;
 165         }
 166       else
 167         pch_ready_to_save_cpp_state = true;
 168     }
 169 }
 170
 171 /* Write the PCH file.  This is called at the end of a compilation which
 172    will produce a PCH file.  */
 173
 174 void
 175 c_common_write_pch (void)
 176 {
 177   timevar_push (TV_PCH_SAVE);
 178
 179   targetm.prepare_pch_save ();
 180
 181   (*debug_hooks->handle_pch) (1);
 182
 183   prepare_target_option_nodes_for_pch ();
 184
 185   cpp_write_pch_deps (parse_in, pch_outfile);
 186
 187   gt_pch_save (pch_outfile);
 188
 189   timevar_push (TV_PCH_CPP_SAVE);
 190   cpp_write_pch_state (parse_in, pch_outfile);
 191   timevar_pop (TV_PCH_CPP_SAVE);
 192
 193   if (fseek (pch_outfile, 0, SEEK_SET) != 0
 194       || fwrite (get_ident (), IDENT_LENGTH, 1, pch_outfile) != 1)
 195     fatal_error ("can%'t write %s: %m", pch_file);
 196
 197   fclose (pch_outfile);
 198
 199   timevar_pop (TV_PCH_SAVE);
 200 }
 201
 202 /* Check the PCH file called NAME, open on FD, to see if it can be
 203    used in this compilation.  Return 1 if valid, 0 if the file can't
 204    be used now but might be if it's seen later in the compilation, and
 205    2 if this file could never be used in the compilation.  */
 206
 207 int
 208 c_common_valid_pch (cpp_reader *pfile, const char *name, int fd)
 209 {
 210   int sizeread;
 211   int result;
 212   char ident[IDENT_LENGTH + 16];
 213   const char *pch_ident;
 214   struct c_pch_validity v;
 215
 216   /* Perform a quick test of whether this is a valid
 217      precompiled header for the current language.  */
 218
 219   gcc_assert (memcmp (executable_checksum, no_checksum, 16) != 0);
 220
 221   sizeread = read (fd, ident, IDENT_LENGTH + 16);
 222   if (sizeread == -1)
 223     fatal_error ("can%'t read %s: %m", name);
 224   else if (sizeread != IDENT_LENGTH + 16)
 225     {
 226       if (cpp_get_options (pfile)->warn_invalid_pch)
 227         cpp_error (pfile, CPP_DL_WARNING, "%s: too short to be a PCH file",
 228                    name);
 229       return 2;
 230     }
 231
 232   pch_ident = get_ident();
 233   if (memcmp (ident, pch_ident, IDENT_LENGTH) != 0)
 234     {
 235       if (cpp_get_options (pfile)->warn_invalid_pch)
 236         {
 237           if (memcmp (ident, pch_ident, 5) == 0)
 238             /* It's a PCH, for the right language, but has the wrong version.
 239              */
 240             cpp_error (pfile, CPP_DL_WARNING,
 241                        "%s: not compatible with this GCC version", name);
 242           else if (memcmp (ident, pch_ident, 4) == 0)
 243             /* It's a PCH for the wrong language.  */
 244             cpp_error (pfile, CPP_DL_WARNING, "%s: not for %s", name,
 245                        lang_hooks.name);
 246           else
 247             /* Not any kind of PCH.  */
 248             cpp_error (pfile, CPP_DL_WARNING, "%s: not a PCH file", name);
 249         }
 250       return 2;
 251     }
 252   if (memcmp (ident + IDENT_LENGTH, executable_checksum, 16) != 0)
 253     {
 254       if (cpp_get_options (pfile)->warn_invalid_pch)
 255         cpp_error (pfile, CPP_DL_WARNING,
 256                    "%s: created by a different GCC executable", name);
 257       return 2;
 258     }
 259
 260   /* At this point, we know it's a PCH file created by this
 261      executable, so it ought to be long enough that we can read a
 262      c_pch_validity structure.  */
 263   if (read (fd, &v, sizeof (v)) != sizeof (v))
 264     fatal_error ("can%'t read %s: %m", name);
 265
 266   /* The allowable debug info combinations are that either the PCH file
 267      was built with the same as is being used now, or the PCH file was
 268      built for some kind of debug info but now none is in use.  */
 269   if (v.debug_info_type != write_symbols
 270       && write_symbols != NO_DEBUG)
 271     {
 272       if (cpp_get_options (pfile)->warn_invalid_pch)
 273         cpp_error (pfile, CPP_DL_WARNING,
 274                    "%s: created with -g%s, but used with -g%s", name,
 275                    debug_type_names[v.debug_info_type],
 276                    debug_type_names[write_symbols]);
 277       return 2;
 278     }
 279
 280   /* Check flags that must match exactly.  */
 281   {
 282     size_t i;
 283     for (i = 0; i < MATCH_SIZE; i++)
 284       if (*pch_matching[i].flag_var != v.match[i])
 285         {
 286           if (cpp_get_options (pfile)->warn_invalid_pch)
 287             cpp_error (pfile, CPP_DL_WARNING,
 288                        "%s: settings for %s do not match", name,
 289                        pch_matching[i].flag_name);
 290           return 2;
 291         }
 292   }
 293
 294   /* If the text segment was not loaded at the same address as it was
 295      when the PCH file was created, function pointers loaded from the
 296      PCH will not be valid.  We could in theory remap all the function
 297      pointers, but no support for that exists at present.
 298      Since we have the same executable, it should only be necessary to
 299      check one function.  */
 300   if (v.pch_init != &pch_init)
 301     {
 302       if (cpp_get_options (pfile)->warn_invalid_pch)
 303         cpp_error (pfile, CPP_DL_WARNING,
 304                    "%s: had text segment at different address", name);
 305       return 2;
 306     }
 307
 308   /* Check the target-specific validity data.  */
 309   {
 310     void *this_file_data = xmalloc (v.target_data_length);
 311     const char *msg;
 312
 313     if ((size_t) read (fd, this_file_data, v.target_data_length)
 314         != v.target_data_length)
 315       fatal_error ("can%'t read %s: %m", name);
 316     msg = targetm.pch_valid_p (this_file_data, v.target_data_length);
 317     free (this_file_data);
 318     if (msg != NULL)
 319       {
 320         if (cpp_get_options (pfile)->warn_invalid_pch)
 321           cpp_error (pfile, CPP_DL_WARNING, "%s: %s", name, msg);
 322         return 2;
 323       }
 324   }
 325
 326   /* Check the preprocessor macros are the same as when the PCH was
 327      generated.  */
 328
 329   result = cpp_valid_state (pfile, name, fd);
 330   if (result == -1)
 331     return 2;
 332   else
 333     return result == 0;
 334 }
 335
 336 /* If non-NULL, this function is called after a precompile header file
 337    is loaded.  */
 338 void (*lang_post_pch_load) (void);
 339
 340 /* Load in the PCH file NAME, open on FD.  It was originally searched for
 341    by ORIG_NAME.  */
 342
 343 void
 344 c_common_read_pch (cpp_reader *pfile, const char *name,
 345                    int fd, const char *orig_name ATTRIBUTE_UNUSED)
 346 {
 347   FILE *f;
 348   struct save_macro_data *smd;
 349   expanded_location saved_loc;
 350   bool saved_trace_includes;
 351
 352   timevar_push (TV_PCH_RESTORE);
 353
 354   f = fdopen (fd, "rb");
 355   if (f == NULL)
 356     {
 357       cpp_errno (pfile, CPP_DL_ERROR, "calling fdopen");
 358       close (fd);
 359       goto end;
 360     }
 361
 362   cpp_get_callbacks (parse_in)->valid_pch = NULL;
 363
 364   /* Save the location and then restore it after reading the PCH.  */
 365   saved_loc = expand_location (line_table->highest_line);
 366   saved_trace_includes = line_table->trace_includes;
 367
 368   timevar_push (TV_PCH_CPP_RESTORE);
 369   cpp_prepare_state (pfile, &smd);
 370   timevar_pop (TV_PCH_CPP_RESTORE);
 371
 372   gt_pch_restore (f);
 373   cpp_set_line_map (pfile, line_table);
 374   rebuild_location_adhoc_htab (line_table);
 375
 376   timevar_push (TV_PCH_CPP_RESTORE);
 377   if (cpp_read_state (pfile, name, f, smd) != 0)
 378     {
 379       fclose (f);
 380       timevar_pop (TV_PCH_CPP_RESTORE);
 381       goto end;
 382     }
 383   timevar_pop (TV_PCH_CPP_RESTORE);
 384
 385
 386   fclose (f);
 387
 388   line_table->trace_includes = saved_trace_includes;
 389   linemap_add (line_table, LC_ENTER, 0, saved_loc.file, saved_loc.line);
 390
 391   /* Give the front end a chance to take action after a PCH file has
 392      been loaded.  */
 393   if (lang_post_pch_load)
 394     (*lang_post_pch_load) ();
 395
 396 end:
 397   timevar_pop (TV_PCH_RESTORE);
 398 }
 399
 400 /* Indicate that no more PCH files should be read.  */
 401
 402 void
 403 c_common_no_more_pch (void)
 404 {
 405   if (cpp_get_callbacks (parse_in)->valid_pch)
 406     {
 407       cpp_get_callbacks (parse_in)->valid_pch = NULL;
 408       host_hooks.gt_pch_use_address (NULL, 0, -1, 0);
 409     }
 410 }
 411
 412 /* Handle #pragma GCC pch_preprocess, to load in the PCH file.  */
 413
 414 void
 415 c_common_pch_pragma (cpp_reader *pfile, const char *name)
 416 {
 417   int fd;
 418
 419   if (!cpp_get_options (pfile)->preprocessed)
 420     {
 421       error ("pch_preprocess pragma should only be used with -fpreprocessed");
 422       inform (input_location, "use #include instead");
 423       return;
 424     }
 425
 426   fd = open (name, O_RDONLY | O_BINARY, 0666);
 427   if (fd == -1)
 428     fatal_error ("%s: couldn%'t open PCH file: %m", name);
 429
 430   if (c_common_valid_pch (pfile, name, fd) != 1)
 431     {
 432       if (!cpp_get_options (pfile)->warn_invalid_pch)
 433         inform (input_location, "use -Winvalid-pch for more information");
 434       fatal_error ("%s: PCH file was invalid", name);
 435     }
 436
 437   c_common_read_pch (pfile, name, fd, name);
 438
 439   close (fd);
 440 }
 441