gcc/c-family/c-pch.c

   1 /* Precompiled header implementation for the C languages.
   2    Copyright (C) 2000-2019 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 "target.h"
  24 #include "c-common.h"
  25 #include "timevar.h"
  26 #include "flags.h"
  27 #include "debug.h"
  28 #include "c-pragma.h"
  29 #include "langhooks.h"
  30 #include "hosthooks.h"
  31
  32 /* This is a list of flag variables that must match exactly, and their
  33    names for the error message.  The possible values for *flag_var must
  34    fit in a 'signed char'.  */
  35
  36 static const struct c_pch_matching
  37 {
  38   int *flag_var;
  39   const char *flag_name;
  40 } pch_matching[] = {
  41   { &flag_exceptions, "-fexceptions" },
  42 };
  43
  44 enum {
  45   MATCH_SIZE = ARRAY_SIZE (pch_matching)
  46 };
  47
  48 /* Information about flags and suchlike that affect PCH validity.
  49
  50    Before this structure is read, both an initial 8-character identification
  51    string, and a 16-byte checksum, have been read and validated.  */
  52
  53 struct c_pch_validity
  54 {
  55   unsigned char debug_info_type;
  56   signed char match[MATCH_SIZE];
  57   void (*pch_init) (void);
  58   size_t target_data_length;
  59 };
  60
  61 #define IDENT_LENGTH 8
  62
  63 /* The file we'll be writing the PCH to.  */
  64 static FILE *pch_outfile;
  65
  66 static const char *get_ident (void);
  67
  68 /* Compute an appropriate 8-byte magic number for the PCH file, so that
  69    utilities like file(1) can identify it, and so that GCC can quickly
  70    ignore non-PCH files and PCH files that are of a completely different
  71    format.  */
  72
  73 static const char *
  74 get_ident (void)
  75 {
  76   static char result[IDENT_LENGTH];
  77   static const char templ[] = "gpch.014";
  78   static const char c_language_chars[] = "Co+O";
  79
  80   memcpy (result, templ, IDENT_LENGTH);
  81   result[4] = c_language_chars[c_language];
  82
  83   return result;
  84 }
  85
  86 /* Whether preprocessor state should be saved by pch_init.  */
  87
  88 static bool pch_ready_to_save_cpp_state = false;
  89
  90 /* Prepare to write a PCH file, if one is being written.  This is
  91    called at the start of compilation.  */
  92
  93 void
  94 pch_init (void)
  95 {
  96   FILE *f;
  97   struct c_pch_validity v;
  98   void *target_validity;
  99   static const char partial_pch[] = "gpcWrite";
 100
 101   if (!pch_file)
 102     return;
 103
 104   f = fopen (pch_file, "w+b");
 105   if (f == NULL)
 106     fatal_error (input_location, "cannot create precompiled header %s: %m",
 107                  pch_file);
 108   pch_outfile = f;
 109
 110   memset (&v, '\0', sizeof (v));
 111   v.debug_info_type = write_symbols;
 112   {
 113     size_t i;
 114     for (i = 0; i < MATCH_SIZE; i++)
 115       {
 116         v.match[i] = *pch_matching[i].flag_var;
 117         gcc_assert (v.match[i] == *pch_matching[i].flag_var);
 118       }
 119   }
 120   v.pch_init = &pch_init;
 121   target_validity = targetm.get_pch_validity (&v.target_data_length);
 122
 123   if (fwrite (partial_pch, IDENT_LENGTH, 1, f) != 1
 124       || fwrite (executable_checksum, 16, 1, f) != 1
 125       || fwrite (&v, sizeof (v), 1, f) != 1
 126       || fwrite (target_validity, v.target_data_length, 1, f) != 1)
 127     fatal_error (input_location, "cannot write to %s: %m", pch_file);
 128
 129   /* Let the debugging format deal with the PCHness.  */
 130   (*debug_hooks->handle_pch) (0);
 131
 132   if (pch_ready_to_save_cpp_state)
 133     pch_cpp_save_state ();
 134
 135   XDELETE (target_validity);
 136 }
 137
 138 /* Whether preprocessor state has been saved in a PCH file.  */
 139
 140 static bool pch_cpp_state_saved = false;
 141
 142 /* Save preprocessor state in a PCH file, after implicitly included
 143    headers have been read.  If the PCH file has not yet been opened,
 144    record that state should be saved when it is opened.  */
 145
 146 void
 147 pch_cpp_save_state (void)
 148 {
 149   if (!pch_cpp_state_saved)
 150     {
 151       if (pch_outfile)
 152         {
 153           cpp_save_state (parse_in, pch_outfile);
 154           pch_cpp_state_saved = true;
 155         }
 156       else
 157         pch_ready_to_save_cpp_state = true;
 158     }
 159 }
 160
 161 /* Write the PCH file.  This is called at the end of a compilation which
 162    will produce a PCH file.  */
 163
 164 void
 165 c_common_write_pch (void)
 166 {
 167   timevar_push (TV_PCH_SAVE);
 168
 169   targetm.prepare_pch_save ();
 170
 171   (*debug_hooks->handle_pch) (1);
 172
 173   prepare_target_option_nodes_for_pch ();
 174
 175   cpp_write_pch_deps (parse_in, pch_outfile);
 176
 177   gt_pch_save (pch_outfile);
 178
 179   timevar_push (TV_PCH_CPP_SAVE);
 180   cpp_write_pch_state (parse_in, pch_outfile);
 181   timevar_pop (TV_PCH_CPP_SAVE);
 182
 183   if (fseek (pch_outfile, 0, SEEK_SET) != 0
 184       || fwrite (get_ident (), IDENT_LENGTH, 1, pch_outfile) != 1)
 185     fatal_error (input_location, "cannot write %s: %m", pch_file);
 186
 187   fclose (pch_outfile);
 188
 189   timevar_pop (TV_PCH_SAVE);
 190 }
 191
 192 /* Check the PCH file called NAME, open on FD, to see if it can be
 193    used in this compilation.  Return 1 if valid, 0 if the file can't
 194    be used now but might be if it's seen later in the compilation, and
 195    2 if this file could never be used in the compilation.  */
 196
 197 int
 198 c_common_valid_pch (cpp_reader *pfile, const char *name, int fd)
 199 {
 200   int sizeread;
 201   int result;
 202   char ident[IDENT_LENGTH + 16];
 203   const char *pch_ident;
 204   struct c_pch_validity v;
 205
 206   /* Perform a quick test of whether this is a valid
 207      precompiled header for the current language.  */
 208
 209   sizeread = read (fd, ident, IDENT_LENGTH + 16);
 210   if (sizeread == -1)
 211     fatal_error (input_location, "cannot read %s: %m", name);
 212   else if (sizeread != IDENT_LENGTH + 16)
 213     {
 214       if (cpp_get_options (pfile)->warn_invalid_pch)
 215         cpp_error (pfile, CPP_DL_WARNING, "%s: too short to be a PCH file",
 216                    name);
 217       return 2;
 218     }
 219
 220   pch_ident = get_ident();
 221   if (memcmp (ident, pch_ident, IDENT_LENGTH) != 0)
 222     {
 223       if (cpp_get_options (pfile)->warn_invalid_pch)
 224         {
 225           if (memcmp (ident, pch_ident, 5) == 0)
 226             /* It's a PCH, for the right language, but has the wrong version.
 227              */
 228             cpp_error (pfile, CPP_DL_WARNING,
 229                        "%s: not compatible with this GCC version", name);
 230           else if (memcmp (ident, pch_ident, 4) == 0)
 231             /* It's a PCH for the wrong language.  */
 232             cpp_error (pfile, CPP_DL_WARNING, "%s: not for %s", name,
 233                        lang_hooks.name);
 234           else
 235             /* Not any kind of PCH.  */
 236             cpp_error (pfile, CPP_DL_WARNING, "%s: not a PCH file", name);
 237         }
 238       return 2;
 239     }
 240   if (memcmp (ident + IDENT_LENGTH, executable_checksum, 16) != 0)
 241     {
 242       if (cpp_get_options (pfile)->warn_invalid_pch)
 243         cpp_error (pfile, CPP_DL_WARNING,
 244                    "%s: created by a different GCC executable", name);
 245       return 2;
 246     }
 247
 248   /* At this point, we know it's a PCH file created by this
 249      executable, so it ought to be long enough that we can read a
 250      c_pch_validity structure.  */
 251   if (read (fd, &v, sizeof (v)) != sizeof (v))
 252     fatal_error (input_location, "cannot read %s: %m", name);
 253
 254   /* The allowable debug info combinations are that either the PCH file
 255      was built with the same as is being used now, or the PCH file was
 256      built for some kind of debug info but now none is in use.  */
 257   if (v.debug_info_type != write_symbols
 258       && write_symbols != NO_DEBUG)
 259     {
 260       if (cpp_get_options (pfile)->warn_invalid_pch)
 261         cpp_error (pfile, CPP_DL_WARNING,
 262                    "%s: created with -g%s, but used with -g%s", name,
 263                    debug_type_names[v.debug_info_type],
 264                    debug_type_names[write_symbols]);
 265       return 2;
 266     }
 267
 268   /* Check flags that must match exactly.  */
 269   {
 270     size_t i;
 271     for (i = 0; i < MATCH_SIZE; i++)
 272       if (*pch_matching[i].flag_var != v.match[i])
 273         {
 274           if (cpp_get_options (pfile)->warn_invalid_pch)
 275             cpp_error (pfile, CPP_DL_WARNING,
 276                        "%s: settings for %s do not match", name,
 277                        pch_matching[i].flag_name);
 278           return 2;
 279         }
 280   }
 281
 282   /* If the text segment was not loaded at the same address as it was
 283      when the PCH file was created, function pointers loaded from the
 284      PCH will not be valid.  We could in theory remap all the function
 285      pointers, but no support for that exists at present.
 286      Since we have the same executable, it should only be necessary to
 287      check one function.  */
 288   if (v.pch_init != &pch_init)
 289     {
 290       if (cpp_get_options (pfile)->warn_invalid_pch)
 291         cpp_error (pfile, CPP_DL_WARNING,
 292                    "%s: had text segment at different address", name);
 293       return 2;
 294     }
 295
 296   /* Check the target-specific validity data.  */
 297   {
 298     void *this_file_data = xmalloc (v.target_data_length);
 299     const char *msg;
 300
 301     if ((size_t) read (fd, this_file_data, v.target_data_length)
 302         != v.target_data_length)
 303       fatal_error (input_location, "cannot read %s: %m", name);
 304     msg = targetm.pch_valid_p (this_file_data, v.target_data_length);
 305     free (this_file_data);
 306     if (msg != NULL)
 307       {
 308         if (cpp_get_options (pfile)->warn_invalid_pch)
 309           cpp_error (pfile, CPP_DL_WARNING, "%s: %s", name, msg);
 310         return 2;
 311       }
 312   }
 313
 314   /* Check the preprocessor macros are the same as when the PCH was
 315      generated.  */
 316
 317   result = cpp_valid_state (pfile, name, fd);
 318   if (result == -1)
 319     return 2;
 320   else
 321     return result == 0;
 322 }
 323
 324 /* If non-NULL, this function is called after a precompile header file
 325    is loaded.  */
 326 void (*lang_post_pch_load) (void);
 327
 328 /* Load in the PCH file NAME, open on FD.  It was originally searched for
 329    by ORIG_NAME.  */
 330
 331 void
 332 c_common_read_pch (cpp_reader *pfile, const char *name,
 333                    int fd, const char *orig_name ATTRIBUTE_UNUSED)
 334 {
 335   FILE *f;
 336   struct save_macro_data *smd;
 337   expanded_location saved_loc;
 338   bool saved_trace_includes;
 339
 340   timevar_push (TV_PCH_RESTORE);
 341
 342   f = fdopen (fd, "rb");
 343   if (f == NULL)
 344     {
 345       cpp_errno (pfile, CPP_DL_ERROR, "calling fdopen");
 346       close (fd);
 347       goto end;
 348     }
 349
 350   cpp_get_callbacks (parse_in)->valid_pch = NULL;
 351
 352   /* Save the location and then restore it after reading the PCH.  */
 353   saved_loc = expand_location (line_table->highest_line);
 354   saved_trace_includes = line_table->trace_includes;
 355
 356   timevar_push (TV_PCH_CPP_RESTORE);
 357   cpp_prepare_state (pfile, &smd);
 358   timevar_pop (TV_PCH_CPP_RESTORE);
 359
 360   gt_pch_restore (f);
 361   cpp_set_line_map (pfile, line_table);
 362   rebuild_location_adhoc_htab (line_table);
 363
 364   timevar_push (TV_PCH_CPP_RESTORE);
 365   if (cpp_read_state (pfile, name, f, smd) != 0)
 366     {
 367       fclose (f);
 368       timevar_pop (TV_PCH_CPP_RESTORE);
 369       goto end;
 370     }
 371   timevar_pop (TV_PCH_CPP_RESTORE);
 372
 373
 374   fclose (f);
 375
 376   line_table->trace_includes = saved_trace_includes;
 377   linemap_add (line_table, LC_ENTER, 0, saved_loc.file, saved_loc.line);
 378
 379   /* Give the front end a chance to take action after a PCH file has
 380      been loaded.  */
 381   if (lang_post_pch_load)
 382     (*lang_post_pch_load) ();
 383
 384 end:
 385   timevar_pop (TV_PCH_RESTORE);
 386 }
 387
 388 /* Indicate that no more PCH files should be read.  */
 389
 390 void
 391 c_common_no_more_pch (void)
 392 {
 393   if (cpp_get_callbacks (parse_in)->valid_pch)
 394     {
 395       cpp_get_callbacks (parse_in)->valid_pch = NULL;
 396       host_hooks.gt_pch_use_address (NULL, 0, -1, 0);
 397     }
 398 }
 399
 400 /* Handle #pragma GCC pch_preprocess, to load in the PCH file.  */
 401
 402 void
 403 c_common_pch_pragma (cpp_reader *pfile, const char *name)
 404 {
 405   int fd;
 406
 407   if (!cpp_get_options (pfile)->preprocessed)
 408     {
 409       error ("%<pch_preprocess%> pragma should only be used "
 410              "with %<-fpreprocessed%>");
 411       inform (input_location, "use %<#include%> instead");
 412       return;
 413     }
 414
 415   fd = open (name, O_RDONLY | O_BINARY, 0666);
 416   if (fd == -1)
 417     fatal_error (input_location, "%s: couldn%'t open PCH file: %m", name);
 418
 419   if (c_common_valid_pch (pfile, name, fd) != 1)
 420     {
 421       if (!cpp_get_options (pfile)->warn_invalid_pch)
 422         inform (input_location, "use %<-Winvalid-pch%> for more information");
 423       fatal_error (input_location, "%s: PCH file was invalid", name);
 424     }
 425
 426   c_common_read_pch (pfile, name, fd, name);
 427
 428   close (fd);
 429 }
 430