gcc/c-pch.c

   1 /* Precompiled header implementation for the C languages.
   2    Copyright (C) 2000, 2002, 2003, 2004 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 2, 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 COPYING.  If not, write to
  18 the Free Software Foundation, 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "version.h"
  25 #include "cpplib.h"
  26 #include "tree.h"
  27 #include "flags.h"
  28 #include "c-common.h"
  29 #include "output.h"
  30 #include "toplev.h"
  31 #include "debug.h"
  32 #include "c-pragma.h"
  33 #include "ggc.h"
  34 #include "langhooks.h"
  35 #include "hosthooks.h"
  36 #include "target.h"
  37
  38 /* This is a list of flag variables that must match exactly, and their
  39    names for the error message.  The possible values for *flag_var must
  40    fit in a 'signed char'.  */
  41
  42 static const struct c_pch_matching
  43 {
  44   int *flag_var;
  45   const char *flag_name;
  46 } pch_matching[] = {
  47   { &flag_exceptions, "-fexceptions" },
  48   { &flag_unit_at_a_time, "-funit-at-a-time" }
  49 };
  50
  51 enum {
  52   MATCH_SIZE = ARRAY_SIZE (pch_matching)
  53 };
  54
  55 /* This structure is read very early when validating the PCH, and
  56    might be read for a PCH which is for a completely different compiler
  57    for a different operating system.  Thus, it should really only contain
  58    'unsigned char' entries, at least in the initial entries.
  59
  60    If you add or change entries before version_length, you should increase
  61    the version number in get_ident().
  62
  63    There are a bunch of fields named *_length; those are lengths of data that
  64    follows this structure in the same order as the fields in the structure.  */
  65
  66 struct c_pch_validity
  67 {
  68   unsigned char host_machine_length;
  69   unsigned char target_machine_length;
  70   unsigned char version_length;
  71   unsigned char debug_info_type;
  72   signed char match[MATCH_SIZE];
  73   void (*pch_init) (void);
  74   size_t target_data_length;
  75 };
  76
  77 struct c_pch_header
  78 {
  79   unsigned long asm_size;
  80 };
  81
  82 #define IDENT_LENGTH 8
  83
  84 /* The file we'll be writing the PCH to.  */
  85 static FILE *pch_outfile;
  86
  87 /* The position in the assembler output file when pch_init was called.  */
  88 static long asm_file_startpos;
  89
  90 /* The host and target machines.  */
  91 static const char host_machine[] = HOST_MACHINE;
  92 static const char target_machine[] = TARGET_MACHINE;
  93
  94 static const char *get_ident (void);
  95
  96 /* Compute an appropriate 8-byte magic number for the PCH file, so that
  97    utilities like file(1) can identify it, and so that GCC can quickly
  98    ignore non-PCH files and PCH files that are of a completely different
  99    format.  */
 100
 101 static const char *
 102 get_ident(void)
 103 {
 104   static char result[IDENT_LENGTH];
 105   static const char template[IDENT_LENGTH] = "gpch.012";
 106   static const char c_language_chars[] = "Co+O";
 107
 108   memcpy (result, template, IDENT_LENGTH);
 109   result[4] = c_language_chars[c_language];
 110
 111   return result;
 112 }
 113
 114 /* Prepare to write a PCH file.  This is called at the start of
 115    compilation.  */
 116
 117 void
 118 pch_init (void)
 119 {
 120   FILE *f;
 121   struct c_pch_validity v;
 122   void *target_validity;
 123   static const char partial_pch[IDENT_LENGTH] = "gpcWrite";
 124
 125   if (! pch_file)
 126     return;
 127
 128   f = fopen (pch_file, "w+b");
 129   if (f == NULL)
 130     fatal_error ("can't create precompiled header %s: %m", pch_file);
 131   pch_outfile = f;
 132
 133   if (strlen (host_machine) > 255 || strlen (target_machine) > 255
 134       || strlen (version_string) > 255)
 135     abort ();
 136
 137   v.host_machine_length = strlen (host_machine);
 138   v.target_machine_length = strlen (target_machine);
 139   v.version_length = strlen (version_string);
 140   v.debug_info_type = write_symbols;
 141   {
 142     size_t i;
 143     for (i = 0; i < MATCH_SIZE; i++)
 144       {
 145         v.match[i] = *pch_matching[i].flag_var;
 146         if (v.match[i] != *pch_matching[i].flag_var)
 147           abort ();
 148       }
 149   }
 150   v.pch_init = &pch_init;
 151   target_validity = targetm.get_pch_validity (&v.target_data_length);
 152
 153   if (fwrite (partial_pch, IDENT_LENGTH, 1, f) != 1
 154       || fwrite (&v, sizeof (v), 1, f) != 1
 155       || fwrite (host_machine, v.host_machine_length, 1, f) != 1
 156       || fwrite (target_machine, v.target_machine_length, 1, f) != 1
 157       || fwrite (version_string, v.version_length, 1, f) != 1
 158       || fwrite (target_validity, v.target_data_length, 1, f) != 1)
 159     fatal_error ("can't write to %s: %m", pch_file);
 160
 161   /* We need to be able to re-read the output.  */
 162   /* The driver always provides a valid -o option.  */
 163   if (asm_file_name == NULL
 164       || strcmp (asm_file_name, "-") == 0)
 165     fatal_error ("`%s' is not a valid output file", asm_file_name);
 166
 167   asm_file_startpos = ftell (asm_out_file);
 168
 169   /* Let the debugging format deal with the PCHness.  */
 170   (*debug_hooks->handle_pch) (0);
 171
 172   cpp_save_state (parse_in, f);
 173 }
 174
 175 /* Write the PCH file.  This is called at the end of a compilation which
 176    will produce a PCH file.  */
 177
 178 void
 179 c_common_write_pch (void)
 180 {
 181   char *buf;
 182   long asm_file_end;
 183   long written;
 184   struct c_pch_header h;
 185
 186   (*debug_hooks->handle_pch) (1);
 187
 188   cpp_write_pch_deps (parse_in, pch_outfile);
 189
 190   asm_file_end = ftell (asm_out_file);
 191   h.asm_size = asm_file_end - asm_file_startpos;
 192
 193   if (fwrite (&h, sizeof (h), 1, pch_outfile) != 1)
 194     fatal_error ("can't write %s: %m", pch_file);
 195
 196   buf = xmalloc (16384);
 197   fflush (asm_out_file);
 198
 199   if (fseek (asm_out_file, asm_file_startpos, SEEK_SET) != 0)
 200     fatal_error ("can't seek in %s: %m", asm_file_name);
 201
 202   for (written = asm_file_startpos; written < asm_file_end; )
 203     {
 204       long size = asm_file_end - written;
 205       if (size > 16384)
 206         size = 16384;
 207       if (fread (buf, size, 1, asm_out_file) != 1)
 208         fatal_error ("can't read %s: %m", asm_file_name);
 209       if (fwrite (buf, size, 1, pch_outfile) != 1)
 210         fatal_error ("can't write %s: %m", pch_file);
 211       written += size;
 212     }
 213   free (buf);
 214   /* asm_out_file can be written afterwards, so must be flushed first.  */
 215   fflush (asm_out_file);
 216
 217   gt_pch_save (pch_outfile);
 218   cpp_write_pch_state (parse_in, pch_outfile);
 219
 220   if (fseek (pch_outfile, 0, SEEK_SET) != 0
 221       || fwrite (get_ident (), IDENT_LENGTH, 1, pch_outfile) != 1)
 222     fatal_error ("can't write %s: %m", pch_file);
 223
 224   fclose (pch_outfile);
 225 }
 226
 227 /* Check the PCH file called NAME, open on FD, to see if it can be
 228    used in this compilation.  Return 1 if valid, 0 if the file can't
 229    be used now but might be if it's seen later in the compilation, and
 230    2 if this file could never be used in the compilation.  */
 231
 232 int
 233 c_common_valid_pch (cpp_reader *pfile, const char *name, int fd)
 234 {
 235   int sizeread;
 236   int result;
 237   char ident[IDENT_LENGTH];
 238   char short_strings[256 * 3];
 239   int strings_length;
 240   const char *pch_ident;
 241   struct c_pch_validity v;
 242
 243   /* Perform a quick test of whether this is a valid
 244      precompiled header for the current language.  */
 245
 246   sizeread = read (fd, ident, IDENT_LENGTH);
 247   if (sizeread == -1)
 248     fatal_error ("can't read %s: %m", name);
 249   else if (sizeread != IDENT_LENGTH)
 250     return 2;
 251
 252   pch_ident = get_ident();
 253   if (memcmp (ident, pch_ident, IDENT_LENGTH) != 0)
 254     {
 255       if (cpp_get_options (pfile)->warn_invalid_pch)
 256         {
 257           if (memcmp (ident, pch_ident, 5) == 0)
 258             /* It's a PCH, for the right language, but has the wrong version.
 259              */
 260             cpp_error (pfile, CPP_DL_WARNING,
 261                        "%s: not compatible with this GCC version", name);
 262           else if (memcmp (ident, pch_ident, 4) == 0)
 263             /* It's a PCH for the wrong language.  */
 264             cpp_error (pfile, CPP_DL_WARNING, "%s: not for %s", name,
 265                        lang_hooks.name);
 266           else
 267             /* Not any kind of PCH.  */
 268             cpp_error (pfile, CPP_DL_WARNING, "%s: not a PCH file", name);
 269         }
 270       return 2;
 271     }
 272
 273   /* At this point, we know it's a PCH file, so it ought to be long enough
 274      that we can read a c_pch_validity structure.  */
 275   if (read (fd, &v, sizeof (v)) != sizeof (v))
 276     fatal_error ("can't read %s: %m", name);
 277
 278   strings_length = (v.host_machine_length + v.target_machine_length
 279                     + v.version_length);
 280   if (read (fd, short_strings, strings_length) != strings_length)
 281     fatal_error ("can't read %s: %m", name);
 282   if (v.host_machine_length != strlen (host_machine)
 283       || memcmp (host_machine, short_strings, strlen (host_machine)) != 0)
 284     {
 285       if (cpp_get_options (pfile)->warn_invalid_pch)
 286         cpp_error (pfile, CPP_DL_WARNING,
 287                    "%s: created on host `%.*s', but used on host `%s'", name,
 288                    v.host_machine_length, short_strings, host_machine);
 289       return 2;
 290     }
 291   if (v.target_machine_length != strlen (target_machine)
 292       || memcmp (target_machine, short_strings + v.host_machine_length,
 293                  strlen (target_machine)) != 0)
 294     {
 295       if (cpp_get_options (pfile)->warn_invalid_pch)
 296         cpp_error (pfile, CPP_DL_WARNING,
 297                    "%s: created for target `%.*s', but used for target `%s'",
 298                    name, v.target_machine_length,
 299                    short_strings + v.host_machine_length, target_machine);
 300       return 2;
 301     }
 302   if (v.version_length != strlen (version_string)
 303       || memcmp (version_string,
 304                  (short_strings + v.host_machine_length
 305                   + v.target_machine_length),
 306                  v.version_length) != 0)
 307     {
 308       if (cpp_get_options (pfile)->warn_invalid_pch)
 309         cpp_error (pfile, CPP_DL_WARNING,
 310                    "%s: created by version `%.*s', but this is version `%s'",
 311                    name, v.version_length,
 312                    (short_strings + v.host_machine_length
 313                     + v.target_machine_length),
 314                    version_string);
 315       return 2;
 316     }
 317
 318   /* The allowable debug info combinations are that either the PCH file
 319      was built with the same as is being used now, or the PCH file was
 320      built for some kind of debug info but now none is in use.  */
 321   if (v.debug_info_type != write_symbols
 322       && write_symbols != NO_DEBUG)
 323     {
 324       if (cpp_get_options (pfile)->warn_invalid_pch)
 325         cpp_error (pfile, CPP_DL_WARNING,
 326                    "%s: created with -g%s, but used with -g%s", name,
 327                    debug_type_names[v.debug_info_type],
 328                    debug_type_names[write_symbols]);
 329       return 2;
 330     }
 331
 332   /* Check flags that must match exactly.  */
 333   {
 334     size_t i;
 335     for (i = 0; i < MATCH_SIZE; i++)
 336       if (*pch_matching[i].flag_var != v.match[i])
 337         {
 338           if (cpp_get_options (pfile)->warn_invalid_pch)
 339             cpp_error (pfile, CPP_DL_WARNING,
 340                        "%s: settings for %s do not match", name,
 341                        pch_matching[i].flag_name);
 342           return 2;
 343         }
 344   }
 345
 346   /* If the text segment was not loaded at the same address as it was
 347      when the PCH file was created, function pointers loaded from the
 348      PCH will not be valid.  We could in theory remap all the function
 349      pointers, but no support for that exists at present.  */
 350   if (v.pch_init != &pch_init)
 351     {
 352       if (cpp_get_options (pfile)->warn_invalid_pch)
 353         cpp_error (pfile, CPP_DL_WARNING,
 354                    "%s: had text segment at different address", name);
 355       return 2;
 356     }
 357
 358   /* Check the target-specific validity data.  */
 359   {
 360     void *this_file_data = xmalloc (v.target_data_length);
 361     const char *msg;
 362
 363     if ((size_t) read (fd, this_file_data, v.target_data_length)
 364         != v.target_data_length)
 365       fatal_error ("can't read %s: %m", name);
 366     msg = targetm.pch_valid_p (this_file_data, v.target_data_length);
 367     free (this_file_data);
 368     if (msg != NULL)
 369       {
 370         if (cpp_get_options (pfile)->warn_invalid_pch)
 371           cpp_error (pfile, CPP_DL_WARNING, "%s: %s", name, msg);
 372         return 2;
 373       }
 374   }
 375
 376   /* Check the preprocessor macros are the same as when the PCH was
 377      generated.  */
 378
 379   result = cpp_valid_state (pfile, name, fd);
 380   if (result == -1)
 381     return 2;
 382   else
 383     return result == 0;
 384 }
 385
 386 /* Load in the PCH file NAME, open on FD.  It was originally searched for
 387    by ORIG_NAME.  */
 388
 389 void
 390 c_common_read_pch (cpp_reader *pfile, const char *name,
 391                    int fd, const char *orig_name ATTRIBUTE_UNUSED)
 392 {
 393   FILE *f;
 394   struct c_pch_header h;
 395   char *buf;
 396   unsigned long written;
 397   struct save_macro_data *smd;
 398
 399   f = fdopen (fd, "rb");
 400   if (f == NULL)
 401     {
 402       cpp_errno (pfile, CPP_DL_ERROR, "calling fdopen");
 403       return;
 404     }
 405
 406   cpp_get_callbacks (parse_in)->valid_pch = NULL;
 407
 408   if (fread (&h, sizeof (h), 1, f) != 1)
 409     {
 410       cpp_errno (pfile, CPP_DL_ERROR, "reading");
 411       return;
 412     }
 413
 414   buf = xmalloc (16384);
 415   for (written = 0; written < h.asm_size; )
 416     {
 417       long size = h.asm_size - written;
 418       if (size > 16384)
 419         size = 16384;
 420       if (fread (buf, size, 1, f) != 1
 421           || fwrite (buf, size, 1, asm_out_file) != 1)
 422         cpp_errno (pfile, CPP_DL_ERROR, "reading");
 423       written += size;
 424     }
 425   free (buf);
 426
 427   cpp_prepare_state (pfile, &smd);
 428
 429   gt_pch_restore (f);
 430
 431   if (cpp_read_state (pfile, name, f, smd) != 0)
 432     return;
 433
 434   fclose (f);
 435 }
 436
 437 /* Indicate that no more PCH files should be read.  */
 438
 439 void
 440 c_common_no_more_pch (void)
 441 {
 442   if (cpp_get_callbacks (parse_in)->valid_pch)
 443     {
 444       cpp_get_callbacks (parse_in)->valid_pch = NULL;
 445       host_hooks.gt_pch_use_address (NULL, 0, -1, 0);
 446     }
 447 }