gcc/cp/repo.c

   1 /* Code to maintain a C++ template repository.
   2    Copyright (C) 1995-2015 Free Software Foundation, Inc.
   3    Contributed by Jason Merrill (jason@cygnus.com)
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License 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 /* My strategy here is as follows:
  22
  23    Everything should be emitted in a translation unit where it is used.
  24    The results of the automatic process should be easily reproducible with
  25    explicit code.  */
  26
  27 #include "config.h"
  28 #include "system.h"
  29 #include "coretypes.h"
  30 #include "tm.h"
  31 #include "alias.h"
  32 #include "tree.h"
  33 #include "stringpool.h"
  34 #include "cp-tree.h"
  35 #include "obstack.h"
  36 #include "toplev.h"
  37 #include "diagnostic-core.h"
  38 #include "flags.h"
  39
  40 static const char *extract_string (const char **);
  41 static const char *get_base_filename (const char *);
  42 static FILE *open_repo_file (const char *);
  43 static char *afgets (FILE *);
  44 static FILE *reopen_repo_file_for_write (void);
  45
  46 static GTY(()) vec<tree, va_gc> *pending_repo;
  47 static char *repo_name;
  48
  49 static const char *old_args, *old_dir, *old_main;
  50
  51 static struct obstack temporary_obstack;
  52 static bool temporary_obstack_initialized_p;
  53
  54 /* Parse a reasonable subset of shell quoting syntax.  */
  55
  56 static const char *
  57 extract_string (const char **pp)
  58 {
  59   const char *p = *pp;
  60   int backquote = 0;
  61   int inside = 0;
  62
  63   for (;;)
  64     {
  65       char c = *p;
  66       if (c == '\0')
  67         break;
  68       ++p;
  69       if (backquote)
  70         {
  71           obstack_1grow (&temporary_obstack, c);
  72           backquote = 0;
  73         }
  74       else if (! inside && c == ' ')
  75         break;
  76       else if (! inside && c == '\\')
  77         backquote = 1;
  78       else if (c == '\'')
  79         inside = !inside;
  80       else
  81         obstack_1grow (&temporary_obstack, c);
  82     }
  83
  84   obstack_1grow (&temporary_obstack, '\0');
  85   *pp = p;
  86   return (char *) obstack_finish (&temporary_obstack);
  87 }
  88
  89 static const char *
  90 get_base_filename (const char *filename)
  91 {
  92   const char *p = getenv ("COLLECT_GCC_OPTIONS");
  93   const char *output = NULL;
  94   int compiling = 0;
  95
  96   while (p && *p)
  97     {
  98       const char *q = extract_string (&p);
  99
 100       if (strcmp (q, "-o") == 0)
 101         {
 102           if (flag_compare_debug)
 103             /* Just in case aux_base_name was based on a name with two
 104                or more '.'s, add an arbitrary extension that will be
 105                stripped by the caller.  */
 106             output = concat (aux_base_name, ".o", NULL);
 107           else
 108             output = extract_string (&p);
 109         }
 110       else if (strcmp (q, "-c") == 0)
 111         compiling = 1;
 112     }
 113
 114   if (compiling && output)
 115     return output;
 116
 117   if (p && ! compiling)
 118     {
 119       warning (0, "-frepo must be used with -c");
 120       flag_use_repository = 0;
 121       return NULL;
 122     }
 123
 124   return lbasename (filename);
 125 }
 126
 127 static FILE *
 128 open_repo_file (const char *filename)
 129 {
 130   const char *p;
 131   const char *s = get_base_filename (filename);
 132
 133   if (s == NULL)
 134     return NULL;
 135
 136   p = lbasename (s);
 137   p = strrchr (p, '.');
 138   if (! p)
 139     p = s + strlen (s);
 140
 141   repo_name = XNEWVEC (char, p - s + 5);
 142   memcpy (repo_name, s, p - s);
 143   memcpy (repo_name + (p - s), ".rpo", 5);
 144
 145   return fopen (repo_name, "r");
 146 }
 147
 148 static char *
 149 afgets (FILE *stream)
 150 {
 151   int c;
 152   while ((c = getc (stream)) != EOF && c != '\n')
 153     obstack_1grow (&temporary_obstack, c);
 154   if (obstack_object_size (&temporary_obstack) == 0)
 155     return NULL;
 156   obstack_1grow (&temporary_obstack, '\0');
 157   return (char *) obstack_finish (&temporary_obstack);
 158 }
 159
 160 void
 161 init_repo (void)
 162 {
 163   char *buf;
 164   const char *p;
 165   FILE *repo_file;
 166
 167   if (! flag_use_repository)
 168     return;
 169
 170   /* When a PCH file is loaded, the entire identifier table is
 171      replaced, with the result that IDENTIFIER_REPO_CHOSEN is cleared.
 172      So, we have to reread the repository file.  */
 173   lang_post_pch_load = init_repo;
 174
 175   if (!temporary_obstack_initialized_p)
 176     gcc_obstack_init (&temporary_obstack);
 177
 178   repo_file = open_repo_file (main_input_filename);
 179
 180   if (repo_file == 0)
 181     return;
 182
 183   while ((buf = afgets (repo_file)))
 184     {
 185       switch (buf[0])
 186         {
 187         case 'A':
 188           old_args = ggc_strdup (buf + 2);
 189           break;
 190         case 'D':
 191           old_dir = ggc_strdup (buf + 2);
 192           break;
 193         case 'M':
 194           old_main = ggc_strdup (buf + 2);
 195           break;
 196         case 'O':
 197           /* A symbol that we were able to define the last time this
 198              file was compiled.  */
 199           break;
 200         case 'C':
 201           /* A symbol that the prelinker has requested that we
 202              define.  */
 203           {
 204             tree id = get_identifier (buf + 2);
 205             IDENTIFIER_REPO_CHOSEN (id) = 1;
 206           }
 207           break;
 208         default:
 209           error ("mysterious repository information in %s", repo_name);
 210         }
 211       obstack_free (&temporary_obstack, buf);
 212     }
 213   fclose (repo_file);
 214
 215   if (old_args && !get_random_seed (true)
 216       && (p = strstr (old_args, "'-frandom-seed=")))
 217     set_random_seed (extract_string (&p) + strlen ("-frandom-seed="));
 218 }
 219
 220 static FILE *
 221 reopen_repo_file_for_write (void)
 222 {
 223   FILE *repo_file = fopen (repo_name, "w");
 224
 225   if (repo_file == 0)
 226     {
 227       error ("can%'t create repository information file %qs", repo_name);
 228       flag_use_repository = 0;
 229     }
 230
 231   return repo_file;
 232 }
 233
 234 /* Emit any pending repos.  */
 235
 236 void
 237 finish_repo (void)
 238 {
 239   tree val;
 240   char *dir, *args;
 241   FILE *repo_file;
 242   unsigned ix;
 243
 244   if (!flag_use_repository || flag_compare_debug)
 245     return;
 246
 247   if (seen_error ())
 248     return;
 249
 250   repo_file = reopen_repo_file_for_write ();
 251   if (repo_file == 0)
 252     goto out;
 253
 254   fprintf (repo_file, "M %s\n", main_input_filename);
 255   dir = getpwd ();
 256   fprintf (repo_file, "D %s\n", dir);
 257   args = getenv ("COLLECT_GCC_OPTIONS");
 258   if (args)
 259     {
 260       fprintf (repo_file, "A %s", args);
 261       /* If -frandom-seed is not among the ARGS, then add the value
 262          that we chose.  That will ensure that the names of types from
 263          anonymous namespaces will get the same mangling when this
 264          file is recompiled.  */
 265       if (!strstr (args, "'-frandom-seed="))
 266         fprintf (repo_file, " '-frandom-seed=" HOST_WIDE_INT_PRINT_HEX_PURE "'",
 267                  get_random_seed (false));
 268       fprintf (repo_file, "\n");
 269     }
 270
 271   FOR_EACH_VEC_SAFE_ELT_REVERSE (pending_repo, ix, val)
 272     {
 273       tree name = DECL_ASSEMBLER_NAME (val);
 274       char type = IDENTIFIER_REPO_CHOSEN (name) ? 'C' : 'O';
 275       fprintf (repo_file, "%c %s\n", type, IDENTIFIER_POINTER (name));
 276     }
 277
 278  out:
 279   if (repo_file)
 280     fclose (repo_file);
 281 }
 282
 283 /* DECL is a FUNCTION_DECL or VAR_DECL with vague linkage whose
 284    definition is available in this translation unit.  Returns 0 if
 285    this definition should not be emitted in this translation unit
 286    because it will be emitted elsewhere.  Returns 1 if the repository
 287    file indicates that that DECL should be emitted in this translation
 288    unit, or 2 if the repository file is not in use.  */
 289
 290 int
 291 repo_emit_p (tree decl)
 292 {
 293   int ret = 0;
 294   gcc_assert (TREE_PUBLIC (decl));
 295   gcc_assert (VAR_OR_FUNCTION_DECL_P (decl));
 296   gcc_assert (!DECL_REALLY_EXTERN (decl)
 297               /* A clone might not have its linkage flags updated yet
 298                  because we call import_export_decl before
 299                  maybe_clone_body.  */
 300               || DECL_ABSTRACT_ORIGIN (decl));
 301
 302   /* When not using the repository, emit everything.  */
 303   if (!flag_use_repository)
 304     return 2;
 305
 306   /* Only template instantiations are managed by the repository.  This
 307      is an artificial restriction; the code in the prelinker and here
 308      will work fine if all entities with vague linkage are managed by
 309      the repository.  */
 310   if (VAR_P (decl))
 311     {
 312       tree type = NULL_TREE;
 313       if (DECL_VTABLE_OR_VTT_P (decl))
 314         type = DECL_CONTEXT (decl);
 315       else if (DECL_TINFO_P (decl))
 316         type = TREE_TYPE (DECL_NAME (decl));
 317       if (!DECL_TEMPLATE_INSTANTIATION (decl)
 318           && (!TYPE_LANG_SPECIFIC (type)
 319               || !CLASSTYPE_TEMPLATE_INSTANTIATION (type)))
 320         return 2;
 321       /* Const static data members initialized by constant expressions must
 322          be processed where needed so that their definitions are
 323          available.  Still record them into *.rpo files, so if they
 324          weren't actually emitted and collect2 requests them, they can
 325          be provided.  */
 326       if (decl_maybe_constant_var_p (decl)
 327           && DECL_CLASS_SCOPE_P (decl))
 328         ret = 2;
 329     }
 330   else if (!DECL_TEMPLATE_INSTANTIATION (decl))
 331     return 2;
 332
 333   if (DECL_EXPLICIT_INSTANTIATION (decl))
 334     return 2;
 335
 336   /* For constructors and destructors, the repository contains
 337      information about the clones -- not the original function --
 338      because only the clones are emitted in the object file.  */
 339   if (DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (decl)
 340       || DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (decl))
 341     {
 342       int emit_p = 0;
 343       tree clone;
 344       /* There is no early exit from this loop because we want to
 345          ensure that all of the clones are marked as available in this
 346          object file.  */
 347       FOR_EACH_CLONE (clone, decl)
 348         /* The only possible results from the recursive call to
 349            repo_emit_p are 0 or 1.  */
 350         if (repo_emit_p (clone))
 351           emit_p = 1;
 352       return emit_p;
 353     }
 354
 355   /* Keep track of all available entities.  */
 356   if (!DECL_REPO_AVAILABLE_P (decl))
 357     {
 358       DECL_REPO_AVAILABLE_P (decl) = 1;
 359       vec_safe_push (pending_repo, decl);
 360     }
 361
 362   return IDENTIFIER_REPO_CHOSEN (DECL_ASSEMBLER_NAME (decl)) ? 1 : ret;
 363 }
 364
 365 /* Returns true iff the prelinker has explicitly marked CLASS_TYPE for
 366    export from this translation unit.  */
 367
 368 bool
 369 repo_export_class_p (const_tree class_type)
 370 {
 371   if (!flag_use_repository)
 372     return false;
 373   if (!CLASSTYPE_VTABLES (class_type))
 374     return false;
 375   /* If the virtual table has been assigned to this translation unit,
 376      export the class.  */
 377   return (IDENTIFIER_REPO_CHOSEN
 378           (DECL_ASSEMBLER_NAME (CLASSTYPE_VTABLES (class_type))));
 379 }
 380
 381 #include "gt-cp-repo.h"