gcc/multiple_target.c

   1 /* Pass for parsing functions with multiple target attributes.
   2
   3    Contributed by Evgeny Stupachenko <evstupac@gmail.com>
   4
   5    Copyright (C) 2015-2017 Free Software Foundation, Inc.
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify it under
  10 the terms of the GNU General Public License as published by the Free
  11 Software Foundation; either version 3, or (at your option) any later
  12 version.
  13
  14 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  15 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  17 for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with GCC; see the file COPYING3.  If not see
  21 <http://www.gnu.org/licenses/>.  */
  22
  23 #include "config.h"
  24 #include "system.h"
  25 #include "coretypes.h"
  26 #include "backend.h"
  27 #include "tree.h"
  28 #include "stringpool.h"
  29 #include "gimple.h"
  30 #include "diagnostic-core.h"
  31 #include "gimple-ssa.h"
  32 #include "cgraph.h"
  33 #include "tree-pass.h"
  34 #include "target.h"
  35 #include "attribs.h"
  36 #include "pretty-print.h"
  37 #include "gimple-iterator.h"
  38 #include "gimple-walk.h"
  39
  40 /* Walker callback that replaces all FUNCTION_DECL of a function that's
  41    going to be versioned.  */
  42
  43 static tree
  44 replace_function_decl (tree *op, int *walk_subtrees, void *data)
  45 {
  46   struct walk_stmt_info *wi = (struct walk_stmt_info *) data;
  47   cgraph_function_version_info *info = (cgraph_function_version_info *)wi->info;
  48
  49   if (TREE_CODE (*op) == FUNCTION_DECL
  50       && info->this_node->decl == *op)
  51     {
  52       *op = info->dispatcher_resolver;
  53       *walk_subtrees = 0;
  54     }
  55
  56   return NULL;
  57 }
  58
  59 /* If the call in NODE has multiple target attribute with multiple fields,
  60    replace it with dispatcher call and create dispatcher (once).  */
  61
  62 static void
  63 create_dispatcher_calls (struct cgraph_node *node)
  64 {
  65   ipa_ref *ref;
  66
  67   if (!DECL_FUNCTION_VERSIONED (node->decl))
  68     return;
  69
  70   auto_vec<cgraph_edge *> edges_to_redirect;
  71   auto_vec<ipa_ref *> references_to_redirect;
  72
  73   for (unsigned i = 0; node->iterate_referring (i, ref); i++)
  74     references_to_redirect.safe_push (ref);
  75
  76   /* We need to remember NEXT_CALLER as it could be modified in the loop.  */
  77   for (cgraph_edge *e = node->callers; e ; e = e->next_caller)
  78     edges_to_redirect.safe_push (e);
  79
  80   if (!edges_to_redirect.is_empty () || !references_to_redirect.is_empty ())
  81     {
  82       if (!targetm.has_ifunc_p ())
  83         {
  84           error_at (DECL_SOURCE_LOCATION (node->decl),
  85                     "the call requires ifunc, which is not"
  86                     " supported by this target");
  87           return;
  88         }
  89       else if (!targetm.get_function_versions_dispatcher)
  90         {
  91           error_at (DECL_SOURCE_LOCATION (node->decl),
  92                     "target does not support function version dispatcher");
  93           return;
  94         }
  95
  96       tree idecl = targetm.get_function_versions_dispatcher (node->decl);
  97       if (!idecl)
  98         {
  99           error_at (DECL_SOURCE_LOCATION (node->decl),
 100                     "default target_clones attribute was not set");
 101           return;
 102         }
 103
 104       cgraph_node *inode = cgraph_node::get (idecl);
 105       gcc_assert (inode);
 106       tree resolver_decl = targetm.generate_version_dispatcher_body (inode);
 107
 108       /* Update aliases.  */
 109       inode->alias = true;
 110       inode->alias_target = resolver_decl;
 111       if (!inode->analyzed)
 112         inode->resolve_alias (cgraph_node::get (resolver_decl));
 113
 114       /* Redirect edges.  */
 115       unsigned i;
 116       cgraph_edge *e;
 117       FOR_EACH_VEC_ELT (edges_to_redirect, i, e)
 118         {
 119           e->redirect_callee (inode);
 120           e->redirect_call_stmt_to_callee ();
 121         }
 122
 123       /* Redirect references.  */
 124       FOR_EACH_VEC_ELT (references_to_redirect, i, ref)
 125         {
 126           if (ref->use == IPA_REF_ADDR)
 127             {
 128               struct walk_stmt_info wi;
 129               memset (&wi, 0, sizeof (wi));
 130               wi.info = (void *)node->function_version ();
 131
 132               if (dyn_cast<varpool_node *> (ref->referring))
 133                 {
 134                   hash_set<tree> visited_nodes;
 135                   walk_tree (&DECL_INITIAL (ref->referring->decl),
 136                              replace_function_decl, &wi, &visited_nodes);
 137                 }
 138               else
 139                 {
 140                   gimple_stmt_iterator it = gsi_for_stmt (ref->stmt);
 141                   if (ref->referring->decl != resolver_decl)
 142                     walk_gimple_stmt (&it, NULL, replace_function_decl, &wi);
 143                 }
 144             }
 145           else
 146             gcc_unreachable ();
 147         }
 148     }
 149
 150   symtab->change_decl_assembler_name (node->decl,
 151                                       clone_function_name (node->decl,
 152                                                            "default"));
 153 }
 154
 155 /* Return length of attribute names string,
 156    if arglist chain > 1, -1 otherwise.  */
 157
 158 static int
 159 get_attr_len (tree arglist)
 160 {
 161   tree arg;
 162   int str_len_sum = 0;
 163   int argnum = 0;
 164
 165   for (arg = arglist; arg; arg = TREE_CHAIN (arg))
 166     {
 167       const char *str = TREE_STRING_POINTER (TREE_VALUE (arg));
 168       size_t len = strlen (str);
 169       str_len_sum += len + 1;
 170       for (const char *p = strchr (str, ','); p; p = strchr (p + 1, ','))
 171         argnum++;
 172       argnum++;
 173     }
 174   if (argnum <= 1)
 175     return -1;
 176   return str_len_sum;
 177 }
 178
 179 /* Create string with attributes separated by comma.
 180    Return number of attributes.  */
 181
 182 static int
 183 get_attr_str (tree arglist, char *attr_str)
 184 {
 185   tree arg;
 186   size_t str_len_sum = 0;
 187   int argnum = 0;
 188
 189   for (arg = arglist; arg; arg = TREE_CHAIN (arg))
 190     {
 191       const char *str = TREE_STRING_POINTER (TREE_VALUE (arg));
 192       size_t len = strlen (str);
 193       for (const char *p = strchr (str, ','); p; p = strchr (p + 1, ','))
 194         argnum++;
 195       memcpy (attr_str + str_len_sum, str, len);
 196       attr_str[str_len_sum + len] = TREE_CHAIN (arg) ? ',' : '\0';
 197       str_len_sum += len + 1;
 198       argnum++;
 199     }
 200   return argnum;
 201 }
 202
 203 /* Return number of attributes separated by comma and put them into ARGS.
 204    If there is no DEFAULT attribute return -1.  */
 205
 206 static int
 207 separate_attrs (char *attr_str, char **attrs)
 208 {
 209   int i = 0;
 210   bool has_default = false;
 211
 212   for (char *attr = strtok (attr_str, ",");
 213        attr != NULL; attr = strtok (NULL, ","))
 214     {
 215       if (strcmp (attr, "default") == 0)
 216         {
 217           has_default = true;
 218           continue;
 219         }
 220       attrs[i++] = attr;
 221     }
 222   if (!has_default)
 223     return -1;
 224   return i;
 225 }
 226
 227 /*  Return true if symbol is valid in assembler name.  */
 228
 229 static bool
 230 is_valid_asm_symbol (char c)
 231 {
 232   if ('a' <= c && c <= 'z')
 233     return true;
 234   if ('A' <= c && c <= 'Z')
 235     return true;
 236   if ('0' <= c && c <= '9')
 237     return true;
 238   if (c == '_')
 239     return true;
 240   return false;
 241 }
 242
 243 /*  Replace all not valid assembler symbols with '_'.  */
 244
 245 static void
 246 create_new_asm_name (char *old_asm_name, char *new_asm_name)
 247 {
 248   int i;
 249   int old_name_len = strlen (old_asm_name);
 250
 251   /* Replace all not valid assembler symbols with '_'.  */
 252   for (i = 0; i < old_name_len; i++)
 253     if (!is_valid_asm_symbol (old_asm_name[i]))
 254       new_asm_name[i] = '_';
 255     else
 256       new_asm_name[i] = old_asm_name[i];
 257   new_asm_name[old_name_len] = '\0';
 258 }
 259
 260 /*  Creates target clone of NODE.  */
 261
 262 static cgraph_node *
 263 create_target_clone (cgraph_node *node, bool definition, char *name)
 264 {
 265   cgraph_node *new_node;
 266
 267   if (definition)
 268     {
 269       new_node = node->create_version_clone_with_body (vNULL, NULL,
 270                                                        NULL, false,
 271                                                        NULL, NULL,
 272                                                        name);
 273       new_node->force_output = true;
 274     }
 275   else
 276     {
 277       tree new_decl = copy_node (node->decl);
 278       new_node = cgraph_node::get_create (new_decl);
 279       /* Generate a new name for the new version.  */
 280       symtab->change_decl_assembler_name (new_node->decl,
 281                                           clone_function_name (node->decl,
 282                                                                name));
 283     }
 284   return new_node;
 285 }
 286
 287 /* If the function in NODE has multiple target attributes
 288    create the appropriate clone for each valid target attribute.  */
 289
 290 static bool
 291 expand_target_clones (struct cgraph_node *node, bool definition)
 292 {
 293   int i;
 294   /* Parsing target attributes separated by comma.  */
 295   tree attr_target = lookup_attribute ("target_clones",
 296                                        DECL_ATTRIBUTES (node->decl));
 297   /* No targets specified.  */
 298   if (!attr_target)
 299     return false;
 300
 301   tree arglist = TREE_VALUE (attr_target);
 302   int attr_len = get_attr_len (arglist);
 303
 304   /* No need to clone for 1 target attribute.  */
 305   if (attr_len == -1)
 306     {
 307       warning_at (DECL_SOURCE_LOCATION (node->decl),
 308                   0,
 309                   "single target_clones attribute is ignored");
 310       return false;
 311     }
 312
 313   char *attr_str = XNEWVEC (char, attr_len);
 314   int attrnum = get_attr_str (arglist, attr_str);
 315   char **attrs = XNEWVEC (char *, attrnum);
 316
 317   attrnum = separate_attrs (attr_str, attrs);
 318   if (attrnum == -1)
 319     {
 320       error_at (DECL_SOURCE_LOCATION (node->decl),
 321                 "default target was not set");
 322       XDELETEVEC (attrs);
 323       XDELETEVEC (attr_str);
 324       return false;
 325     }
 326
 327   cgraph_function_version_info *decl1_v = NULL;
 328   cgraph_function_version_info *decl2_v = NULL;
 329   cgraph_function_version_info *before = NULL;
 330   cgraph_function_version_info *after = NULL;
 331   decl1_v = node->function_version ();
 332   if (decl1_v == NULL)
 333     decl1_v = node->insert_new_function_version ();
 334   before = decl1_v;
 335   DECL_FUNCTION_VERSIONED (node->decl) = 1;
 336
 337   for (i = 0; i < attrnum; i++)
 338     {
 339       char *attr = attrs[i];
 340       char *suffix = XNEWVEC (char, strlen (attr) + 1);
 341
 342       create_new_asm_name (attr, suffix);
 343       /* Create new target clone.  */
 344       cgraph_node *new_node = create_target_clone (node, definition, suffix);
 345       new_node->local.local = false;
 346       XDELETEVEC (suffix);
 347
 348       /* Set new attribute for the clone.  */
 349       tree attributes = make_attribute ("target", attr,
 350                                         DECL_ATTRIBUTES (new_node->decl));
 351       DECL_ATTRIBUTES (new_node->decl) = attributes;
 352       location_t saved_loc = input_location;
 353       input_location = DECL_SOURCE_LOCATION (node->decl);
 354       if (!targetm.target_option.valid_attribute_p (new_node->decl, NULL,
 355                                                     TREE_VALUE (attributes),
 356                                                     0))
 357         return false;
 358
 359       input_location = saved_loc;
 360       decl2_v = new_node->function_version ();
 361       if (decl2_v != NULL)
 362         continue;
 363       decl2_v = new_node->insert_new_function_version ();
 364
 365       /* Chain decl2_v and decl1_v.  All semantically identical versions
 366          will be chained together.  */
 367       after = decl2_v;
 368       while (before->next != NULL)
 369         before = before->next;
 370       while (after->prev != NULL)
 371         after = after->prev;
 372
 373       before->next = after;
 374       after->prev = before;
 375       DECL_FUNCTION_VERSIONED (new_node->decl) = 1;
 376     }
 377
 378   XDELETEVEC (attrs);
 379   XDELETEVEC (attr_str);
 380
 381   /* Setting new attribute to initial function.  */
 382   tree attributes = make_attribute ("target", "default",
 383                                     DECL_ATTRIBUTES (node->decl));
 384   DECL_ATTRIBUTES (node->decl) = attributes;
 385   node->local.local = false;
 386   location_t saved_loc = input_location;
 387   input_location = DECL_SOURCE_LOCATION (node->decl);
 388   bool ret
 389     = targetm.target_option.valid_attribute_p (node->decl, NULL,
 390                                                TREE_VALUE (attributes), 0);
 391   input_location = saved_loc;
 392   return ret;
 393 }
 394
 395 static unsigned int
 396 ipa_target_clone (void)
 397 {
 398   struct cgraph_node *node;
 399
 400   bool target_clone_pass = false;
 401   FOR_EACH_FUNCTION (node)
 402     target_clone_pass |= expand_target_clones (node, node->definition);
 403
 404   if (target_clone_pass)
 405     FOR_EACH_FUNCTION (node)
 406       create_dispatcher_calls (node);
 407
 408   return 0;
 409 }
 410
 411 namespace {
 412
 413 const pass_data pass_data_target_clone =
 414 {
 415   SIMPLE_IPA_PASS,              /* type */
 416   "targetclone",                /* name */
 417   OPTGROUP_NONE,                /* optinfo_flags */
 418   TV_NONE,                      /* tv_id */
 419   ( PROP_ssa | PROP_cfg ),      /* properties_required */
 420   0,                            /* properties_provided */
 421   0,                            /* properties_destroyed */
 422   0,                            /* todo_flags_start */
 423   TODO_update_ssa               /* todo_flags_finish */
 424 };
 425
 426 class pass_target_clone : public simple_ipa_opt_pass
 427 {
 428 public:
 429   pass_target_clone (gcc::context *ctxt)
 430     : simple_ipa_opt_pass (pass_data_target_clone, ctxt)
 431   {}
 432
 433   /* opt_pass methods: */
 434   virtual bool gate (function *);
 435   virtual unsigned int execute (function *) { return ipa_target_clone (); }
 436 };
 437
 438 bool
 439 pass_target_clone::gate (function *)
 440 {
 441   return true;
 442 }
 443
 444 } // anon namespace
 445
 446 simple_ipa_opt_pass *
 447 make_pass_target_clone (gcc::context *ctxt)
 448 {
 449   return new pass_target_clone (ctxt);
 450 }