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) 2015-2018 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 #include "tree-inline.h"
  40 #include "intl.h"
  41
  42 /* Walker callback that replaces all FUNCTION_DECL of a function that's
  43    going to be versioned.  */
  44
  45 static tree
  46 replace_function_decl (tree *op, int *walk_subtrees, void *data)
  47 {
  48   struct walk_stmt_info *wi = (struct walk_stmt_info *) data;
  49   cgraph_function_version_info *info = (cgraph_function_version_info *)wi->info;
  50
  51   if (TREE_CODE (*op) == FUNCTION_DECL
  52       && info->this_node->decl == *op)
  53     {
  54       *op = info->dispatcher_resolver;
  55       *walk_subtrees = 0;
  56     }
  57
  58   return NULL;
  59 }
  60
  61 /* If the call in NODE has multiple target attribute with multiple fields,
  62    replace it with dispatcher call and create dispatcher (once).  */
  63
  64 static void
  65 create_dispatcher_calls (struct cgraph_node *node)
  66 {
  67   ipa_ref *ref;
  68
  69   if (!DECL_FUNCTION_VERSIONED (node->decl)
  70       || !is_function_default_version (node->decl))
  71     return;
  72
  73   if (!targetm.has_ifunc_p ())
  74     {
  75       error_at (DECL_SOURCE_LOCATION (node->decl),
  76                 "the call requires ifunc, which is not"
  77                 " supported by this target");
  78       return;
  79     }
  80   else if (!targetm.get_function_versions_dispatcher)
  81     {
  82       error_at (DECL_SOURCE_LOCATION (node->decl),
  83                 "target does not support function version dispatcher");
  84       return;
  85     }
  86
  87   tree idecl = targetm.get_function_versions_dispatcher (node->decl);
  88   if (!idecl)
  89     {
  90       error_at (DECL_SOURCE_LOCATION (node->decl),
  91                 "default target_clones attribute was not set");
  92       return;
  93     }
  94
  95   cgraph_node *inode = cgraph_node::get (idecl);
  96   gcc_assert (inode);
  97   tree resolver_decl = targetm.generate_version_dispatcher_body (inode);
  98
  99   /* Update aliases.  */
 100   inode->alias = true;
 101   inode->alias_target = resolver_decl;
 102   if (!inode->analyzed)
 103     inode->resolve_alias (cgraph_node::get (resolver_decl));
 104
 105   auto_vec<cgraph_edge *> edges_to_redirect;
 106   auto_vec<ipa_ref *> references_to_redirect;
 107
 108   for (unsigned i = 0; node->iterate_referring (i, ref); i++)
 109     references_to_redirect.safe_push (ref);
 110
 111   /* We need to remember NEXT_CALLER as it could be modified in the loop.  */
 112   for (cgraph_edge *e = node->callers; e ; e = e->next_caller)
 113     edges_to_redirect.safe_push (e);
 114
 115   if (!edges_to_redirect.is_empty () || !references_to_redirect.is_empty ())
 116     {
 117       /* Redirect edges.  */
 118       unsigned i;
 119       cgraph_edge *e;
 120       FOR_EACH_VEC_ELT (edges_to_redirect, i, e)
 121         {
 122           e->redirect_callee (inode);
 123           e->redirect_call_stmt_to_callee ();
 124         }
 125
 126       /* Redirect references.  */
 127       FOR_EACH_VEC_ELT (references_to_redirect, i, ref)
 128         {
 129           if (ref->use == IPA_REF_ADDR)
 130             {
 131               struct walk_stmt_info wi;
 132               memset (&wi, 0, sizeof (wi));
 133               wi.info = (void *)node->function_version ();
 134
 135               if (dyn_cast<varpool_node *> (ref->referring))
 136                 {
 137                   hash_set<tree> visited_nodes;
 138                   walk_tree (&DECL_INITIAL (ref->referring->decl),
 139                              replace_function_decl, &wi, &visited_nodes);
 140                 }
 141               else
 142                 {
 143                   gimple_stmt_iterator it = gsi_for_stmt (ref->stmt);
 144                   if (ref->referring->decl != resolver_decl)
 145                     walk_gimple_stmt (&it, NULL, replace_function_decl, &wi);
 146                 }
 147
 148               symtab_node *source = ref->referring;
 149               ref->remove_reference ();
 150               source->create_reference (inode, IPA_REF_ADDR);
 151             }
 152           else if (ref->use == IPA_REF_ALIAS)
 153             {
 154               symtab_node *source = ref->referring;
 155               ref->remove_reference ();
 156               source->create_reference (inode, IPA_REF_ALIAS);
 157               source->add_to_same_comdat_group (inode);
 158             }
 159           else
 160             gcc_unreachable ();
 161         }
 162     }
 163
 164   TREE_PUBLIC (node->decl) = 0;
 165   symtab->change_decl_assembler_name (node->decl,
 166                                       clone_function_name (node->decl,
 167                                                            "default"));
 168 }
 169
 170 /* Return length of attribute names string,
 171    if arglist chain > 1, -1 otherwise.  */
 172
 173 static int
 174 get_attr_len (tree arglist)
 175 {
 176   tree arg;
 177   int str_len_sum = 0;
 178   int argnum = 0;
 179
 180   for (arg = arglist; arg; arg = TREE_CHAIN (arg))
 181     {
 182       const char *str = TREE_STRING_POINTER (TREE_VALUE (arg));
 183       size_t len = strlen (str);
 184       str_len_sum += len + 1;
 185       for (const char *p = strchr (str, ','); p; p = strchr (p + 1, ','))
 186         argnum++;
 187       argnum++;
 188     }
 189   if (argnum <= 1)
 190     return -1;
 191   return str_len_sum;
 192 }
 193
 194 /* Create string with attributes separated by comma.
 195    Return number of attributes.  */
 196
 197 static int
 198 get_attr_str (tree arglist, char *attr_str)
 199 {
 200   tree arg;
 201   size_t str_len_sum = 0;
 202   int argnum = 0;
 203
 204   for (arg = arglist; arg; arg = TREE_CHAIN (arg))
 205     {
 206       const char *str = TREE_STRING_POINTER (TREE_VALUE (arg));
 207       size_t len = strlen (str);
 208       for (const char *p = strchr (str, ','); p; p = strchr (p + 1, ','))
 209         argnum++;
 210       memcpy (attr_str + str_len_sum, str, len);
 211       attr_str[str_len_sum + len] = TREE_CHAIN (arg) ? ',' : '\0';
 212       str_len_sum += len + 1;
 213       argnum++;
 214     }
 215   return argnum;
 216 }
 217
 218 /* Return number of attributes separated by comma and put them into ARGS.
 219    If there is no DEFAULT attribute return -1.  */
 220
 221 static int
 222 separate_attrs (char *attr_str, char **attrs)
 223 {
 224   int i = 0;
 225   bool has_default = false;
 226
 227   for (char *attr = strtok (attr_str, ",");
 228        attr != NULL; attr = strtok (NULL, ","))
 229     {
 230       if (strcmp (attr, "default") == 0)
 231         {
 232           has_default = true;
 233           continue;
 234         }
 235       attrs[i++] = attr;
 236     }
 237   if (!has_default)
 238     return -1;
 239   return i;
 240 }
 241
 242 /*  Return true if symbol is valid in assembler name.  */
 243
 244 static bool
 245 is_valid_asm_symbol (char c)
 246 {
 247   if ('a' <= c && c <= 'z')
 248     return true;
 249   if ('A' <= c && c <= 'Z')
 250     return true;
 251   if ('0' <= c && c <= '9')
 252     return true;
 253   if (c == '_')
 254     return true;
 255   return false;
 256 }
 257
 258 /*  Replace all not valid assembler symbols with '_'.  */
 259
 260 static void
 261 create_new_asm_name (char *old_asm_name, char *new_asm_name)
 262 {
 263   int i;
 264   int old_name_len = strlen (old_asm_name);
 265
 266   /* Replace all not valid assembler symbols with '_'.  */
 267   for (i = 0; i < old_name_len; i++)
 268     if (!is_valid_asm_symbol (old_asm_name[i]))
 269       new_asm_name[i] = '_';
 270     else
 271       new_asm_name[i] = old_asm_name[i];
 272   new_asm_name[old_name_len] = '\0';
 273 }
 274
 275 /*  Creates target clone of NODE.  */
 276
 277 static cgraph_node *
 278 create_target_clone (cgraph_node *node, bool definition, char *name)
 279 {
 280   cgraph_node *new_node;
 281
 282   if (definition)
 283     {
 284       new_node = node->create_version_clone_with_body (vNULL, NULL,
 285                                                        NULL, false,
 286                                                        NULL, NULL,
 287                                                        name);
 288       new_node->force_output = true;
 289     }
 290   else
 291     {
 292       tree new_decl = copy_node (node->decl);
 293       new_node = cgraph_node::get_create (new_decl);
 294       /* Generate a new name for the new version.  */
 295       symtab->change_decl_assembler_name (new_node->decl,
 296                                           clone_function_name (node->decl,
 297                                                                name));
 298     }
 299   return new_node;
 300 }
 301
 302 /* If the function in NODE has multiple target attributes
 303    create the appropriate clone for each valid target attribute.  */
 304
 305 static bool
 306 expand_target_clones (struct cgraph_node *node, bool definition)
 307 {
 308   int i;
 309   /* Parsing target attributes separated by comma.  */
 310   tree attr_target = lookup_attribute ("target_clones",
 311                                        DECL_ATTRIBUTES (node->decl));
 312   /* No targets specified.  */
 313   if (!attr_target)
 314     return false;
 315
 316   tree arglist = TREE_VALUE (attr_target);
 317   int attr_len = get_attr_len (arglist);
 318
 319   /* No need to clone for 1 target attribute.  */
 320   if (attr_len == -1)
 321     {
 322       warning_at (DECL_SOURCE_LOCATION (node->decl),
 323                   0,
 324                   "single target_clones attribute is ignored");
 325       return false;
 326     }
 327
 328   if (node->definition
 329       && !tree_versionable_function_p (node->decl))
 330     {
 331       error_at (DECL_SOURCE_LOCATION (node->decl),
 332                 "clones for %<target_clones%> attribute cannot be created");
 333       const char *reason = NULL;
 334       if (lookup_attribute ("noclone", DECL_ATTRIBUTES (node->decl)))
 335         reason = G_("function %q+F can never be copied "
 336                     "because it has %<noclone%> attribute");
 337       else
 338         reason = copy_forbidden (DECL_STRUCT_FUNCTION (node->decl));
 339       if (reason)
 340         inform (DECL_SOURCE_LOCATION (node->decl), reason, node->decl);
 341       return false;
 342     }
 343
 344   char *attr_str = XNEWVEC (char, attr_len);
 345   int attrnum = get_attr_str (arglist, attr_str);
 346   char **attrs = XNEWVEC (char *, attrnum);
 347
 348   attrnum = separate_attrs (attr_str, attrs);
 349   if (attrnum == -1)
 350     {
 351       error_at (DECL_SOURCE_LOCATION (node->decl),
 352                 "default target was not set");
 353       XDELETEVEC (attrs);
 354       XDELETEVEC (attr_str);
 355       return false;
 356     }
 357
 358   cgraph_function_version_info *decl1_v = NULL;
 359   cgraph_function_version_info *decl2_v = NULL;
 360   cgraph_function_version_info *before = NULL;
 361   cgraph_function_version_info *after = NULL;
 362   decl1_v = node->function_version ();
 363   if (decl1_v == NULL)
 364     decl1_v = node->insert_new_function_version ();
 365   before = decl1_v;
 366   DECL_FUNCTION_VERSIONED (node->decl) = 1;
 367
 368   for (i = 0; i < attrnum; i++)
 369     {
 370       char *attr = attrs[i];
 371       char *suffix = XNEWVEC (char, strlen (attr) + 1);
 372
 373       create_new_asm_name (attr, suffix);
 374       /* Create new target clone.  */
 375       cgraph_node *new_node = create_target_clone (node, definition, suffix);
 376       new_node->local.local = false;
 377       XDELETEVEC (suffix);
 378
 379       /* Set new attribute for the clone.  */
 380       tree attributes = make_attribute ("target", attr,
 381                                         DECL_ATTRIBUTES (new_node->decl));
 382       DECL_ATTRIBUTES (new_node->decl) = attributes;
 383       location_t saved_loc = input_location;
 384       input_location = DECL_SOURCE_LOCATION (node->decl);
 385       if (!targetm.target_option.valid_attribute_p (new_node->decl, NULL,
 386                                                     TREE_VALUE (attributes),
 387                                                     0))
 388         return false;
 389
 390       input_location = saved_loc;
 391       decl2_v = new_node->function_version ();
 392       if (decl2_v != NULL)
 393         continue;
 394       decl2_v = new_node->insert_new_function_version ();
 395
 396       /* Chain decl2_v and decl1_v.  All semantically identical versions
 397          will be chained together.  */
 398       after = decl2_v;
 399       while (before->next != NULL)
 400         before = before->next;
 401       while (after->prev != NULL)
 402         after = after->prev;
 403
 404       before->next = after;
 405       after->prev = before;
 406       DECL_FUNCTION_VERSIONED (new_node->decl) = 1;
 407     }
 408
 409   XDELETEVEC (attrs);
 410   XDELETEVEC (attr_str);
 411
 412   /* Setting new attribute to initial function.  */
 413   tree attributes = make_attribute ("target", "default",
 414                                     DECL_ATTRIBUTES (node->decl));
 415   DECL_ATTRIBUTES (node->decl) = attributes;
 416   node->local.local = false;
 417   location_t saved_loc = input_location;
 418   input_location = DECL_SOURCE_LOCATION (node->decl);
 419   bool ret
 420     = targetm.target_option.valid_attribute_p (node->decl, NULL,
 421                                                TREE_VALUE (attributes), 0);
 422   input_location = saved_loc;
 423   return ret;
 424 }
 425
 426 static unsigned int
 427 ipa_target_clone (void)
 428 {
 429   struct cgraph_node *node;
 430
 431   bool target_clone_pass = false;
 432   FOR_EACH_FUNCTION (node)
 433     target_clone_pass |= expand_target_clones (node, node->definition);
 434
 435   if (target_clone_pass)
 436     FOR_EACH_FUNCTION (node)
 437       create_dispatcher_calls (node);
 438
 439   return 0;
 440 }
 441
 442 namespace {
 443
 444 const pass_data pass_data_target_clone =
 445 {
 446   SIMPLE_IPA_PASS,              /* type */
 447   "targetclone",                /* name */
 448   OPTGROUP_NONE,                /* optinfo_flags */
 449   TV_NONE,                      /* tv_id */
 450   ( PROP_ssa | PROP_cfg ),      /* properties_required */
 451   0,                            /* properties_provided */
 452   0,                            /* properties_destroyed */
 453   0,                            /* todo_flags_start */
 454   TODO_update_ssa               /* todo_flags_finish */
 455 };
 456
 457 class pass_target_clone : public simple_ipa_opt_pass
 458 {
 459 public:
 460   pass_target_clone (gcc::context *ctxt)
 461     : simple_ipa_opt_pass (pass_data_target_clone, ctxt)
 462   {}
 463
 464   /* opt_pass methods: */
 465   virtual bool gate (function *);
 466   virtual unsigned int execute (function *) { return ipa_target_clone (); }
 467 };
 468
 469 bool
 470 pass_target_clone::gate (function *)
 471 {
 472   return true;
 473 }
 474
 475 } // anon namespace
 476
 477 simple_ipa_opt_pass *
 478 make_pass_target_clone (gcc::context *ctxt)
 479 {
 480   return new pass_target_clone (ctxt);
 481 }