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