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   if (!targetm.has_ifunc_p ())
  72     {
  73       error_at (DECL_SOURCE_LOCATION (node->decl),
  74                 "the call requires ifunc, which is not"
  75                 " supported by this target");
  76       return;
  77     }
  78   else if (!targetm.get_function_versions_dispatcher)
  79     {
  80       error_at (DECL_SOURCE_LOCATION (node->decl),
  81                 "target does not support function version dispatcher");
  82       return;
  83     }
  84
  85   tree idecl = targetm.get_function_versions_dispatcher (node->decl);
  86   if (!idecl)
  87     {
  88       error_at (DECL_SOURCE_LOCATION (node->decl),
  89                 "default target_clones attribute was not set");
  90       return;
  91     }
  92
  93   cgraph_node *inode = cgraph_node::get (idecl);
  94   gcc_assert (inode);
  95   tree resolver_decl = targetm.generate_version_dispatcher_body (inode);
  96
  97   /* Update aliases.  */
  98   inode->alias = true;
  99   inode->alias_target = resolver_decl;
 100   if (!inode->analyzed)
 101     inode->resolve_alias (cgraph_node::get (resolver_decl));
 102
 103   auto_vec<cgraph_edge *> edges_to_redirect;
 104   auto_vec<ipa_ref *> references_to_redirect;
 105
 106   for (unsigned i = 0; node->iterate_referring (i, ref); i++)
 107     references_to_redirect.safe_push (ref);
 108
 109   /* We need to remember NEXT_CALLER as it could be modified in the loop.  */
 110   for (cgraph_edge *e = node->callers; e ; e = e->next_caller)
 111     edges_to_redirect.safe_push (e);
 112
 113   if (!edges_to_redirect.is_empty () || !references_to_redirect.is_empty ())
 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   TREE_PUBLIC (node->decl) = 0;
 152   symtab->change_decl_assembler_name (node->decl,
 153                                       clone_function_name (node->decl,
 154                                                            "default"));
 155 }
 156
 157 /* Return length of attribute names string,
 158    if arglist chain > 1, -1 otherwise.  */
 159
 160 static int
 161 get_attr_len (tree arglist)
 162 {
 163   tree arg;
 164   int str_len_sum = 0;
 165   int argnum = 0;
 166
 167   for (arg = arglist; arg; arg = TREE_CHAIN (arg))
 168     {
 169       const char *str = TREE_STRING_POINTER (TREE_VALUE (arg));
 170       size_t len = strlen (str);
 171       str_len_sum += len + 1;
 172       for (const char *p = strchr (str, ','); p; p = strchr (p + 1, ','))
 173         argnum++;
 174       argnum++;
 175     }
 176   if (argnum <= 1)
 177     return -1;
 178   return str_len_sum;
 179 }
 180
 181 /* Create string with attributes separated by comma.
 182    Return number of attributes.  */
 183
 184 static int
 185 get_attr_str (tree arglist, char *attr_str)
 186 {
 187   tree arg;
 188   size_t str_len_sum = 0;
 189   int argnum = 0;
 190
 191   for (arg = arglist; arg; arg = TREE_CHAIN (arg))
 192     {
 193       const char *str = TREE_STRING_POINTER (TREE_VALUE (arg));
 194       size_t len = strlen (str);
 195       for (const char *p = strchr (str, ','); p; p = strchr (p + 1, ','))
 196         argnum++;
 197       memcpy (attr_str + str_len_sum, str, len);
 198       attr_str[str_len_sum + len] = TREE_CHAIN (arg) ? ',' : '\0';
 199       str_len_sum += len + 1;
 200       argnum++;
 201     }
 202   return argnum;
 203 }
 204
 205 /* Return number of attributes separated by comma and put them into ARGS.
 206    If there is no DEFAULT attribute return -1.  */
 207
 208 static int
 209 separate_attrs (char *attr_str, char **attrs)
 210 {
 211   int i = 0;
 212   bool has_default = false;
 213
 214   for (char *attr = strtok (attr_str, ",");
 215        attr != NULL; attr = strtok (NULL, ","))
 216     {
 217       if (strcmp (attr, "default") == 0)
 218         {
 219           has_default = true;
 220           continue;
 221         }
 222       attrs[i++] = attr;
 223     }
 224   if (!has_default)
 225     return -1;
 226   return i;
 227 }
 228
 229 /*  Return true if symbol is valid in assembler name.  */
 230
 231 static bool
 232 is_valid_asm_symbol (char c)
 233 {
 234   if ('a' <= c && c <= 'z')
 235     return true;
 236   if ('A' <= c && c <= 'Z')
 237     return true;
 238   if ('0' <= c && c <= '9')
 239     return true;
 240   if (c == '_')
 241     return true;
 242   return false;
 243 }
 244
 245 /*  Replace all not valid assembler symbols with '_'.  */
 246
 247 static void
 248 create_new_asm_name (char *old_asm_name, char *new_asm_name)
 249 {
 250   int i;
 251   int old_name_len = strlen (old_asm_name);
 252
 253   /* Replace all not valid assembler symbols with '_'.  */
 254   for (i = 0; i < old_name_len; i++)
 255     if (!is_valid_asm_symbol (old_asm_name[i]))
 256       new_asm_name[i] = '_';
 257     else
 258       new_asm_name[i] = old_asm_name[i];
 259   new_asm_name[old_name_len] = '\0';
 260 }
 261
 262 /*  Creates target clone of NODE.  */
 263
 264 static cgraph_node *
 265 create_target_clone (cgraph_node *node, bool definition, char *name)
 266 {
 267   cgraph_node *new_node;
 268
 269   if (definition)
 270     {
 271       new_node = node->create_version_clone_with_body (vNULL, NULL,
 272                                                        NULL, false,
 273                                                        NULL, NULL,
 274                                                        name);
 275       new_node->force_output = true;
 276     }
 277   else
 278     {
 279       tree new_decl = copy_node (node->decl);
 280       new_node = cgraph_node::get_create (new_decl);
 281       /* Generate a new name for the new version.  */
 282       symtab->change_decl_assembler_name (new_node->decl,
 283                                           clone_function_name (node->decl,
 284                                                                name));
 285     }
 286   return new_node;
 287 }
 288
 289 /* If the function in NODE has multiple target attributes
 290    create the appropriate clone for each valid target attribute.  */
 291
 292 static bool
 293 expand_target_clones (struct cgraph_node *node, bool definition)
 294 {
 295   int i;
 296   /* Parsing target attributes separated by comma.  */
 297   tree attr_target = lookup_attribute ("target_clones",
 298                                        DECL_ATTRIBUTES (node->decl));
 299   /* No targets specified.  */
 300   if (!attr_target)
 301     return false;
 302
 303   tree arglist = TREE_VALUE (attr_target);
 304   int attr_len = get_attr_len (arglist);
 305
 306   /* No need to clone for 1 target attribute.  */
 307   if (attr_len == -1)
 308     {
 309       warning_at (DECL_SOURCE_LOCATION (node->decl),
 310                   0,
 311                   "single target_clones attribute is ignored");
 312       return false;
 313     }
 314
 315   char *attr_str = XNEWVEC (char, attr_len);
 316   int attrnum = get_attr_str (arglist, attr_str);
 317   char **attrs = XNEWVEC (char *, attrnum);
 318
 319   attrnum = separate_attrs (attr_str, attrs);
 320   if (attrnum == -1)
 321     {
 322       error_at (DECL_SOURCE_LOCATION (node->decl),
 323                 "default target was not set");
 324       XDELETEVEC (attrs);
 325       XDELETEVEC (attr_str);
 326       return false;
 327     }
 328
 329   cgraph_function_version_info *decl1_v = NULL;
 330   cgraph_function_version_info *decl2_v = NULL;
 331   cgraph_function_version_info *before = NULL;
 332   cgraph_function_version_info *after = NULL;
 333   decl1_v = node->function_version ();
 334   if (decl1_v == NULL)
 335     decl1_v = node->insert_new_function_version ();
 336   before = decl1_v;
 337   DECL_FUNCTION_VERSIONED (node->decl) = 1;
 338
 339   for (i = 0; i < attrnum; i++)
 340     {
 341       char *attr = attrs[i];
 342       char *suffix = XNEWVEC (char, strlen (attr) + 1);
 343
 344       create_new_asm_name (attr, suffix);
 345       /* Create new target clone.  */
 346       cgraph_node *new_node = create_target_clone (node, definition, suffix);
 347       new_node->local.local = false;
 348       XDELETEVEC (suffix);
 349
 350       /* Set new attribute for the clone.  */
 351       tree attributes = make_attribute ("target", attr,
 352                                         DECL_ATTRIBUTES (new_node->decl));
 353       DECL_ATTRIBUTES (new_node->decl) = attributes;
 354       location_t saved_loc = input_location;
 355       input_location = DECL_SOURCE_LOCATION (node->decl);
 356       if (!targetm.target_option.valid_attribute_p (new_node->decl, NULL,
 357                                                     TREE_VALUE (attributes),
 358                                                     0))
 359         return false;
 360
 361       input_location = saved_loc;
 362       decl2_v = new_node->function_version ();
 363       if (decl2_v != NULL)
 364         continue;
 365       decl2_v = new_node->insert_new_function_version ();
 366
 367       /* Chain decl2_v and decl1_v.  All semantically identical versions
 368          will be chained together.  */
 369       after = decl2_v;
 370       while (before->next != NULL)
 371         before = before->next;
 372       while (after->prev != NULL)
 373         after = after->prev;
 374
 375       before->next = after;
 376       after->prev = before;
 377       DECL_FUNCTION_VERSIONED (new_node->decl) = 1;
 378     }
 379
 380   XDELETEVEC (attrs);
 381   XDELETEVEC (attr_str);
 382
 383   /* Setting new attribute to initial function.  */
 384   tree attributes = make_attribute ("target", "default",
 385                                     DECL_ATTRIBUTES (node->decl));
 386   DECL_ATTRIBUTES (node->decl) = attributes;
 387   node->local.local = false;
 388   location_t saved_loc = input_location;
 389   input_location = DECL_SOURCE_LOCATION (node->decl);
 390   bool ret
 391     = targetm.target_option.valid_attribute_p (node->decl, NULL,
 392                                                TREE_VALUE (attributes), 0);
 393   input_location = saved_loc;
 394   return ret;
 395 }
 396
 397 static unsigned int
 398 ipa_target_clone (void)
 399 {
 400   struct cgraph_node *node;
 401
 402   bool target_clone_pass = false;
 403   FOR_EACH_FUNCTION (node)
 404     target_clone_pass |= expand_target_clones (node, node->definition);
 405
 406   if (target_clone_pass)
 407     FOR_EACH_FUNCTION (node)
 408       create_dispatcher_calls (node);
 409
 410   return 0;
 411 }
 412
 413 namespace {
 414
 415 const pass_data pass_data_target_clone =
 416 {
 417   SIMPLE_IPA_PASS,              /* type */
 418   "targetclone",                /* name */
 419   OPTGROUP_NONE,                /* optinfo_flags */
 420   TV_NONE,                      /* tv_id */
 421   ( PROP_ssa | PROP_cfg ),      /* properties_required */
 422   0,                            /* properties_provided */
 423   0,                            /* properties_destroyed */
 424   0,                            /* todo_flags_start */
 425   TODO_update_ssa               /* todo_flags_finish */
 426 };
 427
 428 class pass_target_clone : public simple_ipa_opt_pass
 429 {
 430 public:
 431   pass_target_clone (gcc::context *ctxt)
 432     : simple_ipa_opt_pass (pass_data_target_clone, ctxt)
 433   {}
 434
 435   /* opt_pass methods: */
 436   virtual bool gate (function *);
 437   virtual unsigned int execute (function *) { return ipa_target_clone (); }
 438 };
 439
 440 bool
 441 pass_target_clone::gate (function *)
 442 {
 443   return true;
 444 }
 445
 446 } // anon namespace
 447
 448 simple_ipa_opt_pass *
 449 make_pass_target_clone (gcc::context *ctxt)
 450 {
 451   return new pass_target_clone (ctxt);
 452 }