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           else
 149             gcc_unreachable ();
 150         }
 151     }
 152
 153   TREE_PUBLIC (node->decl) = 0;
 154   symtab->change_decl_assembler_name (node->decl,
 155                                       clone_function_name (node->decl,
 156                                                            "default"));
 157 }
 158
 159 /* Return length of attribute names string,
 160    if arglist chain > 1, -1 otherwise.  */
 161
 162 static int
 163 get_attr_len (tree arglist)
 164 {
 165   tree arg;
 166   int str_len_sum = 0;
 167   int argnum = 0;
 168
 169   for (arg = arglist; arg; arg = TREE_CHAIN (arg))
 170     {
 171       const char *str = TREE_STRING_POINTER (TREE_VALUE (arg));
 172       size_t len = strlen (str);
 173       str_len_sum += len + 1;
 174       for (const char *p = strchr (str, ','); p; p = strchr (p + 1, ','))
 175         argnum++;
 176       argnum++;
 177     }
 178   if (argnum <= 1)
 179     return -1;
 180   return str_len_sum;
 181 }
 182
 183 /* Create string with attributes separated by comma.
 184    Return number of attributes.  */
 185
 186 static int
 187 get_attr_str (tree arglist, char *attr_str)
 188 {
 189   tree arg;
 190   size_t str_len_sum = 0;
 191   int argnum = 0;
 192
 193   for (arg = arglist; arg; arg = TREE_CHAIN (arg))
 194     {
 195       const char *str = TREE_STRING_POINTER (TREE_VALUE (arg));
 196       size_t len = strlen (str);
 197       for (const char *p = strchr (str, ','); p; p = strchr (p + 1, ','))
 198         argnum++;
 199       memcpy (attr_str + str_len_sum, str, len);
 200       attr_str[str_len_sum + len] = TREE_CHAIN (arg) ? ',' : '\0';
 201       str_len_sum += len + 1;
 202       argnum++;
 203     }
 204   return argnum;
 205 }
 206
 207 /* Return number of attributes separated by comma and put them into ARGS.
 208    If there is no DEFAULT attribute return -1.  */
 209
 210 static int
 211 separate_attrs (char *attr_str, char **attrs)
 212 {
 213   int i = 0;
 214   bool has_default = false;
 215
 216   for (char *attr = strtok (attr_str, ",");
 217        attr != NULL; attr = strtok (NULL, ","))
 218     {
 219       if (strcmp (attr, "default") == 0)
 220         {
 221           has_default = true;
 222           continue;
 223         }
 224       attrs[i++] = attr;
 225     }
 226   if (!has_default)
 227     return -1;
 228   return i;
 229 }
 230
 231 /*  Return true if symbol is valid in assembler name.  */
 232
 233 static bool
 234 is_valid_asm_symbol (char c)
 235 {
 236   if ('a' <= c && c <= 'z')
 237     return true;
 238   if ('A' <= c && c <= 'Z')
 239     return true;
 240   if ('0' <= c && c <= '9')
 241     return true;
 242   if (c == '_')
 243     return true;
 244   return false;
 245 }
 246
 247 /*  Replace all not valid assembler symbols with '_'.  */
 248
 249 static void
 250 create_new_asm_name (char *old_asm_name, char *new_asm_name)
 251 {
 252   int i;
 253   int old_name_len = strlen (old_asm_name);
 254
 255   /* Replace all not valid assembler symbols with '_'.  */
 256   for (i = 0; i < old_name_len; i++)
 257     if (!is_valid_asm_symbol (old_asm_name[i]))
 258       new_asm_name[i] = '_';
 259     else
 260       new_asm_name[i] = old_asm_name[i];
 261   new_asm_name[old_name_len] = '\0';
 262 }
 263
 264 /*  Creates target clone of NODE.  */
 265
 266 static cgraph_node *
 267 create_target_clone (cgraph_node *node, bool definition, char *name)
 268 {
 269   cgraph_node *new_node;
 270
 271   if (definition)
 272     {
 273       new_node = node->create_version_clone_with_body (vNULL, NULL,
 274                                                        NULL, false,
 275                                                        NULL, NULL,
 276                                                        name);
 277       new_node->force_output = true;
 278     }
 279   else
 280     {
 281       tree new_decl = copy_node (node->decl);
 282       new_node = cgraph_node::get_create (new_decl);
 283       /* Generate a new name for the new version.  */
 284       symtab->change_decl_assembler_name (new_node->decl,
 285                                           clone_function_name (node->decl,
 286                                                                name));
 287     }
 288   return new_node;
 289 }
 290
 291 /* If the function in NODE has multiple target attributes
 292    create the appropriate clone for each valid target attribute.  */
 293
 294 static bool
 295 expand_target_clones (struct cgraph_node *node, bool definition)
 296 {
 297   int i;
 298   /* Parsing target attributes separated by comma.  */
 299   tree attr_target = lookup_attribute ("target_clones",
 300                                        DECL_ATTRIBUTES (node->decl));
 301   /* No targets specified.  */
 302   if (!attr_target)
 303     return false;
 304
 305   tree arglist = TREE_VALUE (attr_target);
 306   int attr_len = get_attr_len (arglist);
 307
 308   /* No need to clone for 1 target attribute.  */
 309   if (attr_len == -1)
 310     {
 311       warning_at (DECL_SOURCE_LOCATION (node->decl),
 312                   0,
 313                   "single target_clones attribute is ignored");
 314       return false;
 315     }
 316
 317   if (node->definition
 318       && !tree_versionable_function_p (node->decl))
 319     {
 320       error_at (DECL_SOURCE_LOCATION (node->decl),
 321                 "clones for %<target_clones%> attribute cannot be created");
 322       const char *reason = NULL;
 323       if (lookup_attribute ("noclone", DECL_ATTRIBUTES (node->decl)))
 324         reason = G_("function %q+F can never be copied "
 325                     "because it has %<noclone%> attribute");
 326       else
 327         reason = copy_forbidden (DECL_STRUCT_FUNCTION (node->decl));
 328       if (reason)
 329         inform (DECL_SOURCE_LOCATION (node->decl), reason, node->decl);
 330       return false;
 331     }
 332
 333   char *attr_str = XNEWVEC (char, attr_len);
 334   int attrnum = get_attr_str (arglist, attr_str);
 335   char **attrs = XNEWVEC (char *, attrnum);
 336
 337   attrnum = separate_attrs (attr_str, attrs);
 338   if (attrnum == -1)
 339     {
 340       error_at (DECL_SOURCE_LOCATION (node->decl),
 341                 "default target was not set");
 342       XDELETEVEC (attrs);
 343       XDELETEVEC (attr_str);
 344       return false;
 345     }
 346
 347   cgraph_function_version_info *decl1_v = NULL;
 348   cgraph_function_version_info *decl2_v = NULL;
 349   cgraph_function_version_info *before = NULL;
 350   cgraph_function_version_info *after = NULL;
 351   decl1_v = node->function_version ();
 352   if (decl1_v == NULL)
 353     decl1_v = node->insert_new_function_version ();
 354   before = decl1_v;
 355   DECL_FUNCTION_VERSIONED (node->decl) = 1;
 356
 357   for (i = 0; i < attrnum; i++)
 358     {
 359       char *attr = attrs[i];
 360       char *suffix = XNEWVEC (char, strlen (attr) + 1);
 361
 362       create_new_asm_name (attr, suffix);
 363       /* Create new target clone.  */
 364       cgraph_node *new_node = create_target_clone (node, definition, suffix);
 365       new_node->local.local = false;
 366       XDELETEVEC (suffix);
 367
 368       /* Set new attribute for the clone.  */
 369       tree attributes = make_attribute ("target", attr,
 370                                         DECL_ATTRIBUTES (new_node->decl));
 371       DECL_ATTRIBUTES (new_node->decl) = attributes;
 372       location_t saved_loc = input_location;
 373       input_location = DECL_SOURCE_LOCATION (node->decl);
 374       if (!targetm.target_option.valid_attribute_p (new_node->decl, NULL,
 375                                                     TREE_VALUE (attributes),
 376                                                     0))
 377         return false;
 378
 379       input_location = saved_loc;
 380       decl2_v = new_node->function_version ();
 381       if (decl2_v != NULL)
 382         continue;
 383       decl2_v = new_node->insert_new_function_version ();
 384
 385       /* Chain decl2_v and decl1_v.  All semantically identical versions
 386          will be chained together.  */
 387       after = decl2_v;
 388       while (before->next != NULL)
 389         before = before->next;
 390       while (after->prev != NULL)
 391         after = after->prev;
 392
 393       before->next = after;
 394       after->prev = before;
 395       DECL_FUNCTION_VERSIONED (new_node->decl) = 1;
 396     }
 397
 398   XDELETEVEC (attrs);
 399   XDELETEVEC (attr_str);
 400
 401   /* Setting new attribute to initial function.  */
 402   tree attributes = make_attribute ("target", "default",
 403                                     DECL_ATTRIBUTES (node->decl));
 404   DECL_ATTRIBUTES (node->decl) = attributes;
 405   node->local.local = false;
 406   location_t saved_loc = input_location;
 407   input_location = DECL_SOURCE_LOCATION (node->decl);
 408   bool ret
 409     = targetm.target_option.valid_attribute_p (node->decl, NULL,
 410                                                TREE_VALUE (attributes), 0);
 411   input_location = saved_loc;
 412   return ret;
 413 }
 414
 415 static unsigned int
 416 ipa_target_clone (void)
 417 {
 418   struct cgraph_node *node;
 419
 420   bool target_clone_pass = false;
 421   FOR_EACH_FUNCTION (node)
 422     target_clone_pass |= expand_target_clones (node, node->definition);
 423
 424   if (target_clone_pass)
 425     FOR_EACH_FUNCTION (node)
 426       create_dispatcher_calls (node);
 427
 428   return 0;
 429 }
 430
 431 namespace {
 432
 433 const pass_data pass_data_target_clone =
 434 {
 435   SIMPLE_IPA_PASS,              /* type */
 436   "targetclone",                /* name */
 437   OPTGROUP_NONE,                /* optinfo_flags */
 438   TV_NONE,                      /* tv_id */
 439   ( PROP_ssa | PROP_cfg ),      /* properties_required */
 440   0,                            /* properties_provided */
 441   0,                            /* properties_destroyed */
 442   0,                            /* todo_flags_start */
 443   TODO_update_ssa               /* todo_flags_finish */
 444 };
 445
 446 class pass_target_clone : public simple_ipa_opt_pass
 447 {
 448 public:
 449   pass_target_clone (gcc::context *ctxt)
 450     : simple_ipa_opt_pass (pass_data_target_clone, ctxt)
 451   {}
 452
 453   /* opt_pass methods: */
 454   virtual bool gate (function *);
 455   virtual unsigned int execute (function *) { return ipa_target_clone (); }
 456 };
 457
 458 bool
 459 pass_target_clone::gate (function *)
 460 {
 461   return true;
 462 }
 463
 464 } // anon namespace
 465
 466 simple_ipa_opt_pass *
 467 make_pass_target_clone (gcc::context *ctxt)
 468 {
 469   return new pass_target_clone (ctxt);
 470 }