gcc/tree-emutls.c

   1 /* Lower TLS operations to emulation functions.
   2    Copyright (C) 2006-2018 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it
   7 under the terms of the GNU General Public License as published by the
   8 Free Software Foundation; either version 3, or (at your option) any
   9 later version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT
  12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "backend.h"
  24 #include "target.h"
  25 #include "tree.h"
  26 #include "gimple.h"
  27 #include "tree-pass.h"
  28 #include "ssa.h"
  29 #include "cgraph.h"
  30 #include "fold-const.h"
  31 #include "stor-layout.h"
  32 #include "varasm.h"
  33 #include "gimple-iterator.h"
  34 #include "gimple-walk.h"
  35 #include "langhooks.h"
  36 #include "tree-iterator.h"
  37
  38 /* Whenever a target does not support thread-local storage (TLS) natively,
  39    we can emulate it with some run-time support in libgcc.  This will in
  40    turn rely on "keyed storage" a-la pthread_key_create; essentially all
  41    thread libraries provide such functionality.
  42
  43    In order to coordinate with the libgcc runtime, each TLS variable is
  44    described by a "control variable".  This control variable records the
  45    required size, alignment, and initial value of the TLS variable for
  46    instantiation at runtime.  It also stores an integer token to be used
  47    by the runtime to find the address of the variable within each thread.
  48
  49    On the compiler side, this means that we need to replace all instances
  50    of "tls_var" in the code with "*__emutls_get_addr(&control_var)".  We
  51    also need to eliminate "tls_var" from the symbol table and introduce
  52    "control_var".
  53
  54    We used to perform all of the transformations during conversion to rtl,
  55    and the variable substitutions magically within assemble_variable.
  56    However, this late fiddling of the symbol table conflicts with LTO and
  57    whole-program compilation.  Therefore we must now make all the changes
  58    to the symbol table early in the GIMPLE optimization path, before we
  59    write things out to LTO intermediate files.  */
  60
  61 /* Value for TLS varpool node where a pointer to control variable and
  62    access variable are stored.  */
  63 struct tls_var_data
  64 {
  65   varpool_node *control_var;
  66   tree access;
  67 };
  68
  69 /* TLS map accesses mapping between a TLS varpool node and a pair
  70    made by control variable and access variable.  */
  71 static hash_map<varpool_node *, tls_var_data> *tls_map = NULL;
  72
  73 /* The type of the control structure, shared with the emutls.c runtime.  */
  74 static tree emutls_object_type;
  75
  76 #if !defined (NO_DOT_IN_LABEL)
  77 # define EMUTLS_SEPARATOR       "."
  78 #elif !defined (NO_DOLLAR_IN_LABEL)
  79 # define EMUTLS_SEPARATOR       "$"
  80 #else
  81 # define EMUTLS_SEPARATOR       "_"
  82 #endif
  83
  84 /* Create an IDENTIFIER_NODE by prefixing PREFIX to the
  85    IDENTIFIER_NODE NAME's name.  */
  86
  87 static tree
  88 prefix_name (const char *prefix, tree name)
  89 {
  90   unsigned plen = strlen (prefix);
  91   unsigned nlen = strlen (IDENTIFIER_POINTER (name));
  92   char *toname = (char *) alloca (plen + nlen + 1);
  93
  94   memcpy (toname, prefix, plen);
  95   memcpy (toname + plen, IDENTIFIER_POINTER (name), nlen + 1);
  96
  97   return get_identifier (toname);
  98 }
  99
 100 /* Create an identifier for the struct __emutls_object, given an identifier
 101    of the DECL_ASSEMBLY_NAME of the original object.  */
 102
 103 static tree
 104 get_emutls_object_name (tree name)
 105 {
 106   const char *prefix = (targetm.emutls.var_prefix
 107                         ? targetm.emutls.var_prefix
 108                         : "__emutls_v" EMUTLS_SEPARATOR);
 109   return prefix_name (prefix, name);
 110 }
 111
 112 /* Create the fields of the type for the control variables.  Ordinarily
 113    this must match struct __emutls_object defined in emutls.c.  However
 114    this is a target hook so that VxWorks can define its own layout.  */
 115
 116 tree
 117 default_emutls_var_fields (tree type, tree *name ATTRIBUTE_UNUSED)
 118 {
 119   tree word_type_node, field, next_field;
 120
 121   field = build_decl (UNKNOWN_LOCATION,
 122                       FIELD_DECL, get_identifier ("__templ"), ptr_type_node);
 123   DECL_CONTEXT (field) = type;
 124   next_field = field;
 125
 126   field = build_decl (UNKNOWN_LOCATION,
 127                       FIELD_DECL, get_identifier ("__offset"),
 128                       ptr_type_node);
 129   DECL_CONTEXT (field) = type;
 130   DECL_CHAIN (field) = next_field;
 131   next_field = field;
 132
 133   word_type_node = lang_hooks.types.type_for_mode (word_mode, 1);
 134   field = build_decl (UNKNOWN_LOCATION,
 135                       FIELD_DECL, get_identifier ("__align"),
 136                       word_type_node);
 137   DECL_CONTEXT (field) = type;
 138   DECL_CHAIN (field) = next_field;
 139   next_field = field;
 140
 141   field = build_decl (UNKNOWN_LOCATION,
 142                       FIELD_DECL, get_identifier ("__size"), word_type_node);
 143   DECL_CONTEXT (field) = type;
 144   DECL_CHAIN (field) = next_field;
 145
 146   return field;
 147 }
 148
 149 /* Initialize emulated tls object TO, which refers to TLS variable DECL and
 150    is initialized by PROXY.  As above, this is the default implementation of
 151    a target hook overridden by VxWorks.  */
 152
 153 tree
 154 default_emutls_var_init (tree to, tree decl, tree proxy)
 155 {
 156   vec<constructor_elt, va_gc> *v;
 157   vec_alloc (v, 4);
 158   constructor_elt elt;
 159   tree type = TREE_TYPE (to);
 160   tree field = TYPE_FIELDS (type);
 161
 162   elt.index = field;
 163   elt.value = fold_convert (TREE_TYPE (field), DECL_SIZE_UNIT (decl));
 164   v->quick_push (elt);
 165
 166   field = DECL_CHAIN (field);
 167   elt.index = field;
 168   elt.value = build_int_cst (TREE_TYPE (field),
 169                              DECL_ALIGN_UNIT (decl));
 170   v->quick_push (elt);
 171
 172   field = DECL_CHAIN (field);
 173   elt.index = field;
 174   elt.value = null_pointer_node;
 175   v->quick_push (elt);
 176
 177   field = DECL_CHAIN (field);
 178   elt.index = field;
 179   elt.value = proxy;
 180   v->quick_push (elt);
 181
 182   return build_constructor (type, v);
 183 }
 184
 185 /* Create the structure for struct __emutls_object.  This should match the
 186    structure at the top of emutls.c, modulo the union there.  */
 187
 188 static tree
 189 get_emutls_object_type (void)
 190 {
 191   tree type, type_name, field;
 192
 193   type = emutls_object_type;
 194   if (type)
 195     return type;
 196
 197   emutls_object_type = type = lang_hooks.types.make_type (RECORD_TYPE);
 198   type_name = NULL;
 199   field = targetm.emutls.var_fields (type, &type_name);
 200   if (!type_name)
 201     type_name = get_identifier ("__emutls_object");
 202   type_name = build_decl (UNKNOWN_LOCATION,
 203                           TYPE_DECL, type_name, type);
 204   TYPE_NAME (type) = type_name;
 205   TYPE_FIELDS (type) = field;
 206   layout_type (type);
 207
 208   return type;
 209 }
 210
 211 /* Create a read-only variable like DECL, with the same DECL_INITIAL.
 212    This will be used for initializing the emulated tls data area.  */
 213
 214 static tree
 215 get_emutls_init_templ_addr (tree decl)
 216 {
 217   tree name, to;
 218
 219   if (targetm.emutls.register_common && !DECL_INITIAL (decl)
 220       && !DECL_SECTION_NAME (decl))
 221     return null_pointer_node;
 222
 223   name = DECL_ASSEMBLER_NAME (decl);
 224   if (!targetm.emutls.tmpl_prefix || targetm.emutls.tmpl_prefix[0])
 225     {
 226       const char *prefix = (targetm.emutls.tmpl_prefix
 227                             ? targetm.emutls.tmpl_prefix
 228                             : "__emutls_t" EMUTLS_SEPARATOR);
 229       name = prefix_name (prefix, name);
 230     }
 231
 232   to = build_decl (DECL_SOURCE_LOCATION (decl),
 233                    VAR_DECL, name, TREE_TYPE (decl));
 234   SET_DECL_ASSEMBLER_NAME (to, DECL_NAME (to));
 235
 236   DECL_ARTIFICIAL (to) = 1;
 237   TREE_USED (to) = TREE_USED (decl);
 238   TREE_READONLY (to) = 1;
 239   DECL_IGNORED_P (to) = 1;
 240   DECL_CONTEXT (to) = DECL_CONTEXT (decl);
 241   DECL_PRESERVE_P (to) = DECL_PRESERVE_P (decl);
 242
 243   DECL_WEAK (to) = DECL_WEAK (decl);
 244   if (DECL_ONE_ONLY (decl))
 245     {
 246       TREE_STATIC (to) = TREE_STATIC (decl);
 247       TREE_PUBLIC (to) = TREE_PUBLIC (decl);
 248       DECL_VISIBILITY (to) = DECL_VISIBILITY (decl);
 249       make_decl_one_only (to, DECL_ASSEMBLER_NAME (to));
 250     }
 251   else
 252     TREE_STATIC (to) = 1;
 253
 254   DECL_VISIBILITY_SPECIFIED (to) = DECL_VISIBILITY_SPECIFIED (decl);
 255   DECL_INITIAL (to) = DECL_INITIAL (decl);
 256   DECL_INITIAL (decl) = NULL;
 257
 258   if (targetm.emutls.tmpl_section)
 259     set_decl_section_name (to, targetm.emutls.tmpl_section);
 260   else
 261     set_decl_section_name (to, DECL_SECTION_NAME (decl));
 262
 263   /* Create varpool node for the new variable and finalize it if it is
 264      not external one.  */
 265   if (DECL_EXTERNAL (to))
 266     varpool_node::get_create (to);
 267   else
 268     varpool_node::add (to);
 269   return build_fold_addr_expr (to);
 270 }
 271
 272 /* Create and return the control variable for the TLS variable DECL.  */
 273
 274 static tree
 275 new_emutls_decl (tree decl, tree alias_of)
 276 {
 277   tree name, to;
 278
 279   name = DECL_ASSEMBLER_NAME (decl);
 280   to = build_decl (DECL_SOURCE_LOCATION (decl), VAR_DECL,
 281                    get_emutls_object_name (name),
 282                    get_emutls_object_type ());
 283
 284   SET_DECL_ASSEMBLER_NAME (to, DECL_NAME (to));
 285
 286   DECL_ARTIFICIAL (to) = 1;
 287   DECL_IGNORED_P (to) = 1;
 288   TREE_READONLY (to) = 0;
 289   TREE_STATIC (to) = 1;
 290
 291   DECL_PRESERVE_P (to) = DECL_PRESERVE_P (decl);
 292   DECL_CONTEXT (to) = DECL_CONTEXT (decl);
 293   TREE_USED (to) = TREE_USED (decl);
 294   TREE_PUBLIC (to) = TREE_PUBLIC (decl);
 295   DECL_EXTERNAL (to) = DECL_EXTERNAL (decl);
 296   DECL_COMMON (to) = DECL_COMMON (decl);
 297   DECL_WEAK (to) = DECL_WEAK (decl);
 298   DECL_VISIBILITY (to) = DECL_VISIBILITY (decl);
 299   DECL_VISIBILITY_SPECIFIED (to) = DECL_VISIBILITY_SPECIFIED (decl);
 300   DECL_DLLIMPORT_P (to) = DECL_DLLIMPORT_P (decl);
 301
 302   DECL_ATTRIBUTES (to) = targetm.merge_decl_attributes (decl, to);
 303
 304   if (DECL_ONE_ONLY (decl))
 305     make_decl_one_only (to, DECL_ASSEMBLER_NAME (to));
 306
 307   set_decl_tls_model (to, TLS_MODEL_EMULATED);
 308
 309   /* If we're not allowed to change the proxy object's alignment,
 310      pretend it has been set by the user.  */
 311   if (targetm.emutls.var_align_fixed)
 312     DECL_USER_ALIGN (to) = 1;
 313
 314   /* If the target wants the control variables grouped, do so.  */
 315   if (!DECL_COMMON (to) && targetm.emutls.var_section)
 316     {
 317       set_decl_section_name (to, targetm.emutls.var_section);
 318     }
 319
 320   /* If this variable is defined locally, then we need to initialize the
 321      control structure with size and alignment information.  Initialization
 322      of COMMON block variables happens elsewhere via a constructor.  */
 323   if (!DECL_EXTERNAL (to)
 324       && (!DECL_COMMON (to)
 325           || (DECL_INITIAL (decl)
 326               && DECL_INITIAL (decl) != error_mark_node)))
 327     {
 328       tree tmpl = get_emutls_init_templ_addr (decl);
 329       DECL_INITIAL (to) = targetm.emutls.var_init (to, decl, tmpl);
 330       record_references_in_initializer (to, false);
 331     }
 332
 333   /* Create varpool node for the new variable and finalize it if it is
 334      not external one.  */
 335   if (DECL_EXTERNAL (to))
 336     varpool_node::get_create (to);
 337   else if (!alias_of)
 338     varpool_node::add (to);
 339   else
 340     {
 341       varpool_node *n;
 342       varpool_node *t = varpool_node::get_for_asmname
 343          (DECL_ASSEMBLER_NAME (DECL_VALUE_EXPR (alias_of)));
 344
 345       n = varpool_node::create_alias (to, t->decl);
 346       n->resolve_alias (t);
 347     }
 348   return to;
 349 }
 350
 351 /* Generate a call statement to initialize CONTROL_DECL for TLS_DECL.
 352    This only needs to happen for TLS COMMON variables; non-COMMON
 353    variables can be initialized statically.  Insert the generated
 354    call statement at the end of PSTMTS.  */
 355
 356 static void
 357 emutls_common_1 (tree tls_decl, tree control_decl, tree *pstmts)
 358 {
 359   tree x;
 360   tree word_type_node;
 361
 362   if (! DECL_COMMON (tls_decl)
 363       || (DECL_INITIAL (tls_decl)
 364           && DECL_INITIAL (tls_decl) != error_mark_node))
 365     return;
 366
 367   word_type_node = lang_hooks.types.type_for_mode (word_mode, 1);
 368
 369   x = build_call_expr (builtin_decl_explicit (BUILT_IN_EMUTLS_REGISTER_COMMON),
 370                        4, build_fold_addr_expr (control_decl),
 371                        fold_convert (word_type_node,
 372                                      DECL_SIZE_UNIT (tls_decl)),
 373                        build_int_cst (word_type_node,
 374                                       DECL_ALIGN_UNIT (tls_decl)),
 375                        get_emutls_init_templ_addr (tls_decl));
 376
 377   append_to_statement_list (x, pstmts);
 378 }
 379
 380 struct lower_emutls_data
 381 {
 382   struct cgraph_node *cfun_node;
 383   struct cgraph_node *builtin_node;
 384   tree builtin_decl;
 385   basic_block bb;
 386   location_t loc;
 387   gimple_seq seq;
 388 };
 389
 390 /* Given a TLS variable DECL, return an SSA_NAME holding its address.
 391    Append any new computation statements required to D->SEQ.  */
 392
 393 static tree
 394 gen_emutls_addr (tree decl, struct lower_emutls_data *d)
 395 {
 396   /* Compute the address of the TLS variable with help from runtime.  */
 397   tls_var_data *data = tls_map->get (varpool_node::get (decl));
 398   tree addr = data->access;
 399
 400   if (addr == NULL)
 401     {
 402       varpool_node *cvar;
 403       tree cdecl;
 404       gcall *x;
 405
 406       cvar = data->control_var;
 407       cdecl = cvar->decl;
 408       TREE_ADDRESSABLE (cdecl) = 1;
 409
 410       addr = create_tmp_var (build_pointer_type (TREE_TYPE (decl)));
 411       x = gimple_build_call (d->builtin_decl, 1, build_fold_addr_expr (cdecl));
 412       gimple_set_location (x, d->loc);
 413
 414       addr = make_ssa_name (addr, x);
 415       gimple_call_set_lhs (x, addr);
 416
 417       gimple_seq_add_stmt (&d->seq, x);
 418
 419       d->cfun_node->create_edge (d->builtin_node, x, d->bb->count);
 420
 421       /* We may be adding a new reference to a new variable to the function.
 422          This means we have to play with the ipa-reference web.  */
 423       d->cfun_node->create_reference (cvar, IPA_REF_ADDR, x);
 424
 425       /* Record this ssa_name for possible use later in the basic block.  */
 426       data->access = addr;
 427     }
 428
 429   return addr;
 430 }
 431
 432 /* Callback for walk_gimple_op.  D = WI->INFO is a struct lower_emutls_data.
 433    Given an operand *PTR within D->STMT, if the operand references a TLS
 434    variable, then lower the reference to a call to the runtime.  Insert
 435    any new statements required into D->SEQ; the caller is responsible for
 436    placing those appropriately.  */
 437
 438 static tree
 439 lower_emutls_1 (tree *ptr, int *walk_subtrees, void *cb_data)
 440 {
 441   struct walk_stmt_info *wi = (struct walk_stmt_info *) cb_data;
 442   struct lower_emutls_data *d = (struct lower_emutls_data *) wi->info;
 443   tree t = *ptr;
 444   bool is_addr = false;
 445   tree addr;
 446
 447   *walk_subtrees = 0;
 448
 449   switch (TREE_CODE (t))
 450     {
 451     case ADDR_EXPR:
 452       /* If this is not a straight-forward "&var", but rather something
 453          like "&var.a", then we may need special handling.  */
 454       if (TREE_CODE (TREE_OPERAND (t, 0)) != VAR_DECL)
 455         {
 456           bool save_changed;
 457
 458           /* If we're allowed more than just is_gimple_val, continue.  */
 459           if (!wi->val_only)
 460             {
 461               *walk_subtrees = 1;
 462               return NULL_TREE;
 463             }
 464
 465           /* See if any substitution would be made.  */
 466           save_changed = wi->changed;
 467           wi->changed = false;
 468           wi->val_only = false;
 469           walk_tree (&TREE_OPERAND (t, 0), lower_emutls_1, wi, NULL);
 470           wi->val_only = true;
 471
 472           /* If so, then extract this entire sub-expression "&p->a" into a
 473              new assignment statement, and substitute yet another SSA_NAME.  */
 474           if (wi->changed)
 475             {
 476               gimple *x;
 477
 478               addr = create_tmp_var (TREE_TYPE (t));
 479               x = gimple_build_assign (addr, t);
 480               gimple_set_location (x, d->loc);
 481
 482               addr = make_ssa_name (addr, x);
 483               gimple_assign_set_lhs (x, addr);
 484
 485               gimple_seq_add_stmt (&d->seq, x);
 486
 487               *ptr = addr;
 488             }
 489           else
 490             wi->changed = save_changed;
 491
 492           return NULL_TREE;
 493         }
 494
 495       t = TREE_OPERAND (t, 0);
 496       is_addr = true;
 497       /* FALLTHRU */
 498
 499     case VAR_DECL:
 500       if (!DECL_THREAD_LOCAL_P (t))
 501         return NULL_TREE;
 502       break;
 503
 504     default:
 505       /* We're not interested in other decls or types, only subexpressions.  */
 506       if (EXPR_P (t))
 507         *walk_subtrees = 1;
 508       /* FALLTHRU */
 509
 510     case SSA_NAME:
 511       /* Special-case the return of SSA_NAME, since it's so common.  */
 512       return NULL_TREE;
 513     }
 514
 515   addr = gen_emutls_addr (t, d);
 516   if (is_addr)
 517     {
 518       /* Replace "&var" with "addr" in the statement.  */
 519       *ptr = addr;
 520     }
 521   else
 522     {
 523       /* Replace "var" with "*addr" in the statement.  */
 524       t = build2 (MEM_REF, TREE_TYPE (t), addr,
 525                   build_int_cst (TREE_TYPE (addr), 0));
 526       *ptr = t;
 527     }
 528
 529   wi->changed = true;
 530   return NULL_TREE;
 531 }
 532
 533 /* Lower all of the operands of STMT.  */
 534
 535 static void
 536 lower_emutls_stmt (gimple *stmt, struct lower_emutls_data *d)
 537 {
 538   struct walk_stmt_info wi;
 539
 540   d->loc = gimple_location (stmt);
 541
 542   memset (&wi, 0, sizeof (wi));
 543   wi.info = d;
 544   wi.val_only = true;
 545   walk_gimple_op (stmt, lower_emutls_1, &wi);
 546
 547   if (wi.changed)
 548     update_stmt (stmt);
 549 }
 550
 551 /* Lower the I'th operand of PHI.  */
 552
 553 static void
 554 lower_emutls_phi_arg (gphi *phi, unsigned int i,
 555                       struct lower_emutls_data *d)
 556 {
 557   struct walk_stmt_info wi;
 558   struct phi_arg_d *pd = gimple_phi_arg (phi, i);
 559
 560   /* Early out for a very common case we don't care about.  */
 561   if (TREE_CODE (pd->def) == SSA_NAME)
 562     return;
 563
 564   d->loc = pd->locus;
 565
 566   memset (&wi, 0, sizeof (wi));
 567   wi.info = d;
 568   wi.val_only = true;
 569   walk_tree (&pd->def, lower_emutls_1, &wi, NULL);
 570
 571   /* For normal statements, we let update_stmt do its job.  But for phi
 572      nodes, we have to manipulate the immediate use list by hand.  */
 573   if (wi.changed)
 574     {
 575       gcc_assert (TREE_CODE (pd->def) == SSA_NAME);
 576       link_imm_use_stmt (&pd->imm_use, pd->def, phi);
 577     }
 578 }
 579
 580 /* Reset access variable for a given TLS variable data DATA.  */
 581
 582 bool
 583 reset_access (varpool_node * const &, tls_var_data *data, void *)
 584 {
 585   data->access = NULL;
 586
 587   return true;
 588 }
 589
 590 /* Clear the access variables, in order to begin a new block.  */
 591
 592 static inline void
 593 clear_access_vars (void)
 594 {
 595   tls_map->traverse<void *, reset_access> (NULL);
 596 }
 597
 598 /* Lower the entire function NODE.  */
 599
 600 static void
 601 lower_emutls_function_body (struct cgraph_node *node)
 602 {
 603   struct lower_emutls_data d;
 604   bool any_edge_inserts = false;
 605
 606   push_cfun (DECL_STRUCT_FUNCTION (node->decl));
 607
 608   d.cfun_node = node;
 609   d.builtin_decl = builtin_decl_explicit (BUILT_IN_EMUTLS_GET_ADDRESS);
 610   /* This is where we introduce the declaration to the IL and so we have to
 611      create a node for it.  */
 612   d.builtin_node = cgraph_node::get_create (d.builtin_decl);
 613
 614   FOR_EACH_BB_FN (d.bb, cfun)
 615     {
 616       unsigned int i, nedge;
 617
 618       /* Lower each of the PHI nodes of the block, as we may have
 619          propagated &tlsvar into a PHI argument.  These loops are
 620          arranged so that we process each edge at once, and each
 621          PHI argument for that edge.  */
 622       if (!gimple_seq_empty_p (phi_nodes (d.bb)))
 623         {
 624           nedge = EDGE_COUNT (d.bb->preds);
 625           for (i = 0; i < nedge; ++i)
 626             {
 627               edge e = EDGE_PRED (d.bb, i);
 628
 629               /* We can re-use any SSA_NAME created on this edge.  */
 630               clear_access_vars ();
 631               d.seq = NULL;
 632
 633               for (gphi_iterator gsi = gsi_start_phis (d.bb);
 634                    !gsi_end_p (gsi);
 635                    gsi_next (&gsi))
 636                 lower_emutls_phi_arg (gsi.phi (), i, &d);
 637
 638               /* Insert all statements generated by all phi nodes for this
 639                  particular edge all at once.  */
 640               if (d.seq)
 641                 {
 642                   gsi_insert_seq_on_edge (e, d.seq);
 643                   any_edge_inserts = true;
 644                 }
 645             }
 646         }
 647
 648       /* We can re-use any SSA_NAME created during this basic block.  */
 649       clear_access_vars ();
 650
 651       /* Lower each of the statements of the block.  */
 652       for (gimple_stmt_iterator gsi = gsi_start_bb (d.bb); !gsi_end_p (gsi);
 653            gsi_next (&gsi))
 654         {
 655           d.seq = NULL;
 656           lower_emutls_stmt (gsi_stmt (gsi), &d);
 657
 658           /* If any new statements were created, insert them immediately
 659              before the first use.  This prevents variable lifetimes from
 660              becoming unnecessarily long.  */
 661           if (d.seq)
 662             gsi_insert_seq_before (&gsi, d.seq, GSI_SAME_STMT);
 663         }
 664     }
 665
 666   if (any_edge_inserts)
 667     gsi_commit_edge_inserts ();
 668
 669   pop_cfun ();
 670 }
 671
 672 /* Create emutls variable for VAR, DATA is pointer to static
 673    ctor body we can add constructors to.
 674    Callback for varpool_for_variable_and_aliases.  */
 675
 676 static bool
 677 create_emultls_var (varpool_node *var, void *data)
 678 {
 679   tree cdecl;
 680   tls_var_data value;
 681
 682   cdecl = new_emutls_decl (var->decl,
 683                            var->alias && var->analyzed
 684                            ? var->get_alias_target ()->decl : NULL);
 685
 686   varpool_node *cvar = varpool_node::get (cdecl);
 687
 688   if (!var->alias)
 689     {
 690       /* Make sure the COMMON block control variable gets initialized.
 691          Note that there's no point in doing this for aliases; we only
 692          need to do this once for the main variable.  */
 693       emutls_common_1 (var->decl, cdecl, (tree *)data);
 694     }
 695   if (var->alias && !var->analyzed)
 696     cvar->alias = true;
 697
 698   /* Indicate that the value of the TLS variable may be found elsewhere,
 699      preventing the variable from re-appearing in the GIMPLE.  We cheat
 700      and use the control variable here (rather than a full call_expr),
 701      which is special-cased inside the DWARF2 output routines.  */
 702   SET_DECL_VALUE_EXPR (var->decl, cdecl);
 703   DECL_HAS_VALUE_EXPR_P (var->decl) = 1;
 704
 705   value.control_var = cvar;
 706   tls_map->put (var, value);
 707
 708   return false;
 709 }
 710
 711 /* Main entry point to the tls lowering pass.  */
 712
 713 static unsigned int
 714 ipa_lower_emutls (void)
 715 {
 716   varpool_node *var;
 717   cgraph_node *func;
 718   bool any_aliases = false;
 719   tree ctor_body = NULL;
 720   hash_set <varpool_node *> visited;
 721   auto_vec <varpool_node *> tls_vars;
 722
 723   /* Examine all global variables for TLS variables.  */
 724   FOR_EACH_VARIABLE (var)
 725     if (DECL_THREAD_LOCAL_P (var->decl)
 726         && !visited.add (var))
 727       {
 728         gcc_checking_assert (TREE_STATIC (var->decl)
 729                              || DECL_EXTERNAL (var->decl));
 730         tls_vars.safe_push (var);
 731         if (var->alias && var->definition
 732             && !visited.add (var->ultimate_alias_target ()))
 733           tls_vars.safe_push (var->ultimate_alias_target ());
 734       }
 735
 736   /* If we found no TLS variables, then there is no further work to do.  */
 737   if (tls_vars.is_empty ())
 738     {
 739       if (dump_file)
 740         fprintf (dump_file, "No TLS variables found.\n");
 741       return 0;
 742     }
 743
 744   tls_map = new hash_map <varpool_node *, tls_var_data> ();
 745
 746   /* Create the control variables for each TLS variable.  */
 747   for (unsigned i = 0; i < tls_vars.length (); i++)
 748     {
 749       var = tls_vars[i];
 750
 751       if (var->alias && !var->analyzed)
 752         any_aliases = true;
 753       else if (!var->alias)
 754         var->call_for_symbol_and_aliases (create_emultls_var, &ctor_body, true);
 755     }
 756
 757   /* If there were any aliases, then frob the alias_pairs vector.  */
 758   if (any_aliases)
 759     {
 760       alias_pair *p;
 761       unsigned int i;
 762       FOR_EACH_VEC_SAFE_ELT (alias_pairs, i, p)
 763         if (DECL_THREAD_LOCAL_P (p->decl))
 764           {
 765             p->decl = tls_map->get
 766               (varpool_node::get (p->decl))->control_var->decl;
 767             p->target = get_emutls_object_name (p->target);
 768           }
 769     }
 770
 771   /* Adjust all uses of TLS variables within the function bodies.  */
 772   FOR_EACH_DEFINED_FUNCTION (func)
 773     if (func->lowered)
 774       lower_emutls_function_body (func);
 775
 776   /* Generate the constructor for any COMMON control variables created.  */
 777   if (ctor_body)
 778     cgraph_build_static_cdtor ('I', ctor_body, DEFAULT_INIT_PRIORITY);
 779
 780   delete tls_map;
 781
 782   return 0;
 783 }
 784
 785 namespace {
 786
 787 const pass_data pass_data_ipa_lower_emutls =
 788 {
 789   SIMPLE_IPA_PASS, /* type */
 790   "emutls", /* name */
 791   OPTGROUP_NONE, /* optinfo_flags */
 792   TV_IPA_OPT, /* tv_id */
 793   ( PROP_cfg | PROP_ssa ), /* properties_required */
 794   0, /* properties_provided */
 795   0, /* properties_destroyed */
 796   0, /* todo_flags_start */
 797   0, /* todo_flags_finish */
 798 };
 799
 800 class pass_ipa_lower_emutls : public simple_ipa_opt_pass
 801 {
 802 public:
 803   pass_ipa_lower_emutls (gcc::context *ctxt)
 804     : simple_ipa_opt_pass (pass_data_ipa_lower_emutls, ctxt)
 805   {}
 806
 807   /* opt_pass methods: */
 808   virtual bool gate (function *)
 809     {
 810       /* If the target supports TLS natively, we need do nothing here.  */
 811       return !targetm.have_tls;
 812     }
 813
 814   virtual unsigned int execute (function *) { return ipa_lower_emutls (); }
 815
 816 }; // class pass_ipa_lower_emutls
 817
 818 } // anon namespace
 819
 820 simple_ipa_opt_pass *
 821 make_pass_ipa_lower_emutls (gcc::context *ctxt)
 822 {
 823   return new pass_ipa_lower_emutls (ctxt);
 824 }