gcc/tree-emutls.c

   1 /* Lower TLS operations to emulation functions.
   2    Copyright (C) 2006-2016 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   int bb_freq;
 387   location_t loc;
 388   gimple_seq seq;
 389 };
 390
 391 /* Given a TLS variable DECL, return an SSA_NAME holding its address.
 392    Append any new computation statements required to D->SEQ.  */
 393
 394 static tree
 395 gen_emutls_addr (tree decl, struct lower_emutls_data *d)
 396 {
 397   /* Compute the address of the TLS variable with help from runtime.  */
 398   tls_var_data *data = tls_map->get (varpool_node::get (decl));
 399   tree addr = data->access;
 400
 401   if (addr == NULL)
 402     {
 403       varpool_node *cvar;
 404       tree cdecl;
 405       gcall *x;
 406
 407       cvar = data->control_var;
 408       cdecl = cvar->decl;
 409       TREE_ADDRESSABLE (cdecl) = 1;
 410
 411       addr = create_tmp_var (build_pointer_type (TREE_TYPE (decl)));
 412       x = gimple_build_call (d->builtin_decl, 1, build_fold_addr_expr (cdecl));
 413       gimple_set_location (x, d->loc);
 414
 415       addr = make_ssa_name (addr, x);
 416       gimple_call_set_lhs (x, addr);
 417
 418       gimple_seq_add_stmt (&d->seq, x);
 419
 420       d->cfun_node->create_edge (d->builtin_node, x, d->bb->count, d->bb_freq);
 421
 422       /* We may be adding a new reference to a new variable to the function.
 423          This means we have to play with the ipa-reference web.  */
 424       d->cfun_node->create_reference (cvar, IPA_REF_ADDR, x);
 425
 426       /* Record this ssa_name for possible use later in the basic block.  */
 427       data->access = addr;
 428     }
 429
 430   return addr;
 431 }
 432
 433 /* Callback for walk_gimple_op.  D = WI->INFO is a struct lower_emutls_data.
 434    Given an operand *PTR within D->STMT, if the operand references a TLS
 435    variable, then lower the reference to a call to the runtime.  Insert
 436    any new statements required into D->SEQ; the caller is responsible for
 437    placing those appropriately.  */
 438
 439 static tree
 440 lower_emutls_1 (tree *ptr, int *walk_subtrees, void *cb_data)
 441 {
 442   struct walk_stmt_info *wi = (struct walk_stmt_info *) cb_data;
 443   struct lower_emutls_data *d = (struct lower_emutls_data *) wi->info;
 444   tree t = *ptr;
 445   bool is_addr = false;
 446   tree addr;
 447
 448   *walk_subtrees = 0;
 449
 450   switch (TREE_CODE (t))
 451     {
 452     case ADDR_EXPR:
 453       /* If this is not a straight-forward "&var", but rather something
 454          like "&var.a", then we may need special handling.  */
 455       if (TREE_CODE (TREE_OPERAND (t, 0)) != VAR_DECL)
 456         {
 457           bool save_changed;
 458
 459           /* If we're allowed more than just is_gimple_val, continue.  */
 460           if (!wi->val_only)
 461             {
 462               *walk_subtrees = 1;
 463               return NULL_TREE;
 464             }
 465
 466           /* See if any substitution would be made.  */
 467           save_changed = wi->changed;
 468           wi->changed = false;
 469           wi->val_only = false;
 470           walk_tree (&TREE_OPERAND (t, 0), lower_emutls_1, wi, NULL);
 471           wi->val_only = true;
 472
 473           /* If so, then extract this entire sub-expression "&p->a" into a
 474              new assignment statement, and substitute yet another SSA_NAME.  */
 475           if (wi->changed)
 476             {
 477               gimple *x;
 478
 479               addr = create_tmp_var (TREE_TYPE (t));
 480               x = gimple_build_assign (addr, t);
 481               gimple_set_location (x, d->loc);
 482
 483               addr = make_ssa_name (addr, x);
 484               gimple_assign_set_lhs (x, addr);
 485
 486               gimple_seq_add_stmt (&d->seq, x);
 487
 488               *ptr = addr;
 489             }
 490           else
 491             wi->changed = save_changed;
 492
 493           return NULL_TREE;
 494         }
 495
 496       t = TREE_OPERAND (t, 0);
 497       is_addr = true;
 498       /* FALLTHRU */
 499
 500     case VAR_DECL:
 501       if (!DECL_THREAD_LOCAL_P (t))
 502         return NULL_TREE;
 503       break;
 504
 505     default:
 506       /* We're not interested in other decls or types, only subexpressions.  */
 507       if (EXPR_P (t))
 508         *walk_subtrees = 1;
 509       /* FALLTHRU */
 510
 511     case SSA_NAME:
 512       /* Special-case the return of SSA_NAME, since it's so common.  */
 513       return NULL_TREE;
 514     }
 515
 516   addr = gen_emutls_addr (t, d);
 517   if (is_addr)
 518     {
 519       /* Replace "&var" with "addr" in the statement.  */
 520       *ptr = addr;
 521     }
 522   else
 523     {
 524       /* Replace "var" with "*addr" in the statement.  */
 525       t = build2 (MEM_REF, TREE_TYPE (t), addr,
 526                   build_int_cst (TREE_TYPE (addr), 0));
 527       *ptr = t;
 528     }
 529
 530   wi->changed = true;
 531   return NULL_TREE;
 532 }
 533
 534 /* Lower all of the operands of STMT.  */
 535
 536 static void
 537 lower_emutls_stmt (gimple *stmt, struct lower_emutls_data *d)
 538 {
 539   struct walk_stmt_info wi;
 540
 541   d->loc = gimple_location (stmt);
 542
 543   memset (&wi, 0, sizeof (wi));
 544   wi.info = d;
 545   wi.val_only = true;
 546   walk_gimple_op (stmt, lower_emutls_1, &wi);
 547
 548   if (wi.changed)
 549     update_stmt (stmt);
 550 }
 551
 552 /* Lower the I'th operand of PHI.  */
 553
 554 static void
 555 lower_emutls_phi_arg (gphi *phi, unsigned int i,
 556                       struct lower_emutls_data *d)
 557 {
 558   struct walk_stmt_info wi;
 559   struct phi_arg_d *pd = gimple_phi_arg (phi, i);
 560
 561   /* Early out for a very common case we don't care about.  */
 562   if (TREE_CODE (pd->def) == SSA_NAME)
 563     return;
 564
 565   d->loc = pd->locus;
 566
 567   memset (&wi, 0, sizeof (wi));
 568   wi.info = d;
 569   wi.val_only = true;
 570   walk_tree (&pd->def, lower_emutls_1, &wi, NULL);
 571
 572   /* For normal statements, we let update_stmt do its job.  But for phi
 573      nodes, we have to manipulate the immediate use list by hand.  */
 574   if (wi.changed)
 575     {
 576       gcc_assert (TREE_CODE (pd->def) == SSA_NAME);
 577       link_imm_use_stmt (&pd->imm_use, pd->def, phi);
 578     }
 579 }
 580
 581 /* Reset access variable for a given TLS variable data DATA.  */
 582
 583 bool
 584 reset_access (varpool_node * const &, tls_var_data *data, void *)
 585 {
 586   data->access = NULL;
 587
 588   return true;
 589 }
 590
 591 /* Clear the access variables, in order to begin a new block.  */
 592
 593 static inline void
 594 clear_access_vars (void)
 595 {
 596   tls_map->traverse<void *, reset_access> (NULL);
 597 }
 598
 599 /* Lower the entire function NODE.  */
 600
 601 static void
 602 lower_emutls_function_body (struct cgraph_node *node)
 603 {
 604   struct lower_emutls_data d;
 605   bool any_edge_inserts = false;
 606
 607   push_cfun (DECL_STRUCT_FUNCTION (node->decl));
 608
 609   d.cfun_node = node;
 610   d.builtin_decl = builtin_decl_explicit (BUILT_IN_EMUTLS_GET_ADDRESS);
 611   /* This is where we introduce the declaration to the IL and so we have to
 612      create a node for it.  */
 613   d.builtin_node = cgraph_node::get_create (d.builtin_decl);
 614
 615   FOR_EACH_BB_FN (d.bb, cfun)
 616     {
 617       unsigned int i, nedge;
 618
 619       /* Lower each of the PHI nodes of the block, as we may have
 620          propagated &tlsvar into a PHI argument.  These loops are
 621          arranged so that we process each edge at once, and each
 622          PHI argument for that edge.  */
 623       if (!gimple_seq_empty_p (phi_nodes (d.bb)))
 624         {
 625           /* The calls will be inserted on the edges, and the frequencies
 626              will be computed during the commit process.  */
 627           d.bb_freq = 0;
 628
 629           nedge = EDGE_COUNT (d.bb->preds);
 630           for (i = 0; i < nedge; ++i)
 631             {
 632               edge e = EDGE_PRED (d.bb, i);
 633
 634               /* We can re-use any SSA_NAME created on this edge.  */
 635               clear_access_vars ();
 636               d.seq = NULL;
 637
 638               for (gphi_iterator gsi = gsi_start_phis (d.bb);
 639                    !gsi_end_p (gsi);
 640                    gsi_next (&gsi))
 641                 lower_emutls_phi_arg (gsi.phi (), i, &d);
 642
 643               /* Insert all statements generated by all phi nodes for this
 644                  particular edge all at once.  */
 645               if (d.seq)
 646                 {
 647                   gsi_insert_seq_on_edge (e, d.seq);
 648                   any_edge_inserts = true;
 649                 }
 650             }
 651         }
 652
 653       d.bb_freq = compute_call_stmt_bb_frequency (current_function_decl, d.bb);
 654
 655       /* We can re-use any SSA_NAME created during this basic block.  */
 656       clear_access_vars ();
 657
 658       /* Lower each of the statements of the block.  */
 659       for (gimple_stmt_iterator gsi = gsi_start_bb (d.bb); !gsi_end_p (gsi);
 660            gsi_next (&gsi))
 661         {
 662           d.seq = NULL;
 663           lower_emutls_stmt (gsi_stmt (gsi), &d);
 664
 665           /* If any new statements were created, insert them immediately
 666              before the first use.  This prevents variable lifetimes from
 667              becoming unnecessarily long.  */
 668           if (d.seq)
 669             gsi_insert_seq_before (&gsi, d.seq, GSI_SAME_STMT);
 670         }
 671     }
 672
 673   if (any_edge_inserts)
 674     gsi_commit_edge_inserts ();
 675
 676   pop_cfun ();
 677 }
 678
 679 /* Create emutls variable for VAR, DATA is pointer to static
 680    ctor body we can add constructors to.
 681    Callback for varpool_for_variable_and_aliases.  */
 682
 683 static bool
 684 create_emultls_var (varpool_node *var, void *data)
 685 {
 686   tree cdecl;
 687   tls_var_data value;
 688
 689   cdecl = new_emutls_decl (var->decl,
 690                            var->alias && var->analyzed
 691                            ? var->get_alias_target ()->decl : NULL);
 692
 693   varpool_node *cvar = varpool_node::get (cdecl);
 694
 695   if (!var->alias)
 696     {
 697       /* Make sure the COMMON block control variable gets initialized.
 698          Note that there's no point in doing this for aliases; we only
 699          need to do this once for the main variable.  */
 700       emutls_common_1 (var->decl, cdecl, (tree *)data);
 701     }
 702   if (var->alias && !var->analyzed)
 703     cvar->alias = true;
 704
 705   /* Indicate that the value of the TLS variable may be found elsewhere,
 706      preventing the variable from re-appearing in the GIMPLE.  We cheat
 707      and use the control variable here (rather than a full call_expr),
 708      which is special-cased inside the DWARF2 output routines.  */
 709   SET_DECL_VALUE_EXPR (var->decl, cdecl);
 710   DECL_HAS_VALUE_EXPR_P (var->decl) = 1;
 711
 712   value.control_var = cvar;
 713   tls_map->put (var, value);
 714
 715   return false;
 716 }
 717
 718 /* Main entry point to the tls lowering pass.  */
 719
 720 static unsigned int
 721 ipa_lower_emutls (void)
 722 {
 723   varpool_node *var;
 724   cgraph_node *func;
 725   bool any_aliases = false;
 726   tree ctor_body = NULL;
 727   hash_set <varpool_node *> visited;
 728   auto_vec <varpool_node *> tls_vars;
 729
 730   /* Examine all global variables for TLS variables.  */
 731   FOR_EACH_VARIABLE (var)
 732     if (DECL_THREAD_LOCAL_P (var->decl)
 733         && !visited.add (var))
 734       {
 735         gcc_checking_assert (TREE_STATIC (var->decl)
 736                              || DECL_EXTERNAL (var->decl));
 737         tls_vars.safe_push (var);
 738         if (var->alias && var->definition
 739             && !visited.add (var->ultimate_alias_target ()))
 740           tls_vars.safe_push (var->ultimate_alias_target ());
 741       }
 742
 743   /* If we found no TLS variables, then there is no further work to do.  */
 744   if (tls_vars.is_empty ())
 745     {
 746       if (dump_file)
 747         fprintf (dump_file, "No TLS variables found.\n");
 748       return 0;
 749     }
 750
 751   tls_map = new hash_map <varpool_node *, tls_var_data> ();
 752
 753   /* Create the control variables for each TLS variable.  */
 754   for (unsigned i = 0; i < tls_vars.length (); i++)
 755     {
 756       var = tls_vars[i];
 757
 758       if (var->alias && !var->analyzed)
 759         any_aliases = true;
 760       else if (!var->alias)
 761         var->call_for_symbol_and_aliases (create_emultls_var, &ctor_body, true);
 762     }
 763
 764   /* If there were any aliases, then frob the alias_pairs vector.  */
 765   if (any_aliases)
 766     {
 767       alias_pair *p;
 768       unsigned int i;
 769       FOR_EACH_VEC_SAFE_ELT (alias_pairs, i, p)
 770         if (DECL_THREAD_LOCAL_P (p->decl))
 771           {
 772             p->decl = tls_map->get
 773               (varpool_node::get (p->decl))->control_var->decl;
 774             p->target = get_emutls_object_name (p->target);
 775           }
 776     }
 777
 778   /* Adjust all uses of TLS variables within the function bodies.  */
 779   FOR_EACH_DEFINED_FUNCTION (func)
 780     if (func->lowered)
 781       lower_emutls_function_body (func);
 782
 783   /* Generate the constructor for any COMMON control variables created.  */
 784   if (ctor_body)
 785     cgraph_build_static_cdtor ('I', ctor_body, DEFAULT_INIT_PRIORITY);
 786
 787   delete tls_map;
 788
 789   return 0;
 790 }
 791
 792 namespace {
 793
 794 const pass_data pass_data_ipa_lower_emutls =
 795 {
 796   SIMPLE_IPA_PASS, /* type */
 797   "emutls", /* name */
 798   OPTGROUP_NONE, /* optinfo_flags */
 799   TV_IPA_OPT, /* tv_id */
 800   ( PROP_cfg | PROP_ssa ), /* properties_required */
 801   0, /* properties_provided */
 802   0, /* properties_destroyed */
 803   0, /* todo_flags_start */
 804   0, /* todo_flags_finish */
 805 };
 806
 807 class pass_ipa_lower_emutls : public simple_ipa_opt_pass
 808 {
 809 public:
 810   pass_ipa_lower_emutls (gcc::context *ctxt)
 811     : simple_ipa_opt_pass (pass_data_ipa_lower_emutls, ctxt)
 812   {}
 813
 814   /* opt_pass methods: */
 815   virtual bool gate (function *)
 816     {
 817       /* If the target supports TLS natively, we need do nothing here.  */
 818       return !targetm.have_tls;
 819     }
 820
 821   virtual unsigned int execute (function *) { return ipa_lower_emutls (); }
 822
 823 }; // class pass_ipa_lower_emutls
 824
 825 } // anon namespace
 826
 827 simple_ipa_opt_pass *
 828 make_pass_ipa_lower_emutls (gcc::context *ctxt)
 829 {
 830   return new pass_ipa_lower_emutls (ctxt);
 831 }