gcc/tree-emutls.c

   1 /* Lower TLS operations to emulation functions.
   2    Copyright (C) 2006-2015 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 "alias.h"
  24 #include "backend.h"
  25 #include "tree.h"
  26 #include "gimple.h"
  27 #include "hard-reg-set.h"
  28 #include "ssa.h"
  29 #include "options.h"
  30 #include "fold-const.h"
  31 #include "stor-layout.h"
  32 #include "varasm.h"
  33 #include "internal-fn.h"
  34 #include "gimple-iterator.h"
  35 #include "gimple-walk.h"
  36 #include "tree-pass.h"
  37 #include "cgraph.h"
  38 #include "langhooks.h"
  39 #include "target.h"
  40 #include "targhooks.h"
  41 #include "tree-iterator.h"
  42
  43 /* Whenever a target does not support thread-local storage (TLS) natively,
  44    we can emulate it with some run-time support in libgcc.  This will in
  45    turn rely on "keyed storage" a-la pthread_key_create; essentially all
  46    thread libraries provide such functionality.
  47
  48    In order to coordinate with the libgcc runtime, each TLS variable is
  49    described by a "control variable".  This control variable records the
  50    required size, alignment, and initial value of the TLS variable for
  51    instantiation at runtime.  It also stores an integer token to be used
  52    by the runtime to find the address of the variable within each thread.
  53
  54    On the compiler side, this means that we need to replace all instances
  55    of "tls_var" in the code with "*__emutls_get_addr(&control_var)".  We
  56    also need to eliminate "tls_var" from the symbol table and introduce
  57    "control_var".
  58
  59    We used to perform all of the transformations during conversion to rtl,
  60    and the variable substitutions magically within assemble_variable.
  61    However, this late fiddling of the symbol table conflicts with LTO and
  62    whole-program compilation.  Therefore we must now make all the changes
  63    to the symbol table early in the GIMPLE optimization path, before we
  64    write things out to LTO intermediate files.  */
  65
  66 /* Value for TLS varpool node where a pointer to control variable and
  67    access variable are stored.  */
  68 struct tls_var_data
  69 {
  70   varpool_node *control_var;
  71   tree access;
  72 };
  73
  74 /* TLS map accesses mapping between a TLS varpool node and a pair
  75    made by control variable and access variable.  */
  76 static hash_map<varpool_node *, tls_var_data> *tls_map = NULL;
  77
  78 /* The type of the control structure, shared with the emutls.c runtime.  */
  79 static tree emutls_object_type;
  80
  81 #if !defined (NO_DOT_IN_LABEL)
  82 # define EMUTLS_SEPARATOR       "."
  83 #elif !defined (NO_DOLLAR_IN_LABEL)
  84 # define EMUTLS_SEPARATOR       "$"
  85 #else
  86 # define EMUTLS_SEPARATOR       "_"
  87 #endif
  88
  89 /* Create an IDENTIFIER_NODE by prefixing PREFIX to the
  90    IDENTIFIER_NODE NAME's name.  */
  91
  92 static tree
  93 prefix_name (const char *prefix, tree name)
  94 {
  95   unsigned plen = strlen (prefix);
  96   unsigned nlen = strlen (IDENTIFIER_POINTER (name));
  97   char *toname = (char *) alloca (plen + nlen + 1);
  98
  99   memcpy (toname, prefix, plen);
 100   memcpy (toname + plen, IDENTIFIER_POINTER (name), nlen + 1);
 101
 102   return get_identifier (toname);
 103 }
 104
 105 /* Create an identifier for the struct __emutls_object, given an identifier
 106    of the DECL_ASSEMBLY_NAME of the original object.  */
 107
 108 static tree
 109 get_emutls_object_name (tree name)
 110 {
 111   const char *prefix = (targetm.emutls.var_prefix
 112                         ? targetm.emutls.var_prefix
 113                         : "__emutls_v" EMUTLS_SEPARATOR);
 114   return prefix_name (prefix, name);
 115 }
 116
 117 /* Create the fields of the type for the control variables.  Ordinarily
 118    this must match struct __emutls_object defined in emutls.c.  However
 119    this is a target hook so that VxWorks can define its own layout.  */
 120
 121 tree
 122 default_emutls_var_fields (tree type, tree *name ATTRIBUTE_UNUSED)
 123 {
 124   tree word_type_node, field, next_field;
 125
 126   field = build_decl (UNKNOWN_LOCATION,
 127                       FIELD_DECL, get_identifier ("__templ"), ptr_type_node);
 128   DECL_CONTEXT (field) = type;
 129   next_field = field;
 130
 131   field = build_decl (UNKNOWN_LOCATION,
 132                       FIELD_DECL, get_identifier ("__offset"),
 133                       ptr_type_node);
 134   DECL_CONTEXT (field) = type;
 135   DECL_CHAIN (field) = next_field;
 136   next_field = field;
 137
 138   word_type_node = lang_hooks.types.type_for_mode (word_mode, 1);
 139   field = build_decl (UNKNOWN_LOCATION,
 140                       FIELD_DECL, get_identifier ("__align"),
 141                       word_type_node);
 142   DECL_CONTEXT (field) = type;
 143   DECL_CHAIN (field) = next_field;
 144   next_field = field;
 145
 146   field = build_decl (UNKNOWN_LOCATION,
 147                       FIELD_DECL, get_identifier ("__size"), word_type_node);
 148   DECL_CONTEXT (field) = type;
 149   DECL_CHAIN (field) = next_field;
 150
 151   return field;
 152 }
 153
 154 /* Initialize emulated tls object TO, which refers to TLS variable DECL and
 155    is initialized by PROXY.  As above, this is the default implementation of
 156    a target hook overridden by VxWorks.  */
 157
 158 tree
 159 default_emutls_var_init (tree to, tree decl, tree proxy)
 160 {
 161   vec<constructor_elt, va_gc> *v;
 162   vec_alloc (v, 4);
 163   constructor_elt elt;
 164   tree type = TREE_TYPE (to);
 165   tree field = TYPE_FIELDS (type);
 166
 167   elt.index = field;
 168   elt.value = fold_convert (TREE_TYPE (field), DECL_SIZE_UNIT (decl));
 169   v->quick_push (elt);
 170
 171   field = DECL_CHAIN (field);
 172   elt.index = field;
 173   elt.value = build_int_cst (TREE_TYPE (field),
 174                              DECL_ALIGN_UNIT (decl));
 175   v->quick_push (elt);
 176
 177   field = DECL_CHAIN (field);
 178   elt.index = field;
 179   elt.value = null_pointer_node;
 180   v->quick_push (elt);
 181
 182   field = DECL_CHAIN (field);
 183   elt.index = field;
 184   elt.value = proxy;
 185   v->quick_push (elt);
 186
 187   return build_constructor (type, v);
 188 }
 189
 190 /* Create the structure for struct __emutls_object.  This should match the
 191    structure at the top of emutls.c, modulo the union there.  */
 192
 193 static tree
 194 get_emutls_object_type (void)
 195 {
 196   tree type, type_name, field;
 197
 198   type = emutls_object_type;
 199   if (type)
 200     return type;
 201
 202   emutls_object_type = type = lang_hooks.types.make_type (RECORD_TYPE);
 203   type_name = NULL;
 204   field = targetm.emutls.var_fields (type, &type_name);
 205   if (!type_name)
 206     type_name = get_identifier ("__emutls_object");
 207   type_name = build_decl (UNKNOWN_LOCATION,
 208                           TYPE_DECL, type_name, type);
 209   TYPE_NAME (type) = type_name;
 210   TYPE_FIELDS (type) = field;
 211   layout_type (type);
 212
 213   return type;
 214 }
 215
 216 /* Create a read-only variable like DECL, with the same DECL_INITIAL.
 217    This will be used for initializing the emulated tls data area.  */
 218
 219 static tree
 220 get_emutls_init_templ_addr (tree decl)
 221 {
 222   tree name, to;
 223
 224   if (targetm.emutls.register_common && !DECL_INITIAL (decl)
 225       && !DECL_SECTION_NAME (decl))
 226     return null_pointer_node;
 227
 228   name = DECL_ASSEMBLER_NAME (decl);
 229   if (!targetm.emutls.tmpl_prefix || targetm.emutls.tmpl_prefix[0])
 230     {
 231       const char *prefix = (targetm.emutls.tmpl_prefix
 232                             ? targetm.emutls.tmpl_prefix
 233                             : "__emutls_t" EMUTLS_SEPARATOR);
 234       name = prefix_name (prefix, name);
 235     }
 236
 237   to = build_decl (DECL_SOURCE_LOCATION (decl),
 238                    VAR_DECL, name, TREE_TYPE (decl));
 239   SET_DECL_ASSEMBLER_NAME (to, DECL_NAME (to));
 240
 241   DECL_ARTIFICIAL (to) = 1;
 242   TREE_USED (to) = TREE_USED (decl);
 243   TREE_READONLY (to) = 1;
 244   DECL_IGNORED_P (to) = 1;
 245   DECL_CONTEXT (to) = DECL_CONTEXT (decl);
 246   DECL_PRESERVE_P (to) = DECL_PRESERVE_P (decl);
 247
 248   DECL_WEAK (to) = DECL_WEAK (decl);
 249   if (DECL_ONE_ONLY (decl))
 250     {
 251       TREE_STATIC (to) = TREE_STATIC (decl);
 252       TREE_PUBLIC (to) = TREE_PUBLIC (decl);
 253       DECL_VISIBILITY (to) = DECL_VISIBILITY (decl);
 254       make_decl_one_only (to, DECL_ASSEMBLER_NAME (to));
 255     }
 256   else
 257     TREE_STATIC (to) = 1;
 258
 259   DECL_VISIBILITY_SPECIFIED (to) = DECL_VISIBILITY_SPECIFIED (decl);
 260   DECL_INITIAL (to) = DECL_INITIAL (decl);
 261   DECL_INITIAL (decl) = NULL;
 262
 263   if (targetm.emutls.tmpl_section)
 264     set_decl_section_name (to, targetm.emutls.tmpl_section);
 265   else
 266     set_decl_section_name (to, DECL_SECTION_NAME (decl));
 267
 268   /* Create varpool node for the new variable and finalize it if it is
 269      not external one.  */
 270   if (DECL_EXTERNAL (to))
 271     varpool_node::get_create (to);
 272   else
 273     varpool_node::add (to);
 274   return build_fold_addr_expr (to);
 275 }
 276
 277 /* Create and return the control variable for the TLS variable DECL.  */
 278
 279 static tree
 280 new_emutls_decl (tree decl, tree alias_of)
 281 {
 282   tree name, to;
 283
 284   name = DECL_ASSEMBLER_NAME (decl);
 285   to = build_decl (DECL_SOURCE_LOCATION (decl), VAR_DECL,
 286                    get_emutls_object_name (name),
 287                    get_emutls_object_type ());
 288
 289   SET_DECL_ASSEMBLER_NAME (to, DECL_NAME (to));
 290
 291   DECL_ARTIFICIAL (to) = 1;
 292   DECL_IGNORED_P (to) = 1;
 293   TREE_READONLY (to) = 0;
 294   TREE_STATIC (to) = 1;
 295
 296   DECL_PRESERVE_P (to) = DECL_PRESERVE_P (decl);
 297   DECL_CONTEXT (to) = DECL_CONTEXT (decl);
 298   TREE_USED (to) = TREE_USED (decl);
 299   TREE_PUBLIC (to) = TREE_PUBLIC (decl);
 300   DECL_EXTERNAL (to) = DECL_EXTERNAL (decl);
 301   DECL_COMMON (to) = DECL_COMMON (decl);
 302   DECL_WEAK (to) = DECL_WEAK (decl);
 303   DECL_VISIBILITY (to) = DECL_VISIBILITY (decl);
 304   DECL_VISIBILITY_SPECIFIED (to) = DECL_VISIBILITY_SPECIFIED (decl);
 305   DECL_DLLIMPORT_P (to) = DECL_DLLIMPORT_P (decl);
 306
 307   DECL_ATTRIBUTES (to) = targetm.merge_decl_attributes (decl, to);
 308
 309   if (DECL_ONE_ONLY (decl))
 310     make_decl_one_only (to, DECL_ASSEMBLER_NAME (to));
 311
 312   set_decl_tls_model (to, TLS_MODEL_EMULATED);
 313
 314   /* If we're not allowed to change the proxy object's alignment,
 315      pretend it has been set by the user.  */
 316   if (targetm.emutls.var_align_fixed)
 317     DECL_USER_ALIGN (to) = 1;
 318
 319   /* If the target wants the control variables grouped, do so.  */
 320   if (!DECL_COMMON (to) && targetm.emutls.var_section)
 321     {
 322       set_decl_section_name (to, targetm.emutls.var_section);
 323     }
 324
 325   /* If this variable is defined locally, then we need to initialize the
 326      control structure with size and alignment information.  Initialization
 327      of COMMON block variables happens elsewhere via a constructor.  */
 328   if (!DECL_EXTERNAL (to)
 329       && (!DECL_COMMON (to)
 330           || (DECL_INITIAL (decl)
 331               && DECL_INITIAL (decl) != error_mark_node)))
 332     {
 333       tree tmpl = get_emutls_init_templ_addr (decl);
 334       DECL_INITIAL (to) = targetm.emutls.var_init (to, decl, tmpl);
 335       record_references_in_initializer (to, false);
 336     }
 337
 338   /* Create varpool node for the new variable and finalize it if it is
 339      not external one.  */
 340   if (DECL_EXTERNAL (to))
 341     varpool_node::get_create (to);
 342   else if (!alias_of)
 343     varpool_node::add (to);
 344   else
 345     {
 346       varpool_node *n;
 347       varpool_node *t = varpool_node::get_for_asmname
 348          (DECL_ASSEMBLER_NAME (DECL_VALUE_EXPR (alias_of)));
 349
 350       n = varpool_node::create_alias (to, t->decl);
 351       n->resolve_alias (t);
 352     }
 353   return to;
 354 }
 355
 356 /* Generate a call statement to initialize CONTROL_DECL for TLS_DECL.
 357    This only needs to happen for TLS COMMON variables; non-COMMON
 358    variables can be initialized statically.  Insert the generated
 359    call statement at the end of PSTMTS.  */
 360
 361 static void
 362 emutls_common_1 (tree tls_decl, tree control_decl, tree *pstmts)
 363 {
 364   tree x;
 365   tree word_type_node;
 366
 367   if (! DECL_COMMON (tls_decl)
 368       || (DECL_INITIAL (tls_decl)
 369           && DECL_INITIAL (tls_decl) != error_mark_node))
 370     return;
 371
 372   word_type_node = lang_hooks.types.type_for_mode (word_mode, 1);
 373
 374   x = build_call_expr (builtin_decl_explicit (BUILT_IN_EMUTLS_REGISTER_COMMON),
 375                        4, build_fold_addr_expr (control_decl),
 376                        fold_convert (word_type_node,
 377                                      DECL_SIZE_UNIT (tls_decl)),
 378                        build_int_cst (word_type_node,
 379                                       DECL_ALIGN_UNIT (tls_decl)),
 380                        get_emutls_init_templ_addr (tls_decl));
 381
 382   append_to_statement_list (x, pstmts);
 383 }
 384
 385 struct lower_emutls_data
 386 {
 387   struct cgraph_node *cfun_node;
 388   struct cgraph_node *builtin_node;
 389   tree builtin_decl;
 390   basic_block bb;
 391   int bb_freq;
 392   location_t loc;
 393   gimple_seq seq;
 394 };
 395
 396 /* Given a TLS variable DECL, return an SSA_NAME holding its address.
 397    Append any new computation statements required to D->SEQ.  */
 398
 399 static tree
 400 gen_emutls_addr (tree decl, struct lower_emutls_data *d)
 401 {
 402   /* Compute the address of the TLS variable with help from runtime.  */
 403   tls_var_data *data = tls_map->get (varpool_node::get (decl));
 404   tree addr = data->access;
 405
 406   if (addr == NULL)
 407     {
 408       varpool_node *cvar;
 409       tree cdecl;
 410       gcall *x;
 411
 412       cvar = data->control_var;
 413       cdecl = cvar->decl;
 414       TREE_ADDRESSABLE (cdecl) = 1;
 415
 416       addr = create_tmp_var (build_pointer_type (TREE_TYPE (decl)));
 417       x = gimple_build_call (d->builtin_decl, 1, build_fold_addr_expr (cdecl));
 418       gimple_set_location (x, d->loc);
 419
 420       addr = make_ssa_name (addr, x);
 421       gimple_call_set_lhs (x, addr);
 422
 423       gimple_seq_add_stmt (&d->seq, x);
 424
 425       d->cfun_node->create_edge (d->builtin_node, x, d->bb->count, d->bb_freq);
 426
 427       /* We may be adding a new reference to a new variable to the function.
 428          This means we have to play with the ipa-reference web.  */
 429       d->cfun_node->create_reference (cvar, IPA_REF_ADDR, x);
 430
 431       /* Record this ssa_name for possible use later in the basic block.  */
 432       data->access = addr;
 433     }
 434
 435   return addr;
 436 }
 437
 438 /* Callback for walk_gimple_op.  D = WI->INFO is a struct lower_emutls_data.
 439    Given an operand *PTR within D->STMT, if the operand references a TLS
 440    variable, then lower the reference to a call to the runtime.  Insert
 441    any new statements required into D->SEQ; the caller is responsible for
 442    placing those appropriately.  */
 443
 444 static tree
 445 lower_emutls_1 (tree *ptr, int *walk_subtrees, void *cb_data)
 446 {
 447   struct walk_stmt_info *wi = (struct walk_stmt_info *) cb_data;
 448   struct lower_emutls_data *d = (struct lower_emutls_data *) wi->info;
 449   tree t = *ptr;
 450   bool is_addr = false;
 451   tree addr;
 452
 453   *walk_subtrees = 0;
 454
 455   switch (TREE_CODE (t))
 456     {
 457     case ADDR_EXPR:
 458       /* If this is not a straight-forward "&var", but rather something
 459          like "&var.a", then we may need special handling.  */
 460       if (TREE_CODE (TREE_OPERAND (t, 0)) != VAR_DECL)
 461         {
 462           bool save_changed;
 463
 464           /* If we're allowed more than just is_gimple_val, continue.  */
 465           if (!wi->val_only)
 466             {
 467               *walk_subtrees = 1;
 468               return NULL_TREE;
 469             }
 470
 471           /* See if any substitution would be made.  */
 472           save_changed = wi->changed;
 473           wi->changed = false;
 474           wi->val_only = false;
 475           walk_tree (&TREE_OPERAND (t, 0), lower_emutls_1, wi, NULL);
 476           wi->val_only = true;
 477
 478           /* If so, then extract this entire sub-expression "&p->a" into a
 479              new assignment statement, and substitute yet another SSA_NAME.  */
 480           if (wi->changed)
 481             {
 482               gimple x;
 483
 484               addr = create_tmp_var (TREE_TYPE (t));
 485               x = gimple_build_assign (addr, t);
 486               gimple_set_location (x, d->loc);
 487
 488               addr = make_ssa_name (addr, x);
 489               gimple_assign_set_lhs (x, addr);
 490
 491               gimple_seq_add_stmt (&d->seq, x);
 492
 493               *ptr = addr;
 494             }
 495           else
 496             wi->changed = save_changed;
 497
 498           return NULL_TREE;
 499         }
 500
 501       t = TREE_OPERAND (t, 0);
 502       is_addr = true;
 503       /* FALLTHRU */
 504
 505     case VAR_DECL:
 506       if (!DECL_THREAD_LOCAL_P (t))
 507         return NULL_TREE;
 508       break;
 509
 510     default:
 511       /* We're not interested in other decls or types, only subexpressions.  */
 512       if (EXPR_P (t))
 513         *walk_subtrees = 1;
 514       /* FALLTHRU */
 515
 516     case SSA_NAME:
 517       /* Special-case the return of SSA_NAME, since it's so common.  */
 518       return NULL_TREE;
 519     }
 520
 521   addr = gen_emutls_addr (t, d);
 522   if (is_addr)
 523     {
 524       /* Replace "&var" with "addr" in the statement.  */
 525       *ptr = addr;
 526     }
 527   else
 528     {
 529       /* Replace "var" with "*addr" in the statement.  */
 530       t = build2 (MEM_REF, TREE_TYPE (t), addr,
 531                   build_int_cst (TREE_TYPE (addr), 0));
 532       *ptr = t;
 533     }
 534
 535   wi->changed = true;
 536   return NULL_TREE;
 537 }
 538
 539 /* Lower all of the operands of STMT.  */
 540
 541 static void
 542 lower_emutls_stmt (gimple stmt, struct lower_emutls_data *d)
 543 {
 544   struct walk_stmt_info wi;
 545
 546   d->loc = gimple_location (stmt);
 547
 548   memset (&wi, 0, sizeof (wi));
 549   wi.info = d;
 550   wi.val_only = true;
 551   walk_gimple_op (stmt, lower_emutls_1, &wi);
 552
 553   if (wi.changed)
 554     update_stmt (stmt);
 555 }
 556
 557 /* Lower the I'th operand of PHI.  */
 558
 559 static void
 560 lower_emutls_phi_arg (gphi *phi, unsigned int i,
 561                       struct lower_emutls_data *d)
 562 {
 563   struct walk_stmt_info wi;
 564   struct phi_arg_d *pd = gimple_phi_arg (phi, i);
 565
 566   /* Early out for a very common case we don't care about.  */
 567   if (TREE_CODE (pd->def) == SSA_NAME)
 568     return;
 569
 570   d->loc = pd->locus;
 571
 572   memset (&wi, 0, sizeof (wi));
 573   wi.info = d;
 574   wi.val_only = true;
 575   walk_tree (&pd->def, lower_emutls_1, &wi, NULL);
 576
 577   /* For normal statements, we let update_stmt do its job.  But for phi
 578      nodes, we have to manipulate the immediate use list by hand.  */
 579   if (wi.changed)
 580     {
 581       gcc_assert (TREE_CODE (pd->def) == SSA_NAME);
 582       link_imm_use_stmt (&pd->imm_use, pd->def, phi);
 583     }
 584 }
 585
 586 /* Reset access variable for a given TLS variable data DATA.  */
 587
 588 bool
 589 reset_access (varpool_node * const &, tls_var_data *data, void *)
 590 {
 591   data->access = NULL;
 592
 593   return true;
 594 }
 595
 596 /* Clear the access variables, in order to begin a new block.  */
 597
 598 static inline void
 599 clear_access_vars (void)
 600 {
 601   tls_map->traverse<void *, reset_access> (NULL);
 602 }
 603
 604 /* Lower the entire function NODE.  */
 605
 606 static void
 607 lower_emutls_function_body (struct cgraph_node *node)
 608 {
 609   struct lower_emutls_data d;
 610   bool any_edge_inserts = false;
 611
 612   push_cfun (DECL_STRUCT_FUNCTION (node->decl));
 613
 614   d.cfun_node = node;
 615   d.builtin_decl = builtin_decl_explicit (BUILT_IN_EMUTLS_GET_ADDRESS);
 616   /* This is where we introduce the declaration to the IL and so we have to
 617      create a node for it.  */
 618   d.builtin_node = cgraph_node::get_create (d.builtin_decl);
 619
 620   FOR_EACH_BB_FN (d.bb, cfun)
 621     {
 622       unsigned int i, nedge;
 623
 624       /* Lower each of the PHI nodes of the block, as we may have
 625          propagated &tlsvar into a PHI argument.  These loops are
 626          arranged so that we process each edge at once, and each
 627          PHI argument for that edge.  */
 628       if (!gimple_seq_empty_p (phi_nodes (d.bb)))
 629         {
 630           /* The calls will be inserted on the edges, and the frequencies
 631              will be computed during the commit process.  */
 632           d.bb_freq = 0;
 633
 634           nedge = EDGE_COUNT (d.bb->preds);
 635           for (i = 0; i < nedge; ++i)
 636             {
 637               edge e = EDGE_PRED (d.bb, i);
 638
 639               /* We can re-use any SSA_NAME created on this edge.  */
 640               clear_access_vars ();
 641               d.seq = NULL;
 642
 643               for (gphi_iterator gsi = gsi_start_phis (d.bb);
 644                    !gsi_end_p (gsi);
 645                    gsi_next (&gsi))
 646                 lower_emutls_phi_arg (gsi.phi (), i, &d);
 647
 648               /* Insert all statements generated by all phi nodes for this
 649                  particular edge all at once.  */
 650               if (d.seq)
 651                 {
 652                   gsi_insert_seq_on_edge (e, d.seq);
 653                   any_edge_inserts = true;
 654                 }
 655             }
 656         }
 657
 658       d.bb_freq = compute_call_stmt_bb_frequency (current_function_decl, d.bb);
 659
 660       /* We can re-use any SSA_NAME created during this basic block.  */
 661       clear_access_vars ();
 662
 663       /* Lower each of the statements of the block.  */
 664       for (gimple_stmt_iterator gsi = gsi_start_bb (d.bb); !gsi_end_p (gsi);
 665            gsi_next (&gsi))
 666         {
 667           d.seq = NULL;
 668           lower_emutls_stmt (gsi_stmt (gsi), &d);
 669
 670           /* If any new statements were created, insert them immediately
 671              before the first use.  This prevents variable lifetimes from
 672              becoming unnecessarily long.  */
 673           if (d.seq)
 674             gsi_insert_seq_before (&gsi, d.seq, GSI_SAME_STMT);
 675         }
 676     }
 677
 678   if (any_edge_inserts)
 679     gsi_commit_edge_inserts ();
 680
 681   pop_cfun ();
 682 }
 683
 684 /* Create emutls variable for VAR, DATA is pointer to static
 685    ctor body we can add constructors to.
 686    Callback for varpool_for_variable_and_aliases.  */
 687
 688 static bool
 689 create_emultls_var (varpool_node *var, void *data)
 690 {
 691   tree cdecl;
 692   tls_var_data value;
 693
 694   cdecl = new_emutls_decl (var->decl,
 695                            var->alias && var->analyzed
 696                            ? var->get_alias_target ()->decl : NULL);
 697
 698   varpool_node *cvar = varpool_node::get (cdecl);
 699
 700   if (!var->alias)
 701     {
 702       /* Make sure the COMMON block control variable gets initialized.
 703          Note that there's no point in doing this for aliases; we only
 704          need to do this once for the main variable.  */
 705       emutls_common_1 (var->decl, cdecl, (tree *)data);
 706     }
 707   if (var->alias && !var->analyzed)
 708     cvar->alias = true;
 709
 710   /* Indicate that the value of the TLS variable may be found elsewhere,
 711      preventing the variable from re-appearing in the GIMPLE.  We cheat
 712      and use the control variable here (rather than a full call_expr),
 713      which is special-cased inside the DWARF2 output routines.  */
 714   SET_DECL_VALUE_EXPR (var->decl, cdecl);
 715   DECL_HAS_VALUE_EXPR_P (var->decl) = 1;
 716
 717   value.control_var = cvar;
 718   tls_map->put (var, value);
 719
 720   return false;
 721 }
 722
 723 /* Main entry point to the tls lowering pass.  */
 724
 725 static unsigned int
 726 ipa_lower_emutls (void)
 727 {
 728   varpool_node *var;
 729   cgraph_node *func;
 730   bool any_aliases = false;
 731   tree ctor_body = NULL;
 732   hash_set <varpool_node *> visited;
 733   auto_vec <varpool_node *> tls_vars;
 734
 735   /* Examine all global variables for TLS variables.  */
 736   FOR_EACH_VARIABLE (var)
 737     if (DECL_THREAD_LOCAL_P (var->decl)
 738         && !visited.add (var))
 739       {
 740         gcc_checking_assert (TREE_STATIC (var->decl)
 741                              || DECL_EXTERNAL (var->decl));
 742         tls_vars.safe_push (var);
 743         if (var->alias && var->definition
 744             && !visited.add (var->ultimate_alias_target ()))
 745           tls_vars.safe_push (var->ultimate_alias_target ());
 746       }
 747
 748   /* If we found no TLS variables, then there is no further work to do.  */
 749   if (tls_vars.is_empty ())
 750     {
 751       if (dump_file)
 752         fprintf (dump_file, "No TLS variables found.\n");
 753       return 0;
 754     }
 755
 756   tls_map = new hash_map <varpool_node *, tls_var_data> ();
 757
 758   /* Create the control variables for each TLS variable.  */
 759   for (unsigned i = 0; i < tls_vars.length (); i++)
 760     {
 761       var = tls_vars[i];
 762
 763       if (var->alias && !var->analyzed)
 764         any_aliases = true;
 765       else if (!var->alias)
 766         var->call_for_symbol_and_aliases (create_emultls_var, &ctor_body, true);
 767     }
 768
 769   /* If there were any aliases, then frob the alias_pairs vector.  */
 770   if (any_aliases)
 771     {
 772       alias_pair *p;
 773       unsigned int i;
 774       FOR_EACH_VEC_SAFE_ELT (alias_pairs, i, p)
 775         if (DECL_THREAD_LOCAL_P (p->decl))
 776           {
 777             p->decl = tls_map->get
 778               (varpool_node::get (p->decl))->control_var->decl;
 779             p->target = get_emutls_object_name (p->target);
 780           }
 781     }
 782
 783   /* Adjust all uses of TLS variables within the function bodies.  */
 784   FOR_EACH_DEFINED_FUNCTION (func)
 785     if (func->lowered)
 786       lower_emutls_function_body (func);
 787
 788   /* Generate the constructor for any COMMON control variables created.  */
 789   if (ctor_body)
 790     cgraph_build_static_cdtor ('I', ctor_body, DEFAULT_INIT_PRIORITY);
 791
 792   delete tls_map;
 793
 794   return 0;
 795 }
 796
 797 namespace {
 798
 799 const pass_data pass_data_ipa_lower_emutls =
 800 {
 801   SIMPLE_IPA_PASS, /* type */
 802   "emutls", /* name */
 803   OPTGROUP_NONE, /* optinfo_flags */
 804   TV_IPA_OPT, /* tv_id */
 805   ( PROP_cfg | PROP_ssa ), /* properties_required */
 806   0, /* properties_provided */
 807   0, /* properties_destroyed */
 808   0, /* todo_flags_start */
 809   0, /* todo_flags_finish */
 810 };
 811
 812 class pass_ipa_lower_emutls : public simple_ipa_opt_pass
 813 {
 814 public:
 815   pass_ipa_lower_emutls (gcc::context *ctxt)
 816     : simple_ipa_opt_pass (pass_data_ipa_lower_emutls, ctxt)
 817   {}
 818
 819   /* opt_pass methods: */
 820   virtual bool gate (function *)
 821     {
 822       /* If the target supports TLS natively, we need do nothing here.  */
 823       return !targetm.have_tls;
 824     }
 825
 826   virtual unsigned int execute (function *) { return ipa_lower_emutls (); }
 827
 828 }; // class pass_ipa_lower_emutls
 829
 830 } // anon namespace
 831
 832 simple_ipa_opt_pass *
 833 make_pass_ipa_lower_emutls (gcc::context *ctxt)
 834 {
 835   return new pass_ipa_lower_emutls (ctxt);
 836 }