gcc/tree-emutls.c

   1 /* Lower TLS operations to emulation functions.
   2    Copyright (C) 2006-2013 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 "tree.h"
  24 #include "gimple.h"
  25 #include "tree-pass.h"
  26 #include "tree-flow.h"
  27 #include "cgraph.h"
  28 #include "langhooks.h"
  29 #include "target.h"
  30 #include "targhooks.h"
  31 #include "tree-iterator.h"
  32
  33
  34 /* Whenever a target does not support thread-local storage (TLS) natively,
  35    we can emulate it with some run-time support in libgcc.  This will in
  36    turn rely on "keyed storage" a-la pthread_key_create; essentially all
  37    thread libraries provide such functionality.
  38
  39    In order to coordinate with the libgcc runtime, each TLS variable is
  40    described by a "control variable".  This control variable records the
  41    required size, alignment, and initial value of the TLS variable for
  42    instantiation at runtime.  It also stores an integer token to be used
  43    by the runtime to find the address of the variable within each thread.
  44
  45    On the compiler side, this means that we need to replace all instances
  46    of "tls_var" in the code with "*__emutls_get_addr(&control_var)".  We
  47    also need to eliminate "tls_var" from the symbol table and introduce
  48    "control_var".
  49
  50    We used to perform all of the transformations during conversion to rtl,
  51    and the variable substitutions magically within assemble_variable.
  52    However, this late fiddling of the symbol table conflicts with LTO and
  53    whole-program compilation.  Therefore we must now make all the changes
  54    to the symbol table early in the GIMPLE optimization path, before we
  55    write things out to LTO intermediate files.  */
  56
  57 /* These two vectors, once fully populated, are kept in lock-step so that
  58    the index of a TLS variable equals the index of its control variable in
  59    the other vector.  */
  60 static varpool_node_set tls_vars;
  61 static vec<varpool_node_ptr> control_vars;
  62
  63 /* For the current basic block, an SSA_NAME that has computed the address
  64    of the TLS variable at the corresponding index.  */
  65 static vec<tree> access_vars;
  66
  67 /* The type of the control structure, shared with the emutls.c runtime.  */
  68 static tree emutls_object_type;
  69
  70 #if !defined (NO_DOT_IN_LABEL)
  71 # define EMUTLS_SEPARATOR       "."
  72 #elif !defined (NO_DOLLAR_IN_LABEL)
  73 # define EMUTLS_SEPARATOR       "$"
  74 #else
  75 # define EMUTLS_SEPARATOR       "_"
  76 #endif
  77
  78 /* Create an IDENTIFIER_NODE by prefixing PREFIX to the
  79    IDENTIFIER_NODE NAME's name.  */
  80
  81 static tree
  82 prefix_name (const char *prefix, tree name)
  83 {
  84   unsigned plen = strlen (prefix);
  85   unsigned nlen = strlen (IDENTIFIER_POINTER (name));
  86   char *toname = (char *) alloca (plen + nlen + 1);
  87
  88   memcpy (toname, prefix, plen);
  89   memcpy (toname + plen, IDENTIFIER_POINTER (name), nlen + 1);
  90
  91   return get_identifier (toname);
  92 }
  93
  94 /* Create an identifier for the struct __emutls_object, given an identifier
  95    of the DECL_ASSEMBLY_NAME of the original object.  */
  96
  97 static tree
  98 get_emutls_object_name (tree name)
  99 {
 100   const char *prefix = (targetm.emutls.var_prefix
 101                         ? targetm.emutls.var_prefix
 102                         : "__emutls_v" EMUTLS_SEPARATOR);
 103   return prefix_name (prefix, name);
 104 }
 105
 106 /* Create the fields of the type for the control variables.  Ordinarily
 107    this must match struct __emutls_object defined in emutls.c.  However
 108    this is a target hook so that VxWorks can define its own layout.  */
 109
 110 tree
 111 default_emutls_var_fields (tree type, tree *name ATTRIBUTE_UNUSED)
 112 {
 113   tree word_type_node, field, next_field;
 114
 115   field = build_decl (UNKNOWN_LOCATION,
 116                       FIELD_DECL, get_identifier ("__templ"), ptr_type_node);
 117   DECL_CONTEXT (field) = type;
 118   next_field = field;
 119
 120   field = build_decl (UNKNOWN_LOCATION,
 121                       FIELD_DECL, get_identifier ("__offset"),
 122                       ptr_type_node);
 123   DECL_CONTEXT (field) = type;
 124   DECL_CHAIN (field) = next_field;
 125   next_field = field;
 126
 127   word_type_node = lang_hooks.types.type_for_mode (word_mode, 1);
 128   field = build_decl (UNKNOWN_LOCATION,
 129                       FIELD_DECL, get_identifier ("__align"),
 130                       word_type_node);
 131   DECL_CONTEXT (field) = type;
 132   DECL_CHAIN (field) = next_field;
 133   next_field = field;
 134
 135   field = build_decl (UNKNOWN_LOCATION,
 136                       FIELD_DECL, get_identifier ("__size"), word_type_node);
 137   DECL_CONTEXT (field) = type;
 138   DECL_CHAIN (field) = next_field;
 139
 140   return field;
 141 }
 142
 143 /* Initialize emulated tls object TO, which refers to TLS variable DECL and
 144    is initialized by PROXY.  As above, this is the default implementation of
 145    a target hook overridden by VxWorks.  */
 146
 147 tree
 148 default_emutls_var_init (tree to, tree decl, tree proxy)
 149 {
 150   vec<constructor_elt, va_gc> *v;
 151   vec_alloc (v, 4);
 152   constructor_elt elt;
 153   tree type = TREE_TYPE (to);
 154   tree field = TYPE_FIELDS (type);
 155
 156   elt.index = field;
 157   elt.value = fold_convert (TREE_TYPE (field), DECL_SIZE_UNIT (decl));
 158   v->quick_push (elt);
 159
 160   field = DECL_CHAIN (field);
 161   elt.index = field;
 162   elt.value = build_int_cst (TREE_TYPE (field),
 163                              DECL_ALIGN_UNIT (decl));
 164   v->quick_push (elt);
 165
 166   field = DECL_CHAIN (field);
 167   elt.index = field;
 168   elt.value = null_pointer_node;
 169   v->quick_push (elt);
 170
 171   field = DECL_CHAIN (field);
 172   elt.index = field;
 173   elt.value = proxy;
 174   v->quick_push (elt);
 175
 176   return build_constructor (type, v);
 177 }
 178
 179 /* Create the structure for struct __emutls_object.  This should match the
 180    structure at the top of emutls.c, modulo the union there.  */
 181
 182 static tree
 183 get_emutls_object_type (void)
 184 {
 185   tree type, type_name, field;
 186
 187   type = emutls_object_type;
 188   if (type)
 189     return type;
 190
 191   emutls_object_type = type = lang_hooks.types.make_type (RECORD_TYPE);
 192   type_name = NULL;
 193   field = targetm.emutls.var_fields (type, &type_name);
 194   if (!type_name)
 195     type_name = get_identifier ("__emutls_object");
 196   type_name = build_decl (UNKNOWN_LOCATION,
 197                           TYPE_DECL, type_name, type);
 198   TYPE_NAME (type) = type_name;
 199   TYPE_FIELDS (type) = field;
 200   layout_type (type);
 201
 202   return type;
 203 }
 204
 205 /* Create a read-only variable like DECL, with the same DECL_INITIAL.
 206    This will be used for initializing the emulated tls data area.  */
 207
 208 static tree
 209 get_emutls_init_templ_addr (tree decl)
 210 {
 211   tree name, to;
 212
 213   if (targetm.emutls.register_common && !DECL_INITIAL (decl)
 214       && !DECL_SECTION_NAME (decl))
 215     return null_pointer_node;
 216
 217   name = DECL_ASSEMBLER_NAME (decl);
 218   if (!targetm.emutls.tmpl_prefix || targetm.emutls.tmpl_prefix[0])
 219     {
 220       const char *prefix = (targetm.emutls.tmpl_prefix
 221                             ? targetm.emutls.tmpl_prefix
 222                             : "__emutls_t" EMUTLS_SEPARATOR);
 223       name = prefix_name (prefix, name);
 224     }
 225
 226   to = build_decl (DECL_SOURCE_LOCATION (decl),
 227                    VAR_DECL, name, TREE_TYPE (decl));
 228   SET_DECL_ASSEMBLER_NAME (to, DECL_NAME (to));
 229
 230   DECL_ARTIFICIAL (to) = 1;
 231   TREE_USED (to) = TREE_USED (decl);
 232   TREE_READONLY (to) = 1;
 233   DECL_IGNORED_P (to) = 1;
 234   DECL_CONTEXT (to) = DECL_CONTEXT (decl);
 235   DECL_SECTION_NAME (to) = DECL_SECTION_NAME (decl);
 236   DECL_PRESERVE_P (to) = DECL_PRESERVE_P (decl);
 237
 238   DECL_WEAK (to) = DECL_WEAK (decl);
 239   if (DECL_ONE_ONLY (decl))
 240     {
 241       make_decl_one_only (to, DECL_ASSEMBLER_NAME (to));
 242       TREE_STATIC (to) = TREE_STATIC (decl);
 243       TREE_PUBLIC (to) = TREE_PUBLIC (decl);
 244       DECL_VISIBILITY (to) = DECL_VISIBILITY (decl);
 245     }
 246   else
 247     TREE_STATIC (to) = 1;
 248
 249   DECL_VISIBILITY_SPECIFIED (to) = DECL_VISIBILITY_SPECIFIED (decl);
 250   DECL_INITIAL (to) = DECL_INITIAL (decl);
 251   DECL_INITIAL (decl) = NULL;
 252
 253   if (targetm.emutls.tmpl_section)
 254     {
 255       DECL_SECTION_NAME (to)
 256         = build_string (strlen (targetm.emutls.tmpl_section),
 257                         targetm.emutls.tmpl_section);
 258     }
 259
 260   /* Create varpool node for the new variable and finalize it if it is
 261      not external one.  */
 262   if (DECL_EXTERNAL (to))
 263     varpool_node_for_decl (to);
 264   else
 265     varpool_add_new_variable (to);
 266   return build_fold_addr_expr (to);
 267 }
 268
 269 /* Create and return the control variable for the TLS variable DECL.  */
 270
 271 static tree
 272 new_emutls_decl (tree decl, tree alias_of)
 273 {
 274   tree name, to;
 275
 276   name = DECL_ASSEMBLER_NAME (decl);
 277   to = build_decl (DECL_SOURCE_LOCATION (decl), VAR_DECL,
 278                    get_emutls_object_name (name),
 279                    get_emutls_object_type ());
 280
 281   SET_DECL_ASSEMBLER_NAME (to, DECL_NAME (to));
 282
 283   DECL_TLS_MODEL (to) = TLS_MODEL_EMULATED;
 284   DECL_ARTIFICIAL (to) = 1;
 285   DECL_IGNORED_P (to) = 1;
 286   TREE_READONLY (to) = 0;
 287   TREE_STATIC (to) = 1;
 288
 289   DECL_PRESERVE_P (to) = DECL_PRESERVE_P (decl);
 290   DECL_CONTEXT (to) = DECL_CONTEXT (decl);
 291   TREE_USED (to) = TREE_USED (decl);
 292   TREE_PUBLIC (to) = TREE_PUBLIC (decl);
 293   DECL_EXTERNAL (to) = DECL_EXTERNAL (decl);
 294   DECL_COMMON (to) = DECL_COMMON (decl);
 295   DECL_WEAK (to) = DECL_WEAK (decl);
 296   DECL_VISIBILITY (to) = DECL_VISIBILITY (decl);
 297   DECL_VISIBILITY_SPECIFIED (to) = DECL_VISIBILITY_SPECIFIED (decl);
 298   DECL_DLLIMPORT_P (to) = DECL_DLLIMPORT_P (decl);
 299
 300   DECL_ATTRIBUTES (to) = targetm.merge_decl_attributes (decl, to);
 301
 302   if (DECL_ONE_ONLY (decl))
 303     make_decl_one_only (to, DECL_ASSEMBLER_NAME (to));
 304
 305   /* If we're not allowed to change the proxy object's alignment,
 306      pretend it has been set by the user.  */
 307   if (targetm.emutls.var_align_fixed)
 308     DECL_USER_ALIGN (to) = 1;
 309
 310   /* If the target wants the control variables grouped, do so.  */
 311   if (!DECL_COMMON (to) && targetm.emutls.var_section)
 312     {
 313       DECL_SECTION_NAME (to)
 314         = build_string (strlen (targetm.emutls.var_section),
 315                         targetm.emutls.var_section);
 316     }
 317
 318   /* If this variable is defined locally, then we need to initialize the
 319      control structure with size and alignment information.  Initialization
 320      of COMMON block variables happens elsewhere via a constructor.  */
 321   if (!DECL_EXTERNAL (to)
 322       && (!DECL_COMMON (to)
 323           || (DECL_INITIAL (decl)
 324               && DECL_INITIAL (decl) != error_mark_node)))
 325     {
 326       tree tmpl = get_emutls_init_templ_addr (decl);
 327       DECL_INITIAL (to) = targetm.emutls.var_init (to, decl, tmpl);
 328       record_references_in_initializer (to, false);
 329     }
 330
 331   /* Create varpool node for the new variable and finalize it if it is
 332      not external one.  */
 333   if (DECL_EXTERNAL (to))
 334     varpool_node_for_decl (to);
 335   else if (!alias_of)
 336     varpool_add_new_variable (to);
 337   else
 338     varpool_create_variable_alias (to,
 339                                    varpool_node_for_asm
 340                                     (DECL_ASSEMBLER_NAME (DECL_VALUE_EXPR (alias_of)))->symbol.decl);
 341   return to;
 342 }
 343
 344 /* Look up the index of the TLS variable DECL.  This index can then be
 345    used in both the control_vars and access_vars arrays.  */
 346
 347 static unsigned int
 348 emutls_index (tree decl)
 349 {
 350   varpool_node_set_iterator i;
 351
 352   i = varpool_node_set_find (tls_vars, varpool_get_node (decl));
 353   gcc_assert (i.index != ~0u);
 354
 355   return i.index;
 356 }
 357
 358 /* Look up the control variable for the TLS variable DECL.  */
 359
 360 static tree
 361 emutls_decl (tree decl)
 362 {
 363   struct varpool_node *var;
 364   unsigned int i;
 365
 366   i = emutls_index (decl);
 367   var = control_vars[i];
 368   return var->symbol.decl;
 369 }
 370
 371 /* Generate a call statement to initialize CONTROL_DECL for TLS_DECL.
 372    This only needs to happen for TLS COMMON variables; non-COMMON
 373    variables can be initialized statically.  Insert the generated
 374    call statement at the end of PSTMTS.  */
 375
 376 static void
 377 emutls_common_1 (tree tls_decl, tree control_decl, tree *pstmts)
 378 {
 379   tree x;
 380   tree word_type_node;
 381
 382   if (! DECL_COMMON (tls_decl)
 383       || (DECL_INITIAL (tls_decl)
 384           && DECL_INITIAL (tls_decl) != error_mark_node))
 385     return;
 386
 387   word_type_node = lang_hooks.types.type_for_mode (word_mode, 1);
 388
 389   x = build_call_expr (builtin_decl_explicit (BUILT_IN_EMUTLS_REGISTER_COMMON),
 390                        4, build_fold_addr_expr (control_decl),
 391                        fold_convert (word_type_node,
 392                                      DECL_SIZE_UNIT (tls_decl)),
 393                        build_int_cst (word_type_node,
 394                                       DECL_ALIGN_UNIT (tls_decl)),
 395                        get_emutls_init_templ_addr (tls_decl));
 396
 397   append_to_statement_list (x, pstmts);
 398 }
 399
 400 struct lower_emutls_data
 401 {
 402   struct cgraph_node *cfun_node;
 403   struct cgraph_node *builtin_node;
 404   tree builtin_decl;
 405   basic_block bb;
 406   int bb_freq;
 407   location_t loc;
 408   gimple_seq seq;
 409 };
 410
 411 /* Given a TLS variable DECL, return an SSA_NAME holding its address.
 412    Append any new computation statements required to D->SEQ.  */
 413
 414 static tree
 415 gen_emutls_addr (tree decl, struct lower_emutls_data *d)
 416 {
 417   unsigned int index;
 418   tree addr;
 419
 420   /* Compute the address of the TLS variable with help from runtime.  */
 421   index = emutls_index (decl);
 422   addr = access_vars[index];
 423   if (addr == NULL)
 424     {
 425       struct varpool_node *cvar;
 426       tree cdecl;
 427       gimple x;
 428
 429       cvar = control_vars[index];
 430       cdecl = cvar->symbol.decl;
 431       TREE_ADDRESSABLE (cdecl) = 1;
 432
 433       addr = create_tmp_var (build_pointer_type (TREE_TYPE (decl)), NULL);
 434       x = gimple_build_call (d->builtin_decl, 1, build_fold_addr_expr (cdecl));
 435       gimple_set_location (x, d->loc);
 436
 437       addr = make_ssa_name (addr, x);
 438       gimple_call_set_lhs (x, addr);
 439
 440       gimple_seq_add_stmt (&d->seq, x);
 441
 442       cgraph_create_edge (d->cfun_node, d->builtin_node, x,
 443                           d->bb->count, d->bb_freq);
 444
 445       /* We may be adding a new reference to a new variable to the function.
 446          This means we have to play with the ipa-reference web.  */
 447       ipa_record_reference ((symtab_node)d->cfun_node, (symtab_node)cvar, IPA_REF_ADDR, x);
 448
 449       /* Record this ssa_name for possible use later in the basic block.  */
 450       access_vars[index] = addr;
 451     }
 452
 453   return addr;
 454 }
 455
 456 /* Callback for walk_gimple_op.  D = WI->INFO is a struct lower_emutls_data.
 457    Given an operand *PTR within D->STMT, if the operand references a TLS
 458    variable, then lower the reference to a call to the runtime.  Insert
 459    any new statements required into D->SEQ; the caller is responsible for
 460    placing those appropriately.  */
 461
 462 static tree
 463 lower_emutls_1 (tree *ptr, int *walk_subtrees, void *cb_data)
 464 {
 465   struct walk_stmt_info *wi = (struct walk_stmt_info *) cb_data;
 466   struct lower_emutls_data *d = (struct lower_emutls_data *) wi->info;
 467   tree t = *ptr;
 468   bool is_addr = false;
 469   tree addr;
 470
 471   *walk_subtrees = 0;
 472
 473   switch (TREE_CODE (t))
 474     {
 475     case ADDR_EXPR:
 476       /* If this is not a straight-forward "&var", but rather something
 477          like "&var.a", then we may need special handling.  */
 478       if (TREE_CODE (TREE_OPERAND (t, 0)) != VAR_DECL)
 479         {
 480           bool save_changed;
 481
 482           /* If we're allowed more than just is_gimple_val, continue.  */
 483           if (!wi->val_only)
 484             {
 485               *walk_subtrees = 1;
 486               return NULL_TREE;
 487             }
 488
 489           /* See if any substitution would be made.  */
 490           save_changed = wi->changed;
 491           wi->changed = false;
 492           wi->val_only = false;
 493           walk_tree (&TREE_OPERAND (t, 0), lower_emutls_1, wi, NULL);
 494           wi->val_only = true;
 495
 496           /* If so, then extract this entire sub-expression "&p->a" into a
 497              new assignment statement, and substitute yet another SSA_NAME.  */
 498           if (wi->changed)
 499             {
 500               gimple x;
 501
 502               addr = create_tmp_var (TREE_TYPE (t), NULL);
 503               x = gimple_build_assign (addr, t);
 504               gimple_set_location (x, d->loc);
 505
 506               addr = make_ssa_name (addr, x);
 507               gimple_assign_set_lhs (x, addr);
 508
 509               gimple_seq_add_stmt (&d->seq, x);
 510
 511               *ptr = addr;
 512             }
 513           else
 514             wi->changed = save_changed;
 515
 516           return NULL_TREE;
 517         }
 518
 519       t = TREE_OPERAND (t, 0);
 520       is_addr = true;
 521       /* FALLTHRU */
 522
 523     case VAR_DECL:
 524       if (!DECL_THREAD_LOCAL_P (t))
 525         return NULL_TREE;
 526       break;
 527
 528     default:
 529       /* We're not interested in other decls or types, only subexpressions.  */
 530       if (EXPR_P (t))
 531         *walk_subtrees = 1;
 532       /* FALLTHRU */
 533
 534     case SSA_NAME:
 535       /* Special-case the return of SSA_NAME, since it's so common.  */
 536       return NULL_TREE;
 537     }
 538
 539   addr = gen_emutls_addr (t, d);
 540   if (is_addr)
 541     {
 542       /* Replace "&var" with "addr" in the statement.  */
 543       *ptr = addr;
 544     }
 545   else
 546     {
 547       /* Replace "var" with "*addr" in the statement.  */
 548       t = build2 (MEM_REF, TREE_TYPE (t), addr,
 549                   build_int_cst (TREE_TYPE (addr), 0));
 550       *ptr = t;
 551     }
 552
 553   wi->changed = true;
 554   return NULL_TREE;
 555 }
 556
 557 /* Lower all of the operands of STMT.  */
 558
 559 static void
 560 lower_emutls_stmt (gimple stmt, struct lower_emutls_data *d)
 561 {
 562   struct walk_stmt_info wi;
 563
 564   d->loc = gimple_location (stmt);
 565
 566   memset (&wi, 0, sizeof (wi));
 567   wi.info = d;
 568   wi.val_only = true;
 569   walk_gimple_op (stmt, lower_emutls_1, &wi);
 570
 571   if (wi.changed)
 572     update_stmt (stmt);
 573 }
 574
 575 /* Lower the I'th operand of PHI.  */
 576
 577 static void
 578 lower_emutls_phi_arg (gimple phi, unsigned int i, struct lower_emutls_data *d)
 579 {
 580   struct walk_stmt_info wi;
 581   struct phi_arg_d *pd = gimple_phi_arg (phi, i);
 582
 583   /* Early out for a very common case we don't care about.  */
 584   if (TREE_CODE (pd->def) == SSA_NAME)
 585     return;
 586
 587   d->loc = pd->locus;
 588
 589   memset (&wi, 0, sizeof (wi));
 590   wi.info = d;
 591   wi.val_only = true;
 592   walk_tree (&pd->def, lower_emutls_1, &wi, NULL);
 593
 594   /* For normal statements, we let update_stmt do its job.  But for phi
 595      nodes, we have to manipulate the immediate use list by hand.  */
 596   if (wi.changed)
 597     {
 598       gcc_assert (TREE_CODE (pd->def) == SSA_NAME);
 599       link_imm_use_stmt (&pd->imm_use, pd->def, phi);
 600     }
 601 }
 602
 603 /* Clear the ACCESS_VARS array, in order to begin a new block.  */
 604
 605 static inline void
 606 clear_access_vars (void)
 607 {
 608   memset (access_vars.address (), 0,
 609           access_vars.length () * sizeof(tree));
 610 }
 611
 612 /* Lower the entire function NODE.  */
 613
 614 static void
 615 lower_emutls_function_body (struct cgraph_node *node)
 616 {
 617   struct lower_emutls_data d;
 618   bool any_edge_inserts = false;
 619
 620   push_cfun (DECL_STRUCT_FUNCTION (node->symbol.decl));
 621
 622   d.cfun_node = node;
 623   d.builtin_decl = builtin_decl_explicit (BUILT_IN_EMUTLS_GET_ADDRESS);
 624   /* This is where we introduce the declaration to the IL and so we have to
 625      create a node for it.  */
 626   d.builtin_node = cgraph_get_create_node (d.builtin_decl);
 627
 628   FOR_EACH_BB (d.bb)
 629     {
 630       gimple_stmt_iterator gsi;
 631       unsigned int i, nedge;
 632
 633       /* Lower each of the PHI nodes of the block, as we may have
 634          propagated &tlsvar into a PHI argument.  These loops are
 635          arranged so that we process each edge at once, and each
 636          PHI argument for that edge.  */
 637       if (!gimple_seq_empty_p (phi_nodes (d.bb)))
 638         {
 639           /* The calls will be inserted on the edges, and the frequencies
 640              will be computed during the commit process.  */
 641           d.bb_freq = 0;
 642
 643           nedge = EDGE_COUNT (d.bb->preds);
 644           for (i = 0; i < nedge; ++i)
 645             {
 646               edge e = EDGE_PRED (d.bb, i);
 647
 648               /* We can re-use any SSA_NAME created on this edge.  */
 649               clear_access_vars ();
 650               d.seq = NULL;
 651
 652               for (gsi = gsi_start_phis (d.bb);
 653                    !gsi_end_p (gsi);
 654                    gsi_next (&gsi))
 655                 lower_emutls_phi_arg (gsi_stmt (gsi), i, &d);
 656
 657               /* Insert all statements generated by all phi nodes for this
 658                  particular edge all at once.  */
 659               if (d.seq)
 660                 {
 661                   gsi_insert_seq_on_edge (e, d.seq);
 662                   any_edge_inserts = true;
 663                 }
 664             }
 665         }
 666
 667       d.bb_freq = compute_call_stmt_bb_frequency (current_function_decl, d.bb);
 668
 669       /* We can re-use any SSA_NAME created during this basic block.  */
 670       clear_access_vars ();
 671
 672       /* Lower each of the statements of the block.  */
 673       for (gsi = gsi_start_bb (d.bb); !gsi_end_p (gsi); gsi_next (&gsi))
 674         {
 675           d.seq = NULL;
 676           lower_emutls_stmt (gsi_stmt (gsi), &d);
 677
 678           /* If any new statements were created, insert them immediately
 679              before the first use.  This prevents variable lifetimes from
 680              becoming unnecessarily long.  */
 681           if (d.seq)
 682             gsi_insert_seq_before (&gsi, d.seq, GSI_SAME_STMT);
 683         }
 684     }
 685
 686   if (any_edge_inserts)
 687     gsi_commit_edge_inserts ();
 688
 689   pop_cfun ();
 690 }
 691
 692 /* Create emutls variable for VAR, DATA is pointer to static
 693    ctor body we can add constructors to.
 694    Callback for varpool_for_variable_and_aliases.  */
 695
 696 static bool
 697 create_emultls_var (struct varpool_node *var, void *data)
 698 {
 699   tree cdecl;
 700   struct varpool_node *cvar;
 701
 702   cdecl = new_emutls_decl (var->symbol.decl, var->alias_of);
 703
 704   cvar = varpool_get_node (cdecl);
 705   control_vars.quick_push (cvar);
 706
 707   if (!var->alias)
 708     {
 709       /* Make sure the COMMON block control variable gets initialized.
 710          Note that there's no point in doing this for aliases; we only
 711          need to do this once for the main variable.  */
 712       emutls_common_1 (var->symbol.decl, cdecl, (tree *)data);
 713     }
 714   if (var->alias && !var->alias_of)
 715     cvar->alias = true;
 716
 717   /* Indicate that the value of the TLS variable may be found elsewhere,
 718      preventing the variable from re-appearing in the GIMPLE.  We cheat
 719      and use the control variable here (rather than a full call_expr),
 720      which is special-cased inside the DWARF2 output routines.  */
 721   SET_DECL_VALUE_EXPR (var->symbol.decl, cdecl);
 722   DECL_HAS_VALUE_EXPR_P (var->symbol.decl) = 1;
 723   return false;
 724 }
 725
 726 /* Main entry point to the tls lowering pass.  */
 727
 728 static unsigned int
 729 ipa_lower_emutls (void)
 730 {
 731   struct varpool_node *var;
 732   struct cgraph_node *func;
 733   bool any_aliases = false;
 734   tree ctor_body = NULL;
 735   unsigned int i, n_tls;
 736
 737   tls_vars = varpool_node_set_new ();
 738
 739   /* Examine all global variables for TLS variables.  */
 740   FOR_EACH_VARIABLE (var)
 741     if (DECL_THREAD_LOCAL_P (var->symbol.decl))
 742       {
 743         gcc_checking_assert (TREE_STATIC (var->symbol.decl)
 744                              || DECL_EXTERNAL (var->symbol.decl));
 745         varpool_node_set_add (tls_vars, var);
 746         if (var->alias && var->analyzed)
 747           varpool_node_set_add (tls_vars, varpool_variable_node (var, NULL));
 748       }
 749
 750   /* If we found no TLS variables, then there is no further work to do.  */
 751   if (!tls_vars->nodes.exists ())
 752     {
 753       tls_vars = NULL;
 754       if (dump_file)
 755         fprintf (dump_file, "No TLS variables found.\n");
 756       return 0;
 757     }
 758
 759   /* Allocate the on-the-side arrays that share indicies with the TLS vars.  */
 760   n_tls = tls_vars->nodes.length ();
 761   control_vars.create (n_tls);
 762   access_vars.create (n_tls);
 763   access_vars.safe_grow_cleared (n_tls);
 764
 765   /* Create the control variables for each TLS variable.  */
 766   FOR_EACH_VEC_ELT (tls_vars->nodes, i, var)
 767     {
 768       var = tls_vars->nodes[i];
 769
 770       if (var->alias && !var->alias_of)
 771         any_aliases = true;
 772       else if (!var->alias)
 773         varpool_for_node_and_aliases (var, create_emultls_var, &ctor_body, true);
 774     }
 775
 776   /* If there were any aliases, then frob the alias_pairs vector.  */
 777   if (any_aliases)
 778     {
 779       alias_pair *p;
 780       FOR_EACH_VEC_SAFE_ELT (alias_pairs, i, p)
 781         if (DECL_THREAD_LOCAL_P (p->decl))
 782           {
 783             p->decl = emutls_decl (p->decl);
 784             p->target = get_emutls_object_name (p->target);
 785           }
 786     }
 787
 788   /* Adjust all uses of TLS variables within the function bodies.  */
 789   FOR_EACH_DEFINED_FUNCTION (func)
 790     if (func->lowered)
 791       lower_emutls_function_body (func);
 792
 793   /* Generate the constructor for any COMMON control variables created.  */
 794   if (ctor_body)
 795     cgraph_build_static_cdtor ('I', ctor_body, DEFAULT_INIT_PRIORITY);
 796
 797   control_vars.release ();
 798   access_vars.release ();
 799   free_varpool_node_set (tls_vars);
 800
 801   return TODO_verify_all;
 802 }
 803
 804 /* If the target supports TLS natively, we need do nothing here.  */
 805
 806 static bool
 807 gate_emutls (void)
 808 {
 809   return !targetm.have_tls;
 810 }
 811
 812 struct simple_ipa_opt_pass pass_ipa_lower_emutls =
 813 {
 814  {
 815   SIMPLE_IPA_PASS,
 816   "emutls",                             /* name */
 817   OPTGROUP_NONE,                        /* optinfo_flags */
 818   gate_emutls,                          /* gate */
 819   ipa_lower_emutls,                     /* execute */
 820   NULL,                                 /* sub */
 821   NULL,                                 /* next */
 822   0,                                    /* static_pass_number */
 823   TV_IPA_OPT,                           /* tv_id */
 824   PROP_cfg | PROP_ssa,                  /* properties_required */
 825   0,                                    /* properties_provided */
 826   0,                                    /* properties_destroyed */
 827   0,                                    /* todo_flags_start */
 828   0,                                    /* todo_flags_finish */
 829  }
 830 };