gcc/c-family/cilk.c

   1 /* This file is part of the Intel(R) Cilk(TM) Plus support
   2    This file contains the CilkPlus Intrinsics
   3    Copyright (C) 2013-2014 Free Software Foundation, Inc.
   4    Contributed by Balaji V. Iyer <balaji.v.iyer@intel.com>,
   5    Intel Corporation
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify it
  10 under the terms of the GNU General Public License as published by
  11 the Free Software Foundation; either version 3, or (at your option)
  12 any later version.
  13
  14 GCC is distributed in the hope that it will be useful, but
  15 WITHOUT ANY WARRANTY; without even the implied warranty of
  16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17 General Public License for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with GCC; see the file COPYING3.  If not see
  21 <http://www.gnu.org/licenses/>.  */
  22
  23 #include "config.h"
  24 #include "system.h"
  25 #include "coretypes.h"
  26 #include "tree.h"
  27 #include "stringpool.h"
  28 #include "calls.h"
  29 #include "langhooks.h"
  30 #include "pointer-set.h"
  31 #include "gimple-expr.h"
  32 #include "gimplify.h"
  33 #include "tree-iterator.h"
  34 #include "tree-inline.h"
  35 #include "c-family/c-common.h"
  36 #include "toplev.h"
  37 #include "cgraph.h"
  38 #include "diagnostic.h"
  39 #include "cilk.h"
  40
  41 enum add_variable_type {
  42     /* Reference to previously-defined variable.  */
  43     ADD_READ,
  44     /* Definition of a new variable in inner-scope.  */
  45     ADD_BIND,
  46     /* Write to possibly previously-defined variable.  */
  47     ADD_WRITE
  48 };
  49
  50 enum cilk_block_type {
  51     /* Indicates a _Cilk_spawn block.  30 was an arbitary number picked for
  52        ease of debugging.  */
  53     CILK_BLOCK_SPAWN = 30,
  54     /* Indicates _Cilk_for statement block.  */
  55     CILK_BLOCK_FOR
  56 };
  57
  58 struct wrapper_data
  59 {
  60   /* Kind of function to be created.  */
  61   enum cilk_block_type type;
  62   /* Signature of helper function.  */
  63   tree fntype;
  64   /* Containing function.  */
  65   tree context;
  66   /* Disposition of all variables in the inner statement.  */
  67   struct pointer_map_t *decl_map;
  68   /* True if this function needs a static chain.  */
  69   bool nested;
  70   /* Arguments to be passed to wrapper function, currently a list.  */
  71   tree arglist;
  72   /* Argument types, a list.  */
  73   tree argtypes;
  74   /* Incoming parameters.  */
  75   tree parms;
  76   /* Outer BLOCK object.  */
  77   tree block;
  78 };
  79
  80 static void extract_free_variables (tree, struct wrapper_data *,
  81                                     enum add_variable_type);
  82 static HOST_WIDE_INT cilk_wrapper_count;
  83
  84 /* Marks the CALL_EXPR or FUNCTION_DECL, FCALL, as a spawned function call
  85    and the current function as a spawner.  Emit error if the function call
  86    is outside a function or if a non function-call is spawned.  */
  87
  88 inline bool
  89 cilk_set_spawn_marker (location_t loc, tree fcall)
  90 {
  91   if (!current_function_decl)
  92     {
  93       error_at (loc, "%<_Cilk_spawn%> may only be used inside a function");
  94       return false;
  95     }
  96   else if (fcall == error_mark_node)
  97     /* Error reporting here is not necessary here since if FCALL is an
  98        error_mark_node, the function marking it as error would have reported
  99        it.  */
 100     return false;
 101   else if (TREE_CODE (fcall) != CALL_EXPR
 102            /* In C++, TARGET_EXPR is generated when we have an overloaded
 103               '=' operator.  */
 104            && TREE_CODE (fcall) != TARGET_EXPR)
 105     {
 106       error_at (loc, "only function calls can be spawned");
 107       return false;
 108     }
 109   else
 110     {
 111       cfun->calls_cilk_spawn = true;
 112       return true;
 113     }
 114 }
 115
 116 /* This function will output the exit conditions for a spawn call.  */
 117
 118 tree
 119 create_cilk_function_exit (tree frame, bool detaches, bool needs_sync)
 120 {
 121   tree epi = alloc_stmt_list ();
 122
 123   if (needs_sync)
 124     append_to_statement_list (build_cilk_sync (), &epi);
 125   tree func_ptr = build1 (ADDR_EXPR, cilk_frame_ptr_type_decl, frame);
 126   tree pop_frame = build_call_expr (cilk_pop_fndecl, 1, func_ptr);
 127   tree worker = cilk_dot (frame, CILK_TI_FRAME_WORKER, 0);
 128   tree current = cilk_arrow (worker, CILK_TI_WORKER_CUR, 0);
 129   tree parent = cilk_dot (frame, CILK_TI_FRAME_PARENT, 0);
 130   tree set_current = build2 (MODIFY_EXPR, void_type_node, current, parent);
 131   append_to_statement_list (set_current, &epi);
 132   append_to_statement_list (pop_frame, &epi);
 133   tree call = build_call_expr (cilk_leave_fndecl, 1, func_ptr);
 134   if (!detaches)
 135     {
 136       tree flags = cilk_dot (frame, CILK_TI_FRAME_FLAGS, false);
 137       tree flags_cmp_expr = fold_build2 (NE_EXPR, TREE_TYPE (flags), flags,
 138                                          build_int_cst (TREE_TYPE (flags),
 139                                                         CILK_FRAME_VERSION));
 140       call = fold_build3 (COND_EXPR, void_type_node, flags_cmp_expr,
 141                           call, build_empty_stmt (EXPR_LOCATION (flags)));
 142     }
 143   append_to_statement_list (call, &epi);
 144   return epi;
 145 }
 146
 147 /* Trying to get the correct cfun for the FUNCTION_DECL indicated by OUTER.  */
 148
 149 static void
 150 pop_cfun_to (tree outer)
 151 {
 152   pop_cfun ();
 153   current_function_decl = outer;
 154   gcc_assert (cfun == DECL_STRUCT_FUNCTION (current_function_decl));
 155   gcc_assert (cfun->decl == current_function_decl);
 156 }
 157
 158 /* This function does whatever is necessary to make the compiler emit a newly
 159    generated function, FNDECL.  */
 160
 161 static void
 162 call_graph_add_fn (tree fndecl)
 163 {
 164   const tree outer = current_function_decl;
 165   struct function *f = DECL_STRUCT_FUNCTION (fndecl);
 166   gcc_assert (TREE_CODE (fndecl) == FUNCTION_DECL);
 167
 168   f->is_cilk_function = 1;
 169   f->curr_properties = cfun->curr_properties;
 170   gcc_assert (cfun == DECL_STRUCT_FUNCTION (outer));
 171   gcc_assert (cfun->decl == outer);
 172
 173   push_cfun (f);
 174   cgraph_node::create (fndecl);
 175   pop_cfun_to (outer);
 176 }
 177
 178 /* Return true if this is a tree which is allowed to contain a spawn as
 179    operand 0.
 180    A spawn call may be wrapped in a series of unary operations such
 181    as conversions.  These conversions need not be "useless"
 182    to be disregarded because they are retained in the spawned
 183    statement.  They are bypassed only to look for a spawn
 184    within.
 185    A comparison to constant is simple enough to allow, and
 186    is used to convert to bool.  */
 187
 188 static bool
 189 cilk_ignorable_spawn_rhs_op (tree exp)
 190 {
 191   enum tree_code code = TREE_CODE (exp);
 192   switch (TREE_CODE_CLASS (code))
 193     {
 194     case tcc_expression:
 195       return code == ADDR_EXPR;
 196     case tcc_comparison:
 197       /* We need the spawn as operand 0 for now.   That's where it
 198          appears in the only case we really care about, conversion
 199          to bool.  */
 200       return (TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST);
 201     case tcc_unary:
 202     case tcc_reference:
 203       return true;
 204     default:
 205       return false;
 206     }
 207 }
 208
 209 /* Helper function for walk_tree.  If *TP is a CILK_SPAWN_STMT, then unwrap
 210    this "wrapper."  The function returns NULL_TREE regardless.  */
 211
 212 static tree
 213 unwrap_cilk_spawn_stmt (tree *tp, int *walk_subtrees, void *)
 214 {
 215   if (TREE_CODE (*tp) == CILK_SPAWN_STMT)
 216     {
 217       *tp = CILK_SPAWN_FN (*tp);
 218       *walk_subtrees = 0;
 219     }
 220   return NULL_TREE;
 221 }
 222
 223 /* Returns true when EXP is a CALL_EXPR with _Cilk_spawn in front.  Unwraps
 224    CILK_SPAWN_STMT wrapper from the CALL_EXPR in *EXP0 statement.  */
 225
 226 static bool
 227 recognize_spawn (tree exp, tree *exp0)
 228 {
 229   bool spawn_found = false;
 230   if (TREE_CODE (exp) == CILK_SPAWN_STMT)
 231     {
 232       /* Remove the CALL_EXPR from CILK_SPAWN_STMT wrapper.  */
 233       exp = CILK_SPAWN_FN (exp);
 234       walk_tree (exp0, unwrap_cilk_spawn_stmt, NULL, NULL);
 235       spawn_found = true;
 236     }
 237   /* _Cilk_spawn can't be wrapped in expression such as PLUS_EXPR.  */
 238   else if (contains_cilk_spawn_stmt (exp))
 239     error ("invalid use of %<_Cilk_spawn%>");
 240   return spawn_found;
 241 }
 242
 243 /* Returns true if *EXP0 is a recognized form of spawn.  Recognized forms are,
 244    after conversion to void, a call expression at outer level or an assignment
 245    at outer level with the right hand side being a spawned call.
 246    In addition to this, it also unwraps the CILK_SPAWN_STMT cover from the
 247    CALL_EXPR that is being spawned.
 248    Note that `=' in C++ may turn into a CALL_EXPR rather than a MODIFY_EXPR.  */
 249
 250 bool
 251 cilk_detect_spawn_and_unwrap (tree *exp0)
 252 {
 253   tree exp = *exp0;
 254
 255   if (!TREE_SIDE_EFFECTS (exp))
 256     return false;
 257
 258   /* Strip off any conversion to void.  It does not affect whether spawn
 259      is supported here.  */
 260   if (TREE_CODE (exp) == CONVERT_EXPR && VOID_TYPE_P (TREE_TYPE (exp)))
 261     exp = TREE_OPERAND (exp, 0);
 262
 263   if (TREE_CODE (exp) == MODIFY_EXPR || TREE_CODE (exp) == INIT_EXPR)
 264     exp = TREE_OPERAND (exp, 1);
 265
 266   while (cilk_ignorable_spawn_rhs_op (exp))
 267     exp = TREE_OPERAND (exp, 0);
 268
 269   if (TREE_CODE (exp) == TARGET_EXPR)
 270     if (TARGET_EXPR_INITIAL (exp)
 271         && TREE_CODE (TARGET_EXPR_INITIAL (exp)) != AGGR_INIT_EXPR)
 272       exp = TARGET_EXPR_INITIAL (exp);
 273
 274   /* Happens with C++ TARGET_EXPR.  */
 275   if (exp == NULL_TREE)
 276     return false;
 277
 278   while (TREE_CODE (exp) == CLEANUP_POINT_EXPR || TREE_CODE (exp) == EXPR_STMT)
 279     exp = TREE_OPERAND (exp, 0);
 280
 281   /* Now we should have a CALL_EXPR with a CILK_SPAWN_STMT wrapper around
 282      it, or return false.  */
 283   if (recognize_spawn (exp, exp0))
 284     return true;
 285   return false;
 286 }
 287
 288 /* This function will build and return a FUNCTION_DECL using information
 289    from *WD.  */
 290
 291 static tree
 292 create_cilk_helper_decl (struct wrapper_data *wd)
 293 {
 294   char name[20];
 295   if (wd->type == CILK_BLOCK_FOR)
 296     sprintf (name, "_cilk_for_" HOST_WIDE_INT_PRINT_DEC, cilk_wrapper_count++);
 297   else if (wd->type == CILK_BLOCK_SPAWN)
 298     sprintf (name, "_cilk_spn_" HOST_WIDE_INT_PRINT_DEC, cilk_wrapper_count++);
 299   else
 300     gcc_unreachable ();
 301
 302   clean_symbol_name (name);
 303   tree fndecl = build_decl (UNKNOWN_LOCATION, FUNCTION_DECL,
 304                             get_identifier (name), wd->fntype);
 305
 306   TREE_PUBLIC (fndecl) = 0;
 307   TREE_STATIC (fndecl) = 1;
 308   TREE_USED (fndecl) = 1;
 309   DECL_ARTIFICIAL (fndecl) = 0;
 310   DECL_IGNORED_P (fndecl) = 0;
 311   DECL_EXTERNAL (fndecl) = 0;
 312
 313   DECL_CONTEXT (fndecl) = wd->context;
 314   tree block = make_node (BLOCK);
 315   DECL_INITIAL (fndecl) = block;
 316   TREE_USED (block) = 1;
 317   BLOCK_SUPERCONTEXT (block) = fndecl;
 318   gcc_assert (!DECL_SAVED_TREE (fndecl));
 319
 320   /* Inlining would defeat the purpose of this wrapper.
 321      Either it secretly switches stack frames or it allocates
 322      a stable stack frame to hold function arguments even if
 323      the parent stack frame is stolen.  */
 324   DECL_UNINLINABLE (fndecl) = 1;
 325
 326   tree result_decl = build_decl (UNKNOWN_LOCATION, RESULT_DECL, NULL_TREE,
 327                                  void_type_node);
 328   DECL_ARTIFICIAL (result_decl) = 0;
 329   DECL_IGNORED_P (result_decl) = 1;
 330   DECL_CONTEXT (result_decl) = fndecl;
 331   DECL_RESULT (fndecl) = result_decl;
 332
 333   return fndecl;
 334 }
 335
 336 /* A function used by walk tree to find wrapper parms.  */
 337
 338 static bool
 339 wrapper_parm_cb (const void *key0, void **val0, void *data)
 340 {
 341   struct wrapper_data *wd = (struct wrapper_data *) data;
 342   tree arg = * (tree *)&key0;
 343   tree val = (tree)*val0;
 344   tree parm;
 345
 346   if (val == error_mark_node || val == arg)
 347     return true;
 348
 349   if (TREE_CODE (val) == PAREN_EXPR)
 350     {
 351       /* We should not reach here with a register receiver.
 352          We may see a register variable modified in the
 353          argument list.  Because register variables are
 354          worker-local we don't need to work hard to support
 355          them in code that spawns.  */
 356       if ((TREE_CODE (arg) == VAR_DECL) && DECL_HARD_REGISTER (arg))
 357         {
 358           error_at (EXPR_LOCATION (arg),
 359                     "explicit register variable %qD may not be modified in "
 360                     "spawn", arg);
 361           arg = null_pointer_node;
 362         }
 363       else
 364         arg = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (arg)), arg);
 365
 366       val = TREE_OPERAND (val, 0);
 367       *val0 = val;
 368       gcc_assert (TREE_CODE (val) == INDIRECT_REF);
 369       parm = TREE_OPERAND (val, 0);
 370       STRIP_NOPS (parm);
 371     }
 372   else
 373     parm = val;
 374   TREE_CHAIN (parm) = wd->parms;
 375   wd->parms = parm;
 376   wd->argtypes = tree_cons (NULL_TREE, TREE_TYPE (parm), wd->argtypes);
 377   wd->arglist = tree_cons (NULL_TREE, arg, wd->arglist);
 378   return true;
 379 }
 380
 381 /* This function is used to build a wrapper of a certain type.  */
 382
 383 static void
 384 build_wrapper_type (struct wrapper_data *wd)
 385 {
 386   wd->arglist = NULL_TREE;
 387   wd->parms = NULL_TREE;
 388   wd->argtypes = void_list_node;
 389
 390   pointer_map_traverse (wd->decl_map, wrapper_parm_cb, wd);
 391   gcc_assert (wd->type != CILK_BLOCK_FOR);
 392
 393   /* Now build a function.
 394      Its return type is void (all side effects are via explicit parameters).
 395      Its parameters are WRAPPER_PARMS with type WRAPPER_TYPES.
 396      Actual arguments in the caller are WRAPPER_ARGS.  */
 397   wd->fntype = build_function_type (void_type_node, wd->argtypes);
 398 }
 399
 400 /* This function checks all the CALL_EXPRs in *TP found by cilk_outline.  */
 401
 402 static tree
 403 check_outlined_calls (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
 404                       void *data)
 405 {
 406   bool *throws = (bool *) data;
 407   tree t = *tp;
 408   int flags;
 409
 410   if (TREE_CODE (t) != CALL_EXPR)
 411     return 0;
 412   flags = call_expr_flags (t);
 413
 414   if (!(flags & ECF_NOTHROW) && flag_exceptions)
 415     *throws = true;
 416   if (flags & ECF_RETURNS_TWICE)
 417     error_at (EXPR_LOCATION (t),
 418               "cannot spawn call to function that returns twice");
 419   return 0;
 420 }
 421
 422 /* Each DECL in the source code (spawned statement) is passed to this function
 423    once.  Each instance of the DECL is replaced with the result of this
 424    function.
 425
 426    The parameters of the wrapper should have been entered into the map already.
 427    This function only deals with variables with scope limited to the
 428    spawned expression.  */
 429
 430 static tree
 431 copy_decl_for_cilk (tree decl, copy_body_data *id)
 432 {
 433   switch (TREE_CODE (decl))
 434     {
 435     case VAR_DECL:
 436       return copy_decl_no_change (decl, id);
 437
 438     case LABEL_DECL:
 439       error_at (EXPR_LOCATION (decl), "invalid use of label %q+D in "
 440                 "%<_Cilk_spawn%>",
 441                 decl);
 442       return error_mark_node;
 443
 444     case RESULT_DECL:
 445     case PARM_DECL:
 446       /* RESULT_DECL and PARM_DECL has already been entered into the map.  */
 447     default:
 448       gcc_unreachable ();
 449       return error_mark_node;
 450     }
 451 }
 452
 453 /* Copy all local variables.  */
 454
 455 static bool
 456 for_local_cb (const void *k_v, void **vp, void *p)
 457 {
 458   tree k = *(tree *) &k_v;
 459   tree v = (tree) *vp;
 460
 461   if (v == error_mark_node)
 462     *vp = copy_decl_no_change (k, (copy_body_data *) p);
 463   return true;
 464 }
 465
 466 /* Copy all local declarations from a _Cilk_spawned function's body.  */
 467
 468 static bool
 469 wrapper_local_cb (const void *k_v, void **vp, void *data)
 470 {
 471   copy_body_data *id = (copy_body_data *) data;
 472   tree key = *(tree *) &k_v;
 473   tree val = (tree) *vp;
 474
 475   if (val == error_mark_node)
 476     *vp = copy_decl_for_cilk (key, id);
 477
 478   return true;
 479 }
 480
 481 /* Alter a tree STMT from OUTER_FN to form the body of INNER_FN.  */
 482
 483 void
 484 cilk_outline (tree inner_fn, tree *stmt_p, void *w)
 485 {
 486   struct wrapper_data *wd = (struct wrapper_data *) w;
 487   const tree outer_fn = wd->context;
 488   const bool nested = (wd->type == CILK_BLOCK_FOR);
 489   copy_body_data id;
 490   bool throws;
 491
 492   DECL_STATIC_CHAIN (outer_fn) = 1;
 493
 494   memset (&id, 0, sizeof (id));
 495   /* Copy from the function containing the spawn...  */
 496   id.src_fn = outer_fn;
 497
 498   /* ...to the wrapper.  */
 499   id.dst_fn = inner_fn;
 500   id.src_cfun = DECL_STRUCT_FUNCTION (outer_fn);
 501
 502   /* There shall be no RETURN in spawn helper.  */
 503   id.retvar = 0;
 504   id.decl_map = wd->decl_map;
 505   id.copy_decl = nested ? copy_decl_no_change : copy_decl_for_cilk;
 506   id.block = DECL_INITIAL (inner_fn);
 507   id.transform_lang_insert_block = NULL;
 508
 509   id.transform_new_cfg = true;
 510   id.transform_call_graph_edges = CB_CGE_MOVE;
 511   id.remap_var_for_cilk = true;
 512   id.regimplify = true; /* unused? */
 513
 514   insert_decl_map (&id, wd->block, DECL_INITIAL (inner_fn));
 515
 516   /* We don't want the private variables any more.  */
 517   pointer_map_traverse (wd->decl_map, nested ? for_local_cb : wrapper_local_cb,
 518                         &id);
 519   walk_tree (stmt_p, copy_tree_body_r, (void *) &id, NULL);
 520
 521   /* See if this function can throw or calls something that should
 522      not be spawned.  The exception part is only necessary if
 523      flag_exceptions && !flag_non_call_exceptions.  */
 524   throws = false ;
 525   (void) walk_tree_without_duplicates (stmt_p, check_outlined_calls, &throws);
 526 }
 527
 528 /* Generate the body of a wrapper function that assigns the
 529    result of the expression RHS into RECEIVER.  RECEIVER must
 530    be NULL if this is not a spawn -- the wrapper will return
 531    a value.  If this is a spawn, the wrapper will return void.  */
 532
 533 static tree
 534 create_cilk_wrapper_body (tree stmt, struct wrapper_data *wd)
 535 {
 536   const tree outer = current_function_decl;
 537   tree fndecl;
 538   tree p;
 539
 540    /* Build the type of the wrapper and its argument list from the
 541      variables that it requires.  */
 542   build_wrapper_type (wd);
 543
 544   /* Emit a function that takes WRAPPER_PARMS incoming and applies ARGS
 545      (modified) to the wrapped function.  Return the wrapper and modified ARGS
 546      to the caller to generate a function call.  */
 547   fndecl = create_cilk_helper_decl (wd);
 548   push_struct_function (fndecl);
 549   if (wd->nested && (wd->type == CILK_BLOCK_FOR))
 550     {
 551       gcc_assert (TREE_VALUE (wd->arglist) == NULL_TREE);
 552       TREE_VALUE (wd->arglist) = build2 (FDESC_EXPR, ptr_type_node,
 553                                          fndecl, integer_one_node);
 554     }
 555   DECL_ARGUMENTS (fndecl) = wd->parms;
 556
 557   for (p = wd->parms; p; p = TREE_CHAIN (p))
 558     DECL_CONTEXT (p) = fndecl;
 559
 560   gcc_assert (!DECL_SAVED_TREE (fndecl));
 561   cilk_install_body_with_frame_cleanup (fndecl, stmt, (void *) wd);
 562   gcc_assert (DECL_SAVED_TREE (fndecl));
 563
 564   pop_cfun_to (outer);
 565
 566   /* Recognize the new function.  */
 567   call_graph_add_fn (fndecl);
 568   return fndecl;
 569 }
 570
 571 /* Initializes the wrapper data structure.  */
 572
 573 static void
 574 init_wd (struct wrapper_data *wd, enum cilk_block_type type)
 575 {
 576   wd->type = type;
 577   wd->fntype = NULL_TREE;
 578   wd->context = current_function_decl;
 579   wd->decl_map = pointer_map_create ();
 580   /* _Cilk_for bodies are always nested.  Others start off as
 581      normal functions.  */
 582   wd->nested = (type == CILK_BLOCK_FOR);
 583   wd->arglist = NULL_TREE;
 584   wd->argtypes = NULL_TREE;
 585   wd->block = NULL_TREE;
 586 }
 587
 588 /* Clears the wrapper data structure.  */
 589
 590 static void
 591 free_wd (struct wrapper_data *wd)
 592 {
 593   pointer_map_destroy (wd->decl_map);
 594   wd->nested = false;
 595   wd->arglist = NULL_TREE;
 596   wd->argtypes = NULL_TREE;
 597   wd->parms = NULL_TREE;
 598 }
 599
 600
 601  /* Given a variable in an expression to be extracted into
 602    a helper function, declare the helper function parameter
 603    to receive it.
 604
 605    On entry the value of the (key, value) pair may be
 606
 607    (*, error_mark_node) -- Variable is private to helper function,
 608    do nothing.
 609
 610    (var, var) -- Reference to outer scope (function or global scope).
 611
 612    (var, integer 0) -- Capture by value, save newly-declared PARM_DECL
 613    for value in value slot.
 614
 615    (var, integer 1) -- Capture by reference, declare pointer to type
 616    as new PARM_DECL and store (spawn_stmt (indirect_ref (parm)).
 617
 618    (var, ???) -- Pure output argument, handled similarly to above.
 619 */
 620
 621 static bool
 622 declare_one_free_variable (const void *var0, void **map0,
 623                            void *data ATTRIBUTE_UNUSED)
 624 {
 625   const_tree var = (const_tree) var0;
 626   tree map = (tree)*map0;
 627   tree var_type = TREE_TYPE (var), arg_type;
 628   bool by_reference;
 629   tree parm;
 630
 631   gcc_assert (DECL_P (var));
 632
 633   /* Ignore truly local variables.  */
 634   if (map == error_mark_node)
 635     return true;
 636   /* Ignore references to the parent function.  */
 637   if (map == var)
 638     return true;
 639
 640   gcc_assert (TREE_CODE (map) == INTEGER_CST);
 641
 642   /* A value is passed by reference if:
 643
 644      1. It is addressable, so that a copy may not be made.
 645      2. It is modified in the spawned statement.
 646      In the future this function may want to arrange
 647      a warning if the spawned statement is a loop body
 648      because an output argument would indicate a race.
 649      Note: Earlier passes must have marked the variable addressable.
 650      3. It is expensive to copy.  */
 651   by_reference =
 652     (TREE_ADDRESSABLE (var_type)
 653      /* Arrays must be passed by reference.  This is required for C
 654         semantics -- arrays are not first class objects.  Other
 655         aggregate types can and should be passed by reference if
 656         they are not passed to the spawned function.  We aren't yet
 657         distinguishing safe uses in argument calculation from unsafe
 658         uses as outgoing function arguments, so we make a copy to
 659         stabilize the value.  */
 660      || TREE_CODE (var_type) == ARRAY_TYPE
 661      || (tree) map == integer_one_node);
 662
 663   if (by_reference)
 664     var_type = build_qualified_type (build_pointer_type (var_type),
 665                                      TYPE_QUAL_RESTRICT);
 666   gcc_assert (!TREE_ADDRESSABLE (var_type));
 667
 668   /* Maybe promote to int.  */
 669   if (INTEGRAL_TYPE_P (var_type) && COMPLETE_TYPE_P (var_type)
 670       && tree_int_cst_lt (TYPE_SIZE (var_type), TYPE_SIZE (integer_type_node)))
 671     arg_type = integer_type_node;
 672   else
 673     arg_type = var_type;
 674
 675   parm = build_decl (UNKNOWN_LOCATION, PARM_DECL, NULL_TREE, var_type);
 676   DECL_ARG_TYPE (parm) = arg_type;
 677   DECL_ARTIFICIAL (parm) = 0;
 678   TREE_READONLY (parm) = 1;
 679
 680   if (by_reference)
 681     {
 682       parm = build1 (INDIRECT_REF, TREE_TYPE (var_type), parm);
 683       parm = build1 (PAREN_EXPR, void_type_node, parm);
 684     }
 685   *map0 = parm;
 686   return true;
 687 }
 688
 689 /* Returns a wrapper function for a _Cilk_spawn.  */
 690
 691 static tree
 692 create_cilk_wrapper (tree exp, tree *args_out)
 693 {
 694   struct wrapper_data wd;
 695   tree fndecl;
 696
 697   init_wd (&wd, CILK_BLOCK_SPAWN);
 698
 699   if (TREE_CODE (exp) == CONVERT_EXPR)
 700     exp = TREE_OPERAND (exp, 0);
 701
 702   /* Special handling for top level INIT_EXPR.  Usually INIT_EXPR means the
 703      variable is defined in the spawned expression and can be private to the
 704      spawn helper.  A top level INIT_EXPR defines a variable to be initialized
 705      by spawn and the variable must remain in the outer function.  */
 706   if (TREE_CODE (exp) == INIT_EXPR)
 707     {
 708       extract_free_variables (TREE_OPERAND (exp, 0), &wd, ADD_WRITE);
 709       extract_free_variables (TREE_OPERAND (exp, 1), &wd, ADD_READ);
 710       /* TREE_TYPE should be void.  Be defensive.  */
 711       if (TREE_TYPE (exp) != void_type_node)
 712         extract_free_variables (TREE_TYPE (exp), &wd, ADD_READ);
 713     }
 714   else
 715     extract_free_variables (exp, &wd, ADD_READ);
 716   pointer_map_traverse (wd.decl_map, declare_one_free_variable, &wd);
 717   wd.block = TREE_BLOCK (exp);
 718   if (!wd.block)
 719     wd.block = DECL_INITIAL (current_function_decl);
 720
 721   /* Now fvars maps the old variable to incoming variable.  Update
 722      the expression and arguments to refer to the new names.  */
 723   fndecl = create_cilk_wrapper_body (exp, &wd);
 724   *args_out = wd.arglist;
 725
 726   free_wd (&wd);
 727
 728   return fndecl;
 729 }
 730
 731 /* Transform *SPAWN_P, a spawned CALL_EXPR, to gimple.  *SPAWN_P can be a
 732    CALL_EXPR, INIT_EXPR or MODIFY_EXPR.  Returns GS_OK if everything is fine,
 733    and GS_UNHANDLED, otherwise.  */
 734
 735 int
 736 gimplify_cilk_spawn (tree *spawn_p)
 737 {
 738   tree expr = *spawn_p;
 739   tree function, call1, call2, new_args;
 740   tree ii_args = NULL_TREE;
 741   int total_args = 0, ii = 0;
 742   tree *arg_array;
 743   tree setjmp_cond_expr = NULL_TREE;
 744   tree setjmp_expr, spawn_expr, setjmp_value = NULL_TREE;
 745
 746   cfun->calls_cilk_spawn = 1;
 747   cfun->is_cilk_function = 1;
 748
 749   /* Remove CLEANUP_POINT_EXPR and EXPR_STMT from *spawn_p.  */
 750   while (TREE_CODE (expr) == CLEANUP_POINT_EXPR
 751          || TREE_CODE (expr) == EXPR_STMT)
 752     expr = TREE_OPERAND (expr, 0);
 753
 754   new_args = NULL;
 755   function = create_cilk_wrapper (expr, &new_args);
 756
 757   /* This should give the number of parameters.  */
 758   total_args = list_length (new_args);
 759   if (total_args)
 760     arg_array = XNEWVEC (tree, total_args);
 761   else
 762     arg_array = NULL;
 763
 764   ii_args = new_args;
 765   for (ii = 0; ii < total_args; ii++)
 766     {
 767       arg_array[ii] = TREE_VALUE (ii_args);
 768       ii_args = TREE_CHAIN (ii_args);
 769     }
 770
 771   TREE_USED (function) = 1;
 772   rest_of_decl_compilation (function, 0, 0);
 773
 774   call1 = cilk_call_setjmp (cfun->cilk_frame_decl);
 775
 776   if (arg_array == NULL || *arg_array == NULL_TREE)
 777     call2 = build_call_expr (function, 0);
 778   else
 779     call2 = build_call_expr_loc_array (EXPR_LOCATION (*spawn_p), function,
 780                                          total_args, arg_array);
 781   *spawn_p = alloc_stmt_list ();
 782   tree f_ptr_type = build_pointer_type (TREE_TYPE (cfun->cilk_frame_decl));
 783   tree frame_ptr = build1 (ADDR_EXPR, f_ptr_type, cfun->cilk_frame_decl);
 784   tree save_fp = build_call_expr (cilk_save_fp_fndecl, 1, frame_ptr);
 785   append_to_statement_list (save_fp, spawn_p);
 786   setjmp_value = create_tmp_var (TREE_TYPE (call1), NULL);
 787   setjmp_expr = fold_build2 (MODIFY_EXPR, void_type_node, setjmp_value, call1);
 788
 789   append_to_statement_list_force (setjmp_expr, spawn_p);
 790
 791   setjmp_cond_expr = fold_build2 (EQ_EXPR, TREE_TYPE (call1), setjmp_value,
 792                                   build_int_cst (TREE_TYPE (call1), 0));
 793   spawn_expr = fold_build3 (COND_EXPR, void_type_node, setjmp_cond_expr,
 794                             call2, build_empty_stmt (EXPR_LOCATION (call1)));
 795   append_to_statement_list (spawn_expr, spawn_p);
 796
 797   return GS_OK;
 798 }
 799
 800 /* Make the frames necessary for a spawn call.  */
 801
 802 tree
 803 make_cilk_frame (tree fn)
 804 {
 805   struct function *f = DECL_STRUCT_FUNCTION (fn);
 806   tree decl;
 807
 808   if (f->cilk_frame_decl)
 809     return f->cilk_frame_decl;
 810
 811   decl = build_decl (EXPR_LOCATION (fn), VAR_DECL, NULL_TREE,
 812                      cilk_frame_type_decl);
 813   DECL_CONTEXT (decl) = fn;
 814   DECL_SEEN_IN_BIND_EXPR_P (decl) = 1;
 815   f->cilk_frame_decl = decl;
 816   return decl;
 817 }
 818
 819 /* Returns a STATEMENT_LIST with all the pedigree operations required for
 820    install body with frame cleanup functions.  FRAME_PTR is the pointer to
 821    __cilkrts_stack_frame created by make_cilk_frame.  */
 822
 823 tree
 824 cilk_install_body_pedigree_operations (tree frame_ptr)
 825 {
 826   tree body_list = alloc_stmt_list ();
 827   tree enter_frame = build_call_expr (cilk_enter_fast_fndecl, 1, frame_ptr);
 828   append_to_statement_list (enter_frame, &body_list);
 829
 830   tree parent = cilk_arrow (frame_ptr, CILK_TI_FRAME_PARENT, 0);
 831   tree worker = cilk_arrow (frame_ptr, CILK_TI_FRAME_WORKER, 0);
 832
 833   tree pedigree = cilk_arrow (frame_ptr, CILK_TI_FRAME_PEDIGREE, 0);
 834   tree pedigree_rank = cilk_dot (pedigree, CILK_TI_PEDIGREE_RANK, 0);
 835   tree parent_pedigree = cilk_dot (pedigree, CILK_TI_PEDIGREE_PARENT, 0);
 836   tree pedigree_parent = cilk_arrow (parent, CILK_TI_FRAME_PEDIGREE, 0);
 837   tree pedigree_parent_rank = cilk_dot (pedigree_parent,
 838                                         CILK_TI_PEDIGREE_RANK, 0);
 839   tree pedigree_parent_parent = cilk_dot (pedigree_parent,
 840                                      CILK_TI_PEDIGREE_PARENT, 0);
 841   tree worker_pedigree = cilk_arrow (worker, CILK_TI_WORKER_PEDIGREE, 1);
 842   tree w_pedigree_rank = cilk_dot (worker_pedigree, CILK_TI_PEDIGREE_RANK, 0);
 843   tree w_pedigree_parent = cilk_dot (worker_pedigree,
 844                                      CILK_TI_PEDIGREE_PARENT, 0);
 845
 846   /* sf.pedigree.rank = worker->pedigree.rank.  */
 847   tree exp1 = build2 (MODIFY_EXPR, void_type_node, pedigree_rank,
 848                      w_pedigree_rank);
 849   append_to_statement_list (exp1, &body_list);
 850
 851   /* sf.pedigree.parent = worker->pedigree.parent.  */
 852   exp1 = build2 (MODIFY_EXPR, void_type_node, parent_pedigree,
 853                  w_pedigree_parent);
 854   append_to_statement_list (exp1, &body_list);
 855
 856   /* sf.call_parent->pedigree.rank = worker->pedigree.rank.  */
 857   exp1 = build2 (MODIFY_EXPR, void_type_node, pedigree_parent_rank,
 858                  w_pedigree_rank);
 859   append_to_statement_list (exp1, &body_list);
 860
 861   /* sf.call_parent->pedigree.parent = worker->pedigree.parent.  */
 862   exp1 = build2 (MODIFY_EXPR, void_type_node, pedigree_parent_parent,
 863                  w_pedigree_parent);
 864   append_to_statement_list (exp1, &body_list);
 865
 866   /* sf->worker.pedigree.rank = 0.  */
 867   exp1 = build2 (MODIFY_EXPR, void_type_node, w_pedigree_rank,
 868                  build_zero_cst (uint64_type_node));
 869   append_to_statement_list (exp1, &body_list);
 870
 871   /* sf->pedigree.parent = &sf->pedigree.  */
 872   exp1 = build2 (MODIFY_EXPR, void_type_node, w_pedigree_parent,
 873                  build1 (ADDR_EXPR,
 874                          build_pointer_type (cilk_pedigree_type_decl),
 875                          pedigree));
 876   append_to_statement_list (exp1, &body_list);
 877   return body_list;
 878 }
 879
 880 /* Add a new variable, VAR to a variable list in WD->DECL_MAP.  HOW indicates
 881    whether the variable is previously defined, currently defined, or a variable
 882    that is being written to.  */
 883
 884 static void
 885 add_variable (struct wrapper_data *wd, tree var, enum add_variable_type how)
 886 {
 887   void **valp;
 888
 889   valp = pointer_map_contains (wd->decl_map, (void *) var);
 890   if (valp)
 891     {
 892       tree val = (tree) *valp;
 893       /* If the variable is local, do nothing.  */
 894       if (val == error_mark_node)
 895         return;
 896       /* If the variable was entered with itself as value,
 897          meaning it belongs to an outer scope, do not alter
 898          the value.  */
 899       if (val == var)
 900         return;
 901       /* A statement expression may cause a variable to be
 902          bound twice, once in BIND_EXPR and again in a
 903          DECL_EXPR.  That case caused a return in the
 904          test above.  Any other duplicate definition is
 905          an error.  */
 906       gcc_assert (how != ADD_BIND);
 907       if (how != ADD_WRITE)
 908         return;
 909       /* This variable might have been entered as read but is now written.  */
 910       *valp = (void *) var;
 911       wd->nested = true;
 912       return;
 913     }
 914   else
 915     {
 916       tree val = NULL_TREE;
 917
 918       /* Nested function rewriting silently discards hard register
 919          assignments for function scope variables, and they wouldn't
 920          work anyway.  Warn here.  This misses one case: if the
 921          register variable is used as the loop bound or increment it
 922          has already been added to the map.  */
 923       if ((how != ADD_BIND) && (TREE_CODE (var) == VAR_DECL)
 924           && !DECL_EXTERNAL (var) && DECL_HARD_REGISTER (var))
 925         warning (0, "register assignment ignored for %qD used in Cilk block",
 926                  var);
 927
 928       switch (how)
 929         {
 930           /* ADD_BIND means always make a fresh new variable.  */
 931         case ADD_BIND:
 932           val = error_mark_node;
 933           break;
 934           /* ADD_READ means
 935              1. For cilk_for, refer to the outer scope definition as-is
 936              2. For a spawned block, take a scalar in an rgument
 937              and otherwise refer to the outer scope definition as-is.
 938              3. For a spawned call, take a scalar in an argument.  */
 939         case ADD_READ:
 940           switch (wd->type)
 941             {
 942             case CILK_BLOCK_FOR:
 943               val = var;
 944               break;
 945             case CILK_BLOCK_SPAWN:
 946               if (TREE_ADDRESSABLE (var))
 947                 {
 948                   val = var;
 949                   wd->nested = true;
 950                   break;
 951                 }
 952               val = integer_zero_node;
 953               break;
 954             }
 955           break;
 956         case ADD_WRITE:
 957           switch (wd->type)
 958             {
 959             case CILK_BLOCK_FOR:
 960               val = var;
 961               wd->nested = true;
 962               break;
 963             case CILK_BLOCK_SPAWN:
 964               if (TREE_ADDRESSABLE (var))
 965                 val = integer_one_node;
 966               else
 967                 {
 968                   val = var;
 969                   wd->nested = true;
 970                 }
 971               break;
 972             }
 973         }
 974       *pointer_map_insert (wd->decl_map, (void *) var) = val;
 975     }
 976 }
 977
 978 /* Find the variables referenced in an expression T.  This does not avoid
 979    duplicates because a variable may be read in one context and written in
 980    another.  HOW describes the context in which the reference is seen.  If
 981    NESTED is true a nested function is being generated and variables in the
 982    original context should not be remapped.  */
 983
 984 static void
 985 extract_free_variables (tree t, struct wrapper_data *wd,
 986                         enum add_variable_type how)
 987 {
 988   if (t == NULL_TREE)
 989     return;
 990
 991   enum tree_code code = TREE_CODE (t);
 992   bool is_expr = IS_EXPR_CODE_CLASS (TREE_CODE_CLASS (code));
 993
 994   if (is_expr)
 995     extract_free_variables (TREE_TYPE (t), wd, ADD_READ);
 996
 997   switch (code)
 998     {
 999     case ERROR_MARK:
1000     case IDENTIFIER_NODE:
1001     case VOID_CST:
1002     case INTEGER_CST:
1003     case REAL_CST:
1004     case FIXED_CST:
1005     case STRING_CST:
1006     case BLOCK:
1007     case PLACEHOLDER_EXPR:
1008     case FIELD_DECL:
1009     case VOID_TYPE:
1010     case REAL_TYPE:
1011       /* These do not contain variable references.  */
1012       return;
1013
1014     case SSA_NAME:
1015       /* Currently we don't see SSA_NAME.  */
1016       extract_free_variables (SSA_NAME_VAR (t), wd, how);
1017       return;
1018
1019     case LABEL_DECL:
1020       /* This might be a reference to a label outside the Cilk block,
1021          which is an error, or a reference to a label in the Cilk block
1022          that we haven't seen yet.  We can't tell.  Ignore it.  An
1023          invalid use will cause an error later in copy_decl_for_cilk.  */
1024       return;
1025
1026     case RESULT_DECL:
1027       if (wd->type != CILK_BLOCK_SPAWN)
1028         TREE_ADDRESSABLE (t) = 1;
1029     case VAR_DECL:
1030     case PARM_DECL:
1031       if (!TREE_STATIC (t) && !DECL_EXTERNAL (t))
1032         add_variable (wd, t, how);
1033       return;
1034
1035     case NON_LVALUE_EXPR:
1036     case CONVERT_EXPR:
1037     case NOP_EXPR:
1038       extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_READ);
1039       return;
1040
1041     case VEC_INIT_EXPR:
1042     case INIT_EXPR:
1043       extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_BIND);
1044       extract_free_variables (TREE_OPERAND (t, 1), wd, ADD_READ);
1045       return;
1046
1047     case MODIFY_EXPR:
1048     case PREDECREMENT_EXPR:
1049     case PREINCREMENT_EXPR:
1050     case POSTDECREMENT_EXPR:
1051     case POSTINCREMENT_EXPR:
1052       /* These write their result.  */
1053       extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_WRITE);
1054       extract_free_variables (TREE_OPERAND (t, 1), wd, ADD_READ);
1055       return;
1056
1057     case ADDR_EXPR:
1058       /* This might modify its argument, and the value needs to be
1059          passed by reference in any case to preserve identity and
1060          type if is a promoting type.  In the case of a nested loop
1061          just notice that we touch the variable.  It will already
1062          be addressable, and marking it modified will cause a spurious
1063          warning about writing the control variable.  */
1064       if (wd->type != CILK_BLOCK_SPAWN)
1065         extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_READ);
1066       else
1067         extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_WRITE);
1068       return;
1069
1070     case ARRAY_REF:
1071       /* Treating ARRAY_REF and BIT_FIELD_REF identically may
1072          mark the array as written but the end result is correct
1073          because the array is passed by pointer anyway.  */
1074     case BIT_FIELD_REF:
1075       /* Propagate the access type to the object part of which
1076          is being accessed here.  As for ADDR_EXPR, don't do this
1077          in a nested loop, unless the access is to a fixed index.  */
1078       if (wd->type != CILK_BLOCK_FOR || TREE_CONSTANT (TREE_OPERAND (t, 1)))
1079         extract_free_variables (TREE_OPERAND (t, 0), wd, how);
1080       else
1081         extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_READ);
1082       extract_free_variables (TREE_OPERAND (t, 1), wd, ADD_READ);
1083       extract_free_variables (TREE_OPERAND (t, 2), wd, ADD_READ);
1084       return;
1085
1086     case TREE_LIST:
1087       extract_free_variables (TREE_PURPOSE (t), wd, ADD_READ);
1088       extract_free_variables (TREE_VALUE (t), wd, ADD_READ);
1089       extract_free_variables (TREE_CHAIN (t), wd, ADD_READ);
1090       return;
1091
1092     case TREE_VEC:
1093       {
1094         int len = TREE_VEC_LENGTH (t);
1095         int i;
1096         for (i = 0; i < len; i++)
1097           extract_free_variables (TREE_VEC_ELT (t, i), wd, ADD_READ);
1098         return;
1099       }
1100
1101     case VECTOR_CST:
1102       {
1103         unsigned ii = 0;
1104         for (ii = 0; ii < VECTOR_CST_NELTS (t); ii++)
1105           extract_free_variables (VECTOR_CST_ELT (t, ii), wd, ADD_READ);
1106         break;
1107       }
1108
1109     case COMPLEX_CST:
1110       extract_free_variables (TREE_REALPART (t), wd, ADD_READ);
1111       extract_free_variables (TREE_IMAGPART (t), wd, ADD_READ);
1112       return;
1113
1114     case BIND_EXPR:
1115       {
1116         tree decl;
1117         for (decl = BIND_EXPR_VARS (t); decl; decl = TREE_CHAIN (decl))
1118           {
1119             add_variable (wd, decl, ADD_BIND);
1120             /* A self-referential initialization is no problem because
1121                we already entered the variable into the map as local.  */
1122             extract_free_variables (DECL_INITIAL (decl), wd, ADD_READ);
1123             extract_free_variables (DECL_SIZE (decl), wd, ADD_READ);
1124             extract_free_variables (DECL_SIZE_UNIT (decl), wd, ADD_READ);
1125           }
1126         extract_free_variables (BIND_EXPR_BODY (t), wd, ADD_READ);
1127         return;
1128       }
1129
1130     case STATEMENT_LIST:
1131       {
1132         tree_stmt_iterator i;
1133         for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
1134           extract_free_variables (*tsi_stmt_ptr (i), wd, ADD_READ);
1135         return;
1136       }
1137
1138     case TARGET_EXPR:
1139       {
1140         extract_free_variables (TREE_OPERAND (t, 0), wd, ADD_BIND);
1141         extract_free_variables (TREE_OPERAND (t, 1), wd, ADD_READ);
1142         extract_free_variables (TREE_OPERAND (t, 2), wd, ADD_READ);
1143         if (TREE_OPERAND (t, 3) != TREE_OPERAND (t, 1))
1144           extract_free_variables (TREE_OPERAND (t, 3), wd, ADD_READ);
1145         return;
1146       }
1147
1148     case RETURN_EXPR:
1149       if (TREE_NO_WARNING (t))
1150         {
1151           gcc_assert (errorcount);
1152           return;
1153         }
1154       return;
1155
1156     case DECL_EXPR:
1157       if (TREE_CODE (DECL_EXPR_DECL (t)) != TYPE_DECL)
1158         extract_free_variables (DECL_EXPR_DECL (t), wd, ADD_BIND);
1159       return;
1160
1161     case INTEGER_TYPE:
1162     case ENUMERAL_TYPE:
1163     case BOOLEAN_TYPE:
1164       extract_free_variables (TYPE_MIN_VALUE (t), wd, ADD_READ);
1165       extract_free_variables (TYPE_MAX_VALUE (t), wd, ADD_READ);
1166       return;
1167
1168     case POINTER_TYPE:
1169       extract_free_variables (TREE_TYPE (t), wd, ADD_READ);
1170       break;
1171
1172     case ARRAY_TYPE:
1173       extract_free_variables (TREE_TYPE (t), wd, ADD_READ);
1174       extract_free_variables (TYPE_DOMAIN (t), wd, ADD_READ);
1175       return;
1176
1177     case RECORD_TYPE:
1178       extract_free_variables (TYPE_FIELDS (t), wd, ADD_READ);
1179       return;
1180
1181     case METHOD_TYPE:
1182       extract_free_variables (TYPE_ARG_TYPES (t), wd, ADD_READ);
1183       extract_free_variables (TYPE_METHOD_BASETYPE (t), wd, ADD_READ);
1184       return;
1185
1186     case AGGR_INIT_EXPR:
1187     case CALL_EXPR:
1188       {
1189         int len = 0;
1190         int ii = 0;
1191         if (TREE_CODE (TREE_OPERAND (t, 0)) == INTEGER_CST)
1192           {
1193             len = TREE_INT_CST_LOW (TREE_OPERAND (t, 0));
1194
1195             for (ii = 0; ii < len; ii++)
1196               extract_free_variables (TREE_OPERAND (t, ii), wd, ADD_READ);
1197             extract_free_variables (TREE_TYPE (t), wd, ADD_READ);
1198           }
1199         break;
1200       }
1201
1202     case CONSTRUCTOR:
1203       {
1204         unsigned HOST_WIDE_INT idx = 0;
1205         constructor_elt *ce;
1206         for (idx = 0; vec_safe_iterate (CONSTRUCTOR_ELTS (t), idx, &ce); idx++)
1207           extract_free_variables (ce->value, wd, ADD_READ);
1208         break;
1209       }
1210
1211     default:
1212       if (is_expr)
1213         {
1214           int i, len;
1215
1216           /* Walk over all the sub-trees of this operand.  */
1217           len = TREE_CODE_LENGTH (code);
1218
1219           /* Go through the subtrees.  We need to do this in forward order so
1220              that the scope of a FOR_EXPR is handled properly.  */
1221           for (i = 0; i < len; ++i)
1222             extract_free_variables (TREE_OPERAND (t, i), wd, ADD_READ);
1223         }
1224     }
1225 }
1226
1227 /* Add appropriate frames needed for a Cilk spawned function call, FNDECL.
1228    Returns the __cilkrts_stack_frame * variable.  */
1229
1230 tree
1231 insert_cilk_frame (tree fndecl)
1232 {
1233   tree addr, body, enter, out, orig_body;
1234   location_t loc = EXPR_LOCATION (fndecl);
1235
1236   if (!cfun || cfun->decl != fndecl)
1237     push_cfun (DECL_STRUCT_FUNCTION (fndecl));
1238
1239   tree decl = cfun->cilk_frame_decl;
1240   if (!decl)
1241     {
1242       tree *saved_tree = &DECL_SAVED_TREE (fndecl);
1243       decl = make_cilk_frame (fndecl);
1244       add_local_decl (cfun, decl);
1245
1246       addr = build1 (ADDR_EXPR, cilk_frame_ptr_type_decl, decl);
1247       enter = build_call_expr (cilk_enter_fndecl, 1, addr);
1248       out = create_cilk_function_exit (cfun->cilk_frame_decl, false, true);
1249
1250       /* The new body will be:
1251          __cilkrts_enter_frame_1 (&sf);
1252          try {
1253             orig_body;
1254          }
1255          finally {
1256              __cilkrts_pop_frame (&sf);
1257              __cilkrts_leave_frame (&sf);
1258          }  */
1259
1260       body = alloc_stmt_list ();
1261       orig_body = *saved_tree;
1262
1263       if (TREE_CODE (orig_body) == BIND_EXPR)
1264         orig_body = BIND_EXPR_BODY (orig_body);
1265
1266       append_to_statement_list (enter, &body);
1267       append_to_statement_list (build_stmt (loc, TRY_FINALLY_EXPR, orig_body,
1268                                             out), &body);
1269       if (TREE_CODE (*saved_tree) == BIND_EXPR)
1270         BIND_EXPR_BODY (*saved_tree) = body;
1271       else
1272         *saved_tree = body;
1273     }
1274   return decl;
1275 }
1276
1277 /* Wraps CALL, a CALL_EXPR, into a CILK_SPAWN_STMT tree and returns it.  */
1278
1279 tree
1280 build_cilk_spawn (location_t loc, tree call)
1281 {
1282   if (!cilk_set_spawn_marker (loc, call))
1283     return error_mark_node;
1284   tree spawn_stmt = build1 (CILK_SPAWN_STMT, TREE_TYPE (call), call);
1285   TREE_SIDE_EFFECTS (spawn_stmt) = 1;
1286   return spawn_stmt;
1287 }
1288
1289 /* Returns a tree of type CILK_SYNC_STMT.  */
1290
1291 tree
1292 build_cilk_sync (void)
1293 {
1294   tree sync = build0 (CILK_SYNC_STMT, void_type_node);
1295   TREE_SIDE_EFFECTS (sync) = 1;
1296   return sync;
1297 }
1298
1299 /* Helper for contains_cilk_spawn_stmt, callback for walk_tree.  Return
1300    non-null tree if TP contains CILK_SPAWN_STMT.  */
1301
1302 static tree
1303 contains_cilk_spawn_stmt_walker (tree *tp, int *, void *)
1304 {
1305   if (TREE_CODE (*tp) == CILK_SPAWN_STMT)
1306     return *tp;
1307   else
1308     return NULL_TREE;
1309 }
1310
1311 /* Returns true if EXPR or any of its subtrees contain CILK_SPAWN_STMT
1312    node.  */
1313
1314 bool
1315 contains_cilk_spawn_stmt (tree expr)
1316 {
1317   return walk_tree (&expr, contains_cilk_spawn_stmt_walker, NULL, NULL)
1318          != NULL_TREE;
1319 }