1// Copyright 2012 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "src/v8.h"
6
7#include "src/scopes.h"
8
9#include "src/accessors.h"
10#include "src/bootstrapper.h"
11#include "src/compiler.h"
12#include "src/messages.h"
13#include "src/scopeinfo.h"
14
15namespace v8 {
16namespace internal {
17
18// ----------------------------------------------------------------------------
19// Implementation of LocalsMap
20//
21// Note: We are storing the handle locations as key values in the hash map.
22//       When inserting a new variable via Declare(), we rely on the fact that
23//       the handle location remains alive for the duration of that variable
24//       use. Because a Variable holding a handle with the same location exists
25//       this is ensured.
26
27VariableMap::VariableMap(Zone* zone)
28    : ZoneHashMap(ZoneHashMap::PointersMatch, 8, ZoneAllocationPolicy(zone)),
29      zone_(zone) {}
30VariableMap::~VariableMap() {}
31
32
33Variable* VariableMap::Declare(Scope* scope, const AstRawString* name,
34                               VariableMode mode, bool is_valid_lhs,
35                               Variable::Kind kind,
36                               InitializationFlag initialization_flag,
37                               MaybeAssignedFlag maybe_assigned_flag,
38                               Interface* interface) {
39  // AstRawStrings are unambiguous, i.e., the same string is always represented
40  // by the same AstRawString*.
41  // FIXME(marja): fix the type of Lookup.
42  Entry* p = ZoneHashMap::Lookup(const_cast<AstRawString*>(name), name->hash(),
43                                 true, ZoneAllocationPolicy(zone()));
44  if (p->value == NULL) {
45    // The variable has not been declared yet -> insert it.
46    DCHECK(p->key == name);
47    p->value = new (zone())
48        Variable(scope, name, mode, is_valid_lhs, kind, initialization_flag,
49                 maybe_assigned_flag, interface);
50  }
51  return reinterpret_cast<Variable*>(p->value);
52}
53
54
55Variable* VariableMap::Lookup(const AstRawString* name) {
56  Entry* p = ZoneHashMap::Lookup(const_cast<AstRawString*>(name), name->hash(),
57                                 false, ZoneAllocationPolicy(NULL));
58  if (p != NULL) {
59    DCHECK(reinterpret_cast<const AstRawString*>(p->key) == name);
60    DCHECK(p->value != NULL);
61    return reinterpret_cast<Variable*>(p->value);
62  }
63  return NULL;
64}
65
66
67// ----------------------------------------------------------------------------
68// Implementation of Scope
69
70Scope::Scope(Scope* outer_scope, ScopeType scope_type,
71             AstValueFactory* ast_value_factory, Zone* zone)
72    : isolate_(zone->isolate()),
73      inner_scopes_(4, zone),
74      variables_(zone),
75      internals_(4, zone),
76      temps_(4, zone),
77      params_(4, zone),
78      unresolved_(16, zone),
79      decls_(4, zone),
80      interface_(FLAG_harmony_modules &&
81                 (scope_type == MODULE_SCOPE || scope_type == GLOBAL_SCOPE)
82                     ? Interface::NewModule(zone) : NULL),
83      already_resolved_(false),
84      ast_value_factory_(ast_value_factory),
85      zone_(zone) {
86  SetDefaults(scope_type, outer_scope, Handle<ScopeInfo>::null());
87  // The outermost scope must be a global scope.
88  DCHECK(scope_type == GLOBAL_SCOPE || outer_scope != NULL);
89  DCHECK(!HasIllegalRedeclaration());
90}
91
92
93Scope::Scope(Scope* inner_scope,
94             ScopeType scope_type,
95             Handle<ScopeInfo> scope_info,
96             AstValueFactory* value_factory,
97             Zone* zone)
98    : isolate_(zone->isolate()),
99      inner_scopes_(4, zone),
100      variables_(zone),
101      internals_(4, zone),
102      temps_(4, zone),
103      params_(4, zone),
104      unresolved_(16, zone),
105      decls_(4, zone),
106      interface_(NULL),
107      already_resolved_(true),
108      ast_value_factory_(value_factory),
109      zone_(zone) {
110  SetDefaults(scope_type, NULL, scope_info);
111  if (!scope_info.is_null()) {
112    num_heap_slots_ = scope_info_->ContextLength();
113  }
114  // Ensure at least MIN_CONTEXT_SLOTS to indicate a materialized context.
115  num_heap_slots_ = Max(num_heap_slots_,
116                        static_cast<int>(Context::MIN_CONTEXT_SLOTS));
117  AddInnerScope(inner_scope);
118}
119
120
121Scope::Scope(Scope* inner_scope, const AstRawString* catch_variable_name,
122             AstValueFactory* value_factory, Zone* zone)
123    : isolate_(zone->isolate()),
124      inner_scopes_(1, zone),
125      variables_(zone),
126      internals_(0, zone),
127      temps_(0, zone),
128      params_(0, zone),
129      unresolved_(0, zone),
130      decls_(0, zone),
131      interface_(NULL),
132      already_resolved_(true),
133      ast_value_factory_(value_factory),
134      zone_(zone) {
135  SetDefaults(CATCH_SCOPE, NULL, Handle<ScopeInfo>::null());
136  AddInnerScope(inner_scope);
137  ++num_var_or_const_;
138  num_heap_slots_ = Context::MIN_CONTEXT_SLOTS;
139  Variable* variable = variables_.Declare(this,
140                                          catch_variable_name,
141                                          VAR,
142                                          true,  // Valid left-hand side.
143                                          Variable::NORMAL,
144                                          kCreatedInitialized);
145  AllocateHeapSlot(variable);
146}
147
148
149void Scope::SetDefaults(ScopeType scope_type,
150                        Scope* outer_scope,
151                        Handle<ScopeInfo> scope_info) {
152  outer_scope_ = outer_scope;
153  scope_type_ = scope_type;
154  scope_name_ = ast_value_factory_->empty_string();
155  dynamics_ = NULL;
156  receiver_ = NULL;
157  function_ = NULL;
158  arguments_ = NULL;
159  illegal_redecl_ = NULL;
160  scope_inside_with_ = false;
161  scope_contains_with_ = false;
162  scope_calls_eval_ = false;
163  asm_module_ = false;
164  asm_function_ = outer_scope != NULL && outer_scope->asm_module_;
165  // Inherit the strict mode from the parent scope.
166  strict_mode_ = outer_scope != NULL ? outer_scope->strict_mode_ : SLOPPY;
167  outer_scope_calls_sloppy_eval_ = false;
168  inner_scope_calls_eval_ = false;
169  force_eager_compilation_ = false;
170  force_context_allocation_ = (outer_scope != NULL && !is_function_scope())
171      ? outer_scope->has_forced_context_allocation() : false;
172  num_var_or_const_ = 0;
173  num_stack_slots_ = 0;
174  num_heap_slots_ = 0;
175  num_modules_ = 0;
176  module_var_ = NULL,
177  scope_info_ = scope_info;
178  start_position_ = RelocInfo::kNoPosition;
179  end_position_ = RelocInfo::kNoPosition;
180  if (!scope_info.is_null()) {
181    scope_calls_eval_ = scope_info->CallsEval();
182    strict_mode_ = scope_info->strict_mode();
183  }
184}
185
186
187Scope* Scope::DeserializeScopeChain(Context* context, Scope* global_scope,
188                                    Zone* zone) {
189  // Reconstruct the outer scope chain from a closure's context chain.
190  Scope* current_scope = NULL;
191  Scope* innermost_scope = NULL;
192  bool contains_with = false;
193  while (!context->IsNativeContext()) {
194    if (context->IsWithContext()) {
195      Scope* with_scope = new(zone) Scope(current_scope,
196                                          WITH_SCOPE,
197                                          Handle<ScopeInfo>::null(),
198                                          global_scope->ast_value_factory_,
199                                          zone);
200      current_scope = with_scope;
201      // All the inner scopes are inside a with.
202      contains_with = true;
203      for (Scope* s = innermost_scope; s != NULL; s = s->outer_scope()) {
204        s->scope_inside_with_ = true;
205      }
206    } else if (context->IsGlobalContext()) {
207      ScopeInfo* scope_info = ScopeInfo::cast(context->extension());
208      current_scope = new(zone) Scope(current_scope,
209                                      GLOBAL_SCOPE,
210                                      Handle<ScopeInfo>(scope_info),
211                                      global_scope->ast_value_factory_,
212                                      zone);
213    } else if (context->IsModuleContext()) {
214      ScopeInfo* scope_info = ScopeInfo::cast(context->module()->scope_info());
215      current_scope = new(zone) Scope(current_scope,
216                                      MODULE_SCOPE,
217                                      Handle<ScopeInfo>(scope_info),
218                                      global_scope->ast_value_factory_,
219                                      zone);
220    } else if (context->IsFunctionContext()) {
221      ScopeInfo* scope_info = context->closure()->shared()->scope_info();
222      current_scope = new(zone) Scope(current_scope,
223                                      FUNCTION_SCOPE,
224                                      Handle<ScopeInfo>(scope_info),
225                                      global_scope->ast_value_factory_,
226                                      zone);
227      if (scope_info->IsAsmFunction()) current_scope->asm_function_ = true;
228      if (scope_info->IsAsmModule()) current_scope->asm_module_ = true;
229    } else if (context->IsBlockContext()) {
230      ScopeInfo* scope_info = ScopeInfo::cast(context->extension());
231      current_scope = new(zone) Scope(current_scope,
232                                      BLOCK_SCOPE,
233                                      Handle<ScopeInfo>(scope_info),
234                                      global_scope->ast_value_factory_,
235                                      zone);
236    } else {
237      DCHECK(context->IsCatchContext());
238      String* name = String::cast(context->extension());
239      current_scope = new (zone) Scope(
240          current_scope,
241          global_scope->ast_value_factory_->GetString(Handle<String>(name)),
242          global_scope->ast_value_factory_, zone);
243    }
244    if (contains_with) current_scope->RecordWithStatement();
245    if (innermost_scope == NULL) innermost_scope = current_scope;
246
247    // Forget about a with when we move to a context for a different function.
248    if (context->previous()->closure() != context->closure()) {
249      contains_with = false;
250    }
251    context = context->previous();
252  }
253
254  global_scope->AddInnerScope(current_scope);
255  global_scope->PropagateScopeInfo(false);
256  return (innermost_scope == NULL) ? global_scope : innermost_scope;
257}
258
259
260bool Scope::Analyze(CompilationInfo* info) {
261  DCHECK(info->function() != NULL);
262  Scope* scope = info->function()->scope();
263  Scope* top = scope;
264
265  // Traverse the scope tree up to the first unresolved scope or the global
266  // scope and start scope resolution and variable allocation from that scope.
267  while (!top->is_global_scope() &&
268         !top->outer_scope()->already_resolved()) {
269    top = top->outer_scope();
270  }
271
272  // Allocate the variables.
273  {
274    AstNodeFactory<AstNullVisitor> ast_node_factory(
275        info->zone(), info->ast_value_factory(), info->ast_node_id_gen());
276    if (!top->AllocateVariables(info, &ast_node_factory)) return false;
277  }
278
279#ifdef DEBUG
280  if (info->isolate()->bootstrapper()->IsActive()
281          ? FLAG_print_builtin_scopes
282          : FLAG_print_scopes) {
283    scope->Print();
284  }
285
286  if (FLAG_harmony_modules && FLAG_print_interfaces && top->is_global_scope()) {
287    PrintF("global : ");
288    top->interface()->Print();
289  }
290#endif
291
292  info->PrepareForCompilation(scope);
293  return true;
294}
295
296
297void Scope::Initialize() {
298  DCHECK(!already_resolved());
299
300  // Add this scope as a new inner scope of the outer scope.
301  if (outer_scope_ != NULL) {
302    outer_scope_->inner_scopes_.Add(this, zone());
303    scope_inside_with_ = outer_scope_->scope_inside_with_ || is_with_scope();
304  } else {
305    scope_inside_with_ = is_with_scope();
306  }
307
308  // Declare convenience variables.
309  // Declare and allocate receiver (even for the global scope, and even
310  // if naccesses_ == 0).
311  // NOTE: When loading parameters in the global scope, we must take
312  // care not to access them as properties of the global object, but
313  // instead load them directly from the stack. Currently, the only
314  // such parameter is 'this' which is passed on the stack when
315  // invoking scripts
316  if (is_declaration_scope()) {
317    Variable* var =
318        variables_.Declare(this,
319                           ast_value_factory_->this_string(),
320                           VAR,
321                           false,
322                           Variable::THIS,
323                           kCreatedInitialized);
324    var->AllocateTo(Variable::PARAMETER, -1);
325    receiver_ = var;
326  } else {
327    DCHECK(outer_scope() != NULL);
328    receiver_ = outer_scope()->receiver();
329  }
330
331  if (is_function_scope()) {
332    // Declare 'arguments' variable which exists in all functions.
333    // Note that it might never be accessed, in which case it won't be
334    // allocated during variable allocation.
335    variables_.Declare(this,
336                       ast_value_factory_->arguments_string(),
337                       VAR,
338                       true,
339                       Variable::ARGUMENTS,
340                       kCreatedInitialized);
341  }
342}
343
344
345Scope* Scope::FinalizeBlockScope() {
346  DCHECK(is_block_scope());
347  DCHECK(internals_.is_empty());
348  DCHECK(temps_.is_empty());
349  DCHECK(params_.is_empty());
350
351  if (num_var_or_const() > 0) return this;
352
353  // Remove this scope from outer scope.
354  for (int i = 0; i < outer_scope_->inner_scopes_.length(); i++) {
355    if (outer_scope_->inner_scopes_[i] == this) {
356      outer_scope_->inner_scopes_.Remove(i);
357      break;
358    }
359  }
360
361  // Reparent inner scopes.
362  for (int i = 0; i < inner_scopes_.length(); i++) {
363    outer_scope()->AddInnerScope(inner_scopes_[i]);
364  }
365
366  // Move unresolved variables
367  for (int i = 0; i < unresolved_.length(); i++) {
368    outer_scope()->unresolved_.Add(unresolved_[i], zone());
369  }
370
371  return NULL;
372}
373
374
375Variable* Scope::LookupLocal(const AstRawString* name) {
376  Variable* result = variables_.Lookup(name);
377  if (result != NULL || scope_info_.is_null()) {
378    return result;
379  }
380  // The Scope is backed up by ScopeInfo. This means it cannot operate in a
381  // heap-independent mode, and all strings must be internalized immediately. So
382  // it's ok to get the Handle<String> here.
383  Handle<String> name_handle = name->string();
384  // If we have a serialized scope info, we might find the variable there.
385  // There should be no local slot with the given name.
386  DCHECK(scope_info_->StackSlotIndex(*name_handle) < 0);
387
388  // Check context slot lookup.
389  VariableMode mode;
390  Variable::Location location = Variable::CONTEXT;
391  InitializationFlag init_flag;
392  MaybeAssignedFlag maybe_assigned_flag;
393  int index = ScopeInfo::ContextSlotIndex(scope_info_, name_handle, &mode,
394                                          &init_flag, &maybe_assigned_flag);
395  if (index < 0) {
396    // Check parameters.
397    index = scope_info_->ParameterIndex(*name_handle);
398    if (index < 0) return NULL;
399
400    mode = DYNAMIC;
401    location = Variable::LOOKUP;
402    init_flag = kCreatedInitialized;
403    // Be conservative and flag parameters as maybe assigned. Better information
404    // would require ScopeInfo to serialize the maybe_assigned bit also for
405    // parameters.
406    maybe_assigned_flag = kMaybeAssigned;
407  }
408
409  Variable* var = variables_.Declare(this, name, mode, true, Variable::NORMAL,
410                                     init_flag, maybe_assigned_flag);
411  var->AllocateTo(location, index);
412  return var;
413}
414
415
416Variable* Scope::LookupFunctionVar(const AstRawString* name,
417                                   AstNodeFactory<AstNullVisitor>* factory) {
418  if (function_ != NULL && function_->proxy()->raw_name() == name) {
419    return function_->proxy()->var();
420  } else if (!scope_info_.is_null()) {
421    // If we are backed by a scope info, try to lookup the variable there.
422    VariableMode mode;
423    int index = scope_info_->FunctionContextSlotIndex(*(name->string()), &mode);
424    if (index < 0) return NULL;
425    Variable* var = new(zone()) Variable(
426        this, name, mode, true /* is valid LHS */,
427        Variable::NORMAL, kCreatedInitialized);
428    VariableProxy* proxy = factory->NewVariableProxy(var);
429    VariableDeclaration* declaration = factory->NewVariableDeclaration(
430        proxy, mode, this, RelocInfo::kNoPosition);
431    DeclareFunctionVar(declaration);
432    var->AllocateTo(Variable::CONTEXT, index);
433    return var;
434  } else {
435    return NULL;
436  }
437}
438
439
440Variable* Scope::Lookup(const AstRawString* name) {
441  for (Scope* scope = this;
442       scope != NULL;
443       scope = scope->outer_scope()) {
444    Variable* var = scope->LookupLocal(name);
445    if (var != NULL) return var;
446  }
447  return NULL;
448}
449
450
451Variable* Scope::DeclareParameter(const AstRawString* name, VariableMode mode) {
452  DCHECK(!already_resolved());
453  DCHECK(is_function_scope());
454  Variable* var = variables_.Declare(this, name, mode, true, Variable::NORMAL,
455                                     kCreatedInitialized);
456  params_.Add(var, zone());
457  return var;
458}
459
460
461Variable* Scope::DeclareLocal(const AstRawString* name, VariableMode mode,
462                              InitializationFlag init_flag,
463                              MaybeAssignedFlag maybe_assigned_flag,
464                              Interface* interface) {
465  DCHECK(!already_resolved());
466  // This function handles VAR, LET, and CONST modes.  DYNAMIC variables are
467  // introduces during variable allocation, INTERNAL variables are allocated
468  // explicitly, and TEMPORARY variables are allocated via NewTemporary().
469  DCHECK(IsDeclaredVariableMode(mode));
470  ++num_var_or_const_;
471  return variables_.Declare(this, name, mode, true, Variable::NORMAL, init_flag,
472                            maybe_assigned_flag, interface);
473}
474
475
476Variable* Scope::DeclareDynamicGlobal(const AstRawString* name) {
477  DCHECK(is_global_scope());
478  return variables_.Declare(this,
479                            name,
480                            DYNAMIC_GLOBAL,
481                            true,
482                            Variable::NORMAL,
483                            kCreatedInitialized);
484}
485
486
487void Scope::RemoveUnresolved(VariableProxy* var) {
488  // Most likely (always?) any variable we want to remove
489  // was just added before, so we search backwards.
490  for (int i = unresolved_.length(); i-- > 0;) {
491    if (unresolved_[i] == var) {
492      unresolved_.Remove(i);
493      return;
494    }
495  }
496}
497
498
499Variable* Scope::NewInternal(const AstRawString* name) {
500  DCHECK(!already_resolved());
501  Variable* var = new(zone()) Variable(this,
502                                       name,
503                                       INTERNAL,
504                                       false,
505                                       Variable::NORMAL,
506                                       kCreatedInitialized);
507  internals_.Add(var, zone());
508  return var;
509}
510
511
512Variable* Scope::NewTemporary(const AstRawString* name) {
513  DCHECK(!already_resolved());
514  Variable* var = new(zone()) Variable(this,
515                                       name,
516                                       TEMPORARY,
517                                       true,
518                                       Variable::NORMAL,
519                                       kCreatedInitialized);
520  temps_.Add(var, zone());
521  return var;
522}
523
524
525void Scope::AddDeclaration(Declaration* declaration) {
526  decls_.Add(declaration, zone());
527}
528
529
530void Scope::SetIllegalRedeclaration(Expression* expression) {
531  // Record only the first illegal redeclaration.
532  if (!HasIllegalRedeclaration()) {
533    illegal_redecl_ = expression;
534  }
535  DCHECK(HasIllegalRedeclaration());
536}
537
538
539void Scope::VisitIllegalRedeclaration(AstVisitor* visitor) {
540  DCHECK(HasIllegalRedeclaration());
541  illegal_redecl_->Accept(visitor);
542}
543
544
545Declaration* Scope::CheckConflictingVarDeclarations() {
546  int length = decls_.length();
547  for (int i = 0; i < length; i++) {
548    Declaration* decl = decls_[i];
549    if (decl->mode() != VAR) continue;
550    const AstRawString* name = decl->proxy()->raw_name();
551
552    // Iterate through all scopes until and including the declaration scope.
553    Scope* previous = NULL;
554    Scope* current = decl->scope();
555    do {
556      // There is a conflict if there exists a non-VAR binding.
557      Variable* other_var = current->variables_.Lookup(name);
558      if (other_var != NULL && other_var->mode() != VAR) {
559        return decl;
560      }
561      previous = current;
562      current = current->outer_scope_;
563    } while (!previous->is_declaration_scope());
564  }
565  return NULL;
566}
567
568
569class VarAndOrder {
570 public:
571  VarAndOrder(Variable* var, int order) : var_(var), order_(order) { }
572  Variable* var() const { return var_; }
573  int order() const { return order_; }
574  static int Compare(const VarAndOrder* a, const VarAndOrder* b) {
575    return a->order_ - b->order_;
576  }
577
578 private:
579  Variable* var_;
580  int order_;
581};
582
583
584void Scope::CollectStackAndContextLocals(ZoneList<Variable*>* stack_locals,
585                                         ZoneList<Variable*>* context_locals) {
586  DCHECK(stack_locals != NULL);
587  DCHECK(context_locals != NULL);
588
589  // Collect internals which are always allocated on the heap.
590  for (int i = 0; i < internals_.length(); i++) {
591    Variable* var = internals_[i];
592    if (var->is_used()) {
593      DCHECK(var->IsContextSlot());
594      context_locals->Add(var, zone());
595    }
596  }
597
598  // Collect temporaries which are always allocated on the stack, unless the
599  // context as a whole has forced context allocation.
600  for (int i = 0; i < temps_.length(); i++) {
601    Variable* var = temps_[i];
602    if (var->is_used()) {
603      if (var->IsContextSlot()) {
604        DCHECK(has_forced_context_allocation());
605        context_locals->Add(var, zone());
606      } else {
607        DCHECK(var->IsStackLocal());
608        stack_locals->Add(var, zone());
609      }
610    }
611  }
612
613  // Collect declared local variables.
614  ZoneList<VarAndOrder> vars(variables_.occupancy(), zone());
615  for (VariableMap::Entry* p = variables_.Start();
616       p != NULL;
617       p = variables_.Next(p)) {
618    Variable* var = reinterpret_cast<Variable*>(p->value);
619    if (var->is_used()) {
620      vars.Add(VarAndOrder(var, p->order), zone());
621    }
622  }
623  vars.Sort(VarAndOrder::Compare);
624  int var_count = vars.length();
625  for (int i = 0; i < var_count; i++) {
626    Variable* var = vars[i].var();
627    if (var->IsStackLocal()) {
628      stack_locals->Add(var, zone());
629    } else if (var->IsContextSlot()) {
630      context_locals->Add(var, zone());
631    }
632  }
633}
634
635
636bool Scope::AllocateVariables(CompilationInfo* info,
637                              AstNodeFactory<AstNullVisitor>* factory) {
638  // 1) Propagate scope information.
639  bool outer_scope_calls_sloppy_eval = false;
640  if (outer_scope_ != NULL) {
641    outer_scope_calls_sloppy_eval =
642        outer_scope_->outer_scope_calls_sloppy_eval() |
643        outer_scope_->calls_sloppy_eval();
644  }
645  PropagateScopeInfo(outer_scope_calls_sloppy_eval);
646
647  // 2) Allocate module instances.
648  if (FLAG_harmony_modules && (is_global_scope() || is_module_scope())) {
649    DCHECK(num_modules_ == 0);
650    AllocateModulesRecursively(this);
651  }
652
653  // 3) Resolve variables.
654  if (!ResolveVariablesRecursively(info, factory)) return false;
655
656  // 4) Allocate variables.
657  AllocateVariablesRecursively();
658
659  return true;
660}
661
662
663bool Scope::HasTrivialContext() const {
664  // A function scope has a trivial context if it always is the global
665  // context. We iteratively scan out the context chain to see if
666  // there is anything that makes this scope non-trivial; otherwise we
667  // return true.
668  for (const Scope* scope = this; scope != NULL; scope = scope->outer_scope_) {
669    if (scope->is_eval_scope()) return false;
670    if (scope->scope_inside_with_) return false;
671    if (scope->num_heap_slots_ > 0) return false;
672  }
673  return true;
674}
675
676
677bool Scope::HasTrivialOuterContext() const {
678  Scope* outer = outer_scope_;
679  if (outer == NULL) return true;
680  // Note that the outer context may be trivial in general, but the current
681  // scope may be inside a 'with' statement in which case the outer context
682  // for this scope is not trivial.
683  return !scope_inside_with_ && outer->HasTrivialContext();
684}
685
686
687bool Scope::HasLazyCompilableOuterContext() const {
688  Scope* outer = outer_scope_;
689  if (outer == NULL) return true;
690  // We have to prevent lazy compilation if this scope is inside a with scope
691  // and all declaration scopes between them have empty contexts. Such
692  // declaration scopes may become invisible during scope info deserialization.
693  outer = outer->DeclarationScope();
694  bool found_non_trivial_declarations = false;
695  for (const Scope* scope = outer; scope != NULL; scope = scope->outer_scope_) {
696    if (scope->is_with_scope() && !found_non_trivial_declarations) return false;
697    if (scope->is_declaration_scope() && scope->num_heap_slots() > 0) {
698      found_non_trivial_declarations = true;
699    }
700  }
701  return true;
702}
703
704
705bool Scope::AllowsLazyCompilation() const {
706  return !force_eager_compilation_ && HasLazyCompilableOuterContext();
707}
708
709
710bool Scope::AllowsLazyCompilationWithoutContext() const {
711  return !force_eager_compilation_ && HasTrivialOuterContext();
712}
713
714
715int Scope::ContextChainLength(Scope* scope) {
716  int n = 0;
717  for (Scope* s = this; s != scope; s = s->outer_scope_) {
718    DCHECK(s != NULL);  // scope must be in the scope chain
719    if (s->is_with_scope() || s->num_heap_slots() > 0) n++;
720    // Catch and module scopes always have heap slots.
721    DCHECK(!s->is_catch_scope() || s->num_heap_slots() > 0);
722    DCHECK(!s->is_module_scope() || s->num_heap_slots() > 0);
723  }
724  return n;
725}
726
727
728Scope* Scope::GlobalScope() {
729  Scope* scope = this;
730  while (!scope->is_global_scope()) {
731    scope = scope->outer_scope();
732  }
733  return scope;
734}
735
736
737Scope* Scope::DeclarationScope() {
738  Scope* scope = this;
739  while (!scope->is_declaration_scope()) {
740    scope = scope->outer_scope();
741  }
742  return scope;
743}
744
745
746Handle<ScopeInfo> Scope::GetScopeInfo() {
747  if (scope_info_.is_null()) {
748    scope_info_ = ScopeInfo::Create(this, zone());
749  }
750  return scope_info_;
751}
752
753
754void Scope::GetNestedScopeChain(
755    List<Handle<ScopeInfo> >* chain,
756    int position) {
757  if (!is_eval_scope()) chain->Add(Handle<ScopeInfo>(GetScopeInfo()));
758
759  for (int i = 0; i < inner_scopes_.length(); i++) {
760    Scope* scope = inner_scopes_[i];
761    int beg_pos = scope->start_position();
762    int end_pos = scope->end_position();
763    DCHECK(beg_pos >= 0 && end_pos >= 0);
764    if (beg_pos <= position && position < end_pos) {
765      scope->GetNestedScopeChain(chain, position);
766      return;
767    }
768  }
769}
770
771
772#ifdef DEBUG
773static const char* Header(ScopeType scope_type) {
774  switch (scope_type) {
775    case EVAL_SCOPE: return "eval";
776    case FUNCTION_SCOPE: return "function";
777    case MODULE_SCOPE: return "module";
778    case GLOBAL_SCOPE: return "global";
779    case CATCH_SCOPE: return "catch";
780    case BLOCK_SCOPE: return "block";
781    case WITH_SCOPE: return "with";
782  }
783  UNREACHABLE();
784  return NULL;
785}
786
787
788static void Indent(int n, const char* str) {
789  PrintF("%*s%s", n, "", str);
790}
791
792
793static void PrintName(const AstRawString* name) {
794  PrintF("%.*s", name->length(), name->raw_data());
795}
796
797
798static void PrintLocation(Variable* var) {
799  switch (var->location()) {
800    case Variable::UNALLOCATED:
801      break;
802    case Variable::PARAMETER:
803      PrintF("parameter[%d]", var->index());
804      break;
805    case Variable::LOCAL:
806      PrintF("local[%d]", var->index());
807      break;
808    case Variable::CONTEXT:
809      PrintF("context[%d]", var->index());
810      break;
811    case Variable::LOOKUP:
812      PrintF("lookup");
813      break;
814  }
815}
816
817
818static void PrintVar(int indent, Variable* var) {
819  if (var->is_used() || !var->IsUnallocated()) {
820    Indent(indent, Variable::Mode2String(var->mode()));
821    PrintF(" ");
822    PrintName(var->raw_name());
823    PrintF(";  // ");
824    PrintLocation(var);
825    bool comma = !var->IsUnallocated();
826    if (var->has_forced_context_allocation()) {
827      if (comma) PrintF(", ");
828      PrintF("forced context allocation");
829      comma = true;
830    }
831    if (var->maybe_assigned() == kMaybeAssigned) {
832      if (comma) PrintF(", ");
833      PrintF("maybe assigned");
834    }
835    PrintF("\n");
836  }
837}
838
839
840static void PrintMap(int indent, VariableMap* map) {
841  for (VariableMap::Entry* p = map->Start(); p != NULL; p = map->Next(p)) {
842    Variable* var = reinterpret_cast<Variable*>(p->value);
843    PrintVar(indent, var);
844  }
845}
846
847
848void Scope::Print(int n) {
849  int n0 = (n > 0 ? n : 0);
850  int n1 = n0 + 2;  // indentation
851
852  // Print header.
853  Indent(n0, Header(scope_type_));
854  if (!scope_name_->IsEmpty()) {
855    PrintF(" ");
856    PrintName(scope_name_);
857  }
858
859  // Print parameters, if any.
860  if (is_function_scope()) {
861    PrintF(" (");
862    for (int i = 0; i < params_.length(); i++) {
863      if (i > 0) PrintF(", ");
864      PrintName(params_[i]->raw_name());
865    }
866    PrintF(")");
867  }
868
869  PrintF(" { // (%d, %d)\n", start_position(), end_position());
870
871  // Function name, if any (named function literals, only).
872  if (function_ != NULL) {
873    Indent(n1, "// (local) function name: ");
874    PrintName(function_->proxy()->raw_name());
875    PrintF("\n");
876  }
877
878  // Scope info.
879  if (HasTrivialOuterContext()) {
880    Indent(n1, "// scope has trivial outer context\n");
881  }
882  if (strict_mode() == STRICT) {
883    Indent(n1, "// strict mode scope\n");
884  }
885  if (scope_inside_with_) Indent(n1, "// scope inside 'with'\n");
886  if (scope_contains_with_) Indent(n1, "// scope contains 'with'\n");
887  if (scope_calls_eval_) Indent(n1, "// scope calls 'eval'\n");
888  if (outer_scope_calls_sloppy_eval_) {
889    Indent(n1, "// outer scope calls 'eval' in sloppy context\n");
890  }
891  if (inner_scope_calls_eval_) Indent(n1, "// inner scope calls 'eval'\n");
892  if (num_stack_slots_ > 0) { Indent(n1, "// ");
893  PrintF("%d stack slots\n", num_stack_slots_); }
894  if (num_heap_slots_ > 0) { Indent(n1, "// ");
895  PrintF("%d heap slots\n", num_heap_slots_); }
896
897  // Print locals.
898  if (function_ != NULL) {
899    Indent(n1, "// function var:\n");
900    PrintVar(n1, function_->proxy()->var());
901  }
902
903  if (temps_.length() > 0) {
904    Indent(n1, "// temporary vars:\n");
905    for (int i = 0; i < temps_.length(); i++) {
906      PrintVar(n1, temps_[i]);
907    }
908  }
909
910  if (internals_.length() > 0) {
911    Indent(n1, "// internal vars:\n");
912    for (int i = 0; i < internals_.length(); i++) {
913      PrintVar(n1, internals_[i]);
914    }
915  }
916
917  if (variables_.Start() != NULL) {
918    Indent(n1, "// local vars:\n");
919    PrintMap(n1, &variables_);
920  }
921
922  if (dynamics_ != NULL) {
923    Indent(n1, "// dynamic vars:\n");
924    PrintMap(n1, dynamics_->GetMap(DYNAMIC));
925    PrintMap(n1, dynamics_->GetMap(DYNAMIC_LOCAL));
926    PrintMap(n1, dynamics_->GetMap(DYNAMIC_GLOBAL));
927  }
928
929  // Print inner scopes (disable by providing negative n).
930  if (n >= 0) {
931    for (int i = 0; i < inner_scopes_.length(); i++) {
932      PrintF("\n");
933      inner_scopes_[i]->Print(n1);
934    }
935  }
936
937  Indent(n0, "}\n");
938}
939#endif  // DEBUG
940
941
942Variable* Scope::NonLocal(const AstRawString* name, VariableMode mode) {
943  if (dynamics_ == NULL) dynamics_ = new (zone()) DynamicScopePart(zone());
944  VariableMap* map = dynamics_->GetMap(mode);
945  Variable* var = map->Lookup(name);
946  if (var == NULL) {
947    // Declare a new non-local.
948    InitializationFlag init_flag = (mode == VAR)
949        ? kCreatedInitialized : kNeedsInitialization;
950    var = map->Declare(NULL,
951                       name,
952                       mode,
953                       true,
954                       Variable::NORMAL,
955                       init_flag);
956    // Allocate it by giving it a dynamic lookup.
957    var->AllocateTo(Variable::LOOKUP, -1);
958  }
959  return var;
960}
961
962
963Variable* Scope::LookupRecursive(VariableProxy* proxy,
964                                 BindingKind* binding_kind,
965                                 AstNodeFactory<AstNullVisitor>* factory) {
966  DCHECK(binding_kind != NULL);
967  if (already_resolved() && is_with_scope()) {
968    // Short-cut: if the scope is deserialized from a scope info, variable
969    // allocation is already fixed.  We can simply return with dynamic lookup.
970    *binding_kind = DYNAMIC_LOOKUP;
971    return NULL;
972  }
973
974  // Try to find the variable in this scope.
975  Variable* var = LookupLocal(proxy->raw_name());
976
977  // We found a variable and we are done. (Even if there is an 'eval' in
978  // this scope which introduces the same variable again, the resulting
979  // variable remains the same.)
980  if (var != NULL) {
981    *binding_kind = BOUND;
982    return var;
983  }
984
985  // We did not find a variable locally. Check against the function variable,
986  // if any. We can do this for all scopes, since the function variable is
987  // only present - if at all - for function scopes.
988  *binding_kind = UNBOUND;
989  var = LookupFunctionVar(proxy->raw_name(), factory);
990  if (var != NULL) {
991    *binding_kind = BOUND;
992  } else if (outer_scope_ != NULL) {
993    var = outer_scope_->LookupRecursive(proxy, binding_kind, factory);
994    if (*binding_kind == BOUND && (is_function_scope() || is_with_scope())) {
995      var->ForceContextAllocation();
996    }
997  } else {
998    DCHECK(is_global_scope());
999  }
1000
1001  if (is_with_scope()) {
1002    DCHECK(!already_resolved());
1003    // The current scope is a with scope, so the variable binding can not be
1004    // statically resolved. However, note that it was necessary to do a lookup
1005    // in the outer scope anyway, because if a binding exists in an outer scope,
1006    // the associated variable has to be marked as potentially being accessed
1007    // from inside of an inner with scope (the property may not be in the 'with'
1008    // object).
1009    if (var != NULL && proxy->is_assigned()) var->set_maybe_assigned();
1010    *binding_kind = DYNAMIC_LOOKUP;
1011    return NULL;
1012  } else if (calls_sloppy_eval()) {
1013    // A variable binding may have been found in an outer scope, but the current
1014    // scope makes a sloppy 'eval' call, so the found variable may not be
1015    // the correct one (the 'eval' may introduce a binding with the same name).
1016    // In that case, change the lookup result to reflect this situation.
1017    if (*binding_kind == BOUND) {
1018      *binding_kind = BOUND_EVAL_SHADOWED;
1019    } else if (*binding_kind == UNBOUND) {
1020      *binding_kind = UNBOUND_EVAL_SHADOWED;
1021    }
1022  }
1023  return var;
1024}
1025
1026
1027bool Scope::ResolveVariable(CompilationInfo* info,
1028                            VariableProxy* proxy,
1029                            AstNodeFactory<AstNullVisitor>* factory) {
1030  DCHECK(info->global_scope()->is_global_scope());
1031
1032  // If the proxy is already resolved there's nothing to do
1033  // (functions and consts may be resolved by the parser).
1034  if (proxy->var() != NULL) return true;
1035
1036  // Otherwise, try to resolve the variable.
1037  BindingKind binding_kind;
1038  Variable* var = LookupRecursive(proxy, &binding_kind, factory);
1039  switch (binding_kind) {
1040    case BOUND:
1041      // We found a variable binding.
1042      break;
1043
1044    case BOUND_EVAL_SHADOWED:
1045      // We either found a variable binding that might be shadowed by eval  or
1046      // gave up on it (e.g. by encountering a local with the same in the outer
1047      // scope which was not promoted to a context, this can happen if we use
1048      // debugger to evaluate arbitrary expressions at a break point).
1049      if (var->IsGlobalObjectProperty()) {
1050        var = NonLocal(proxy->raw_name(), DYNAMIC_GLOBAL);
1051      } else if (var->is_dynamic()) {
1052        var = NonLocal(proxy->raw_name(), DYNAMIC);
1053      } else {
1054        Variable* invalidated = var;
1055        var = NonLocal(proxy->raw_name(), DYNAMIC_LOCAL);
1056        var->set_local_if_not_shadowed(invalidated);
1057      }
1058      break;
1059
1060    case UNBOUND:
1061      // No binding has been found. Declare a variable on the global object.
1062      var = info->global_scope()->DeclareDynamicGlobal(proxy->raw_name());
1063      break;
1064
1065    case UNBOUND_EVAL_SHADOWED:
1066      // No binding has been found. But some scope makes a sloppy 'eval' call.
1067      var = NonLocal(proxy->raw_name(), DYNAMIC_GLOBAL);
1068      break;
1069
1070    case DYNAMIC_LOOKUP:
1071      // The variable could not be resolved statically.
1072      var = NonLocal(proxy->raw_name(), DYNAMIC);
1073      break;
1074  }
1075
1076  DCHECK(var != NULL);
1077  if (proxy->is_assigned()) var->set_maybe_assigned();
1078
1079  if (FLAG_harmony_scoping && strict_mode() == STRICT &&
1080      var->is_const_mode() && proxy->is_assigned()) {
1081    // Assignment to const. Throw a syntax error.
1082    MessageLocation location(
1083        info->script(), proxy->position(), proxy->position());
1084    Isolate* isolate = info->isolate();
1085    Factory* factory = isolate->factory();
1086    Handle<JSArray> array = factory->NewJSArray(0);
1087    Handle<Object> error;
1088    MaybeHandle<Object> maybe_error =
1089        factory->NewSyntaxError("harmony_const_assign", array);
1090    if (maybe_error.ToHandle(&error)) isolate->Throw(*error, &location);
1091    return false;
1092  }
1093
1094  if (FLAG_harmony_modules) {
1095    bool ok;
1096#ifdef DEBUG
1097    if (FLAG_print_interface_details) {
1098      PrintF("# Resolve %.*s:\n", var->raw_name()->length(),
1099             var->raw_name()->raw_data());
1100    }
1101#endif
1102    proxy->interface()->Unify(var->interface(), zone(), &ok);
1103    if (!ok) {
1104#ifdef DEBUG
1105      if (FLAG_print_interfaces) {
1106        PrintF("SCOPES TYPE ERROR\n");
1107        PrintF("proxy: ");
1108        proxy->interface()->Print();
1109        PrintF("var: ");
1110        var->interface()->Print();
1111      }
1112#endif
1113
1114      // Inconsistent use of module. Throw a syntax error.
1115      // TODO(rossberg): generate more helpful error message.
1116      MessageLocation location(
1117          info->script(), proxy->position(), proxy->position());
1118      Isolate* isolate = info->isolate();
1119      Factory* factory = isolate->factory();
1120      Handle<JSArray> array = factory->NewJSArray(1);
1121      JSObject::SetElement(array, 0, var->name(), NONE, STRICT).Assert();
1122      Handle<Object> error;
1123      MaybeHandle<Object> maybe_error =
1124          factory->NewSyntaxError("module_type_error", array);
1125      if (maybe_error.ToHandle(&error)) isolate->Throw(*error, &location);
1126      return false;
1127    }
1128  }
1129
1130  proxy->BindTo(var);
1131
1132  return true;
1133}
1134
1135
1136bool Scope::ResolveVariablesRecursively(
1137    CompilationInfo* info,
1138    AstNodeFactory<AstNullVisitor>* factory) {
1139  DCHECK(info->global_scope()->is_global_scope());
1140
1141  // Resolve unresolved variables for this scope.
1142  for (int i = 0; i < unresolved_.length(); i++) {
1143    if (!ResolveVariable(info, unresolved_[i], factory)) return false;
1144  }
1145
1146  // Resolve unresolved variables for inner scopes.
1147  for (int i = 0; i < inner_scopes_.length(); i++) {
1148    if (!inner_scopes_[i]->ResolveVariablesRecursively(info, factory))
1149      return false;
1150  }
1151
1152  return true;
1153}
1154
1155
1156void Scope::PropagateScopeInfo(bool outer_scope_calls_sloppy_eval ) {
1157  if (outer_scope_calls_sloppy_eval) {
1158    outer_scope_calls_sloppy_eval_ = true;
1159  }
1160
1161  bool calls_sloppy_eval =
1162      this->calls_sloppy_eval() || outer_scope_calls_sloppy_eval_;
1163  for (int i = 0; i < inner_scopes_.length(); i++) {
1164    Scope* inner = inner_scopes_[i];
1165    inner->PropagateScopeInfo(calls_sloppy_eval);
1166    if (inner->scope_calls_eval_ || inner->inner_scope_calls_eval_) {
1167      inner_scope_calls_eval_ = true;
1168    }
1169    if (inner->force_eager_compilation_) {
1170      force_eager_compilation_ = true;
1171    }
1172    if (asm_module_ && inner->scope_type() == FUNCTION_SCOPE) {
1173      inner->asm_function_ = true;
1174    }
1175  }
1176}
1177
1178
1179bool Scope::MustAllocate(Variable* var) {
1180  // Give var a read/write use if there is a chance it might be accessed
1181  // via an eval() call.  This is only possible if the variable has a
1182  // visible name.
1183  if ((var->is_this() || !var->raw_name()->IsEmpty()) &&
1184      (var->has_forced_context_allocation() ||
1185       scope_calls_eval_ ||
1186       inner_scope_calls_eval_ ||
1187       scope_contains_with_ ||
1188       is_catch_scope() ||
1189       is_block_scope() ||
1190       is_module_scope() ||
1191       is_global_scope())) {
1192    var->set_is_used();
1193    if (scope_calls_eval_ || inner_scope_calls_eval_) var->set_maybe_assigned();
1194  }
1195  // Global variables do not need to be allocated.
1196  return !var->IsGlobalObjectProperty() && var->is_used();
1197}
1198
1199
1200bool Scope::MustAllocateInContext(Variable* var) {
1201  // If var is accessed from an inner scope, or if there is a possibility
1202  // that it might be accessed from the current or an inner scope (through
1203  // an eval() call or a runtime with lookup), it must be allocated in the
1204  // context.
1205  //
1206  // Exceptions: If the scope as a whole has forced context allocation, all
1207  // variables will have context allocation, even temporaries.  Otherwise
1208  // temporary variables are always stack-allocated.  Catch-bound variables are
1209  // always context-allocated.
1210  if (has_forced_context_allocation()) return true;
1211  if (var->mode() == TEMPORARY) return false;
1212  if (var->mode() == INTERNAL) return true;
1213  if (is_catch_scope() || is_block_scope() || is_module_scope()) return true;
1214  if (is_global_scope() && IsLexicalVariableMode(var->mode())) return true;
1215  return var->has_forced_context_allocation() ||
1216      scope_calls_eval_ ||
1217      inner_scope_calls_eval_ ||
1218      scope_contains_with_;
1219}
1220
1221
1222bool Scope::HasArgumentsParameter() {
1223  for (int i = 0; i < params_.length(); i++) {
1224    if (params_[i]->name().is_identical_to(
1225            isolate_->factory()->arguments_string())) {
1226      return true;
1227    }
1228  }
1229  return false;
1230}
1231
1232
1233void Scope::AllocateStackSlot(Variable* var) {
1234  var->AllocateTo(Variable::LOCAL, num_stack_slots_++);
1235}
1236
1237
1238void Scope::AllocateHeapSlot(Variable* var) {
1239  var->AllocateTo(Variable::CONTEXT, num_heap_slots_++);
1240}
1241
1242
1243void Scope::AllocateParameterLocals() {
1244  DCHECK(is_function_scope());
1245  Variable* arguments = LookupLocal(ast_value_factory_->arguments_string());
1246  DCHECK(arguments != NULL);  // functions have 'arguments' declared implicitly
1247
1248  bool uses_sloppy_arguments = false;
1249
1250  if (MustAllocate(arguments) && !HasArgumentsParameter()) {
1251    // 'arguments' is used. Unless there is also a parameter called
1252    // 'arguments', we must be conservative and allocate all parameters to
1253    // the context assuming they will be captured by the arguments object.
1254    // If we have a parameter named 'arguments', a (new) value is always
1255    // assigned to it via the function invocation. Then 'arguments' denotes
1256    // that specific parameter value and cannot be used to access the
1257    // parameters, which is why we don't need to allocate an arguments
1258    // object in that case.
1259
1260    // We are using 'arguments'. Tell the code generator that is needs to
1261    // allocate the arguments object by setting 'arguments_'.
1262    arguments_ = arguments;
1263
1264    // In strict mode 'arguments' does not alias formal parameters.
1265    // Therefore in strict mode we allocate parameters as if 'arguments'
1266    // were not used.
1267    uses_sloppy_arguments = strict_mode() == SLOPPY;
1268  }
1269
1270  // The same parameter may occur multiple times in the parameters_ list.
1271  // If it does, and if it is not copied into the context object, it must
1272  // receive the highest parameter index for that parameter; thus iteration
1273  // order is relevant!
1274  for (int i = params_.length() - 1; i >= 0; --i) {
1275    Variable* var = params_[i];
1276    DCHECK(var->scope() == this);
1277    if (uses_sloppy_arguments || has_forced_context_allocation()) {
1278      // Force context allocation of the parameter.
1279      var->ForceContextAllocation();
1280    }
1281
1282    if (MustAllocate(var)) {
1283      if (MustAllocateInContext(var)) {
1284        DCHECK(var->IsUnallocated() || var->IsContextSlot());
1285        if (var->IsUnallocated()) {
1286          AllocateHeapSlot(var);
1287        }
1288      } else {
1289        DCHECK(var->IsUnallocated() || var->IsParameter());
1290        if (var->IsUnallocated()) {
1291          var->AllocateTo(Variable::PARAMETER, i);
1292        }
1293      }
1294    }
1295  }
1296}
1297
1298
1299void Scope::AllocateNonParameterLocal(Variable* var) {
1300  DCHECK(var->scope() == this);
1301  DCHECK(!var->IsVariable(isolate_->factory()->dot_result_string()) ||
1302         !var->IsStackLocal());
1303  if (var->IsUnallocated() && MustAllocate(var)) {
1304    if (MustAllocateInContext(var)) {
1305      AllocateHeapSlot(var);
1306    } else {
1307      AllocateStackSlot(var);
1308    }
1309  }
1310}
1311
1312
1313void Scope::AllocateNonParameterLocals() {
1314  // All variables that have no rewrite yet are non-parameter locals.
1315  for (int i = 0; i < temps_.length(); i++) {
1316    AllocateNonParameterLocal(temps_[i]);
1317  }
1318
1319  for (int i = 0; i < internals_.length(); i++) {
1320    AllocateNonParameterLocal(internals_[i]);
1321  }
1322
1323  ZoneList<VarAndOrder> vars(variables_.occupancy(), zone());
1324  for (VariableMap::Entry* p = variables_.Start();
1325       p != NULL;
1326       p = variables_.Next(p)) {
1327    Variable* var = reinterpret_cast<Variable*>(p->value);
1328    vars.Add(VarAndOrder(var, p->order), zone());
1329  }
1330  vars.Sort(VarAndOrder::Compare);
1331  int var_count = vars.length();
1332  for (int i = 0; i < var_count; i++) {
1333    AllocateNonParameterLocal(vars[i].var());
1334  }
1335
1336  // For now, function_ must be allocated at the very end.  If it gets
1337  // allocated in the context, it must be the last slot in the context,
1338  // because of the current ScopeInfo implementation (see
1339  // ScopeInfo::ScopeInfo(FunctionScope* scope) constructor).
1340  if (function_ != NULL) {
1341    AllocateNonParameterLocal(function_->proxy()->var());
1342  }
1343}
1344
1345
1346void Scope::AllocateVariablesRecursively() {
1347  // Allocate variables for inner scopes.
1348  for (int i = 0; i < inner_scopes_.length(); i++) {
1349    inner_scopes_[i]->AllocateVariablesRecursively();
1350  }
1351
1352  // If scope is already resolved, we still need to allocate
1353  // variables in inner scopes which might not had been resolved yet.
1354  if (already_resolved()) return;
1355  // The number of slots required for variables.
1356  num_stack_slots_ = 0;
1357  num_heap_slots_ = Context::MIN_CONTEXT_SLOTS;
1358
1359  // Allocate variables for this scope.
1360  // Parameters must be allocated first, if any.
1361  if (is_function_scope()) AllocateParameterLocals();
1362  AllocateNonParameterLocals();
1363
1364  // Force allocation of a context for this scope if necessary. For a 'with'
1365  // scope and for a function scope that makes an 'eval' call we need a context,
1366  // even if no local variables were statically allocated in the scope.
1367  // Likewise for modules.
1368  bool must_have_context = is_with_scope() || is_module_scope() ||
1369      (is_function_scope() && calls_eval());
1370
1371  // If we didn't allocate any locals in the local context, then we only
1372  // need the minimal number of slots if we must have a context.
1373  if (num_heap_slots_ == Context::MIN_CONTEXT_SLOTS && !must_have_context) {
1374    num_heap_slots_ = 0;
1375  }
1376
1377  // Allocation done.
1378  DCHECK(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS);
1379}
1380
1381
1382void Scope::AllocateModulesRecursively(Scope* host_scope) {
1383  if (already_resolved()) return;
1384  if (is_module_scope()) {
1385    DCHECK(interface_->IsFrozen());
1386    DCHECK(module_var_ == NULL);
1387    module_var_ =
1388        host_scope->NewInternal(ast_value_factory_->dot_module_string());
1389    ++host_scope->num_modules_;
1390  }
1391
1392  for (int i = 0; i < inner_scopes_.length(); i++) {
1393    Scope* inner_scope = inner_scopes_.at(i);
1394    inner_scope->AllocateModulesRecursively(host_scope);
1395  }
1396}
1397
1398
1399int Scope::StackLocalCount() const {
1400  return num_stack_slots() -
1401      (function_ != NULL && function_->proxy()->var()->IsStackLocal() ? 1 : 0);
1402}
1403
1404
1405int Scope::ContextLocalCount() const {
1406  if (num_heap_slots() == 0) return 0;
1407  return num_heap_slots() - Context::MIN_CONTEXT_SLOTS -
1408      (function_ != NULL && function_->proxy()->var()->IsContextSlot() ? 1 : 0);
1409}
1410
1411} }  // namespace v8::internal
1412