// Copyright 2011 the V8 project authors. All rights reserved. // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following // disclaimer in the documentation and/or other materials provided // with the distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. #include "v8.h" #include "scopes.h" #include "bootstrapper.h" #include "compiler.h" #include "messages.h" #include "scopeinfo.h" #include "allocation-inl.h" namespace v8 { namespace internal { // ---------------------------------------------------------------------------- // A Zone allocator for use with LocalsMap. // TODO(isolates): It is probably worth it to change the Allocator class to // take a pointer to an isolate. class ZoneAllocator: public Allocator { public: /* nothing to do */ virtual ~ZoneAllocator() {} virtual void* New(size_t size) { return ZONE->New(static_cast<int>(size)); } /* ignored - Zone is freed in one fell swoop */ virtual void Delete(void* p) {} }; static ZoneAllocator* LocalsMapAllocator = ::new ZoneAllocator(); // ---------------------------------------------------------------------------- // Implementation of LocalsMap // // Note: We are storing the handle locations as key values in the hash map. // When inserting a new variable via Declare(), we rely on the fact that // the handle location remains alive for the duration of that variable // use. Because a Variable holding a handle with the same location exists // this is ensured. static bool Match(void* key1, void* key2) { String* name1 = *reinterpret_cast<String**>(key1); String* name2 = *reinterpret_cast<String**>(key2); ASSERT(name1->IsSymbol()); ASSERT(name2->IsSymbol()); return name1 == name2; } VariableMap::VariableMap() : HashMap(Match, LocalsMapAllocator, 8) {} VariableMap::~VariableMap() {} Variable* VariableMap::Declare( Scope* scope, Handle<String> name, VariableMode mode, bool is_valid_lhs, Variable::Kind kind, InitializationFlag initialization_flag) { HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), true); if (p->value == NULL) { // The variable has not been declared yet -> insert it. ASSERT(p->key == name.location()); p->value = new Variable(scope, name, mode, is_valid_lhs, kind, initialization_flag); } return reinterpret_cast<Variable*>(p->value); } Variable* VariableMap::Lookup(Handle<String> name) { HashMap::Entry* p = HashMap::Lookup(name.location(), name->Hash(), false); if (p != NULL) { ASSERT(*reinterpret_cast<String**>(p->key) == *name); ASSERT(p->value != NULL); return reinterpret_cast<Variable*>(p->value); } return NULL; } // ---------------------------------------------------------------------------- // Implementation of Scope Scope::Scope(Scope* outer_scope, ScopeType type) : isolate_(Isolate::Current()), inner_scopes_(4), variables_(), temps_(4), params_(4), unresolved_(16), decls_(4), already_resolved_(false) { SetDefaults(type, outer_scope, Handle<ScopeInfo>::null()); // At some point we might want to provide outer scopes to // eval scopes (by walking the stack and reading the scope info). // In that case, the ASSERT below needs to be adjusted. ASSERT_EQ(type == GLOBAL_SCOPE, outer_scope == NULL); ASSERT(!HasIllegalRedeclaration()); } Scope::Scope(Scope* inner_scope, ScopeType type, Handle<ScopeInfo> scope_info) : isolate_(Isolate::Current()), inner_scopes_(4), variables_(), temps_(4), params_(4), unresolved_(16), decls_(4), already_resolved_(true) { SetDefaults(type, NULL, scope_info); if (!scope_info.is_null()) { num_heap_slots_ = scope_info_->ContextLength(); if (*scope_info != ScopeInfo::Empty()) { language_mode_ = scope_info->language_mode(); } } else if (is_with_scope()) { num_heap_slots_ = Context::MIN_CONTEXT_SLOTS; } AddInnerScope(inner_scope); } Scope::Scope(Scope* inner_scope, Handle<String> catch_variable_name) : isolate_(Isolate::Current()), inner_scopes_(1), variables_(), temps_(0), params_(0), unresolved_(0), decls_(0), already_resolved_(true) { SetDefaults(CATCH_SCOPE, NULL, Handle<ScopeInfo>::null()); AddInnerScope(inner_scope); ++num_var_or_const_; num_heap_slots_ = Context::MIN_CONTEXT_SLOTS; Variable* variable = variables_.Declare(this, catch_variable_name, VAR, true, // Valid left-hand side. Variable::NORMAL, kCreatedInitialized); AllocateHeapSlot(variable); } void Scope::SetDefaults(ScopeType type, Scope* outer_scope, Handle<ScopeInfo> scope_info) { outer_scope_ = outer_scope; type_ = type; scope_name_ = isolate_->factory()->empty_symbol(); dynamics_ = NULL; receiver_ = NULL; function_ = NULL; arguments_ = NULL; illegal_redecl_ = NULL; scope_inside_with_ = false; scope_contains_with_ = false; scope_calls_eval_ = false; // Inherit the strict mode from the parent scope. language_mode_ = (outer_scope != NULL) ? outer_scope->language_mode_ : CLASSIC_MODE; outer_scope_calls_non_strict_eval_ = false; inner_scope_calls_eval_ = false; force_eager_compilation_ = false; num_var_or_const_ = 0; num_stack_slots_ = 0; num_heap_slots_ = 0; scope_info_ = scope_info; start_position_ = RelocInfo::kNoPosition; end_position_ = RelocInfo::kNoPosition; if (!scope_info.is_null()) { scope_calls_eval_ = scope_info->CallsEval(); language_mode_ = scope_info->language_mode(); } } Scope* Scope::DeserializeScopeChain(Context* context, Scope* global_scope) { // Reconstruct the outer scope chain from a closure's context chain. Scope* current_scope = NULL; Scope* innermost_scope = NULL; bool contains_with = false; while (!context->IsGlobalContext()) { if (context->IsWithContext()) { Scope* with_scope = new Scope(current_scope, WITH_SCOPE, Handle<ScopeInfo>::null()); current_scope = with_scope; // All the inner scopes are inside a with. contains_with = true; for (Scope* s = innermost_scope; s != NULL; s = s->outer_scope()) { s->scope_inside_with_ = true; } } else if (context->IsFunctionContext()) { ScopeInfo* scope_info = context->closure()->shared()->scope_info(); current_scope = new Scope(current_scope, FUNCTION_SCOPE, Handle<ScopeInfo>(scope_info)); } else if (context->IsBlockContext()) { ScopeInfo* scope_info = ScopeInfo::cast(context->extension()); current_scope = new Scope(current_scope, BLOCK_SCOPE, Handle<ScopeInfo>(scope_info)); } else { ASSERT(context->IsCatchContext()); String* name = String::cast(context->extension()); current_scope = new Scope(current_scope, Handle<String>(name)); } if (contains_with) current_scope->RecordWithStatement(); if (innermost_scope == NULL) innermost_scope = current_scope; // Forget about a with when we move to a context for a different function. if (context->previous()->closure() != context->closure()) { contains_with = false; } context = context->previous(); } global_scope->AddInnerScope(current_scope); global_scope->PropagateScopeInfo(false); return (innermost_scope == NULL) ? global_scope : innermost_scope; } bool Scope::Analyze(CompilationInfo* info) { ASSERT(info->function() != NULL); Scope* scope = info->function()->scope(); Scope* top = scope; // Traverse the scope tree up to the first unresolved scope or the global // scope and start scope resolution and variable allocation from that scope. while (!top->is_global_scope() && !top->outer_scope()->already_resolved()) { top = top->outer_scope(); } // Allocated the variables. top->AllocateVariables(info->global_scope()); #ifdef DEBUG if (info->isolate()->bootstrapper()->IsActive() ? FLAG_print_builtin_scopes : FLAG_print_scopes) { scope->Print(); } #endif if (FLAG_harmony_scoping) { VariableProxy* proxy = scope->CheckAssignmentToConst(); if (proxy != NULL) { // Found an assignment to const. Throw a syntax error. MessageLocation location(info->script(), proxy->position(), proxy->position()); Isolate* isolate = info->isolate(); Factory* factory = isolate->factory(); Handle<JSArray> array = factory->NewJSArray(0); Handle<Object> result = factory->NewSyntaxError("harmony_const_assign", array); isolate->Throw(*result, &location); return false; } } info->SetScope(scope); return true; } void Scope::Initialize() { ASSERT(!already_resolved()); // Add this scope as a new inner scope of the outer scope. if (outer_scope_ != NULL) { outer_scope_->inner_scopes_.Add(this); scope_inside_with_ = outer_scope_->scope_inside_with_ || is_with_scope(); } else { scope_inside_with_ = is_with_scope(); } // Declare convenience variables. // Declare and allocate receiver (even for the global scope, and even // if naccesses_ == 0). // NOTE: When loading parameters in the global scope, we must take // care not to access them as properties of the global object, but // instead load them directly from the stack. Currently, the only // such parameter is 'this' which is passed on the stack when // invoking scripts if (is_declaration_scope()) { Variable* var = variables_.Declare(this, isolate_->factory()->this_symbol(), VAR, false, Variable::THIS, kCreatedInitialized); var->AllocateTo(Variable::PARAMETER, -1); receiver_ = var; } else { ASSERT(outer_scope() != NULL); receiver_ = outer_scope()->receiver(); } if (is_function_scope()) { // Declare 'arguments' variable which exists in all functions. // Note that it might never be accessed, in which case it won't be // allocated during variable allocation. variables_.Declare(this, isolate_->factory()->arguments_symbol(), VAR, true, Variable::ARGUMENTS, kCreatedInitialized); } } Scope* Scope::FinalizeBlockScope() { ASSERT(is_block_scope()); ASSERT(temps_.is_empty()); ASSERT(params_.is_empty()); if (num_var_or_const() > 0) return this; // Remove this scope from outer scope. for (int i = 0; i < outer_scope_->inner_scopes_.length(); i++) { if (outer_scope_->inner_scopes_[i] == this) { outer_scope_->inner_scopes_.Remove(i); break; } } // Reparent inner scopes. for (int i = 0; i < inner_scopes_.length(); i++) { outer_scope()->AddInnerScope(inner_scopes_[i]); } // Move unresolved variables for (int i = 0; i < unresolved_.length(); i++) { outer_scope()->unresolved_.Add(unresolved_[i]); } return NULL; } Variable* Scope::LocalLookup(Handle<String> name) { Variable* result = variables_.Lookup(name); if (result != NULL || scope_info_.is_null()) { return result; } // If we have a serialized scope info, we might find the variable there. // There should be no local slot with the given name. ASSERT(scope_info_->StackSlotIndex(*name) < 0); // Check context slot lookup. VariableMode mode; InitializationFlag init_flag; int index = scope_info_->ContextSlotIndex(*name, &mode, &init_flag); if (index < 0) { // Check parameters. mode = VAR; init_flag = kCreatedInitialized; index = scope_info_->ParameterIndex(*name); if (index < 0) return NULL; } Variable* var = variables_.Declare(this, name, mode, true, Variable::NORMAL, init_flag); var->AllocateTo(Variable::CONTEXT, index); return var; } Variable* Scope::LookupFunctionVar(Handle<String> name) { if (function_ != NULL && function_->name().is_identical_to(name)) { return function_->var(); } else if (!scope_info_.is_null()) { // If we are backed by a scope info, try to lookup the variable there. VariableMode mode; int index = scope_info_->FunctionContextSlotIndex(*name, &mode); if (index < 0) return NULL; Variable* var = DeclareFunctionVar(name, mode); var->AllocateTo(Variable::CONTEXT, index); return var; } else { return NULL; } } Variable* Scope::Lookup(Handle<String> name) { for (Scope* scope = this; scope != NULL; scope = scope->outer_scope()) { Variable* var = scope->LocalLookup(name); if (var != NULL) return var; } return NULL; } Variable* Scope::DeclareFunctionVar(Handle<String> name, VariableMode mode) { ASSERT(is_function_scope() && function_ == NULL); Variable* function_var = new Variable( this, name, mode, true, Variable::NORMAL, kCreatedInitialized); function_ = new(isolate_->zone()) VariableProxy(isolate_, function_var); return function_var; } void Scope::DeclareParameter(Handle<String> name, VariableMode mode) { ASSERT(!already_resolved()); ASSERT(is_function_scope()); Variable* var = variables_.Declare( this, name, mode, true, Variable::NORMAL, kCreatedInitialized); params_.Add(var); } Variable* Scope::DeclareLocal(Handle<String> name, VariableMode mode, InitializationFlag init_flag) { ASSERT(!already_resolved()); // This function handles VAR and CONST modes. DYNAMIC variables are // introduces during variable allocation, INTERNAL variables are allocated // explicitly, and TEMPORARY variables are allocated via NewTemporary(). ASSERT(mode == VAR || mode == CONST || mode == CONST_HARMONY || mode == LET); ++num_var_or_const_; return variables_.Declare(this, name, mode, true, Variable::NORMAL, init_flag); } Variable* Scope::DeclareGlobal(Handle<String> name) { ASSERT(is_global_scope()); return variables_.Declare(this, name, DYNAMIC_GLOBAL, true, Variable::NORMAL, kCreatedInitialized); } VariableProxy* Scope::NewUnresolved(Handle<String> name, int position) { // Note that we must not share the unresolved variables with // the same name because they may be removed selectively via // RemoveUnresolved(). ASSERT(!already_resolved()); VariableProxy* proxy = new(isolate_->zone()) VariableProxy( isolate_, name, false, position); unresolved_.Add(proxy); return proxy; } void Scope::RemoveUnresolved(VariableProxy* var) { // Most likely (always?) any variable we want to remove // was just added before, so we search backwards. for (int i = unresolved_.length(); i-- > 0;) { if (unresolved_[i] == var) { unresolved_.Remove(i); return; } } } Variable* Scope::NewTemporary(Handle<String> name) { ASSERT(!already_resolved()); Variable* var = new Variable(this, name, TEMPORARY, true, Variable::NORMAL, kCreatedInitialized); temps_.Add(var); return var; } void Scope::AddDeclaration(Declaration* declaration) { decls_.Add(declaration); } void Scope::SetIllegalRedeclaration(Expression* expression) { // Record only the first illegal redeclaration. if (!HasIllegalRedeclaration()) { illegal_redecl_ = expression; } ASSERT(HasIllegalRedeclaration()); } void Scope::VisitIllegalRedeclaration(AstVisitor* visitor) { ASSERT(HasIllegalRedeclaration()); illegal_redecl_->Accept(visitor); } Declaration* Scope::CheckConflictingVarDeclarations() { int length = decls_.length(); for (int i = 0; i < length; i++) { Declaration* decl = decls_[i]; if (decl->mode() != VAR) continue; Handle<String> name = decl->proxy()->name(); // Iterate through all scopes until and including the declaration scope. Scope* previous = NULL; Scope* current = decl->scope(); do { // There is a conflict if there exists a non-VAR binding. Variable* other_var = current->variables_.Lookup(name); if (other_var != NULL && other_var->mode() != VAR) { return decl; } previous = current; current = current->outer_scope_; } while (!previous->is_declaration_scope()); } return NULL; } VariableProxy* Scope::CheckAssignmentToConst() { // Check this scope. if (is_extended_mode()) { for (int i = 0; i < unresolved_.length(); i++) { ASSERT(unresolved_[i]->var() != NULL); if (unresolved_[i]->var()->is_const_mode() && unresolved_[i]->IsLValue()) { return unresolved_[i]; } } } // Check inner scopes. for (int i = 0; i < inner_scopes_.length(); i++) { VariableProxy* proxy = inner_scopes_[i]->CheckAssignmentToConst(); if (proxy != NULL) return proxy; } // No assignments to const found. return NULL; } void Scope::CollectStackAndContextLocals(ZoneList<Variable*>* stack_locals, ZoneList<Variable*>* context_locals) { ASSERT(stack_locals != NULL); ASSERT(context_locals != NULL); // Collect temporaries which are always allocated on the stack. for (int i = 0; i < temps_.length(); i++) { Variable* var = temps_[i]; if (var->is_used()) { ASSERT(var->IsStackLocal()); stack_locals->Add(var); } } // Collect declared local variables. for (VariableMap::Entry* p = variables_.Start(); p != NULL; p = variables_.Next(p)) { Variable* var = reinterpret_cast<Variable*>(p->value); if (var->is_used()) { if (var->IsStackLocal()) { stack_locals->Add(var); } else if (var->IsContextSlot()) { context_locals->Add(var); } } } } void Scope::AllocateVariables(Scope* global_scope) { // 1) Propagate scope information. bool outer_scope_calls_non_strict_eval = false; if (outer_scope_ != NULL) { outer_scope_calls_non_strict_eval = outer_scope_->outer_scope_calls_non_strict_eval() | outer_scope_->calls_non_strict_eval(); } PropagateScopeInfo(outer_scope_calls_non_strict_eval); // 2) Resolve variables. ResolveVariablesRecursively(global_scope); // 3) Allocate variables. AllocateVariablesRecursively(); } bool Scope::AllowsLazyCompilation() const { return !force_eager_compilation_ && HasTrivialOuterContext(); } bool Scope::HasTrivialContext() const { // A function scope has a trivial context if it always is the global // context. We iteratively scan out the context chain to see if // there is anything that makes this scope non-trivial; otherwise we // return true. for (const Scope* scope = this; scope != NULL; scope = scope->outer_scope_) { if (scope->is_eval_scope()) return false; if (scope->scope_inside_with_) return false; if (scope->num_heap_slots_ > 0) return false; } return true; } bool Scope::HasTrivialOuterContext() const { Scope* outer = outer_scope_; if (outer == NULL) return true; // Note that the outer context may be trivial in general, but the current // scope may be inside a 'with' statement in which case the outer context // for this scope is not trivial. return !scope_inside_with_ && outer->HasTrivialContext(); } int Scope::ContextChainLength(Scope* scope) { int n = 0; for (Scope* s = this; s != scope; s = s->outer_scope_) { ASSERT(s != NULL); // scope must be in the scope chain if (s->num_heap_slots() > 0) n++; } return n; } Scope* Scope::DeclarationScope() { Scope* scope = this; while (!scope->is_declaration_scope()) { scope = scope->outer_scope(); } return scope; } Handle<ScopeInfo> Scope::GetScopeInfo() { if (scope_info_.is_null()) { scope_info_ = ScopeInfo::Create(this); } return scope_info_; } void Scope::GetNestedScopeChain( List<Handle<ScopeInfo> >* chain, int position) { if (!is_eval_scope()) chain->Add(Handle<ScopeInfo>(GetScopeInfo())); for (int i = 0; i < inner_scopes_.length(); i++) { Scope* scope = inner_scopes_[i]; int beg_pos = scope->start_position(); int end_pos = scope->end_position(); ASSERT(beg_pos >= 0 && end_pos >= 0); if (beg_pos <= position && position < end_pos) { scope->GetNestedScopeChain(chain, position); return; } } } #ifdef DEBUG static const char* Header(ScopeType type) { switch (type) { case EVAL_SCOPE: return "eval"; case FUNCTION_SCOPE: return "function"; case GLOBAL_SCOPE: return "global"; case CATCH_SCOPE: return "catch"; case BLOCK_SCOPE: return "block"; case WITH_SCOPE: return "with"; } UNREACHABLE(); return NULL; } static void Indent(int n, const char* str) { PrintF("%*s%s", n, "", str); } static void PrintName(Handle<String> name) { SmartArrayPointer<char> s = name->ToCString(DISALLOW_NULLS); PrintF("%s", *s); } static void PrintLocation(Variable* var) { switch (var->location()) { case Variable::UNALLOCATED: break; case Variable::PARAMETER: PrintF("parameter[%d]", var->index()); break; case Variable::LOCAL: PrintF("local[%d]", var->index()); break; case Variable::CONTEXT: PrintF("context[%d]", var->index()); break; case Variable::LOOKUP: PrintF("lookup"); break; } } static void PrintVar(int indent, Variable* var) { if (var->is_used() || !var->IsUnallocated()) { Indent(indent, Variable::Mode2String(var->mode())); PrintF(" "); PrintName(var->name()); PrintF("; // "); PrintLocation(var); if (var->has_forced_context_allocation()) { if (!var->IsUnallocated()) PrintF(", "); PrintF("forced context allocation"); } PrintF("\n"); } } static void PrintMap(int indent, VariableMap* map) { for (VariableMap::Entry* p = map->Start(); p != NULL; p = map->Next(p)) { Variable* var = reinterpret_cast<Variable*>(p->value); PrintVar(indent, var); } } void Scope::Print(int n) { int n0 = (n > 0 ? n : 0); int n1 = n0 + 2; // indentation // Print header. Indent(n0, Header(type_)); if (scope_name_->length() > 0) { PrintF(" "); PrintName(scope_name_); } // Print parameters, if any. if (is_function_scope()) { PrintF(" ("); for (int i = 0; i < params_.length(); i++) { if (i > 0) PrintF(", "); PrintName(params_[i]->name()); } PrintF(")"); } PrintF(" { // (%d, %d)\n", start_position(), end_position()); // Function name, if any (named function literals, only). if (function_ != NULL) { Indent(n1, "// (local) function name: "); PrintName(function_->name()); PrintF("\n"); } // Scope info. if (HasTrivialOuterContext()) { Indent(n1, "// scope has trivial outer context\n"); } switch (language_mode()) { case CLASSIC_MODE: break; case STRICT_MODE: Indent(n1, "// strict mode scope\n"); break; case EXTENDED_MODE: Indent(n1, "// extended mode scope\n"); break; } if (scope_inside_with_) Indent(n1, "// scope inside 'with'\n"); if (scope_contains_with_) Indent(n1, "// scope contains 'with'\n"); if (scope_calls_eval_) Indent(n1, "// scope calls 'eval'\n"); if (outer_scope_calls_non_strict_eval_) { Indent(n1, "// outer scope calls 'eval' in non-strict context\n"); } if (inner_scope_calls_eval_) Indent(n1, "// inner scope calls 'eval'\n"); if (num_stack_slots_ > 0) { Indent(n1, "// "); PrintF("%d stack slots\n", num_stack_slots_); } if (num_heap_slots_ > 0) { Indent(n1, "// "); PrintF("%d heap slots\n", num_heap_slots_); } // Print locals. Indent(n1, "// function var\n"); if (function_ != NULL) { PrintVar(n1, function_->var()); } Indent(n1, "// temporary vars\n"); for (int i = 0; i < temps_.length(); i++) { PrintVar(n1, temps_[i]); } Indent(n1, "// local vars\n"); PrintMap(n1, &variables_); Indent(n1, "// dynamic vars\n"); if (dynamics_ != NULL) { PrintMap(n1, dynamics_->GetMap(DYNAMIC)); PrintMap(n1, dynamics_->GetMap(DYNAMIC_LOCAL)); PrintMap(n1, dynamics_->GetMap(DYNAMIC_GLOBAL)); } // Print inner scopes (disable by providing negative n). if (n >= 0) { for (int i = 0; i < inner_scopes_.length(); i++) { PrintF("\n"); inner_scopes_[i]->Print(n1); } } Indent(n0, "}\n"); } #endif // DEBUG Variable* Scope::NonLocal(Handle<String> name, VariableMode mode) { if (dynamics_ == NULL) dynamics_ = new DynamicScopePart(); VariableMap* map = dynamics_->GetMap(mode); Variable* var = map->Lookup(name); if (var == NULL) { // Declare a new non-local. InitializationFlag init_flag = (mode == VAR) ? kCreatedInitialized : kNeedsInitialization; var = map->Declare(NULL, name, mode, true, Variable::NORMAL, init_flag); // Allocate it by giving it a dynamic lookup. var->AllocateTo(Variable::LOOKUP, -1); } return var; } Variable* Scope::LookupRecursive(Handle<String> name, BindingKind* binding_kind) { ASSERT(binding_kind != NULL); // Try to find the variable in this scope. Variable* var = LocalLookup(name); // We found a variable and we are done. (Even if there is an 'eval' in // this scope which introduces the same variable again, the resulting // variable remains the same.) if (var != NULL) { *binding_kind = BOUND; return var; } // We did not find a variable locally. Check against the function variable, // if any. We can do this for all scopes, since the function variable is // only present - if at all - for function scopes. *binding_kind = UNBOUND; var = LookupFunctionVar(name); if (var != NULL) { *binding_kind = BOUND; } else if (outer_scope_ != NULL) { var = outer_scope_->LookupRecursive(name, binding_kind); if (*binding_kind == BOUND && (is_function_scope() || is_with_scope())) { var->ForceContextAllocation(); } } else { ASSERT(is_global_scope()); } if (is_with_scope()) { // The current scope is a with scope, so the variable binding can not be // statically resolved. However, note that it was necessary to do a lookup // in the outer scope anyway, because if a binding exists in an outer scope, // the associated variable has to be marked as potentially being accessed // from inside of an inner with scope (the property may not be in the 'with' // object). *binding_kind = DYNAMIC_LOOKUP; return NULL; } else if (calls_non_strict_eval()) { // A variable binding may have been found in an outer scope, but the current // scope makes a non-strict 'eval' call, so the found variable may not be // the correct one (the 'eval' may introduce a binding with the same name). // In that case, change the lookup result to reflect this situation. if (*binding_kind == BOUND) { *binding_kind = BOUND_EVAL_SHADOWED; } else if (*binding_kind == UNBOUND) { *binding_kind = UNBOUND_EVAL_SHADOWED; } } return var; } void Scope::ResolveVariable(Scope* global_scope, VariableProxy* proxy) { ASSERT(global_scope == NULL || global_scope->is_global_scope()); // If the proxy is already resolved there's nothing to do // (functions and consts may be resolved by the parser). if (proxy->var() != NULL) return; // Otherwise, try to resolve the variable. BindingKind binding_kind; Variable* var = LookupRecursive(proxy->name(), &binding_kind); switch (binding_kind) { case BOUND: // We found a variable binding. break; case BOUND_EVAL_SHADOWED: // We found a variable variable binding that might be shadowed // by 'eval' introduced variable bindings. if (var->is_global()) { var = NonLocal(proxy->name(), DYNAMIC_GLOBAL); } else { Variable* invalidated = var; var = NonLocal(proxy->name(), DYNAMIC_LOCAL); var->set_local_if_not_shadowed(invalidated); } break; case UNBOUND: // No binding has been found. Declare a variable in global scope. ASSERT(global_scope != NULL); var = global_scope->DeclareGlobal(proxy->name()); break; case UNBOUND_EVAL_SHADOWED: // No binding has been found. But some scope makes a // non-strict 'eval' call. var = NonLocal(proxy->name(), DYNAMIC_GLOBAL); break; case DYNAMIC_LOOKUP: // The variable could not be resolved statically. var = NonLocal(proxy->name(), DYNAMIC); break; } ASSERT(var != NULL); proxy->BindTo(var); } void Scope::ResolveVariablesRecursively(Scope* global_scope) { ASSERT(global_scope == NULL || global_scope->is_global_scope()); // Resolve unresolved variables for this scope. for (int i = 0; i < unresolved_.length(); i++) { ResolveVariable(global_scope, unresolved_[i]); } // Resolve unresolved variables for inner scopes. for (int i = 0; i < inner_scopes_.length(); i++) { inner_scopes_[i]->ResolveVariablesRecursively(global_scope); } } bool Scope::PropagateScopeInfo(bool outer_scope_calls_non_strict_eval ) { if (outer_scope_calls_non_strict_eval) { outer_scope_calls_non_strict_eval_ = true; } bool calls_non_strict_eval = this->calls_non_strict_eval() || outer_scope_calls_non_strict_eval_; for (int i = 0; i < inner_scopes_.length(); i++) { Scope* inner_scope = inner_scopes_[i]; if (inner_scope->PropagateScopeInfo(calls_non_strict_eval)) { inner_scope_calls_eval_ = true; } if (inner_scope->force_eager_compilation_) { force_eager_compilation_ = true; } } return scope_calls_eval_ || inner_scope_calls_eval_; } bool Scope::MustAllocate(Variable* var) { // Give var a read/write use if there is a chance it might be accessed // via an eval() call. This is only possible if the variable has a // visible name. if ((var->is_this() || var->name()->length() > 0) && (var->has_forced_context_allocation() || scope_calls_eval_ || inner_scope_calls_eval_ || scope_contains_with_ || is_catch_scope() || is_block_scope())) { var->set_is_used(true); } // Global variables do not need to be allocated. return !var->is_global() && var->is_used(); } bool Scope::MustAllocateInContext(Variable* var) { // If var is accessed from an inner scope, or if there is a possibility // that it might be accessed from the current or an inner scope (through // an eval() call or a runtime with lookup), it must be allocated in the // context. // // Exceptions: temporary variables are never allocated in a context; // catch-bound variables are always allocated in a context. if (var->mode() == TEMPORARY) return false; if (is_catch_scope() || is_block_scope()) return true; return var->has_forced_context_allocation() || scope_calls_eval_ || inner_scope_calls_eval_ || scope_contains_with_ || var->is_global(); } bool Scope::HasArgumentsParameter() { for (int i = 0; i < params_.length(); i++) { if (params_[i]->name().is_identical_to( isolate_->factory()->arguments_symbol())) { return true; } } return false; } void Scope::AllocateStackSlot(Variable* var) { var->AllocateTo(Variable::LOCAL, num_stack_slots_++); } void Scope::AllocateHeapSlot(Variable* var) { var->AllocateTo(Variable::CONTEXT, num_heap_slots_++); } void Scope::AllocateParameterLocals() { ASSERT(is_function_scope()); Variable* arguments = LocalLookup(isolate_->factory()->arguments_symbol()); ASSERT(arguments != NULL); // functions have 'arguments' declared implicitly bool uses_nonstrict_arguments = false; if (MustAllocate(arguments) && !HasArgumentsParameter()) { // 'arguments' is used. Unless there is also a parameter called // 'arguments', we must be conservative and allocate all parameters to // the context assuming they will be captured by the arguments object. // If we have a parameter named 'arguments', a (new) value is always // assigned to it via the function invocation. Then 'arguments' denotes // that specific parameter value and cannot be used to access the // parameters, which is why we don't need to allocate an arguments // object in that case. // We are using 'arguments'. Tell the code generator that is needs to // allocate the arguments object by setting 'arguments_'. arguments_ = arguments; // In strict mode 'arguments' does not alias formal parameters. // Therefore in strict mode we allocate parameters as if 'arguments' // were not used. uses_nonstrict_arguments = is_classic_mode(); } // The same parameter may occur multiple times in the parameters_ list. // If it does, and if it is not copied into the context object, it must // receive the highest parameter index for that parameter; thus iteration // order is relevant! for (int i = params_.length() - 1; i >= 0; --i) { Variable* var = params_[i]; ASSERT(var->scope() == this); if (uses_nonstrict_arguments) { // Force context allocation of the parameter. var->ForceContextAllocation(); } if (MustAllocate(var)) { if (MustAllocateInContext(var)) { ASSERT(var->IsUnallocated() || var->IsContextSlot()); if (var->IsUnallocated()) { AllocateHeapSlot(var); } } else { ASSERT(var->IsUnallocated() || var->IsParameter()); if (var->IsUnallocated()) { var->AllocateTo(Variable::PARAMETER, i); } } } } } void Scope::AllocateNonParameterLocal(Variable* var) { ASSERT(var->scope() == this); ASSERT(!var->IsVariable(isolate_->factory()->result_symbol()) || !var->IsStackLocal()); if (var->IsUnallocated() && MustAllocate(var)) { if (MustAllocateInContext(var)) { AllocateHeapSlot(var); } else { AllocateStackSlot(var); } } } void Scope::AllocateNonParameterLocals() { // All variables that have no rewrite yet are non-parameter locals. for (int i = 0; i < temps_.length(); i++) { AllocateNonParameterLocal(temps_[i]); } for (VariableMap::Entry* p = variables_.Start(); p != NULL; p = variables_.Next(p)) { Variable* var = reinterpret_cast<Variable*>(p->value); AllocateNonParameterLocal(var); } // For now, function_ must be allocated at the very end. If it gets // allocated in the context, it must be the last slot in the context, // because of the current ScopeInfo implementation (see // ScopeInfo::ScopeInfo(FunctionScope* scope) constructor). if (function_ != NULL) { AllocateNonParameterLocal(function_->var()); } } void Scope::AllocateVariablesRecursively() { // Allocate variables for inner scopes. for (int i = 0; i < inner_scopes_.length(); i++) { inner_scopes_[i]->AllocateVariablesRecursively(); } // If scope is already resolved, we still need to allocate // variables in inner scopes which might not had been resolved yet. if (already_resolved()) return; // The number of slots required for variables. num_stack_slots_ = 0; num_heap_slots_ = Context::MIN_CONTEXT_SLOTS; // Allocate variables for this scope. // Parameters must be allocated first, if any. if (is_function_scope()) AllocateParameterLocals(); AllocateNonParameterLocals(); // Force allocation of a context for this scope if necessary. For a 'with' // scope and for a function scope that makes an 'eval' call we need a context, // even if no local variables were statically allocated in the scope. bool must_have_context = is_with_scope() || (is_function_scope() && calls_eval()); // If we didn't allocate any locals in the local context, then we only // need the minimal number of slots if we must have a context. if (num_heap_slots_ == Context::MIN_CONTEXT_SLOTS && !must_have_context) { num_heap_slots_ = 0; } // Allocation done. ASSERT(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS); } int Scope::StackLocalCount() const { return num_stack_slots() - (function_ != NULL && function_->var()->IsStackLocal() ? 1 : 0); } int Scope::ContextLocalCount() const { if (num_heap_slots() == 0) return 0; return num_heap_slots() - Context::MIN_CONTEXT_SLOTS - (function_ != NULL && function_->var()->IsContextSlot() ? 1 : 0); } } } // namespace v8::internal