// Copyright 2012 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "src/v8.h" #include "src/scopes.h" #include "src/accessors.h" #include "src/bootstrapper.h" #include "src/compiler.h" #include "src/messages.h" #include "src/scopeinfo.h" namespace v8 { namespace internal { // ---------------------------------------------------------------------------- // 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. VariableMap::VariableMap(Zone* zone) : ZoneHashMap(ZoneHashMap::PointersMatch, 8, ZoneAllocationPolicy(zone)), zone_(zone) {} VariableMap::~VariableMap() {} Variable* VariableMap::Declare(Scope* scope, const AstRawString* name, VariableMode mode, bool is_valid_lhs, Variable::Kind kind, InitializationFlag initialization_flag, MaybeAssignedFlag maybe_assigned_flag, Interface* interface) { // AstRawStrings are unambiguous, i.e., the same string is always represented // by the same AstRawString*. // FIXME(marja): fix the type of Lookup. Entry* p = ZoneHashMap::Lookup(const_cast(name), name->hash(), true, ZoneAllocationPolicy(zone())); if (p->value == NULL) { // The variable has not been declared yet -> insert it. DCHECK(p->key == name); p->value = new (zone()) Variable(scope, name, mode, is_valid_lhs, kind, initialization_flag, maybe_assigned_flag, interface); } return reinterpret_cast(p->value); } Variable* VariableMap::Lookup(const AstRawString* name) { Entry* p = ZoneHashMap::Lookup(const_cast(name), name->hash(), false, ZoneAllocationPolicy(NULL)); if (p != NULL) { DCHECK(reinterpret_cast(p->key) == name); DCHECK(p->value != NULL); return reinterpret_cast(p->value); } return NULL; } // ---------------------------------------------------------------------------- // Implementation of Scope Scope::Scope(Scope* outer_scope, ScopeType scope_type, AstValueFactory* ast_value_factory, Zone* zone) : isolate_(zone->isolate()), inner_scopes_(4, zone), variables_(zone), internals_(4, zone), temps_(4, zone), params_(4, zone), unresolved_(16, zone), decls_(4, zone), interface_(FLAG_harmony_modules && (scope_type == MODULE_SCOPE || scope_type == GLOBAL_SCOPE) ? Interface::NewModule(zone) : NULL), already_resolved_(false), ast_value_factory_(ast_value_factory), zone_(zone) { SetDefaults(scope_type, outer_scope, Handle::null()); // The outermost scope must be a global scope. DCHECK(scope_type == GLOBAL_SCOPE || outer_scope != NULL); DCHECK(!HasIllegalRedeclaration()); } Scope::Scope(Scope* inner_scope, ScopeType scope_type, Handle scope_info, AstValueFactory* value_factory, Zone* zone) : isolate_(zone->isolate()), inner_scopes_(4, zone), variables_(zone), internals_(4, zone), temps_(4, zone), params_(4, zone), unresolved_(16, zone), decls_(4, zone), interface_(NULL), already_resolved_(true), ast_value_factory_(value_factory), zone_(zone) { SetDefaults(scope_type, NULL, scope_info); if (!scope_info.is_null()) { num_heap_slots_ = scope_info_->ContextLength(); } // Ensure at least MIN_CONTEXT_SLOTS to indicate a materialized context. num_heap_slots_ = Max(num_heap_slots_, static_cast(Context::MIN_CONTEXT_SLOTS)); AddInnerScope(inner_scope); } Scope::Scope(Scope* inner_scope, const AstRawString* catch_variable_name, AstValueFactory* value_factory, Zone* zone) : isolate_(zone->isolate()), inner_scopes_(1, zone), variables_(zone), internals_(0, zone), temps_(0, zone), params_(0, zone), unresolved_(0, zone), decls_(0, zone), interface_(NULL), already_resolved_(true), ast_value_factory_(value_factory), zone_(zone) { SetDefaults(CATCH_SCOPE, NULL, Handle::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 scope_type, Scope* outer_scope, Handle scope_info) { outer_scope_ = outer_scope; scope_type_ = scope_type; scope_name_ = ast_value_factory_->empty_string(); dynamics_ = NULL; receiver_ = NULL; function_ = NULL; arguments_ = NULL; illegal_redecl_ = NULL; scope_inside_with_ = false; scope_contains_with_ = false; scope_calls_eval_ = false; scope_uses_this_ = false; scope_uses_arguments_ = false; asm_module_ = false; asm_function_ = outer_scope != NULL && outer_scope->asm_module_; // Inherit the strict mode from the parent scope. strict_mode_ = outer_scope != NULL ? outer_scope->strict_mode_ : SLOPPY; outer_scope_calls_sloppy_eval_ = false; inner_scope_calls_eval_ = false; inner_scope_uses_this_ = false; inner_scope_uses_arguments_ = false; force_eager_compilation_ = false; force_context_allocation_ = (outer_scope != NULL && !is_function_scope()) ? outer_scope->has_forced_context_allocation() : false; num_var_or_const_ = 0; num_stack_slots_ = 0; num_heap_slots_ = 0; num_modules_ = 0; module_var_ = NULL, scope_info_ = scope_info; start_position_ = RelocInfo::kNoPosition; end_position_ = RelocInfo::kNoPosition; if (!scope_info.is_null()) { scope_calls_eval_ = scope_info->CallsEval(); strict_mode_ = scope_info->strict_mode(); } } Scope* Scope::DeserializeScopeChain(Context* context, Scope* global_scope, Zone* zone) { // 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->IsNativeContext()) { if (context->IsWithContext()) { Scope* with_scope = new(zone) Scope(current_scope, WITH_SCOPE, Handle::null(), global_scope->ast_value_factory_, zone); 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->IsGlobalContext()) { ScopeInfo* scope_info = ScopeInfo::cast(context->extension()); current_scope = new(zone) Scope(current_scope, GLOBAL_SCOPE, Handle(scope_info), global_scope->ast_value_factory_, zone); } else if (context->IsModuleContext()) { ScopeInfo* scope_info = ScopeInfo::cast(context->module()->scope_info()); current_scope = new(zone) Scope(current_scope, MODULE_SCOPE, Handle(scope_info), global_scope->ast_value_factory_, zone); } else if (context->IsFunctionContext()) { ScopeInfo* scope_info = context->closure()->shared()->scope_info(); current_scope = new(zone) Scope(current_scope, FUNCTION_SCOPE, Handle(scope_info), global_scope->ast_value_factory_, zone); if (scope_info->IsAsmFunction()) current_scope->asm_function_ = true; if (scope_info->IsAsmModule()) current_scope->asm_module_ = true; } else if (context->IsBlockContext()) { ScopeInfo* scope_info = ScopeInfo::cast(context->extension()); current_scope = new(zone) Scope(current_scope, BLOCK_SCOPE, Handle(scope_info), global_scope->ast_value_factory_, zone); } else { DCHECK(context->IsCatchContext()); String* name = String::cast(context->extension()); current_scope = new (zone) Scope( current_scope, global_scope->ast_value_factory_->GetString(Handle(name)), global_scope->ast_value_factory_, zone); } 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) { DCHECK(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(); } // Allocate the variables. { AstNodeFactory ast_node_factory(info->ast_value_factory()); if (!top->AllocateVariables(info, &ast_node_factory)) return false; } #ifdef DEBUG if (info->isolate()->bootstrapper()->IsActive() ? FLAG_print_builtin_scopes : FLAG_print_scopes) { scope->Print(); } if (FLAG_harmony_modules && FLAG_print_interfaces && top->is_global_scope()) { PrintF("global : "); top->interface()->Print(); } #endif info->PrepareForCompilation(scope); return true; } void Scope::Initialize() { DCHECK(!already_resolved()); // Add this scope as a new inner scope of the outer scope. if (outer_scope_ != NULL) { outer_scope_->inner_scopes_.Add(this, zone()); 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, ast_value_factory_->this_string(), VAR, false, Variable::THIS, kCreatedInitialized); var->AllocateTo(Variable::PARAMETER, -1); receiver_ = var; } else { DCHECK(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, ast_value_factory_->arguments_string(), VAR, true, Variable::ARGUMENTS, kCreatedInitialized); } } Scope* Scope::FinalizeBlockScope() { DCHECK(is_block_scope()); DCHECK(internals_.is_empty()); DCHECK(temps_.is_empty()); DCHECK(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], zone()); } return NULL; } Variable* Scope::LookupLocal(const AstRawString* name) { Variable* result = variables_.Lookup(name); if (result != NULL || scope_info_.is_null()) { return result; } // The Scope is backed up by ScopeInfo. This means it cannot operate in a // heap-independent mode, and all strings must be internalized immediately. So // it's ok to get the Handle here. Handle name_handle = name->string(); // If we have a serialized scope info, we might find the variable there. // There should be no local slot with the given name. DCHECK(scope_info_->StackSlotIndex(*name_handle) < 0); // Check context slot lookup. VariableMode mode; Variable::Location location = Variable::CONTEXT; InitializationFlag init_flag; MaybeAssignedFlag maybe_assigned_flag; int index = ScopeInfo::ContextSlotIndex(scope_info_, name_handle, &mode, &init_flag, &maybe_assigned_flag); if (index < 0) { // Check parameters. index = scope_info_->ParameterIndex(*name_handle); if (index < 0) return NULL; mode = DYNAMIC; location = Variable::LOOKUP; init_flag = kCreatedInitialized; // Be conservative and flag parameters as maybe assigned. Better information // would require ScopeInfo to serialize the maybe_assigned bit also for // parameters. maybe_assigned_flag = kMaybeAssigned; } Variable* var = variables_.Declare(this, name, mode, true, Variable::NORMAL, init_flag, maybe_assigned_flag); var->AllocateTo(location, index); return var; } Variable* Scope::LookupFunctionVar(const AstRawString* name, AstNodeFactory* factory) { if (function_ != NULL && function_->proxy()->raw_name() == name) { return function_->proxy()->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->string()), &mode); if (index < 0) return NULL; Variable* var = new(zone()) Variable( this, name, mode, true /* is valid LHS */, Variable::NORMAL, kCreatedInitialized); VariableProxy* proxy = factory->NewVariableProxy(var); VariableDeclaration* declaration = factory->NewVariableDeclaration( proxy, mode, this, RelocInfo::kNoPosition); DeclareFunctionVar(declaration); var->AllocateTo(Variable::CONTEXT, index); return var; } else { return NULL; } } Variable* Scope::Lookup(const AstRawString* name) { for (Scope* scope = this; scope != NULL; scope = scope->outer_scope()) { Variable* var = scope->LookupLocal(name); if (var != NULL) return var; } return NULL; } Variable* Scope::DeclareParameter(const AstRawString* name, VariableMode mode) { DCHECK(!already_resolved()); DCHECK(is_function_scope()); Variable* var = variables_.Declare(this, name, mode, true, Variable::NORMAL, kCreatedInitialized); params_.Add(var, zone()); return var; } Variable* Scope::DeclareLocal(const AstRawString* name, VariableMode mode, InitializationFlag init_flag, MaybeAssignedFlag maybe_assigned_flag, Interface* interface) { DCHECK(!already_resolved()); // This function handles VAR, LET, and CONST modes. DYNAMIC variables are // introduces during variable allocation, INTERNAL variables are allocated // explicitly, and TEMPORARY variables are allocated via NewTemporary(). DCHECK(IsDeclaredVariableMode(mode)); ++num_var_or_const_; return variables_.Declare(this, name, mode, true, Variable::NORMAL, init_flag, maybe_assigned_flag, interface); } Variable* Scope::DeclareDynamicGlobal(const AstRawString* name) { DCHECK(is_global_scope()); return variables_.Declare(this, name, DYNAMIC_GLOBAL, true, Variable::NORMAL, kCreatedInitialized); } 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::NewInternal(const AstRawString* name) { DCHECK(!already_resolved()); Variable* var = new(zone()) Variable(this, name, INTERNAL, false, Variable::NORMAL, kCreatedInitialized); internals_.Add(var, zone()); return var; } Variable* Scope::NewTemporary(const AstRawString* name) { DCHECK(!already_resolved()); Variable* var = new(zone()) Variable(this, name, TEMPORARY, true, Variable::NORMAL, kCreatedInitialized); temps_.Add(var, zone()); return var; } void Scope::AddDeclaration(Declaration* declaration) { decls_.Add(declaration, zone()); } void Scope::SetIllegalRedeclaration(Expression* expression) { // Record only the first illegal redeclaration. if (!HasIllegalRedeclaration()) { illegal_redecl_ = expression; } DCHECK(HasIllegalRedeclaration()); } void Scope::VisitIllegalRedeclaration(AstVisitor* visitor) { DCHECK(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; const AstRawString* name = decl->proxy()->raw_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; } class VarAndOrder { public: VarAndOrder(Variable* var, int order) : var_(var), order_(order) { } Variable* var() const { return var_; } int order() const { return order_; } static int Compare(const VarAndOrder* a, const VarAndOrder* b) { return a->order_ - b->order_; } private: Variable* var_; int order_; }; void Scope::CollectStackAndContextLocals(ZoneList* stack_locals, ZoneList* context_locals) { DCHECK(stack_locals != NULL); DCHECK(context_locals != NULL); // Collect internals which are always allocated on the heap. for (int i = 0; i < internals_.length(); i++) { Variable* var = internals_[i]; if (var->is_used()) { DCHECK(var->IsContextSlot()); context_locals->Add(var, zone()); } } // Collect temporaries which are always allocated on the stack, unless the // context as a whole has forced context allocation. for (int i = 0; i < temps_.length(); i++) { Variable* var = temps_[i]; if (var->is_used()) { if (var->IsContextSlot()) { DCHECK(has_forced_context_allocation()); context_locals->Add(var, zone()); } else { DCHECK(var->IsStackLocal()); stack_locals->Add(var, zone()); } } } // Collect declared local variables. ZoneList vars(variables_.occupancy(), zone()); for (VariableMap::Entry* p = variables_.Start(); p != NULL; p = variables_.Next(p)) { Variable* var = reinterpret_cast(p->value); if (var->is_used()) { vars.Add(VarAndOrder(var, p->order), zone()); } } vars.Sort(VarAndOrder::Compare); int var_count = vars.length(); for (int i = 0; i < var_count; i++) { Variable* var = vars[i].var(); if (var->IsStackLocal()) { stack_locals->Add(var, zone()); } else if (var->IsContextSlot()) { context_locals->Add(var, zone()); } } } bool Scope::AllocateVariables(CompilationInfo* info, AstNodeFactory* factory) { // 1) Propagate scope information. bool outer_scope_calls_sloppy_eval = false; if (outer_scope_ != NULL) { outer_scope_calls_sloppy_eval = outer_scope_->outer_scope_calls_sloppy_eval() | outer_scope_->calls_sloppy_eval(); } PropagateScopeInfo(outer_scope_calls_sloppy_eval); // 2) Allocate module instances. if (FLAG_harmony_modules && (is_global_scope() || is_module_scope())) { DCHECK(num_modules_ == 0); AllocateModulesRecursively(this); } // 3) Resolve variables. if (!ResolveVariablesRecursively(info, factory)) return false; // 4) Allocate variables. AllocateVariablesRecursively(); return true; } 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(); } bool Scope::HasLazyCompilableOuterContext() const { Scope* outer = outer_scope_; if (outer == NULL) return true; // We have to prevent lazy compilation if this scope is inside a with scope // and all declaration scopes between them have empty contexts. Such // declaration scopes may become invisible during scope info deserialization. outer = outer->DeclarationScope(); bool found_non_trivial_declarations = false; for (const Scope* scope = outer; scope != NULL; scope = scope->outer_scope_) { if (scope->is_with_scope() && !found_non_trivial_declarations) return false; if (scope->is_declaration_scope() && scope->num_heap_slots() > 0) { found_non_trivial_declarations = true; } } return true; } bool Scope::AllowsLazyCompilation() const { return !force_eager_compilation_ && HasLazyCompilableOuterContext(); } bool Scope::AllowsLazyCompilationWithoutContext() const { return !force_eager_compilation_ && HasTrivialOuterContext(); } int Scope::ContextChainLength(Scope* scope) { int n = 0; for (Scope* s = this; s != scope; s = s->outer_scope_) { DCHECK(s != NULL); // scope must be in the scope chain if (s->is_with_scope() || s->num_heap_slots() > 0) n++; // Catch and module scopes always have heap slots. DCHECK(!s->is_catch_scope() || s->num_heap_slots() > 0); DCHECK(!s->is_module_scope() || s->num_heap_slots() > 0); } return n; } Scope* Scope::GlobalScope() { Scope* scope = this; while (!scope->is_global_scope()) { scope = scope->outer_scope(); } return scope; } Scope* Scope::DeclarationScope() { Scope* scope = this; while (!scope->is_declaration_scope()) { scope = scope->outer_scope(); } return scope; } Handle Scope::GetScopeInfo() { if (scope_info_.is_null()) { scope_info_ = ScopeInfo::Create(this, zone()); } return scope_info_; } void Scope::GetNestedScopeChain( List >* chain, int position) { if (!is_eval_scope()) chain->Add(Handle(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(); DCHECK(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 scope_type) { switch (scope_type) { case EVAL_SCOPE: return "eval"; case FUNCTION_SCOPE: return "function"; case MODULE_SCOPE: return "module"; case GLOBAL_SCOPE: return "global"; case CATCH_SCOPE: return "catch"; case BLOCK_SCOPE: return "block"; case WITH_SCOPE: return "with"; case ARROW_SCOPE: return "arrow"; } UNREACHABLE(); return NULL; } static void Indent(int n, const char* str) { PrintF("%*s%s", n, "", str); } static void PrintName(const AstRawString* name) { PrintF("%.*s", name->length(), name->raw_data()); } 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->raw_name()); PrintF("; // "); PrintLocation(var); bool comma = !var->IsUnallocated(); if (var->has_forced_context_allocation()) { if (comma) PrintF(", "); PrintF("forced context allocation"); comma = true; } if (var->maybe_assigned() == kMaybeAssigned) { if (comma) PrintF(", "); PrintF("maybe assigned"); } 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(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(scope_type_)); if (!scope_name_->IsEmpty()) { 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]->raw_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_->proxy()->raw_name()); PrintF("\n"); } // Scope info. if (HasTrivialOuterContext()) { Indent(n1, "// scope has trivial outer context\n"); } if (strict_mode() == STRICT) { Indent(n1, "// strict mode scope\n"); } 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 (scope_uses_this_) Indent(n1, "// scope uses 'this'\n"); if (scope_uses_arguments_) Indent(n1, "// scope uses 'arguments'\n"); if (inner_scope_uses_this_) Indent(n1, "// inner scope uses 'this'\n"); if (inner_scope_uses_arguments_) { Indent(n1, "// inner scope uses 'arguments'\n"); } if (outer_scope_calls_sloppy_eval_) { Indent(n1, "// outer scope calls 'eval' in sloppy 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. if (function_ != NULL) { Indent(n1, "// function var:\n"); PrintVar(n1, function_->proxy()->var()); } if (temps_.length() > 0) { Indent(n1, "// temporary vars:\n"); for (int i = 0; i < temps_.length(); i++) { PrintVar(n1, temps_[i]); } } if (internals_.length() > 0) { Indent(n1, "// internal vars:\n"); for (int i = 0; i < internals_.length(); i++) { PrintVar(n1, internals_[i]); } } if (variables_.Start() != NULL) { Indent(n1, "// local vars:\n"); PrintMap(n1, &variables_); } if (dynamics_ != NULL) { Indent(n1, "// dynamic vars:\n"); 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(const AstRawString* name, VariableMode mode) { if (dynamics_ == NULL) dynamics_ = new (zone()) DynamicScopePart(zone()); 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(VariableProxy* proxy, BindingKind* binding_kind, AstNodeFactory* factory) { DCHECK(binding_kind != NULL); if (already_resolved() && is_with_scope()) { // Short-cut: if the scope is deserialized from a scope info, variable // allocation is already fixed. We can simply return with dynamic lookup. *binding_kind = DYNAMIC_LOOKUP; return NULL; } // Try to find the variable in this scope. Variable* var = LookupLocal(proxy->raw_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(proxy->raw_name(), factory); if (var != NULL) { *binding_kind = BOUND; } else if (outer_scope_ != NULL) { var = outer_scope_->LookupRecursive(proxy, binding_kind, factory); if (*binding_kind == BOUND && (is_function_scope() || is_with_scope())) { var->ForceContextAllocation(); } } else { DCHECK(is_global_scope()); } if (is_with_scope()) { DCHECK(!already_resolved()); // 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). if (var != NULL && proxy->is_assigned()) var->set_maybe_assigned(); *binding_kind = DYNAMIC_LOOKUP; return NULL; } else if (calls_sloppy_eval()) { // A variable binding may have been found in an outer scope, but the current // scope makes a sloppy '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; } bool Scope::ResolveVariable(CompilationInfo* info, VariableProxy* proxy, AstNodeFactory* factory) { DCHECK(info->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->is_resolved()) return true; // Otherwise, try to resolve the variable. BindingKind binding_kind; Variable* var = LookupRecursive(proxy, &binding_kind, factory); switch (binding_kind) { case BOUND: // We found a variable binding. break; case BOUND_EVAL_SHADOWED: // We either found a variable binding that might be shadowed by eval or // gave up on it (e.g. by encountering a local with the same in the outer // scope which was not promoted to a context, this can happen if we use // debugger to evaluate arbitrary expressions at a break point). if (var->IsGlobalObjectProperty()) { var = NonLocal(proxy->raw_name(), DYNAMIC_GLOBAL); } else if (var->is_dynamic()) { var = NonLocal(proxy->raw_name(), DYNAMIC); } else { Variable* invalidated = var; var = NonLocal(proxy->raw_name(), DYNAMIC_LOCAL); var->set_local_if_not_shadowed(invalidated); } break; case UNBOUND: // No binding has been found. Declare a variable on the global object. var = info->global_scope()->DeclareDynamicGlobal(proxy->raw_name()); break; case UNBOUND_EVAL_SHADOWED: // No binding has been found. But some scope makes a sloppy 'eval' call. var = NonLocal(proxy->raw_name(), DYNAMIC_GLOBAL); break; case DYNAMIC_LOOKUP: // The variable could not be resolved statically. var = NonLocal(proxy->raw_name(), DYNAMIC); break; } DCHECK(var != NULL); if (proxy->is_assigned()) var->set_maybe_assigned(); if (FLAG_harmony_scoping && strict_mode() == STRICT && var->is_const_mode() && proxy->is_assigned()) { // Assignment to const. Throw a syntax error. MessageLocation location( info->script(), proxy->position(), proxy->position()); Isolate* isolate = info->isolate(); Factory* factory = isolate->factory(); Handle array = factory->NewJSArray(0); Handle error; MaybeHandle maybe_error = factory->NewSyntaxError("harmony_const_assign", array); if (maybe_error.ToHandle(&error)) isolate->Throw(*error, &location); return false; } if (FLAG_harmony_modules) { bool ok; #ifdef DEBUG if (FLAG_print_interface_details) { PrintF("# Resolve %.*s:\n", var->raw_name()->length(), var->raw_name()->raw_data()); } #endif proxy->interface()->Unify(var->interface(), zone(), &ok); if (!ok) { #ifdef DEBUG if (FLAG_print_interfaces) { PrintF("SCOPES TYPE ERROR\n"); PrintF("proxy: "); proxy->interface()->Print(); PrintF("var: "); var->interface()->Print(); } #endif // Inconsistent use of module. Throw a syntax error. // TODO(rossberg): generate more helpful error message. MessageLocation location( info->script(), proxy->position(), proxy->position()); Isolate* isolate = info->isolate(); Factory* factory = isolate->factory(); Handle array = factory->NewJSArray(1); JSObject::SetElement(array, 0, var->name(), NONE, STRICT).Assert(); Handle error; MaybeHandle maybe_error = factory->NewSyntaxError("module_type_error", array); if (maybe_error.ToHandle(&error)) isolate->Throw(*error, &location); return false; } } proxy->BindTo(var); return true; } bool Scope::ResolveVariablesRecursively( CompilationInfo* info, AstNodeFactory* factory) { DCHECK(info->global_scope()->is_global_scope()); // Resolve unresolved variables for this scope. for (int i = 0; i < unresolved_.length(); i++) { if (!ResolveVariable(info, unresolved_[i], factory)) return false; } // Resolve unresolved variables for inner scopes. for (int i = 0; i < inner_scopes_.length(); i++) { if (!inner_scopes_[i]->ResolveVariablesRecursively(info, factory)) return false; } return true; } void Scope::PropagateScopeInfo(bool outer_scope_calls_sloppy_eval ) { if (outer_scope_calls_sloppy_eval) { outer_scope_calls_sloppy_eval_ = true; } bool calls_sloppy_eval = this->calls_sloppy_eval() || outer_scope_calls_sloppy_eval_; for (int i = 0; i < inner_scopes_.length(); i++) { Scope* inner = inner_scopes_[i]; inner->PropagateScopeInfo(calls_sloppy_eval); if (inner->scope_calls_eval_ || inner->inner_scope_calls_eval_) { inner_scope_calls_eval_ = true; } // If the inner scope is an arrow function, propagate the flags tracking // usage of this/arguments, but do not propagate them out from normal // functions. if (!inner->is_function_scope() || inner->is_arrow_scope()) { if (inner->scope_uses_this_ || inner->inner_scope_uses_this_) { inner_scope_uses_this_ = true; } if (inner->scope_uses_arguments_ || inner->inner_scope_uses_arguments_) { inner_scope_uses_arguments_ = true; } } if (inner->force_eager_compilation_) { force_eager_compilation_ = true; } if (asm_module_ && inner->scope_type() == FUNCTION_SCOPE) { inner->asm_function_ = true; } } } 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->raw_name()->IsEmpty()) && (var->has_forced_context_allocation() || scope_calls_eval_ || inner_scope_calls_eval_ || scope_contains_with_ || is_catch_scope() || is_block_scope() || is_module_scope() || is_global_scope())) { var->set_is_used(); if (scope_calls_eval_ || inner_scope_calls_eval_) var->set_maybe_assigned(); } // Global variables do not need to be allocated. return !var->IsGlobalObjectProperty() && 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: If the scope as a whole has forced context allocation, all // variables will have context allocation, even temporaries. Otherwise // temporary variables are always stack-allocated. Catch-bound variables are // always context-allocated. if (has_forced_context_allocation()) return true; if (var->mode() == TEMPORARY) return false; if (var->mode() == INTERNAL) return true; if (is_catch_scope() || is_block_scope() || is_module_scope()) return true; if (is_global_scope() && IsLexicalVariableMode(var->mode())) return true; return var->has_forced_context_allocation() || scope_calls_eval_ || inner_scope_calls_eval_ || scope_contains_with_; } bool Scope::HasArgumentsParameter() { for (int i = 0; i < params_.length(); i++) { if (params_[i]->name().is_identical_to( isolate_->factory()->arguments_string())) { 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() { DCHECK(is_function_scope()); Variable* arguments = LookupLocal(ast_value_factory_->arguments_string()); DCHECK(arguments != NULL); // functions have 'arguments' declared implicitly bool uses_sloppy_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_sloppy_arguments = strict_mode() == SLOPPY; } // 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]; DCHECK(var->scope() == this); if (uses_sloppy_arguments || has_forced_context_allocation()) { // Force context allocation of the parameter. var->ForceContextAllocation(); } if (MustAllocate(var)) { if (MustAllocateInContext(var)) { DCHECK(var->IsUnallocated() || var->IsContextSlot()); if (var->IsUnallocated()) { AllocateHeapSlot(var); } } else { DCHECK(var->IsUnallocated() || var->IsParameter()); if (var->IsUnallocated()) { var->AllocateTo(Variable::PARAMETER, i); } } } } } void Scope::AllocateNonParameterLocal(Variable* var) { DCHECK(var->scope() == this); DCHECK(!var->IsVariable(isolate_->factory()->dot_result_string()) || !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 (int i = 0; i < internals_.length(); i++) { AllocateNonParameterLocal(internals_[i]); } ZoneList vars(variables_.occupancy(), zone()); for (VariableMap::Entry* p = variables_.Start(); p != NULL; p = variables_.Next(p)) { Variable* var = reinterpret_cast(p->value); vars.Add(VarAndOrder(var, p->order), zone()); } vars.Sort(VarAndOrder::Compare); int var_count = vars.length(); for (int i = 0; i < var_count; i++) { AllocateNonParameterLocal(vars[i].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_->proxy()->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. // Likewise for modules. bool must_have_context = is_with_scope() || is_module_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. DCHECK(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS); } void Scope::AllocateModulesRecursively(Scope* host_scope) { if (already_resolved()) return; if (is_module_scope()) { DCHECK(interface_->IsFrozen()); DCHECK(module_var_ == NULL); module_var_ = host_scope->NewInternal(ast_value_factory_->dot_module_string()); ++host_scope->num_modules_; } for (int i = 0; i < inner_scopes_.length(); i++) { Scope* inner_scope = inner_scopes_.at(i); inner_scope->AllocateModulesRecursively(host_scope); } } int Scope::StackLocalCount() const { return num_stack_slots() - (function_ != NULL && function_->proxy()->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_->proxy()->var()->IsContextSlot() ? 1 : 0); } } } // namespace v8::internal