| // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file | 
 | // for details. All rights reserved. Use of this source code is governed by a | 
 | // BSD-style license that can be found in the LICENSE file. | 
 | #if !defined(DART_PRECOMPILED_RUNTIME) | 
 |  | 
 | #include "vm/scopes.h" | 
 |  | 
 | #include "vm/compiler/backend/slot.h" | 
 | #include "vm/kernel.h" | 
 | #include "vm/object.h" | 
 | #include "vm/stack_frame.h" | 
 | #include "vm/symbols.h" | 
 |  | 
 | namespace dart { | 
 |  | 
 | DEFINE_FLAG(bool, | 
 |             share_enclosing_context, | 
 |             true, | 
 |             "Allocate captured variables in the existing context of an " | 
 |             "enclosing scope (up to innermost loop) and spare the allocation " | 
 |             "of a local context."); | 
 |  | 
 | LocalScope::LocalScope(LocalScope* parent, int function_level, int loop_level) | 
 |     : parent_(parent), | 
 |       child_(nullptr), | 
 |       sibling_(nullptr), | 
 |       function_level_(function_level), | 
 |       loop_level_(loop_level), | 
 |       context_level_(LocalScope::kUninitializedContextLevel), | 
 |       begin_token_pos_(TokenPosition::kNoSource), | 
 |       end_token_pos_(TokenPosition::kNoSource), | 
 |       variables_(), | 
 |       context_variables_(), | 
 |       context_slots_(new(Thread::Current()->zone()) | 
 |                          ZoneGrowableArray<const Slot*>()) { | 
 |   // Hook this node into the children of the parent, unless the parent has a | 
 |   // different function_level, since the local scope of a nested function can | 
 |   // be discarded after it has been parsed. | 
 |   if ((parent != nullptr) && (parent->function_level() == function_level)) { | 
 |     sibling_ = parent->child_; | 
 |     parent->child_ = this; | 
 |   } | 
 | } | 
 |  | 
 | bool LocalScope::IsNestedWithin(LocalScope* scope) const { | 
 |   const LocalScope* current_scope = this; | 
 |   while (current_scope != nullptr) { | 
 |     if (current_scope == scope) { | 
 |       return true; | 
 |     } | 
 |     current_scope = current_scope->parent(); | 
 |   } | 
 |   return false; | 
 | } | 
 |  | 
 | bool LocalScope::AddVariable(LocalVariable* variable) { | 
 |   ASSERT(variable != nullptr); | 
 |   if (LocalLookupVariable(variable->name(), variable->kernel_offset()) != | 
 |       nullptr) { | 
 |     return false; | 
 |   } | 
 |   variables_.Add(variable); | 
 |   if (variable->owner() == nullptr) { | 
 |     // Variables must be added to their owner scope first. Subsequent calls | 
 |     // to 'add' treat the variable as an alias. | 
 |     variable->set_owner(this); | 
 |   } | 
 |   return true; | 
 | } | 
 |  | 
 | bool LocalScope::InsertParameterAt(intptr_t pos, LocalVariable* parameter) { | 
 |   ASSERT(parameter != nullptr); | 
 |   if (LocalLookupVariable(parameter->name(), parameter->kernel_offset()) != | 
 |       nullptr) { | 
 |     return false; | 
 |   } | 
 |   variables_.InsertAt(pos, parameter); | 
 |   // InsertParameterAt is not used to add aliases of parameters. | 
 |   ASSERT(parameter->owner() == nullptr); | 
 |   parameter->set_owner(this); | 
 |   return true; | 
 | } | 
 |  | 
 | void LocalScope::AllocateContextVariable(LocalVariable* variable, | 
 |                                          LocalScope** context_owner) { | 
 |   ASSERT(variable->is_captured()); | 
 |   ASSERT(variable->owner() == this); | 
 |   // The context level in the owner scope of a captured variable indicates at | 
 |   // code generation time how far to walk up the context chain in order to | 
 |   // access the variable from the current context level. | 
 |   if ((*context_owner) == nullptr) { | 
 |     ASSERT(num_context_variables() == 0); | 
 |     // This scope becomes the current context owner. | 
 |     set_context_level(1); | 
 |     *context_owner = this; | 
 |   } else if (!FLAG_share_enclosing_context && ((*context_owner) != this)) { | 
 |     // The captured variable is in a child scope of the context owner and we do | 
 |     // not share contexts. | 
 |     // This scope will allocate and chain a new context. | 
 |     ASSERT(num_context_variables() == 0); | 
 |     // This scope becomes the current context owner. | 
 |     set_context_level((*context_owner)->context_level() + 1); | 
 |     *context_owner = this; | 
 |   } else if ((*context_owner)->loop_level() < loop_level()) { | 
 |     ASSERT(FLAG_share_enclosing_context); | 
 |     // The captured variable is at a deeper loop level than the current context. | 
 |     // This scope will allocate and chain a new context. | 
 |     ASSERT(num_context_variables() == 0); | 
 |     // This scope becomes the current context owner. | 
 |     set_context_level((*context_owner)->context_level() + 1); | 
 |     *context_owner = this; | 
 |   } else { | 
 |     // Allocate the captured variable in the current context. | 
 |     if (!HasContextLevel()) { | 
 |       ASSERT(variable->owner() != *context_owner); | 
 |       set_context_level((*context_owner)->context_level()); | 
 |     } else { | 
 |       ASSERT(context_level() == (*context_owner)->context_level()); | 
 |     } | 
 |   } | 
 |  | 
 |   (*context_owner)->AddContextVariable(variable); | 
 | } | 
 |  | 
 | void LocalScope::AddContextVariable(LocalVariable* variable) { | 
 |   variable->set_index(VariableIndex(context_variables_.length())); | 
 |   context_variables_.Add(variable); | 
 |   context_slots_->Add( | 
 |       &Slot::GetContextVariableSlotFor(Thread::Current(), *variable)); | 
 | } | 
 |  | 
 | VariableIndex LocalScope::AllocateVariables(const Function& function, | 
 |                                             VariableIndex first_parameter_index, | 
 |                                             int num_parameters, | 
 |                                             VariableIndex first_local_index, | 
 |                                             LocalScope* context_owner, | 
 |                                             bool* found_captured_variables) { | 
 |   // We should not allocate variables of nested functions while compiling an | 
 |   // enclosing function. | 
 |   ASSERT(function_level() == 0); | 
 |   ASSERT(num_parameters >= 0); | 
 |   // Parameters must be listed first and must all appear in the top scope. | 
 |   ASSERT(num_parameters <= num_variables()); | 
 |   int pos = 0;  // Current variable position. | 
 |   VariableIndex next_index = | 
 |       first_parameter_index;  // Current free frame index. | 
 |  | 
 |   LocalVariable* suspend_state_var = nullptr; | 
 |   for (intptr_t i = 0; i < num_variables(); i++) { | 
 |     LocalVariable* variable = VariableAt(i); | 
 |     if (variable->owner() == this && | 
 |         variable->name().Equals(Symbols::SuspendStateVar())) { | 
 |       ASSERT(!variable->is_captured()); | 
 |       suspend_state_var = variable; | 
 |     } | 
 |   } | 
 |  | 
 |   if (suspend_state_var != nullptr) { | 
 |     suspend_state_var->set_index( | 
 |         VariableIndex(SuspendState::kSuspendStateVarIndex)); | 
 |     ASSERT(next_index.value() == SuspendState::kSuspendStateVarIndex - 1); | 
 |   } | 
 |  | 
 |   while (pos < num_parameters) { | 
 |     LocalVariable* parameter = VariableAt(pos); | 
 |     pos++; | 
 |     // Parsing formal parameter default values may add local variable aliases | 
 |     // to the local scope before the formal parameters are added. However, | 
 |     // the parameters get inserted in front of the aliases, therefore, no | 
 |     // aliases can be encountered among the first num_parameters variables. | 
 |     ASSERT(parameter->owner() == this); | 
 |     if (parameter->is_captured()) { | 
 |       // A captured parameter has a slot allocated in the frame and one in the | 
 |       // context, where it gets copied to. The parameter index reflects the | 
 |       // context allocation index. | 
 |       next_index = VariableIndex(next_index.value() - 1); | 
 |       AllocateContextVariable(parameter, &context_owner); | 
 |       *found_captured_variables = true; | 
 |     } else { | 
 |       parameter->set_index(next_index); | 
 |       next_index = VariableIndex(next_index.value() - 1); | 
 |     } | 
 |   } | 
 |   // No overlapping of parameters and locals. | 
 |   ASSERT(next_index.value() >= first_local_index.value()); | 
 |   next_index = first_local_index; | 
 |   for (; pos < num_variables(); pos++) { | 
 |     LocalVariable* variable = VariableAt(pos); | 
 |     if (variable == suspend_state_var) { | 
 |       continue; | 
 |     } | 
 |  | 
 |     if (variable->owner() == this) { | 
 |       if (variable->is_captured()) { | 
 |         AllocateContextVariable(variable, &context_owner); | 
 |         *found_captured_variables = true; | 
 |       } else { | 
 |         variable->set_index(next_index); | 
 |         next_index = VariableIndex(next_index.value() - 1); | 
 |       } | 
 |     } | 
 |   } | 
 |   // Allocate variables of all children. | 
 |   VariableIndex min_index = next_index; | 
 |   LocalScope* child = this->child(); | 
 |   while (child != nullptr) { | 
 |     // Ignored, since no parameters. | 
 |     const VariableIndex dummy_parameter_index(0); | 
 |  | 
 |     // No parameters in children scopes. | 
 |     const int num_parameters_in_child = 0; | 
 |     VariableIndex child_next_index = child->AllocateVariables( | 
 |         function, dummy_parameter_index, num_parameters_in_child, next_index, | 
 |         context_owner, found_captured_variables); | 
 |     if (child_next_index.value() < min_index.value()) { | 
 |       min_index = child_next_index; | 
 |     } | 
 |     child = child->sibling(); | 
 |   } | 
 |   return min_index; | 
 | } | 
 |  | 
 | LocalVariable::LocalVariable(TokenPosition declaration_pos, | 
 |                              TokenPosition token_pos, | 
 |                              const String& name, | 
 |                              const AbstractType& static_type, | 
 |                              intptr_t kernel_offset) | 
 |     : LocalVariable(declaration_pos, | 
 |                     token_pos, | 
 |                     name, | 
 |                     static_type, | 
 |                     kernel_offset, | 
 |                     new CompileType(CompileType::FromAbstractType( | 
 |                         static_type, | 
 |                         CompileType::kCanBeNull, | 
 |                         CompileType::kCannotBeSentinel))) {} | 
 |  | 
 | // The VM creates synthetic variables that start with ":" and the CFE creates | 
 | // synthetic variables with no name. | 
 | bool LocalVariable::IsFilteredIdentifier(const String& name) { | 
 |   if (name.ptr() == Symbols::Empty().ptr()) { | 
 |     return true; | 
 |   } | 
 |   if (name.ptr() == Symbols::FunctionTypeArgumentsVar().ptr()) { | 
 |     // Keep :function_type_arguments for accessing type variables in debugging. | 
 |     return false; | 
 |   } | 
 |   return name.CharAt(0) == ':'; | 
 | } | 
 |  | 
 | LocalVarDescriptorsPtr LocalScope::GetVarDescriptors( | 
 |     const Function& func, | 
 |     ZoneGrowableArray<intptr_t>* context_level_array) { | 
 |   LocalVarDescriptorsBuilder vars; | 
 |   vars.AddDeoptIdToContextLevelMappings(context_level_array); | 
 |  | 
 |   // First enter all variables from scopes of outer functions. | 
 |   const ContextScope& context_scope = | 
 |       ContextScope::Handle(func.context_scope()); | 
 |   if (!context_scope.IsNull()) { | 
 |     ASSERT(func.HasParent()); | 
 |     for (int i = 0; i < context_scope.num_variables(); i++) { | 
 |       if (context_scope.IsInvisibleAt(i)) { | 
 |         continue; | 
 |       } | 
 |       String& name = String::Handle(context_scope.NameAt(i)); | 
 |       ASSERT(!LocalVariable::IsFilteredIdentifier(name)); | 
 |  | 
 |       LocalVarDescriptorsBuilder::VarDesc desc; | 
 |       desc.name = &name; | 
 |       desc.info.set_kind(UntaggedLocalVarDescriptors::kContextVar); | 
 |       desc.info.scope_id = context_scope.ContextLevelAt(i); | 
 |       desc.info.declaration_pos = context_scope.DeclarationTokenIndexAt(i); | 
 |       desc.info.begin_pos = begin_token_pos(); | 
 |       desc.info.end_pos = end_token_pos(); | 
 |       ASSERT((desc.info.begin_pos.IsReal() != desc.info.end_pos.IsReal()) || | 
 |              (desc.info.begin_pos <= desc.info.end_pos)); | 
 |       desc.info.set_index(context_scope.ContextIndexAt(i)); | 
 |       vars.Add(desc); | 
 |     } | 
 |   } | 
 |   // Now collect all variables from local scopes. | 
 |   int16_t scope_id = 0; | 
 |   CollectLocalVariables(&vars, &scope_id); | 
 |  | 
 |   return vars.Done(); | 
 | } | 
 |  | 
 | // Add visible variables that are declared in this scope to vars, then | 
 | // collect visible variables of children, followed by siblings. | 
 | void LocalScope::CollectLocalVariables(LocalVarDescriptorsBuilder* vars, | 
 |                                        int16_t* scope_id) { | 
 |   (*scope_id)++; | 
 |   for (int i = 0; i < this->variables_.length(); i++) { | 
 |     LocalVariable* var = variables_[i]; | 
 |     if (var->owner() == this) { | 
 |       if (var->name().ptr() == Symbols::CurrentContextVar().ptr()) { | 
 |         // This is the local variable in which the function saves its | 
 |         // own context before calling a closure function. | 
 |         LocalVarDescriptorsBuilder::VarDesc desc; | 
 |         desc.name = &var->name(); | 
 |         desc.info.set_kind(UntaggedLocalVarDescriptors::kSavedCurrentContext); | 
 |         desc.info.scope_id = 0; | 
 |         desc.info.declaration_pos = TokenPosition::kMinSource; | 
 |         desc.info.begin_pos = TokenPosition::kMinSource; | 
 |         desc.info.end_pos = TokenPosition::kMinSource; | 
 |         desc.info.set_index(var->index().value()); | 
 |         vars->Add(desc); | 
 |       } else if (!var->is_invisible()) { | 
 |         ASSERT(!LocalVariable::IsFilteredIdentifier(var->name())); | 
 |         // This is a regular Dart variable, either stack-based or captured. | 
 |         LocalVarDescriptorsBuilder::VarDesc desc; | 
 |         desc.name = &var->name(); | 
 |         if (var->is_captured()) { | 
 |           desc.info.set_kind(UntaggedLocalVarDescriptors::kContextVar); | 
 |           ASSERT(var->owner() != nullptr); | 
 |           ASSERT(var->owner()->context_level() >= 0); | 
 |           desc.info.scope_id = var->owner()->context_level(); | 
 |         } else { | 
 |           desc.info.set_kind(UntaggedLocalVarDescriptors::kStackVar); | 
 |           desc.info.scope_id = *scope_id; | 
 |         } | 
 |         desc.info.set_index(var->index().value()); | 
 |         desc.info.declaration_pos = var->declaration_token_pos(); | 
 |         desc.info.begin_pos = var->token_pos(); | 
 |         desc.info.end_pos = var->owner()->end_token_pos(); | 
 |         vars->Add(desc); | 
 |       } | 
 |     } | 
 |   } | 
 |   LocalScope* child = this->child(); | 
 |   while (child != nullptr) { | 
 |     child->CollectLocalVariables(vars, scope_id); | 
 |     child = child->sibling(); | 
 |   } | 
 | } | 
 |  | 
 | LocalVariable* LocalScope::LocalLookupVariable(const String& name, | 
 |                                                intptr_t kernel_offset) const { | 
 |   ASSERT(name.IsNull() || name.IsSymbol()); | 
 |   for (intptr_t i = 0; i < variables_.length(); i++) { | 
 |     LocalVariable* var = variables_[i]; | 
 |     if (var->kernel_offset() == kernel_offset) { | 
 |       if (kernel_offset != LocalVariable::kNoKernelOffset) { | 
 |         // Variable from kernel. | 
 |         return var; | 
 |       } else { | 
 |         // Synthetic variable from the VM. | 
 |         ASSERT(kernel_offset == LocalVariable::kNoKernelOffset); | 
 |         ASSERT(name.IsSymbol()); | 
 |         ASSERT(var->name().IsSymbol()); | 
 |         if (var->name().ptr() == name.ptr()) { | 
 |           return var; | 
 |         } | 
 |       } | 
 |     } | 
 |   } | 
 |   return nullptr; | 
 | } | 
 |  | 
 | LocalVariable* LocalScope::LookupVariable(const String& name, | 
 |                                           intptr_t kernel_offset, | 
 |                                           bool test_only) { | 
 |   LocalScope* current_scope = this; | 
 |   while (current_scope != nullptr) { | 
 |     LocalVariable* var = | 
 |         current_scope->LocalLookupVariable(name, kernel_offset); | 
 |     // If testing only, return the variable even if invisible. | 
 |     if ((var != nullptr) && (!var->is_invisible() || test_only)) { | 
 |       if (!test_only && (var->owner()->function_level() != function_level())) { | 
 |         CaptureVariable(var); | 
 |       } | 
 |       return var; | 
 |     } | 
 |     current_scope = current_scope->parent(); | 
 |   } | 
 |   return nullptr; | 
 | } | 
 |  | 
 | LocalVariable* LocalScope::LookupVariableByName(const String& name) { | 
 |   ASSERT(name.IsSymbol()); | 
 |   for (LocalScope* scope = this; scope != nullptr; scope = scope->parent()) { | 
 |     for (intptr_t i = 0, n = scope->variables_.length(); i < n; ++i) { | 
 |       LocalVariable* var = scope->variables_[i]; | 
 |       ASSERT(var->name().IsSymbol()); | 
 |       if (var->name().ptr() == name.ptr()) { | 
 |         return var; | 
 |       } | 
 |     } | 
 |   } | 
 |   return nullptr; | 
 | } | 
 |  | 
 | void LocalScope::CaptureVariable(LocalVariable* variable) { | 
 |   ASSERT(variable != nullptr); | 
 |  | 
 |   // The variable must exist in an enclosing scope, not necessarily in this one. | 
 |   variable->set_is_captured(); | 
 |   const int variable_function_level = variable->owner()->function_level(); | 
 |   LocalScope* scope = this; | 
 |   while (scope->function_level() != variable_function_level) { | 
 |     // Insert an alias of the variable in the top scope of each function | 
 |     // level so that the variable is found in the context. | 
 |     LocalScope* parent_scope = scope->parent(); | 
 |     while ((parent_scope != nullptr) && | 
 |            (parent_scope->function_level() == scope->function_level())) { | 
 |       scope = parent_scope; | 
 |       parent_scope = scope->parent(); | 
 |     } | 
 |     // An alias may already have been added in this scope, and in that case, | 
 |     // in parent scopes as needed. If so, we are done. | 
 |     if (!scope->AddVariable(variable)) { | 
 |       return; | 
 |     } | 
 |     ASSERT(variable->owner() != scope);  // Item is an alias. | 
 |     scope = parent_scope; | 
 |   } | 
 | } | 
 |  | 
 | int LocalScope::NumCapturedVariables() const { | 
 |   // It is not necessary to traverse parent scopes, since we are only interested | 
 |   // in the captured variables referenced in this scope. If this scope is the | 
 |   // top scope at function level 1 and it (or its children scopes) references a | 
 |   // captured variable declared in a parent scope at function level 0, it will | 
 |   // contain an alias for that variable. | 
 |  | 
 |   // Since code generation for nested functions is postponed until first | 
 |   // invocation, the function level of the closure scope can only be 1. | 
 |   ASSERT(function_level() == 1); | 
 |  | 
 |   int num_captured = 0; | 
 |   for (int i = 0; i < num_variables(); i++) { | 
 |     LocalVariable* variable = VariableAt(i); | 
 |     // Count the aliases of captured variables belonging to outer scopes. | 
 |     if (variable->owner()->function_level() != 1) { | 
 |       ASSERT(variable->is_captured()); | 
 |       ASSERT(variable->owner()->function_level() == 0); | 
 |       num_captured++; | 
 |     } | 
 |   } | 
 |   return num_captured; | 
 | } | 
 |  | 
 | ContextScopePtr LocalScope::PreserveOuterScope( | 
 |     const Function& function, | 
 |     intptr_t current_context_level) const { | 
 |   Zone* zone = Thread::Current()->zone(); | 
 |   auto& library = Library::Handle( | 
 |       zone, function.IsNull() | 
 |                 ? Library::null() | 
 |                 : Class::Handle(zone, function.Owner()).library()); | 
 |   // Since code generation for nested functions is postponed until first | 
 |   // invocation, the function level of the closure scope can only be 1. | 
 |   ASSERT(function_level() == 1); | 
 |  | 
 |   // Count the number of referenced captured variables. | 
 |   intptr_t num_captured_vars = NumCapturedVariables(); | 
 |  | 
 |   // Create a ContextScope with space for num_captured_vars descriptors. | 
 |   const ContextScope& context_scope = | 
 |       ContextScope::Handle(ContextScope::New(num_captured_vars, false)); | 
 |  | 
 |   LocalVariable* awaiter_link = nullptr; | 
 |  | 
 |   // Create a descriptor for each referenced captured variable of enclosing | 
 |   // functions to preserve its name and its context allocation information. | 
 |   int captured_idx = 0; | 
 |   for (int i = 0; i < num_variables(); i++) { | 
 |     LocalVariable* variable = VariableAt(i); | 
 |     // Preserve the aliases of captured variables belonging to outer scopes. | 
 |     if (variable->owner()->function_level() != 1) { | 
 |       context_scope.SetTokenIndexAt(captured_idx, variable->token_pos()); | 
 |       context_scope.SetDeclarationTokenIndexAt( | 
 |           captured_idx, variable->declaration_token_pos()); | 
 |       context_scope.SetNameAt(captured_idx, variable->name()); | 
 |       context_scope.ClearFlagsAt(captured_idx); | 
 |       context_scope.SetIsFinalAt(captured_idx, variable->is_final()); | 
 |       context_scope.SetIsLateAt(captured_idx, variable->is_late()); | 
 |       if (variable->is_late()) { | 
 |         context_scope.SetLateInitOffsetAt(captured_idx, | 
 |                                           variable->late_init_offset()); | 
 |       } | 
 |       CompileType* type = variable->inferred_type(); | 
 |       context_scope.SetTypeAt(captured_idx, *type->ToAbstractType()); | 
 |       context_scope.SetCidAt(captured_idx, type->ToNullableCid()); | 
 |       context_scope.SetIsNullableAt(captured_idx, type->is_nullable()); | 
 |       context_scope.SetIsInvisibleAt(captured_idx, variable->is_invisible()); | 
 |       context_scope.SetContextIndexAt(captured_idx, variable->index().value()); | 
 |       // Adjust the context level relative to the current context level, | 
 |       // since the context of the current scope will be at level 0 when | 
 |       // compiling the nested function. | 
 |       intptr_t adjusted_context_level = | 
 |           variable->owner()->context_level() - current_context_level; | 
 |       context_scope.SetContextLevelAt(captured_idx, adjusted_context_level); | 
 |       context_scope.SetKernelOffsetAt(captured_idx, variable->kernel_offset()); | 
 |  | 
 |       // Handle async frame link. | 
 |       const bool is_awaiter_link = variable->ComputeIfIsAwaiterLink(library); | 
 |       context_scope.SetIsAwaiterLinkAt(captured_idx, is_awaiter_link); | 
 |       if (is_awaiter_link) { | 
 |         awaiter_link = variable; | 
 |       } | 
 |       captured_idx++; | 
 |     } | 
 |   } | 
 |   ASSERT(context_scope.num_variables() == captured_idx);  // Verify count. | 
 |  | 
 |   if (awaiter_link != nullptr) { | 
 |     const intptr_t depth = | 
 |         current_context_level - awaiter_link->owner()->context_level(); | 
 |     const intptr_t index = awaiter_link->index().value(); | 
 |     if (Utils::IsUint(8, depth) && Utils::IsUint(8, index)) { | 
 |       function.set_awaiter_link( | 
 |           {static_cast<uint8_t>(depth), static_cast<uint8_t>(index)}); | 
 |     } else if (FLAG_precompiled_mode) { | 
 |       OS::PrintErr( | 
 |           "Warning: @pragma('vm:awaiter-link') marked variable %s is visible " | 
 |           "from the function %s but the link {%" Pd ", %" Pd | 
 |           "} can't be encoded\n", | 
 |           awaiter_link->name().ToCString(), | 
 |           function.IsNull() ? "<?>" : function.ToFullyQualifiedCString(), depth, | 
 |           index); | 
 |     } | 
 |   } | 
 |  | 
 |   return context_scope.ptr(); | 
 | } | 
 |  | 
 | LocalScope* LocalScope::RestoreOuterScope(const ContextScope& context_scope) { | 
 |   // The function level of the outer scope is one less than the function level | 
 |   // of the current function, which is 0. | 
 |   LocalScope* outer_scope = new LocalScope(nullptr, -1, 0); | 
 |   // Add all variables as aliases to the outer scope. | 
 |   for (int i = 0; i < context_scope.num_variables(); i++) { | 
 |     const bool is_late = context_scope.IsLateAt(i); | 
 |     const auto& static_type = AbstractType::ZoneHandle(context_scope.TypeAt(i)); | 
 |     CompileType* inferred_type = | 
 |         new CompileType(context_scope.IsNullableAt(i), is_late, | 
 |                         context_scope.CidAt(i), &static_type); | 
 |     LocalVariable* variable = new LocalVariable( | 
 |         context_scope.DeclarationTokenIndexAt(i), context_scope.TokenIndexAt(i), | 
 |         String::ZoneHandle(context_scope.NameAt(i)), static_type, | 
 |         context_scope.KernelOffsetAt(i), inferred_type); | 
 |     variable->set_is_awaiter_link(context_scope.IsAwaiterLinkAt(i)); | 
 |     variable->set_is_captured(); | 
 |     variable->set_index(VariableIndex(context_scope.ContextIndexAt(i))); | 
 |     if (context_scope.IsFinalAt(i)) { | 
 |       variable->set_is_final(); | 
 |     } | 
 |     if (is_late) { | 
 |       variable->set_is_late(); | 
 |       variable->set_late_init_offset(context_scope.LateInitOffsetAt(i)); | 
 |     } | 
 |     if (context_scope.IsInvisibleAt(i)) { | 
 |       variable->set_invisible(true); | 
 |     } | 
 |     // Create a fake owner scope describing the index and context level of the | 
 |     // variable. Function level and loop level are unused (set to 0), since | 
 |     // context level has already been assigned. | 
 |     LocalScope* owner_scope = new LocalScope(nullptr, 0, 0); | 
 |     owner_scope->set_context_level(context_scope.ContextLevelAt(i)); | 
 |     owner_scope->AddVariable(variable); | 
 |     outer_scope->AddVariable(variable);  // As alias. | 
 |     ASSERT(variable->owner() == owner_scope); | 
 |   } | 
 |   return outer_scope; | 
 | } | 
 |  | 
 | ContextScopePtr LocalScope::CreateImplicitClosureScope(const Function& func) { | 
 |   const intptr_t kNumCapturedVars = 1; | 
 |  | 
 |   // Create a ContextScope with space for kNumCapturedVars descriptors. | 
 |   const ContextScope& context_scope = | 
 |       ContextScope::Handle(ContextScope::New(kNumCapturedVars, true)); | 
 |  | 
 |   // Create a descriptor for 'this' variable. | 
 |   context_scope.SetTokenIndexAt(0, func.token_pos()); | 
 |   context_scope.SetDeclarationTokenIndexAt(0, func.token_pos()); | 
 |   context_scope.SetNameAt(0, Symbols::This()); | 
 |   context_scope.ClearFlagsAt(0); | 
 |   context_scope.SetIsFinalAt(0, true); | 
 |   const AbstractType& type = AbstractType::Handle(func.ParameterTypeAt(0)); | 
 |   context_scope.SetTypeAt(0, type); | 
 |   context_scope.SetCidAt(0, kIllegalCid); | 
 |   context_scope.SetContextIndexAt(0, 0); | 
 |   context_scope.SetContextLevelAt(0, 0); | 
 |   context_scope.SetKernelOffsetAt(0, LocalVariable::kNoKernelOffset); | 
 |   ASSERT(context_scope.num_variables() == kNumCapturedVars);  // Verify count. | 
 |   return context_scope.ptr(); | 
 | } | 
 |  | 
 | static void PrintIndentation(BaseTextBuffer* f, int depth) { | 
 |   for (int i = 0; i < depth; i++) { | 
 |     f->AddString("  "); | 
 |   } | 
 | } | 
 |  | 
 | void LocalScope::PrintTo(BaseTextBuffer* f, int depth) const { | 
 |   PrintIndentation(f, depth); | 
 |   f->AddString("scope: "); | 
 |   f->Printf("function_level: %i, ", function_level_); | 
 |   f->Printf("loop_level: %i, ", loop_level_); | 
 |   if (context_level_ == kUninitializedContextLevel) { | 
 |     f->AddString("context_level: uninitialized, "); | 
 |   } else { | 
 |     f->Printf("context_level: %i, ", context_level_); | 
 |   } | 
 |   int num_variables_ = num_variables(); | 
 |   f->Printf("variables: %i, ", num_variables_); | 
 |   f->Printf("context_variables: %i", num_context_variables()); | 
 |   if (function_level() == 1) { | 
 |     f->Printf(", captured_variables: %i", NumCapturedVariables()); | 
 |   } | 
 |   f->AddString("\n"); | 
 |  | 
 |   for (intptr_t i = 0; i < num_variables_; i++) { | 
 |     LocalVariable* variable = VariableAt(i); | 
 |     variable->PrintTo(f, "variable", depth + 1, this); | 
 |   } | 
 |  | 
 |   for (intptr_t i = 0; i < num_context_variables(); i++) { | 
 |     LocalVariable* variable = context_variables().At(i); | 
 |     variable->PrintTo(f, "context variable", depth + 1, this); | 
 |   } | 
 |  | 
 |   auto* child = child_; | 
 |   while (child != nullptr) { | 
 |     child->PrintTo(f, depth + 1); | 
 |     child = child->sibling(); | 
 |   } | 
 | } | 
 |  | 
 | const char* LocalScope::ToCString() const { | 
 |   char buffer[1024]; | 
 |   BufferFormatter f(buffer, sizeof(buffer)); | 
 |   PrintTo(&f); | 
 |   return Thread::Current()->zone()->MakeCopyOfString(buffer); | 
 | } | 
 |  | 
 | void LocalVariable::PrintTo(BaseTextBuffer* f, | 
 |                             const char* label, | 
 |                             int depth, | 
 |                             const LocalScope* scope) const { | 
 |   PrintIndentation(f, depth); | 
 |   f->Printf("%s: ", label); | 
 |   const char* var_name = name().ToCString(); | 
 |   if (var_name[0] == '\0') { | 
 |     // Follow CFE no-name variable printing convention. | 
 |     var_name = "#t?"; | 
 |   } | 
 |   f->Printf("%s, ", var_name); | 
 |   f->Printf("kernel_offset: %" Pd ", ", kernel_offset()); | 
 |   if (HasIndex()) { | 
 |     auto index_value = index().value(); | 
 |     if (index().value() == VariableIndex::kInvalidIndex) { | 
 |       f->AddString("index: invalid"); | 
 |     } else { | 
 |       f->Printf("index: %i", index_value); | 
 |     } | 
 |   } else { | 
 |     f->AddString("index: none"); | 
 |   } | 
 |   if (is_captured()) { | 
 |     f->AddString(", is_captured"); | 
 |   } | 
 |   if (is_invisible()) { | 
 |     f->AddString(", is_invisible"); | 
 |   } | 
 |   if (scope != nullptr && owner() != scope) { | 
 |     f->AddString(" (not owner)"); | 
 |   } | 
 |   f->AddString("\n"); | 
 | } | 
 |  | 
 | const char* LocalVariable::ToCString() const { | 
 |   char buffer[1024]; | 
 |   BufferFormatter f(buffer, sizeof(buffer)); | 
 |   PrintTo(&f); | 
 |   return Thread::Current()->zone()->MakeCopyOfString(buffer); | 
 | } | 
 |  | 
 | bool LocalVariable::ComputeIfIsAwaiterLink(const Library& library) { | 
 |   if (is_awaiter_link_ == IsAwaiterLink::kUnknown) { | 
 |     RELEASE_ASSERT(annotations_offset_ != kNoKernelOffset); | 
 |     Thread* T = Thread::Current(); | 
 |     Zone* Z = T->zone(); | 
 |     const auto& metadata = Object::Handle( | 
 |         Z, kernel::EvaluateMetadata(library, annotations_offset_, | 
 |                                     /* is_annotations_offset = */ true)); | 
 |     set_is_awaiter_link( | 
 |         FindPragmaInMetadata(T, metadata, Symbols::vm_awaiter_link())); | 
 |   } | 
 |   return is_awaiter_link_ == IsAwaiterLink::kLink; | 
 | } | 
 |  | 
 | bool LocalVariable::Equals(const LocalVariable& other) const { | 
 |   if (HasIndex() && other.HasIndex() && (index() == other.index())) { | 
 |     if (is_captured() == other.is_captured()) { | 
 |       if (!is_captured()) { | 
 |         return true; | 
 |       } | 
 |       if (owner()->context_level() == other.owner()->context_level()) { | 
 |         return true; | 
 |       } | 
 |     } | 
 |   } | 
 |   return false; | 
 | } | 
 |  | 
 | void LocalVarDescriptorsBuilder::AddAll(Zone* zone, | 
 |                                         const LocalVarDescriptors& var_descs) { | 
 |   for (intptr_t i = 0, n = var_descs.Length(); i < n; ++i) { | 
 |     VarDesc desc; | 
 |     desc.name = &String::Handle(zone, var_descs.GetName(i)); | 
 |     var_descs.GetInfo(i, &desc.info); | 
 |     Add(desc); | 
 |   } | 
 | } | 
 |  | 
 | void LocalVarDescriptorsBuilder::AddDeoptIdToContextLevelMappings( | 
 |     ZoneGrowableArray<intptr_t>* context_level_array) { | 
 |   // Record deopt-id -> context-level mappings, using ranges of deopt-ids with | 
 |   // the same context-level. [context_level_array] contains (deopt_id, | 
 |   // context_level) tuples. | 
 |   for (intptr_t start = 0; start < context_level_array->length();) { | 
 |     intptr_t start_deopt_id = (*context_level_array)[start]; | 
 |     intptr_t start_context_level = (*context_level_array)[start + 1]; | 
 |     intptr_t end = start; | 
 |     intptr_t end_deopt_id = start_deopt_id; | 
 |     for (intptr_t peek = start + 2; peek < context_level_array->length(); | 
 |          peek += 2) { | 
 |       intptr_t peek_deopt_id = (*context_level_array)[peek]; | 
 |       intptr_t peek_context_level = (*context_level_array)[peek + 1]; | 
 |       // The range encoding assumes the tuples have ascending deopt_ids. | 
 |       ASSERT(peek_deopt_id > end_deopt_id); | 
 |       if (peek_context_level != start_context_level) break; | 
 |       end = peek; | 
 |       end_deopt_id = peek_deopt_id; | 
 |     } | 
 |  | 
 |     VarDesc desc; | 
 |     desc.name = &Symbols::Empty();  // No name. | 
 |     desc.info.set_kind(UntaggedLocalVarDescriptors::kContextLevel); | 
 |     desc.info.scope_id = 0; | 
 |     // We repurpose the token position fields to store deopt IDs in this case. | 
 |     desc.info.begin_pos = TokenPosition::Deserialize(start_deopt_id); | 
 |     desc.info.end_pos = TokenPosition::Deserialize(end_deopt_id); | 
 |     desc.info.set_index(start_context_level); | 
 |     Add(desc); | 
 |  | 
 |     start = end + 2; | 
 |   } | 
 | } | 
 |  | 
 | LocalVarDescriptorsPtr LocalVarDescriptorsBuilder::Done() { | 
 |   if (vars_.is_empty()) { | 
 |     return Object::empty_var_descriptors().ptr(); | 
 |   } | 
 |   const LocalVarDescriptors& var_desc = | 
 |       LocalVarDescriptors::Handle(LocalVarDescriptors::New(vars_.length())); | 
 |   for (int i = 0; i < vars_.length(); i++) { | 
 |     var_desc.SetVar(i, *(vars_[i].name), &vars_[i].info); | 
 |   } | 
 |   return var_desc.ptr(); | 
 | } | 
 |  | 
 | }  // namespace dart | 
 |  | 
 | #endif  // !defined(DART_PRECOMPILED_RUNTIME) |