src/third_party/v8/src/interpreter/bytecode-generator.cc

// Copyright 2015 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/interpreter/bytecode-generator.h"

#include "src/api/api-inl.h"
#include "src/ast/ast-source-ranges.h"
#include "src/ast/scopes.h"
#include "src/builtins/builtins-constructor.h"
#include "src/codegen/compiler.h"
#include "src/codegen/unoptimized-compilation-info.h"
#include "src/interpreter/bytecode-flags.h"
#include "src/interpreter/bytecode-jump-table.h"
#include "src/interpreter/bytecode-label.h"
#include "src/interpreter/bytecode-register-allocator.h"
#include "src/interpreter/bytecode-register.h"
#include "src/interpreter/control-flow-builders.h"
#include "src/logging/local-logger.h"
#include "src/logging/log.h"
#include "src/objects/debug-objects.h"
#include "src/objects/literal-objects-inl.h"
#include "src/objects/objects-inl.h"
#include "src/objects/smi.h"
#include "src/objects/template-objects-inl.h"
#include "src/parsing/parse-info.h"
#include "src/parsing/token.h"
#include "src/utils/ostreams.h"

namespace v8 {
namespace internal {
namespace interpreter {

// Scoped class tracking context objects created by the visitor. Represents
// mutations of the context chain within the function body, allowing pushing and
// popping of the current {context_register} during visitation.
class BytecodeGenerator::ContextScope {
 public:
  ContextScope(BytecodeGenerator* generator, Scope* scope)
      : generator_(generator),
        scope_(scope),
        outer_(generator_->execution_context()),
        register_(Register::current_context()),
        depth_(0) {
    DCHECK(scope->NeedsContext() || outer_ == nullptr);
    if (outer_) {
      depth_ = outer_->depth_ + 1;

      // Push the outer context into a new context register.
      Register outer_context_reg =
          generator_->register_allocator()->NewRegister();
      outer_->set_register(outer_context_reg);
      generator_->builder()->PushContext(outer_context_reg);
    }
    generator_->set_execution_context(this);
  }

  ~ContextScope() {
    if (outer_) {
      DCHECK_EQ(register_.index(), Register::current_context().index());
      generator_->builder()->PopContext(outer_->reg());
      outer_->set_register(register_);
    }
    generator_->set_execution_context(outer_);
  }

  // Returns the depth of the given |scope| for the current execution context.
  int ContextChainDepth(Scope* scope) {
    return scope_->ContextChainLength(scope);
  }

  // Returns the execution context at |depth| in the current context chain if it
  // is a function local execution context, otherwise returns nullptr.
  ContextScope* Previous(int depth) {
    if (depth > depth_) {
      return nullptr;
    }

    ContextScope* previous = this;
    for (int i = depth; i > 0; --i) {
      previous = previous->outer_;
    }
    return previous;
  }

  Register reg() const { return register_; }

 private:
  const BytecodeArrayBuilder* builder() const { return generator_->builder(); }

  void set_register(Register reg) { register_ = reg; }

  BytecodeGenerator* generator_;
  Scope* scope_;
  ContextScope* outer_;
  Register register_;
  int depth_;
};

// Scoped class for tracking control statements entered by the
// visitor. The pattern derives AstGraphBuilder::ControlScope.
class BytecodeGenerator::ControlScope {
 public:
  explicit ControlScope(BytecodeGenerator* generator)
      : generator_(generator),
        outer_(generator->execution_control()),
        context_(generator->execution_context()) {
    generator_->set_execution_control(this);
  }
  virtual ~ControlScope() { generator_->set_execution_control(outer()); }
  ControlScope(const ControlScope&) = delete;
  ControlScope& operator=(const ControlScope&) = delete;

  void Break(Statement* stmt) {
    PerformCommand(CMD_BREAK, stmt, kNoSourcePosition);
  }
  void Continue(Statement* stmt) {
    PerformCommand(CMD_CONTINUE, stmt, kNoSourcePosition);
  }
  void ReturnAccumulator(int source_position = kNoSourcePosition) {
    PerformCommand(CMD_RETURN, nullptr, source_position);
  }
  void AsyncReturnAccumulator(int source_position = kNoSourcePosition) {
    PerformCommand(CMD_ASYNC_RETURN, nullptr, source_position);
  }

  class DeferredCommands;

 protected:
  enum Command {
    CMD_BREAK,
    CMD_CONTINUE,
    CMD_RETURN,
    CMD_ASYNC_RETURN,
    CMD_RETHROW
  };
  static constexpr bool CommandUsesAccumulator(Command command) {
    return command != CMD_BREAK && command != CMD_CONTINUE;
  }

  void PerformCommand(Command command, Statement* statement,
                      int source_position);
  virtual bool Execute(Command command, Statement* statement,
                       int source_position) = 0;

  // Helper to pop the context chain to a depth expected by this control scope.
  // Note that it is the responsibility of each individual {Execute} method to
  // trigger this when commands are handled and control-flow continues locally.
  void PopContextToExpectedDepth();

  BytecodeGenerator* generator() const { return generator_; }
  ControlScope* outer() const { return outer_; }
  ContextScope* context() const { return context_; }

 private:
  BytecodeGenerator* generator_;
  ControlScope* outer_;
  ContextScope* context_;
};

// Helper class for a try-finally control scope. It can record intercepted
// control-flow commands that cause entry into a finally-block, and re-apply
// them after again leaving that block. Special tokens are used to identify
// paths going through the finally-block to dispatch after leaving the block.
class BytecodeGenerator::ControlScope::DeferredCommands final {
 public:
  // Fixed value tokens for paths we know we need.
  // Fallthrough is set to -1 to make it the fallthrough case of the jump table,
  // where the remaining cases start at 0.
  static const int kFallthroughToken = -1;
  // TODO(leszeks): Rethrow being 0 makes it use up a valuable LdaZero, which
  // means that other commands (such as break or return) have to use LdaSmi.
  // This can very slightly bloat bytecode, so perhaps token values should all
  // be shifted down by 1.
  static const int kRethrowToken = 0;

  DeferredCommands(BytecodeGenerator* generator, Register token_register,
                   Register result_register)
      : generator_(generator),
        deferred_(generator->zone()),
        token_register_(token_register),
        result_register_(result_register),
        return_token_(-1),
        async_return_token_(-1) {
    // There's always a rethrow path.
    // TODO(leszeks): We could decouple deferred_ index and token to allow us
    // to still push this lazily.
    STATIC_ASSERT(kRethrowToken == 0);
    deferred_.push_back({CMD_RETHROW, nullptr, kRethrowToken});
  }

  // One recorded control-flow command.
  struct Entry {
    Command command;       // The command type being applied on this path.
    Statement* statement;  // The target statement for the command or {nullptr}.
    int token;             // A token identifying this particular path.
  };

  // Records a control-flow command while entering the finally-block. This also
  // generates a new dispatch token that identifies one particular path. This
  // expects the result to be in the accumulator.
  void RecordCommand(Command command, Statement* statement) {
    int token = GetTokenForCommand(command, statement);

    DCHECK_LT(token, deferred_.size());
    DCHECK_EQ(deferred_[token].command, command);
    DCHECK_EQ(deferred_[token].statement, statement);
    DCHECK_EQ(deferred_[token].token, token);

    if (CommandUsesAccumulator(command)) {
      builder()->StoreAccumulatorInRegister(result_register_);
    }
    builder()->LoadLiteral(Smi::FromInt(token));
    builder()->StoreAccumulatorInRegister(token_register_);
    if (!CommandUsesAccumulator(command)) {
      // If we're not saving the accumulator in the result register, shove a
      // harmless value there instead so that it is still considered "killed" in
      // the liveness analysis. Normally we would LdaUndefined first, but the
      // Smi token value is just as good, and by reusing it we save a bytecode.
      builder()->StoreAccumulatorInRegister(result_register_);
    }
  }

  // Records the dispatch token to be used to identify the re-throw path when
  // the finally-block has been entered through the exception handler. This
  // expects the exception to be in the accumulator.
  void RecordHandlerReThrowPath() {
    // The accumulator contains the exception object.
    RecordCommand(CMD_RETHROW, nullptr);
  }

  // Records the dispatch token to be used to identify the implicit fall-through
  // path at the end of a try-block into the corresponding finally-block.
  void RecordFallThroughPath() {
    builder()->LoadLiteral(Smi::FromInt(kFallthroughToken));
    builder()->StoreAccumulatorInRegister(token_register_);
    // Since we're not saving the accumulator in the result register, shove a
    // harmless value there instead so that it is still considered "killed" in
    // the liveness analysis. Normally we would LdaUndefined first, but the Smi
    // token value is just as good, and by reusing it we save a bytecode.
    builder()->StoreAccumulatorInRegister(result_register_);
  }

  // Applies all recorded control-flow commands after the finally-block again.
  // This generates a dynamic dispatch on the token from the entry point.
  void ApplyDeferredCommands() {
    if (deferred_.size() == 0) return;

    BytecodeLabel fall_through;

    if (deferred_.size() == 1) {
      // For a single entry, just jump to the fallthrough if we don't match the
      // entry token.
      const Entry& entry = deferred_[0];

      builder()
          ->LoadLiteral(Smi::FromInt(entry.token))
          .CompareReference(token_register_)
          .JumpIfFalse(ToBooleanMode::kAlreadyBoolean, &fall_through);

      if (CommandUsesAccumulator(entry.command)) {
        builder()->LoadAccumulatorWithRegister(result_register_);
      }
      execution_control()->PerformCommand(entry.command, entry.statement,
                                          kNoSourcePosition);
    } else {
      // For multiple entries, build a jump table and switch on the token,
      // jumping to the fallthrough if none of them match.

      BytecodeJumpTable* jump_table =
          builder()->AllocateJumpTable(static_cast<int>(deferred_.size()), 0);
      builder()
          ->LoadAccumulatorWithRegister(token_register_)
          .SwitchOnSmiNoFeedback(jump_table)
          .Jump(&fall_through);
      for (const Entry& entry : deferred_) {
        builder()->Bind(jump_table, entry.token);

        if (CommandUsesAccumulator(entry.command)) {
          builder()->LoadAccumulatorWithRegister(result_register_);
        }
        execution_control()->PerformCommand(entry.command, entry.statement,
                                            kNoSourcePosition);
      }
    }

    builder()->Bind(&fall_through);
  }

  BytecodeArrayBuilder* builder() { return generator_->builder(); }
  ControlScope* execution_control() { return generator_->execution_control(); }

 private:
  int GetTokenForCommand(Command command, Statement* statement) {
    switch (command) {
      case CMD_RETURN:
        return GetReturnToken();
      case CMD_ASYNC_RETURN:
        return GetAsyncReturnToken();
      case CMD_RETHROW:
        return kRethrowToken;
      default:
        // TODO(leszeks): We could also search for entries with the same
        // command and statement.
        return GetNewTokenForCommand(command, statement);
    }
  }

  int GetReturnToken() {
    if (return_token_ == -1) {
      return_token_ = GetNewTokenForCommand(CMD_RETURN, nullptr);
    }
    return return_token_;
  }

  int GetAsyncReturnToken() {
    if (async_return_token_ == -1) {
      async_return_token_ = GetNewTokenForCommand(CMD_ASYNC_RETURN, nullptr);
    }
    return async_return_token_;
  }

  int GetNewTokenForCommand(Command command, Statement* statement) {
    int token = static_cast<int>(deferred_.size());
    deferred_.push_back({command, statement, token});
    return token;
  }

  BytecodeGenerator* generator_;
  ZoneVector<Entry> deferred_;
  Register token_register_;
  Register result_register_;

  // Tokens for commands that don't need a statement.
  int return_token_;
  int async_return_token_;
};

// Scoped class for dealing with control flow reaching the function level.
class BytecodeGenerator::ControlScopeForTopLevel final
    : public BytecodeGenerator::ControlScope {
 public:
  explicit ControlScopeForTopLevel(BytecodeGenerator* generator)
      : ControlScope(generator) {}

 protected:
  bool Execute(Command command, Statement* statement,
               int source_position) override {
    switch (command) {
      case CMD_BREAK:  // We should never see break/continue in top-level.
      case CMD_CONTINUE:
        UNREACHABLE();
      case CMD_RETURN:
        // No need to pop contexts, execution leaves the method body.
        generator()->BuildReturn(source_position);
        return true;
      case CMD_ASYNC_RETURN:
        // No need to pop contexts, execution leaves the method body.
        generator()->BuildAsyncReturn(source_position);
        return true;
      case CMD_RETHROW:
        // No need to pop contexts, execution leaves the method body.
        generator()->BuildReThrow();
        return true;
    }
    return false;
  }
};

// Scoped class for enabling break inside blocks and switch blocks.
class BytecodeGenerator::ControlScopeForBreakable final
    : public BytecodeGenerator::ControlScope {
 public:
  ControlScopeForBreakable(BytecodeGenerator* generator,
                           BreakableStatement* statement,
                           BreakableControlFlowBuilder* control_builder)
      : ControlScope(generator),
        statement_(statement),
        control_builder_(control_builder) {}

 protected:
  bool Execute(Command command, Statement* statement,
               int source_position) override {
    if (statement != statement_) return false;
    switch (command) {
      case CMD_BREAK:
        PopContextToExpectedDepth();
        control_builder_->Break();
        return true;
      case CMD_CONTINUE:
      case CMD_RETURN:
      case CMD_ASYNC_RETURN:
      case CMD_RETHROW:
        break;
    }
    return false;
  }

 private:
  Statement* statement_;
  BreakableControlFlowBuilder* control_builder_;
};

// Scoped class for enabling 'break' and 'continue' in iteration
// constructs, e.g. do...while, while..., for...
class BytecodeGenerator::ControlScopeForIteration final
    : public BytecodeGenerator::ControlScope {
 public:
  ControlScopeForIteration(BytecodeGenerator* generator,
                           IterationStatement* statement,
                           LoopBuilder* loop_builder)
      : ControlScope(generator),
        statement_(statement),
        loop_builder_(loop_builder) {}

 protected:
  bool Execute(Command command, Statement* statement,
               int source_position) override {
    if (statement != statement_) return false;
    switch (command) {
      case CMD_BREAK:
        PopContextToExpectedDepth();
        loop_builder_->Break();
        return true;
      case CMD_CONTINUE:
        PopContextToExpectedDepth();
        loop_builder_->Continue();
        return true;
      case CMD_RETURN:
      case CMD_ASYNC_RETURN:
      case CMD_RETHROW:
        break;
    }
    return false;
  }

 private:
  Statement* statement_;
  LoopBuilder* loop_builder_;
};

// Scoped class for enabling 'throw' in try-catch constructs.
class BytecodeGenerator::ControlScopeForTryCatch final
    : public BytecodeGenerator::ControlScope {
 public:
  ControlScopeForTryCatch(BytecodeGenerator* generator,
                          TryCatchBuilder* try_catch_builder)
      : ControlScope(generator) {}

 protected:
  bool Execute(Command command, Statement* statement,
               int source_position) override {
    switch (command) {
      case CMD_BREAK:
      case CMD_CONTINUE:
      case CMD_RETURN:
      case CMD_ASYNC_RETURN:
        break;
      case CMD_RETHROW:
        // No need to pop contexts, execution re-enters the method body via the
        // stack unwinding mechanism which itself restores contexts correctly.
        generator()->BuildReThrow();
        return true;
    }
    return false;
  }
};

// Scoped class for enabling control flow through try-finally constructs.
class BytecodeGenerator::ControlScopeForTryFinally final
    : public BytecodeGenerator::ControlScope {
 public:
  ControlScopeForTryFinally(BytecodeGenerator* generator,
                            TryFinallyBuilder* try_finally_builder,
                            DeferredCommands* commands)
      : ControlScope(generator),
        try_finally_builder_(try_finally_builder),
        commands_(commands) {}

 protected:
  bool Execute(Command command, Statement* statement,
               int source_position) override {
    switch (command) {
      case CMD_BREAK:
      case CMD_CONTINUE:
      case CMD_RETURN:
      case CMD_ASYNC_RETURN:
      case CMD_RETHROW:
        PopContextToExpectedDepth();
        // We don't record source_position here since we don't generate return
        // bytecode right here and will generate it later as part of finally
        // block. Each return bytecode generated in finally block will get own
        // return source position from corresponded return statement or we'll
        // use end of function if no return statement is presented.
        commands_->RecordCommand(command, statement);
        try_finally_builder_->LeaveTry();
        return true;
    }
    return false;
  }

 private:
  TryFinallyBuilder* try_finally_builder_;
  DeferredCommands* commands_;
};

// Allocate and fetch the coverage indices tracking NaryLogical Expressions.
class BytecodeGenerator::NaryCodeCoverageSlots {
 public:
  NaryCodeCoverageSlots(BytecodeGenerator* generator, NaryOperation* expr)
      : generator_(generator) {
    if (generator_->block_coverage_builder_ == nullptr) return;
    for (size_t i = 0; i < expr->subsequent_length(); i++) {
      coverage_slots_.push_back(
          generator_->AllocateNaryBlockCoverageSlotIfEnabled(expr, i));
    }
  }

  int GetSlotFor(size_t subsequent_expr_index) const {
    if (generator_->block_coverage_builder_ == nullptr) {
      return BlockCoverageBuilder::kNoCoverageArraySlot;
    }
    DCHECK(coverage_slots_.size() > subsequent_expr_index);
    return coverage_slots_[subsequent_expr_index];
  }

 private:
  BytecodeGenerator* generator_;
  std::vector<int> coverage_slots_;
};

void BytecodeGenerator::ControlScope::PerformCommand(Command command,
                                                     Statement* statement,
                                                     int source_position) {
  ControlScope* current = this;
  do {
    if (current->Execute(command, statement, source_position)) {
      return;
    }
    current = current->outer();
  } while (current != nullptr);
  UNREACHABLE();
}

void BytecodeGenerator::ControlScope::PopContextToExpectedDepth() {
  // Pop context to the expected depth. Note that this can in fact pop multiple
  // contexts at once because the {PopContext} bytecode takes a saved register.
  if (generator()->execution_context() != context()) {
    generator()->builder()->PopContext(context()->reg());
  }
}

class BytecodeGenerator::RegisterAllocationScope final {
 public:
  explicit RegisterAllocationScope(BytecodeGenerator* generator)
      : generator_(generator),
        outer_next_register_index_(
            generator->register_allocator()->next_register_index()) {}

  ~RegisterAllocationScope() {
    generator_->register_allocator()->ReleaseRegisters(
        outer_next_register_index_);
  }

  RegisterAllocationScope(const RegisterAllocationScope&) = delete;
  RegisterAllocationScope& operator=(const RegisterAllocationScope&) = delete;

  BytecodeGenerator* generator() const { return generator_; }

 private:
  BytecodeGenerator* generator_;
  int outer_next_register_index_;
};

class BytecodeGenerator::AccumulatorPreservingScope final {
 public:
  explicit AccumulatorPreservingScope(BytecodeGenerator* generator,
                                      AccumulatorPreservingMode mode)
      : generator_(generator) {
    if (mode == AccumulatorPreservingMode::kPreserve) {
      saved_accumulator_register_ =
          generator_->register_allocator()->NewRegister();
      generator_->builder()->StoreAccumulatorInRegister(
          saved_accumulator_register_);
    }
  }

  ~AccumulatorPreservingScope() {
    if (saved_accumulator_register_.is_valid()) {
      generator_->builder()->LoadAccumulatorWithRegister(
          saved_accumulator_register_);
    }
  }

  AccumulatorPreservingScope(const AccumulatorPreservingScope&) = delete;
  AccumulatorPreservingScope& operator=(const AccumulatorPreservingScope&) =
      delete;

 private:
  BytecodeGenerator* generator_;
  Register saved_accumulator_register_;
};

// Scoped base class for determining how the result of an expression will be
// used.
class BytecodeGenerator::ExpressionResultScope {
 public:
  ExpressionResultScope(BytecodeGenerator* generator, Expression::Context kind)
      : outer_(generator->execution_result()),
        allocator_(generator),
        kind_(kind),
        type_hint_(TypeHint::kAny) {
    generator->set_execution_result(this);
  }

  ~ExpressionResultScope() {
    allocator_.generator()->set_execution_result(outer_);
  }

  ExpressionResultScope(const ExpressionResultScope&) = delete;
  ExpressionResultScope& operator=(const ExpressionResultScope&) = delete;

  bool IsEffect() const { return kind_ == Expression::kEffect; }
  bool IsValue() const { return kind_ == Expression::kValue; }
  bool IsTest() const { return kind_ == Expression::kTest; }

  TestResultScope* AsTest() {
    DCHECK(IsTest());
    return reinterpret_cast<TestResultScope*>(this);
  }

  // Specify expression always returns a Boolean result value.
  void SetResultIsBoolean() {
    DCHECK_EQ(type_hint_, TypeHint::kAny);
    type_hint_ = TypeHint::kBoolean;
  }

  void SetResultIsString() {
    DCHECK_EQ(type_hint_, TypeHint::kAny);
    type_hint_ = TypeHint::kString;
  }

  TypeHint type_hint() const { return type_hint_; }

 private:
  ExpressionResultScope* outer_;
  RegisterAllocationScope allocator_;
  Expression::Context kind_;
  TypeHint type_hint_;
};

// Scoped class used when the result of the current expression is not
// expected to produce a result.
class BytecodeGenerator::EffectResultScope final
    : public ExpressionResultScope {
 public:
  explicit EffectResultScope(BytecodeGenerator* generator)
      : ExpressionResultScope(generator, Expression::kEffect) {}
};

// Scoped class used when the result of the current expression to be
// evaluated should go into the interpreter's accumulator.
class BytecodeGenerator::ValueResultScope final : public ExpressionResultScope {
 public:
  explicit ValueResultScope(BytecodeGenerator* generator)
      : ExpressionResultScope(generator, Expression::kValue) {}
};

// Scoped class used when the result of the current expression to be
// evaluated is only tested with jumps to two branches.
class BytecodeGenerator::TestResultScope final : public ExpressionResultScope {
 public:
  TestResultScope(BytecodeGenerator* generator, BytecodeLabels* then_labels,
                  BytecodeLabels* else_labels, TestFallthrough fallthrough)
      : ExpressionResultScope(generator, Expression::kTest),
        result_consumed_by_test_(false),
        fallthrough_(fallthrough),
        then_labels_(then_labels),
        else_labels_(else_labels) {}

  TestResultScope(const TestResultScope&) = delete;
  TestResultScope& operator=(const TestResultScope&) = delete;

  // Used when code special cases for TestResultScope and consumes any
  // possible value by testing and jumping to a then/else label.
  void SetResultConsumedByTest() { result_consumed_by_test_ = true; }
  bool result_consumed_by_test() { return result_consumed_by_test_; }

  // Inverts the control flow of the operation, swapping the then and else
  // labels and the fallthrough.
  void InvertControlFlow() {
    std::swap(then_labels_, else_labels_);
    fallthrough_ = inverted_fallthrough();
  }

  BytecodeLabel* NewThenLabel() { return then_labels_->New(); }
  BytecodeLabel* NewElseLabel() { return else_labels_->New(); }

  BytecodeLabels* then_labels() const { return then_labels_; }
  BytecodeLabels* else_labels() const { return else_labels_; }

  void set_then_labels(BytecodeLabels* then_labels) {
    then_labels_ = then_labels;
  }
  void set_else_labels(BytecodeLabels* else_labels) {
    else_labels_ = else_labels;
  }

  TestFallthrough fallthrough() const { return fallthrough_; }
  TestFallthrough inverted_fallthrough() const {
    switch (fallthrough_) {
      case TestFallthrough::kThen:
        return TestFallthrough::kElse;
      case TestFallthrough::kElse:
        return TestFallthrough::kThen;
      default:
        return TestFallthrough::kNone;
    }
  }
  void set_fallthrough(TestFallthrough fallthrough) {
    fallthrough_ = fallthrough;
  }

 private:
  bool result_consumed_by_test_;
  TestFallthrough fallthrough_;
  BytecodeLabels* then_labels_;
  BytecodeLabels* else_labels_;
};

// Used to build a list of toplevel declaration data.
class BytecodeGenerator::TopLevelDeclarationsBuilder final : public ZoneObject {
 public:
  template <typename LocalIsolate>
  Handle<FixedArray> AllocateDeclarations(UnoptimizedCompilationInfo* info,
                                          BytecodeGenerator* generator,
                                          Handle<Script> script,
                                          LocalIsolate* isolate) {
    DCHECK(has_constant_pool_entry_);

    Handle<FixedArray> data =
        isolate->factory()->NewFixedArray(entry_slots_, AllocationType::kOld);

    int array_index = 0;
    if (info->scope()->is_module_scope()) {
      for (Declaration* decl : *info->scope()->declarations()) {
        Variable* var = decl->var();
        if (!var->is_used()) continue;
        if (var->location() != VariableLocation::MODULE) continue;
#ifdef DEBUG
        int start = array_index;
#endif
        if (decl->IsFunctionDeclaration()) {
          FunctionLiteral* f = static_cast<FunctionDeclaration*>(decl)->fun();
          Handle<SharedFunctionInfo> sfi(
              Compiler::GetSharedFunctionInfo(f, script, isolate));
          // Return a null handle if any initial values can't be created. Caller
          // will set stack overflow.
          if (sfi.is_null()) return Handle<FixedArray>();
          data->set(array_index++, *sfi);
          int literal_index = generator->GetCachedCreateClosureSlot(f);
          data->set(array_index++, Smi::FromInt(literal_index));
          DCHECK(var->IsExport());
          data->set(array_index++, Smi::FromInt(var->index()));
          DCHECK_EQ(start + kModuleFunctionDeclarationSize, array_index);
        } else if (var->IsExport() && var->binding_needs_init()) {
          data->set(array_index++, Smi::FromInt(var->index()));
          DCHECK_EQ(start + kModuleVariableDeclarationSize, array_index);
        }
      }
    } else {
      for (Declaration* decl : *info->scope()->declarations()) {
        Variable* var = decl->var();
        if (!var->is_used()) continue;
        if (var->location() != VariableLocation::UNALLOCATED) continue;
#ifdef DEBUG
        int start = array_index;
#endif
        if (decl->IsVariableDeclaration()) {
          data->set(array_index++, *var->raw_name()->string());
          DCHECK_EQ(start + kGlobalVariableDeclarationSize, array_index);
        } else {
          FunctionLiteral* f = static_cast<FunctionDeclaration*>(decl)->fun();
          Handle<SharedFunctionInfo> sfi(
              Compiler::GetSharedFunctionInfo(f, script, isolate));
          // Return a null handle if any initial values can't be created. Caller
          // will set stack overflow.
          if (sfi.is_null()) return Handle<FixedArray>();
          data->set(array_index++, *sfi);
          int literal_index = generator->GetCachedCreateClosureSlot(f);
          data->set(array_index++, Smi::FromInt(literal_index));
          DCHECK_EQ(start + kGlobalFunctionDeclarationSize, array_index);
        }
      }
    }
    DCHECK_EQ(array_index, data->length());
    return data;
  }

  size_t constant_pool_entry() {
    DCHECK(has_constant_pool_entry_);
    return constant_pool_entry_;
  }

  void set_constant_pool_entry(size_t constant_pool_entry) {
    DCHECK(has_top_level_declaration());
    DCHECK(!has_constant_pool_entry_);
    constant_pool_entry_ = constant_pool_entry;
    has_constant_pool_entry_ = true;
  }

  void record_global_variable_declaration() {
    entry_slots_ += kGlobalVariableDeclarationSize;
  }
  void record_global_function_declaration() {
    entry_slots_ += kGlobalFunctionDeclarationSize;
  }
  void record_module_variable_declaration() {
    entry_slots_ += kModuleVariableDeclarationSize;
  }
  void record_module_function_declaration() {
    entry_slots_ += kModuleFunctionDeclarationSize;
  }
  bool has_top_level_declaration() { return entry_slots_ > 0; }
  bool processed() { return processed_; }
  void mark_processed() { processed_ = true; }

 private:
  const int kGlobalVariableDeclarationSize = 1;
  const int kGlobalFunctionDeclarationSize = 2;
  const int kModuleVariableDeclarationSize = 1;
  const int kModuleFunctionDeclarationSize = 3;

  size_t constant_pool_entry_ = 0;
  int entry_slots_ = 0;
  bool has_constant_pool_entry_ = false;
  bool processed_ = false;
};

class BytecodeGenerator::CurrentScope final {
 public:
  CurrentScope(BytecodeGenerator* generator, Scope* scope)
      : generator_(generator), outer_scope_(generator->current_scope()) {
    if (scope != nullptr) {
      DCHECK_EQ(outer_scope_, scope->outer_scope());
      generator_->set_current_scope(scope);
    }
  }
  ~CurrentScope() {
    if (outer_scope_ != generator_->current_scope()) {
      generator_->set_current_scope(outer_scope_);
    }
  }

 private:
  BytecodeGenerator* generator_;
  Scope* outer_scope_;
};

class BytecodeGenerator::FeedbackSlotCache : public ZoneObject {
 public:
  enum class SlotKind {
    kStoreGlobalSloppy,
    kStoreGlobalStrict,
    kStoreNamedStrict,
    kStoreNamedSloppy,
    kLoadProperty,
    kLoadSuperProperty,
    kLoadGlobalNotInsideTypeof,
    kLoadGlobalInsideTypeof,
    kClosureFeedbackCell
  };

  explicit FeedbackSlotCache(Zone* zone) : map_(zone) {}

  void Put(SlotKind slot_kind, Variable* variable, int slot_index) {
    PutImpl(slot_kind, 0, variable, slot_index);
  }
  void Put(SlotKind slot_kind, AstNode* node, int slot_index) {
    PutImpl(slot_kind, 0, node, slot_index);
  }
  void Put(SlotKind slot_kind, int variable_index, const AstRawString* name,
           int slot_index) {
    PutImpl(slot_kind, variable_index, name, slot_index);
  }
  void Put(SlotKind slot_kind, const AstRawString* name, int slot_index) {
    PutImpl(slot_kind, 0, name, slot_index);
  }

  int Get(SlotKind slot_kind, Variable* variable) const {
    return GetImpl(slot_kind, 0, variable);
  }
  int Get(SlotKind slot_kind, AstNode* node) const {
    return GetImpl(slot_kind, 0, node);
  }
  int Get(SlotKind slot_kind, int variable_index,
          const AstRawString* name) const {
    return GetImpl(slot_kind, variable_index, name);
  }
  int Get(SlotKind slot_kind, const AstRawString* name) const {
    return GetImpl(slot_kind, 0, name);
  }

 private:
  using Key = std::tuple<SlotKind, int, const void*>;

  void PutImpl(SlotKind slot_kind, int index, const void* node,
               int slot_index) {
    Key key = std::make_tuple(slot_kind, index, node);
    auto entry = std::make_pair(key, slot_index);
    map_.insert(entry);
  }

  int GetImpl(SlotKind slot_kind, int index, const void* node) const {
    Key key = std::make_tuple(slot_kind, index, node);
    auto iter = map_.find(key);
    if (iter != map_.end()) {
      return iter->second;
    }
    return -1;
  }

  ZoneMap<Key, int> map_;
};

class BytecodeGenerator::IteratorRecord final {
 public:
  IteratorRecord(Register object_register, Register next_register,
                 IteratorType type = IteratorType::kNormal)
      : type_(type), object_(object_register), next_(next_register) {
    DCHECK(object_.is_valid() && next_.is_valid());
  }

  inline IteratorType type() const { return type_; }
  inline Register object() const { return object_; }
  inline Register next() const { return next_; }

 private:
  IteratorType type_;
  Register object_;
  Register next_;
};

class BytecodeGenerator::OptionalChainNullLabelScope final {
 public:
  explicit OptionalChainNullLabelScope(BytecodeGenerator* bytecode_generator)
      : bytecode_generator_(bytecode_generator),
        labels_(bytecode_generator->zone()) {
    prev_ = bytecode_generator_->optional_chaining_null_labels_;
    bytecode_generator_->optional_chaining_null_labels_ = &labels_;
  }

  ~OptionalChainNullLabelScope() {
    bytecode_generator_->optional_chaining_null_labels_ = prev_;
  }

  BytecodeLabels* labels() { return &labels_; }

 private:
  BytecodeGenerator* bytecode_generator_;
  BytecodeLabels labels_;
  BytecodeLabels* prev_;
};

// LoopScope delimits the scope of {loop}, from its header to its final jump.
// It should be constructed iff a (conceptual) back edge should be produced. In
// the case of creating a LoopBuilder but never emitting the loop, it is valid
// to skip the creation of LoopScope.
class BytecodeGenerator::LoopScope final {
 public:
  explicit LoopScope(BytecodeGenerator* bytecode_generator, LoopBuilder* loop)
      : bytecode_generator_(bytecode_generator),
        parent_loop_scope_(bytecode_generator_->current_loop_scope()),
        loop_builder_(loop) {
    loop_builder_->LoopHeader();
    bytecode_generator_->set_current_loop_scope(this);
    bytecode_generator_->loop_depth_++;
  }

  ~LoopScope() {
    bytecode_generator_->loop_depth_--;
    bytecode_generator_->set_current_loop_scope(parent_loop_scope_);
    DCHECK_GE(bytecode_generator_->loop_depth_, 0);
    loop_builder_->JumpToHeader(
        bytecode_generator_->loop_depth_,
        parent_loop_scope_ ? parent_loop_scope_->loop_builder_ : nullptr);
  }

 private:
  BytecodeGenerator* const bytecode_generator_;
  LoopScope* const parent_loop_scope_;
  LoopBuilder* const loop_builder_;
};

namespace {

template <typename PropertyT>
struct Accessors : public ZoneObject {
  Accessors() : getter(nullptr), setter(nullptr) {}
  PropertyT* getter;
  PropertyT* setter;
};

// A map from property names to getter/setter pairs allocated in the zone that
// also provides a way of accessing the pairs in the order they were first
// added so that the generated bytecode is always the same.
template <typename PropertyT>
class AccessorTable
    : public base::TemplateHashMap<Literal, Accessors<PropertyT>,
                                   bool (*)(void*, void*),
                                   ZoneAllocationPolicy> {
 public:
  explicit AccessorTable(Zone* zone)
      : base::TemplateHashMap<Literal, Accessors<PropertyT>,
                              bool (*)(void*, void*), ZoneAllocationPolicy>(
            Literal::Match, ZoneAllocationPolicy(zone)),
        zone_(zone) {}

  Accessors<PropertyT>* LookupOrInsert(Literal* key) {
    auto it = this->find(key, true);
    if (it->second == nullptr) {
      it->second = zone_->New<Accessors<PropertyT>>();
      ordered_accessors_.push_back({key, it->second});
    }
    return it->second;
  }

  const std::vector<std::pair<Literal*, Accessors<PropertyT>*>>&
  ordered_accessors() {
    return ordered_accessors_;
  }

 private:
  std::vector<std::pair<Literal*, Accessors<PropertyT>*>> ordered_accessors_;

  Zone* zone_;
};

}  // namespace

#ifdef DEBUG

static bool IsInEagerLiterals(
    FunctionLiteral* literal,
    const std::vector<FunctionLiteral*>& eager_literals) {
  for (FunctionLiteral* eager_literal : eager_literals) {
    if (literal == eager_literal) return true;
  }
  return false;
}

#endif  // DEBUG

BytecodeGenerator::BytecodeGenerator(
    Zone* compile_zone, UnoptimizedCompilationInfo* info,
    const AstStringConstants* ast_string_constants,
    std::vector<FunctionLiteral*>* eager_inner_literals)
    : zone_(compile_zone),
      builder_(zone(), info->num_parameters_including_this(),
               info->scope()->num_stack_slots(), info->feedback_vector_spec(),
               info->SourcePositionRecordingMode()),
      info_(info),
      ast_string_constants_(ast_string_constants),
      closure_scope_(info->scope()),
      current_scope_(info->scope()),
      eager_inner_literals_(eager_inner_literals),
      feedback_slot_cache_(zone()->New<FeedbackSlotCache>(zone())),
      top_level_builder_(zone()->New<TopLevelDeclarationsBuilder>()),
      block_coverage_builder_(nullptr),
      function_literals_(0, zone()),
      native_function_literals_(0, zone()),
      object_literals_(0, zone()),
      array_literals_(0, zone()),
      class_literals_(0, zone()),
      template_objects_(0, zone()),
      execution_control_(nullptr),
      execution_context_(nullptr),
      execution_result_(nullptr),
      incoming_new_target_or_generator_(),
      optional_chaining_null_labels_(nullptr),
      dummy_feedback_slot_(feedback_spec(), FeedbackSlotKind::kCompareOp),
      generator_jump_table_(nullptr),
      suspend_count_(0),
      loop_depth_(0),
      current_loop_scope_(nullptr),
      catch_prediction_(HandlerTable::UNCAUGHT) {
  DCHECK_EQ(closure_scope(), closure_scope()->GetClosureScope());
  if (info->has_source_range_map()) {
    block_coverage_builder_ = zone()->New<BlockCoverageBuilder>(
        zone(), builder(), info->source_range_map());
  }
}

namespace {

template <typename Isolate>
struct NullContextScopeHelper;

template <>
struct NullContextScopeHelper<Isolate> {
  using Type = NullContextScope;
};

template <>
struct NullContextScopeHelper<LocalIsolate> {
  class DummyNullContextScope {
   public:
    explicit DummyNullContextScope(LocalIsolate*) {}
  };
  using Type = DummyNullContextScope;
};

template <typename Isolate>
using NullContextScopeFor = typename NullContextScopeHelper<Isolate>::Type;

}  // namespace

template <typename LocalIsolate>
Handle<BytecodeArray> BytecodeGenerator::FinalizeBytecode(
    LocalIsolate* isolate, Handle<Script> script) {
  DCHECK_EQ(ThreadId::Current(), isolate->thread_id());
#ifdef DEBUG
  // Unoptimized compilation should be context-independent. Verify that we don't
  // access the native context by nulling it out during finalization.
  NullContextScopeFor<LocalIsolate> null_context_scope(isolate);
#endif

  AllocateDeferredConstants(isolate, script);

  if (block_coverage_builder_) {
    Handle<CoverageInfo> coverage_info =
        isolate->factory()->NewCoverageInfo(block_coverage_builder_->slots());
    info()->set_coverage_info(coverage_info);
    if (FLAG_trace_block_coverage) {
      StdoutStream os;
      coverage_info->CoverageInfoPrint(os, info()->literal()->GetDebugName());
    }
  }

  if (HasStackOverflow()) return Handle<BytecodeArray>();
  Handle<BytecodeArray> bytecode_array = builder()->ToBytecodeArray(isolate);

  if (incoming_new_target_or_generator_.is_valid()) {
    bytecode_array->set_incoming_new_target_or_generator_register(
        incoming_new_target_or_generator_);
  }

  return bytecode_array;
}

template Handle<BytecodeArray> BytecodeGenerator::FinalizeBytecode(
    Isolate* isolate, Handle<Script> script);
template Handle<BytecodeArray> BytecodeGenerator::FinalizeBytecode(
    LocalIsolate* isolate, Handle<Script> script);

template <typename LocalIsolate>
Handle<ByteArray> BytecodeGenerator::FinalizeSourcePositionTable(
    LocalIsolate* isolate) {
  DCHECK_EQ(ThreadId::Current(), isolate->thread_id());
#ifdef DEBUG
  // Unoptimized compilation should be context-independent. Verify that we don't
  // access the native context by nulling it out during finalization.
  NullContextScopeFor<LocalIsolate> null_context_scope(isolate);
#endif

  Handle<ByteArray> source_position_table =
      builder()->ToSourcePositionTable(isolate);

  LOG_CODE_EVENT(isolate,
                 CodeLinePosInfoRecordEvent(
                     info_->bytecode_array()->GetFirstBytecodeAddress(),
                     *source_position_table));

  return source_position_table;
}

template Handle<ByteArray> BytecodeGenerator::FinalizeSourcePositionTable(
    Isolate* isolate);
template Handle<ByteArray> BytecodeGenerator::FinalizeSourcePositionTable(
    LocalIsolate* isolate);

#ifdef DEBUG
int BytecodeGenerator::CheckBytecodeMatches(BytecodeArray bytecode) {
  return builder()->CheckBytecodeMatches(bytecode);
}
#endif

template <typename LocalIsolate>
void BytecodeGenerator::AllocateDeferredConstants(LocalIsolate* isolate,
                                                  Handle<Script> script) {
  if (top_level_builder()->has_top_level_declaration()) {
    // Build global declaration pair array.
    Handle<FixedArray> declarations = top_level_builder()->AllocateDeclarations(
        info(), this, script, isolate);
    if (declarations.is_null()) return SetStackOverflow();
    builder()->SetDeferredConstantPoolEntry(
        top_level_builder()->constant_pool_entry(), declarations);
  }

  // Find or build shared function infos.
  for (std::pair<FunctionLiteral*, size_t> literal : function_literals_) {
    FunctionLiteral* expr = literal.first;
    Handle<SharedFunctionInfo> shared_info =
        Compiler::GetSharedFunctionInfo(expr, script, isolate);
    if (shared_info.is_null()) return SetStackOverflow();
    builder()->SetDeferredConstantPoolEntry(literal.second, shared_info);
  }

  // Find or build shared function infos for the native function templates.
  for (std::pair<NativeFunctionLiteral*, size_t> literal :
       native_function_literals_) {
    // This should only happen for main-thread compilations.
    DCHECK((std::is_same<Isolate, v8::internal::Isolate>::value));

    NativeFunctionLiteral* expr = literal.first;
    v8::Isolate* v8_isolate = reinterpret_cast<v8::Isolate*>(isolate);

    // Compute the function template for the native function.
    v8::Local<v8::FunctionTemplate> info =
        expr->extension()->GetNativeFunctionTemplate(
            v8_isolate, Utils::ToLocal(expr->name()));
    DCHECK(!info.IsEmpty());

    Handle<SharedFunctionInfo> shared_info =
        FunctionTemplateInfo::GetOrCreateSharedFunctionInfo(
            isolate, Utils::OpenHandle(*info), expr->name());
    DCHECK(!shared_info.is_null());
    builder()->SetDeferredConstantPoolEntry(literal.second, shared_info);
  }

  // Build object literal constant properties
  for (std::pair<ObjectLiteral*, size_t> literal : object_literals_) {
    ObjectLiteral* object_literal = literal.first;
    if (object_literal->properties_count() > 0) {
      // If constant properties is an empty fixed array, we've already added it
      // to the constant pool when visiting the object literal.
      Handle<ObjectBoilerplateDescription> constant_properties =
          object_literal->GetOrBuildBoilerplateDescription(isolate);

      builder()->SetDeferredConstantPoolEntry(literal.second,
                                              constant_properties);
    }
  }

  // Build array literal constant elements
  for (std::pair<ArrayLiteral*, size_t> literal : array_literals_) {
    ArrayLiteral* array_literal = literal.first;
    Handle<ArrayBoilerplateDescription> constant_elements =
        array_literal->GetOrBuildBoilerplateDescription(isolate);
    builder()->SetDeferredConstantPoolEntry(literal.second, constant_elements);
  }

  // Build class literal boilerplates.
  for (std::pair<ClassLiteral*, size_t> literal : class_literals_) {
    ClassLiteral* class_literal = literal.first;
    Handle<ClassBoilerplate> class_boilerplate =
        ClassBoilerplate::BuildClassBoilerplate(isolate, class_literal);
    builder()->SetDeferredConstantPoolEntry(literal.second, class_boilerplate);
  }

  // Build template literals.
  for (std::pair<GetTemplateObject*, size_t> literal : template_objects_) {
    GetTemplateObject* get_template_object = literal.first;
    Handle<TemplateObjectDescription> description =
        get_template_object->GetOrBuildDescription(isolate);
    builder()->SetDeferredConstantPoolEntry(literal.second, description);
  }
}

template void BytecodeGenerator::AllocateDeferredConstants(
    Isolate* isolate, Handle<Script> script);
template void BytecodeGenerator::AllocateDeferredConstants(
    LocalIsolate* isolate, Handle<Script> script);

namespace {
bool NeedsContextInitialization(DeclarationScope* scope) {
  return scope->NeedsContext() && !scope->is_script_scope() &&
         !scope->is_module_scope();
}
}  // namespace

void BytecodeGenerator::GenerateBytecode(uintptr_t stack_limit) {
  DisallowHeapAllocation no_allocation;
  DisallowHandleAllocation no_handles;
  DisallowHandleDereference no_deref;

  InitializeAstVisitor(stack_limit);

  // Initialize the incoming context.
  ContextScope incoming_context(this, closure_scope());

  // Initialize control scope.
  ControlScopeForTopLevel control(this);

  RegisterAllocationScope register_scope(this);

  AllocateTopLevelRegisters();

  builder()->EmitFunctionStartSourcePosition(
      info()->literal()->start_position());

  if (info()->literal()->CanSuspend()) {
    BuildGeneratorPrologue();
  }

  if (NeedsContextInitialization(closure_scope())) {
    // Push a new inner context scope for the function.
    BuildNewLocalActivationContext();
    ContextScope local_function_context(this, closure_scope());
    BuildLocalActivationContextInitialization();
    GenerateBytecodeBody();
  } else {
    GenerateBytecodeBody();
  }

  // Check that we are not falling off the end.
  DCHECK(builder()->RemainderOfBlockIsDead());
}

void BytecodeGenerator::GenerateBytecodeBody() {
  // Build the arguments object if it is used.
  VisitArgumentsObject(closure_scope()->arguments());

  // Build rest arguments array if it is used.
  Variable* rest_parameter = closure_scope()->rest_parameter();
  VisitRestArgumentsArray(rest_parameter);

  // Build assignment to the function name or {.this_function}
  // variables if used.
  VisitThisFunctionVariable(closure_scope()->function_var());
  VisitThisFunctionVariable(closure_scope()->this_function_var());

  // Build assignment to {new.target} variable if it is used.
  VisitNewTargetVariable(closure_scope()->new_target_var());

  // Create a generator object if necessary and initialize the
  // {.generator_object} variable.
  FunctionLiteral* literal = info()->literal();
  if (IsResumableFunction(literal->kind())) {
    BuildGeneratorObjectVariableInitialization();
  }

  // Emit tracing call if requested to do so.
  if (FLAG_trace) builder()->CallRuntime(Runtime::kTraceEnter);

  // Emit type profile call.
  if (info()->flags().collect_type_profile()) {
    feedback_spec()->AddTypeProfileSlot();
    int num_parameters = closure_scope()->num_parameters();
    for (int i = 0; i < num_parameters; i++) {
      Register parameter(builder()->Parameter(i));
      builder()->LoadAccumulatorWithRegister(parameter).CollectTypeProfile(
          closure_scope()->parameter(i)->initializer_position());
    }
  }

  // Increment the function-scope block coverage counter.
  BuildIncrementBlockCoverageCounterIfEnabled(literal, SourceRangeKind::kBody);

  // Visit declarations within the function scope.
  if (closure_scope()->is_script_scope()) {
    VisitGlobalDeclarations(closure_scope()->declarations());
  } else if (closure_scope()->is_module_scope()) {
    VisitModuleDeclarations(closure_scope()->declarations());
  } else {
    VisitDeclarations(closure_scope()->declarations());
  }

  // Emit initializing assignments for module namespace imports (if any).
  VisitModuleNamespaceImports();

  // The derived constructor case is handled in VisitCallSuper.
  if (IsBaseConstructor(function_kind())) {
    if (literal->class_scope_has_private_brand()) {
      BuildPrivateBrandInitialization(builder()->Receiver());
    }

    if (literal->requires_instance_members_initializer()) {
      BuildInstanceMemberInitialization(Register::function_closure(),
                                        builder()->Receiver());
    }
  }

  // Visit statements in the function body.
  VisitStatements(literal->body());

  // Emit an implicit return instruction in case control flow can fall off the
  // end of the function without an explicit return being present on all paths.
  if (!builder()->RemainderOfBlockIsDead()) {
    builder()->LoadUndefined();
    BuildReturn();
  }
}

void BytecodeGenerator::AllocateTopLevelRegisters() {
  if (IsResumableFunction(info()->literal()->kind())) {
    // Either directly use generator_object_var or allocate a new register for
    // the incoming generator object.
    Variable* generator_object_var = closure_scope()->generator_object_var();
    if (generator_object_var->location() == VariableLocation::LOCAL) {
      incoming_new_target_or_generator_ =
          GetRegisterForLocalVariable(generator_object_var);
    } else {
      incoming_new_target_or_generator_ = register_allocator()->NewRegister();
    }
  } else if (closure_scope()->new_target_var()) {
    // Either directly use new_target_var or allocate a new register for
    // the incoming new target object.
    Variable* new_target_var = closure_scope()->new_target_var();
    if (new_target_var->location() == VariableLocation::LOCAL) {
      incoming_new_target_or_generator_ =
          GetRegisterForLocalVariable(new_target_var);
    } else {
      incoming_new_target_or_generator_ = register_allocator()->NewRegister();
    }
  }
}

void BytecodeGenerator::BuildGeneratorPrologue() {
  DCHECK_GT(info()->literal()->suspend_count(), 0);
  DCHECK(generator_object().is_valid());
  generator_jump_table_ =
      builder()->AllocateJumpTable(info()->literal()->suspend_count(), 0);

  // If the generator is not undefined, this is a resume, so perform state
  // dispatch.
  builder()->SwitchOnGeneratorState(generator_object(), generator_jump_table_);

  // Otherwise, fall-through to the ordinary function prologue, after which we
  // will run into the generator object creation and other extra code inserted
  // by the parser.
}

void BytecodeGenerator::VisitBlock(Block* stmt) {
  // Visit declarations and statements.
  CurrentScope current_scope(this, stmt->scope());
  if (stmt->scope() != nullptr && stmt->scope()->NeedsContext()) {
    BuildNewLocalBlockContext(stmt->scope());
    ContextScope scope(this, stmt->scope());
    VisitBlockDeclarationsAndStatements(stmt);
  } else {
    VisitBlockDeclarationsAndStatements(stmt);
  }
}

void BytecodeGenerator::VisitBlockDeclarationsAndStatements(Block* stmt) {
  BlockBuilder block_builder(builder(), block_coverage_builder_, stmt);
  ControlScopeForBreakable execution_control(this, stmt, &block_builder);
  if (stmt->scope() != nullptr) {
    VisitDeclarations(stmt->scope()->declarations());
  }
  VisitStatements(stmt->statements());
}

void BytecodeGenerator::VisitVariableDeclaration(VariableDeclaration* decl) {
  Variable* variable = decl->var();
  // Unused variables don't need to be visited.
  if (!variable->is_used()) return;

  switch (variable->location()) {
    case VariableLocation::UNALLOCATED:
    case VariableLocation::MODULE:
      UNREACHABLE();
    case VariableLocation::LOCAL:
      if (variable->binding_needs_init()) {
        Register destination(builder()->Local(variable->index()));
        builder()->LoadTheHole().StoreAccumulatorInRegister(destination);
      }
      break;
    case VariableLocation::PARAMETER:
      if (variable->binding_needs_init()) {
        Register destination(builder()->Parameter(variable->index()));
        builder()->LoadTheHole().StoreAccumulatorInRegister(destination);
      }
      break;
    case VariableLocation::REPL_GLOBAL:
      // REPL let's are stored in script contexts. They get initialized
      // with the hole the same way as normal context allocated variables.
    case VariableLocation::CONTEXT:
      if (variable->binding_needs_init()) {
        DCHECK_EQ(0, execution_context()->ContextChainDepth(variable->scope()));
        builder()->LoadTheHole().StoreContextSlot(execution_context()->reg(),
                                                  variable->index(), 0);
      }
      break;
    case VariableLocation::LOOKUP: {
      DCHECK_EQ(VariableMode::kDynamic, variable->mode());
      DCHECK(!variable->binding_needs_init());

      Register name = register_allocator()->NewRegister();

      builder()
          ->LoadLiteral(variable->raw_name())
          .StoreAccumulatorInRegister(name)
          .CallRuntime(Runtime::kDeclareEvalVar, name);
      break;
    }
  }
}

void BytecodeGenerator::VisitFunctionDeclaration(FunctionDeclaration* decl) {
  Variable* variable = decl->var();
  DCHECK(variable->mode() == VariableMode::kLet ||
         variable->mode() == VariableMode::kVar ||
         variable->mode() == VariableMode::kDynamic);
  // Unused variables don't need to be visited.
  if (!variable->is_used()) return;

  switch (variable->location()) {
    case VariableLocation::UNALLOCATED:
    case VariableLocation::MODULE:
      UNREACHABLE();
    case VariableLocation::PARAMETER:
    case VariableLocation::LOCAL: {
      VisitFunctionLiteral(decl->fun());
      BuildVariableAssignment(variable, Token::INIT, HoleCheckMode::kElided);
      break;
    }
    case VariableLocation::REPL_GLOBAL:
    case VariableLocation::CONTEXT: {
      DCHECK_EQ(0, execution_context()->ContextChainDepth(variable->scope()));
      VisitFunctionLiteral(decl->fun());
      builder()->StoreContextSlot(execution_context()->reg(), variable->index(),
                                  0);
      break;
    }
    case VariableLocation::LOOKUP: {
      RegisterList args = register_allocator()->NewRegisterList(2);
      builder()
          ->LoadLiteral(variable->raw_name())
          .StoreAccumulatorInRegister(args[0]);
      VisitFunctionLiteral(decl->fun());
      builder()->StoreAccumulatorInRegister(args[1]).CallRuntime(
          Runtime::kDeclareEvalFunction, args);
      break;
    }
  }
  DCHECK_IMPLIES(
      eager_inner_literals_ != nullptr && decl->fun()->ShouldEagerCompile(),
      IsInEagerLiterals(decl->fun(), *eager_inner_literals_));
}

void BytecodeGenerator::VisitModuleNamespaceImports() {
  if (!closure_scope()->is_module_scope()) return;

  RegisterAllocationScope register_scope(this);
  Register module_request = register_allocator()->NewRegister();

  SourceTextModuleDescriptor* descriptor =
      closure_scope()->AsModuleScope()->module();
  for (auto entry : descriptor->namespace_imports()) {
    builder()
        ->LoadLiteral(Smi::FromInt(entry->module_request))
        .StoreAccumulatorInRegister(module_request)
        .CallRuntime(Runtime::kGetModuleNamespace, module_request);
    Variable* var = closure_scope()->LookupInModule(entry->local_name);
    BuildVariableAssignment(var, Token::INIT, HoleCheckMode::kElided);
  }
}

void BytecodeGenerator::BuildDeclareCall(Runtime::FunctionId id) {
  if (!top_level_builder()->has_top_level_declaration()) return;
  DCHECK(!top_level_builder()->processed());

  top_level_builder()->set_constant_pool_entry(
      builder()->AllocateDeferredConstantPoolEntry());

  // Emit code to declare globals.
  RegisterList args = register_allocator()->NewRegisterList(2);
  builder()
      ->LoadConstantPoolEntry(top_level_builder()->constant_pool_entry())
      .StoreAccumulatorInRegister(args[0])
      .MoveRegister(Register::function_closure(), args[1])
      .CallRuntime(id, args);

  top_level_builder()->mark_processed();
}

void BytecodeGenerator::VisitModuleDeclarations(Declaration::List* decls) {
  RegisterAllocationScope register_scope(this);
  for (Declaration* decl : *decls) {
    Variable* var = decl->var();
    if (!var->is_used()) continue;
    if (var->location() == VariableLocation::MODULE) {
      if (decl->IsFunctionDeclaration()) {
        DCHECK(var->IsExport());
        FunctionDeclaration* f = static_cast<FunctionDeclaration*>(decl);
        AddToEagerLiteralsIfEager(f->fun());
        top_level_builder()->record_module_function_declaration();
      } else if (var->IsExport() && var->binding_needs_init()) {
        DCHECK(decl->IsVariableDeclaration());
        top_level_builder()->record_module_variable_declaration();
      }
    } else {
      RegisterAllocationScope register_scope(this);
      Visit(decl);
    }
  }
  BuildDeclareCall(Runtime::kDeclareModuleExports);
}

void BytecodeGenerator::VisitGlobalDeclarations(Declaration::List* decls) {
  RegisterAllocationScope register_scope(this);
  for (Declaration* decl : *decls) {
    Variable* var = decl->var();
    DCHECK(var->is_used());
    if (var->location() == VariableLocation::UNALLOCATED) {
      // var or function.
      if (decl->IsFunctionDeclaration()) {
        top_level_builder()->record_global_function_declaration();
        FunctionDeclaration* f = static_cast<FunctionDeclaration*>(decl);
        AddToEagerLiteralsIfEager(f->fun());
      } else {
        top_level_builder()->record_global_variable_declaration();
      }
    } else {
      // let or const. Handled in NewScriptContext.
      DCHECK(decl->IsVariableDeclaration());
      DCHECK(IsLexicalVariableMode(var->mode()));
    }
  }

  BuildDeclareCall(Runtime::kDeclareGlobals);
}

void BytecodeGenerator::VisitDeclarations(Declaration::List* declarations) {
  for (Declaration* decl : *declarations) {
    RegisterAllocationScope register_scope(this);
    Visit(decl);
  }
}

void BytecodeGenerator::VisitStatements(
    const ZonePtrList<Statement>* statements) {
  for (int i = 0; i < statements->length(); i++) {
    // Allocate an outer register allocations scope for the statement.
    RegisterAllocationScope allocation_scope(this);
    Statement* stmt = statements->at(i);
    Visit(stmt);
    if (builder()->RemainderOfBlockIsDead()) break;
  }
}

void BytecodeGenerator::VisitExpressionStatement(ExpressionStatement* stmt) {
  builder()->SetStatementPosition(stmt);
  VisitForEffect(stmt->expression());
}

void BytecodeGenerator::VisitEmptyStatement(EmptyStatement* stmt) {}

void BytecodeGenerator::VisitIfStatement(IfStatement* stmt) {
  ConditionalControlFlowBuilder conditional_builder(
      builder(), block_coverage_builder_, stmt);
  builder()->SetStatementPosition(stmt);

  if (stmt->condition()->ToBooleanIsTrue()) {
    // Generate then block unconditionally as always true.
    conditional_builder.Then();
    Visit(stmt->then_statement());
  } else if (stmt->condition()->ToBooleanIsFalse()) {
    // Generate else block unconditionally if it exists.
    if (stmt->HasElseStatement()) {
      conditional_builder.Else();
      Visit(stmt->else_statement());
    }
  } else {
    // TODO(oth): If then statement is BreakStatement or
    // ContinueStatement we can reduce number of generated
    // jump/jump_ifs here. See BasicLoops test.
    VisitForTest(stmt->condition(), conditional_builder.then_labels(),
                 conditional_builder.else_labels(), TestFallthrough::kThen);

    conditional_builder.Then();
    Visit(stmt->then_statement());

    if (stmt->HasElseStatement()) {
      conditional_builder.JumpToEnd();
      conditional_builder.Else();
      Visit(stmt->else_statement());
    }
  }
}

void BytecodeGenerator::VisitSloppyBlockFunctionStatement(
    SloppyBlockFunctionStatement* stmt) {
  Visit(stmt->statement());
}

void BytecodeGenerator::VisitContinueStatement(ContinueStatement* stmt) {
  AllocateBlockCoverageSlotIfEnabled(stmt, SourceRangeKind::kContinuation);
  builder()->SetStatementPosition(stmt);
  execution_control()->Continue(stmt->target());
}

void BytecodeGenerator::VisitBreakStatement(BreakStatement* stmt) {
  AllocateBlockCoverageSlotIfEnabled(stmt, SourceRangeKind::kContinuation);
  builder()->SetStatementPosition(stmt);
  execution_control()->Break(stmt->target());
}

void BytecodeGenerator::VisitReturnStatement(ReturnStatement* stmt) {
  AllocateBlockCoverageSlotIfEnabled(stmt, SourceRangeKind::kContinuation);
  builder()->SetStatementPosition(stmt);
  VisitForAccumulatorValue(stmt->expression());
  if (stmt->is_async_return()) {
    execution_control()->AsyncReturnAccumulator(stmt->end_position());
  } else {
    execution_control()->ReturnAccumulator(stmt->end_position());
  }
}

void BytecodeGenerator::VisitWithStatement(WithStatement* stmt) {
  builder()->SetStatementPosition(stmt);
  VisitForAccumulatorValue(stmt->expression());
  BuildNewLocalWithContext(stmt->scope());
  VisitInScope(stmt->statement(), stmt->scope());
}

void BytecodeGenerator::VisitSwitchStatement(SwitchStatement* stmt) {
  // We need this scope because we visit for register values. We have to
  // maintain a execution result scope where registers can be allocated.
  ZonePtrList<CaseClause>* clauses = stmt->cases();
  SwitchBuilder switch_builder(builder(), block_coverage_builder_, stmt,
                               clauses->length());
  ControlScopeForBreakable scope(this, stmt, &switch_builder);
  int default_index = -1;

  builder()->SetStatementPosition(stmt);

  // Keep the switch value in a register until a case matches.
  Register tag = VisitForRegisterValue(stmt->tag());
  FeedbackSlot slot = clauses->length() > 0
                          ? feedback_spec()->AddCompareICSlot()
                          : FeedbackSlot::Invalid();

  // Iterate over all cases and create nodes for label comparison.
  for (int i = 0; i < clauses->length(); i++) {
    CaseClause* clause = clauses->at(i);

    // The default is not a test, remember index.
    if (clause->is_default()) {
      default_index = i;
      continue;
    }

    // Perform label comparison as if via '===' with tag.
    VisitForAccumulatorValue(clause->label());
    builder()->CompareOperation(Token::Value::EQ_STRICT, tag,
                                feedback_index(slot));
    switch_builder.Case(ToBooleanMode::kAlreadyBoolean, i);
  }

  if (default_index >= 0) {
    // Emit default jump if there is a default case.
    switch_builder.DefaultAt(default_index);
  } else {
    // Otherwise if we have reached here none of the cases matched, so jump to
    // the end.
    switch_builder.Break();
  }

  // Iterate over all cases and create the case bodies.
  for (int i = 0; i < clauses->length(); i++) {
    CaseClause* clause = clauses->at(i);
    switch_builder.SetCaseTarget(i, clause);
    VisitStatements(clause->statements());
  }
}

template <typename TryBodyFunc, typename CatchBodyFunc>
void BytecodeGenerator::BuildTryCatch(
    TryBodyFunc try_body_func, CatchBodyFunc catch_body_func,
    HandlerTable::CatchPrediction catch_prediction,
    TryCatchStatement* stmt_for_coverage) {
  TryCatchBuilder try_control_builder(
      builder(),
      stmt_for_coverage == nullptr ? nullptr : block_coverage_builder_,
      stmt_for_coverage, catch_prediction);

  // Preserve the context in a dedicated register, so that it can be restored
  // when the handler is entered by the stack-unwinding machinery.
  // TODO(ignition): Be smarter about register allocation.
  Register context = register_allocator()->NewRegister();
  builder()->MoveRegister(Register::current_context(), context);

  // Evaluate the try-block inside a control scope. This simulates a handler
  // that is intercepting 'throw' control commands.
  try_control_builder.BeginTry(context);
  {
    ControlScopeForTryCatch scope(this, &try_control_builder);
    try_body_func();
  }
  try_control_builder.EndTry();

  catch_body_func(context);

  try_control_builder.EndCatch();
}

template <typename TryBodyFunc, typename FinallyBodyFunc>
void BytecodeGenerator::BuildTryFinally(
    TryBodyFunc try_body_func, FinallyBodyFunc finally_body_func,
    HandlerTable::CatchPrediction catch_prediction,
    TryFinallyStatement* stmt_for_coverage) {
  // We can't know whether the finally block will override ("catch") an
  // exception thrown in the try block, so we just adopt the outer prediction.
  TryFinallyBuilder try_control_builder(
      builder(),
      stmt_for_coverage == nullptr ? nullptr : block_coverage_builder_,
      stmt_for_coverage, catch_prediction);

  // We keep a record of all paths that enter the finally-block to be able to
  // dispatch to the correct continuation point after the statements in the
  // finally-block have been evaluated.
  //
  // The try-finally construct can enter the finally-block in three ways:
  // 1. By exiting the try-block normally, falling through at the end.
  // 2. By exiting the try-block with a function-local control flow transfer
  //    (i.e. through break/continue/return statements).
  // 3. By exiting the try-block with a thrown exception.
  //
  // The result register semantics depend on how the block was entered:
  //  - ReturnStatement: It represents the return value being returned.
  //  - ThrowStatement: It represents the exception being thrown.
  //  - BreakStatement/ContinueStatement: Undefined and not used.
  //  - Falling through into finally-block: Undefined and not used.
  Register token = register_allocator()->NewRegister();
  Register result = register_allocator()->NewRegister();
  ControlScope::DeferredCommands commands(this, token, result);

  // Preserve the context in a dedicated register, so that it can be restored
  // when the handler is entered by the stack-unwinding machinery.
  // TODO(ignition): Be smarter about register allocation.
  Register context = register_allocator()->NewRegister();
  builder()->MoveRegister(Register::current_context(), context);

  // Evaluate the try-block inside a control scope. This simulates a handler
  // that is intercepting all control commands.
  try_control_builder.BeginTry(context);
  {
    ControlScopeForTryFinally scope(this, &try_control_builder, &commands);
    try_body_func();
  }
  try_control_builder.EndTry();

  // Record fall-through and exception cases.
  commands.RecordFallThroughPath();
  try_control_builder.LeaveTry();
  try_control_builder.BeginHandler();
  commands.RecordHandlerReThrowPath();

  // Pending message object is saved on entry.
  try_control_builder.BeginFinally();
  Register message = context;  // Reuse register.

  // Clear message object as we enter the finally block.
  builder()->LoadTheHole().SetPendingMessage().StoreAccumulatorInRegister(
      message);

  // Evaluate the finally-block.
  finally_body_func(token);
  try_control_builder.EndFinally();

  // Pending message object is restored on exit.
  builder()->LoadAccumulatorWithRegister(message).SetPendingMessage();

  // Dynamic dispatch after the finally-block.
  commands.ApplyDeferredCommands();
}

void BytecodeGenerator::VisitIterationBody(IterationStatement* stmt,
                                           LoopBuilder* loop_builder) {
  loop_builder->LoopBody();
  ControlScopeForIteration execution_control(this, stmt, loop_builder);
  Visit(stmt->body());
  loop_builder->BindContinueTarget();
}

void BytecodeGenerator::VisitDoWhileStatement(DoWhileStatement* stmt) {
  LoopBuilder loop_builder(builder(), block_coverage_builder_, stmt);
  if (stmt->cond()->ToBooleanIsFalse()) {
    // Since we know that the condition is false, we don't create a loop.
    // Therefore, we don't create a LoopScope (and thus we don't create a header
    // and a JumpToHeader). However, we still need to iterate once through the
    // body.
    VisitIterationBody(stmt, &loop_builder);
  } else if (stmt->cond()->ToBooleanIsTrue()) {
    LoopScope loop_scope(this, &loop_builder);
    VisitIterationBody(stmt, &loop_builder);
  } else {
    LoopScope loop_scope(this, &loop_builder);
    VisitIterationBody(stmt, &loop_builder);
    builder()->SetExpressionAsStatementPosition(stmt->cond());
    BytecodeLabels loop_backbranch(zone());
    VisitForTest(stmt->cond(), &loop_backbranch, loop_builder.break_labels(),
                 TestFallthrough::kThen);
    loop_backbranch.Bind(builder());
  }
}

void BytecodeGenerator::VisitWhileStatement(WhileStatement* stmt) {
  LoopBuilder loop_builder(builder(), block_coverage_builder_, stmt);

  if (stmt->cond()->ToBooleanIsFalse()) {
    // If the condition is false there is no need to generate the loop.
    return;
  }

  LoopScope loop_scope(this, &loop_builder);
  if (!stmt->cond()->ToBooleanIsTrue()) {
    builder()->SetExpressionAsStatementPosition(stmt->cond());
    BytecodeLabels loop_body(zone());
    VisitForTest(stmt->cond(), &loop_body, loop_builder.break_labels(),
                 TestFallthrough::kThen);
    loop_body.Bind(builder());
  }
  VisitIterationBody(stmt, &loop_builder);
}

void BytecodeGenerator::VisitForStatement(ForStatement* stmt) {
  if (stmt->init() != nullptr) {
    Visit(stmt->init());
  }

  LoopBuilder loop_builder(builder(), block_coverage_builder_, stmt);
  if (stmt->cond() && stmt->cond()->ToBooleanIsFalse()) {
    // If the condition is known to be false there is no need to generate
    // body, next or condition blocks. Init block should be generated.
    return;
  }

  LoopScope loop_scope(this, &loop_builder);
  if (stmt->cond() && !stmt->cond()->ToBooleanIsTrue()) {
    builder()->SetExpressionAsStatementPosition(stmt->cond());
    BytecodeLabels loop_body(zone());
    VisitForTest(stmt->cond(), &loop_body, loop_builder.break_labels(),
                 TestFallthrough::kThen);
    loop_body.Bind(builder());
  }
  VisitIterationBody(stmt, &loop_builder);
  if (stmt->next() != nullptr) {
    builder()->SetStatementPosition(stmt->next());
    Visit(stmt->next());
  }
}

void BytecodeGenerator::VisitForInStatement(ForInStatement* stmt) {
  if (stmt->subject()->IsNullLiteral() ||
      stmt->subject()->IsUndefinedLiteral()) {
    // ForIn generates lots of code, skip if it wouldn't produce any effects.
    return;
  }

  BytecodeLabel subject_undefined_label;
  FeedbackSlot slot = feedback_spec()->AddForInSlot();

  // Prepare the state for executing ForIn.
  builder()->SetExpressionAsStatementPosition(stmt->subject());
  VisitForAccumulatorValue(stmt->subject());
  builder()->JumpIfUndefinedOrNull(&subject_undefined_label);
  Register receiver = register_allocator()->NewRegister();
  builder()->ToObject(receiver);

  // Used as kRegTriple and kRegPair in ForInPrepare and ForInNext.
  RegisterList triple = register_allocator()->NewRegisterList(3);
  Register cache_length = triple[2];
  builder()->ForInEnumerate(receiver);
  builder()->ForInPrepare(triple, feedback_index(slot));

  // Set up loop counter
  Register index = register_allocator()->NewRegister();
  builder()->LoadLiteral(Smi::zero());
  builder()->StoreAccumulatorInRegister(index);

  // The loop
  {
    LoopBuilder loop_builder(builder(), block_coverage_builder_, stmt);
    LoopScope loop_scope(this, &loop_builder);
    builder()->SetExpressionAsStatementPosition(stmt->each());
    builder()->ForInContinue(index, cache_length);
    loop_builder.BreakIfFalse(ToBooleanMode::kAlreadyBoolean);
    builder()->ForInNext(receiver, index, triple.Truncate(2),
                         feedback_index(slot));
    loop_builder.ContinueIfUndefined();

    // Assign accumulator value to the 'each' target.
    {
      EffectResultScope scope(this);
      // Make sure to preserve the accumulator across the PrepareAssignmentLhs
      // call.
      AssignmentLhsData lhs_data = PrepareAssignmentLhs(
          stmt->each(), AccumulatorPreservingMode::kPreserve);
      builder()->SetExpressionPosition(stmt->each());
      BuildAssignment(lhs_data, Token::ASSIGN, LookupHoistingMode::kNormal);
    }

    VisitIterationBody(stmt, &loop_builder);
    builder()->ForInStep(index);
    builder()->StoreAccumulatorInRegister(index);
  }
  builder()->Bind(&subject_undefined_label);
}

// Desugar a for-of statement into an application of the iteration protocol.
//
// for (EACH of SUBJECT) BODY
//
//   becomes
//
// iterator = %GetIterator(SUBJECT)
// try {
//
//   loop {
//     // Make sure we are considered 'done' if .next(), .done or .value fail.
//     done = true
//     value = iterator.next()
//     if (value.done) break;
//     value = value.value
//     done = false
//
//     EACH = value
//     BODY
//   }
//   done = true
//
// } catch(e) {
//   iteration_continuation = RETHROW
// } finally {
//   %FinalizeIteration(iterator, done, iteration_continuation)
// }
void BytecodeGenerator::VisitForOfStatement(ForOfStatement* stmt) {
  EffectResultScope effect_scope(this);

  builder()->SetExpressionAsStatementPosition(stmt->subject());
  VisitForAccumulatorValue(stmt->subject());

  // Store the iterator in a dedicated register so that it can be closed on
  // exit, and the 'done' value in a dedicated register so that it can be
  // changed and accessed independently of the iteration result.
  IteratorRecord iterator = BuildGetIteratorRecord(stmt->type());
  Register done = register_allocator()->NewRegister();
  builder()->LoadFalse();
  builder()->StoreAccumulatorInRegister(done);

  BuildTryFinally(
      // Try block.
      [&]() {
        Register next_result = register_allocator()->NewRegister();

        LoopBuilder loop_builder(builder(), block_coverage_builder_, stmt);
        LoopScope loop_scope(this, &loop_builder);

        builder()->LoadTrue().StoreAccumulatorInRegister(done);

        // Call the iterator's .next() method. Break from the loop if the `done`
        // property is truthy, otherwise load the value from the iterator result
        // and append the argument.
        builder()->SetExpressionAsStatementPosition(stmt->each());
        BuildIteratorNext(iterator, next_result);
        builder()->LoadNamedProperty(
            next_result, ast_string_constants()->done_string(),
            feedback_index(feedback_spec()->AddLoadICSlot()));
        loop_builder.BreakIfTrue(ToBooleanMode::kConvertToBoolean);

        builder()
            // value = value.value
            ->LoadNamedProperty(
                next_result, ast_string_constants()->value_string(),
                feedback_index(feedback_spec()->AddLoadICSlot()));
        // done = false, before the assignment to each happens, so that done is
        // false if the assignment throws.
        builder()
            ->StoreAccumulatorInRegister(next_result)
            .LoadFalse()
            .StoreAccumulatorInRegister(done);

        // Assign to the 'each' target.
        AssignmentLhsData lhs_data = PrepareAssignmentLhs(stmt->each());
        builder()->LoadAccumulatorWithRegister(next_result);
        BuildAssignment(lhs_data, Token::ASSIGN, LookupHoistingMode::kNormal);

        VisitIterationBody(stmt, &loop_builder);
      },
      // Finally block.
      [&](Register iteration_continuation_token) {
        // Finish the iteration in the finally block.
        BuildFinalizeIteration(iterator, done, iteration_continuation_token);
      },
      HandlerTable::UNCAUGHT);
}

void BytecodeGenerator::VisitTryCatchStatement(TryCatchStatement* stmt) {
  // Update catch prediction tracking. The updated catch_prediction value lasts
  // until the end of the try_block in the AST node, and does not apply to the
  // catch_block.
  HandlerTable::CatchPrediction outer_catch_prediction = catch_prediction();
  set_catch_prediction(stmt->GetCatchPrediction(outer_catch_prediction));

  BuildTryCatch(
      // Try body.
      [&]() {
        Visit(stmt->try_block());
        set_catch_prediction(outer_catch_prediction);
      },
      // Catch body.
      [&](Register context) {
        if (stmt->scope()) {
          // Create a catch scope that binds the exception.
          BuildNewLocalCatchContext(stmt->scope());
          builder()->StoreAccumulatorInRegister(context);
        }

        // If requested, clear message object as we enter the catch block.
        if (stmt->ShouldClearPendingException(outer_catch_prediction)) {
          builder()->LoadTheHole().SetPendingMessage();
        }

        // Load the catch context into the accumulator.
        builder()->LoadAccumulatorWithRegister(context);

        // Evaluate the catch-block.
        if (stmt->scope()) {
          VisitInScope(stmt->catch_block(), stmt->scope());
        } else {
          VisitBlock(stmt->catch_block());
        }
      },
      catch_prediction(), stmt);
}

void BytecodeGenerator::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
  BuildTryFinally(
      // Try block.
      [&]() { Visit(stmt->try_block()); },
      // Finally block.
      [&](Register body_continuation_token) { Visit(stmt->finally_block()); },
      catch_prediction(), stmt);
}

void BytecodeGenerator::VisitDebuggerStatement(DebuggerStatement* stmt) {
  builder()->SetStatementPosition(stmt);
  builder()->Debugger();
}

void BytecodeGenerator::VisitFunctionLiteral(FunctionLiteral* expr) {
  DCHECK(expr->scope()->outer_scope() == current_scope());
  uint8_t flags = CreateClosureFlags::Encode(
      expr->pretenure(), closure_scope()->is_function_scope(),
      info()->flags().might_always_opt());
  size_t entry = builder()->AllocateDeferredConstantPoolEntry();
  builder()->CreateClosure(entry, GetCachedCreateClosureSlot(expr), flags);
  function_literals_.push_back(std::make_pair(expr, entry));
  AddToEagerLiteralsIfEager(expr);
}

void BytecodeGenerator::AddToEagerLiteralsIfEager(FunctionLiteral* literal) {
  if (eager_inner_literals_ && literal->ShouldEagerCompile()) {
    DCHECK(!IsInEagerLiterals(literal, *eager_inner_literals_));
    eager_inner_literals_->push_back(literal);
  }
}

bool BytecodeGenerator::ShouldOptimizeAsOneShot() const {
  if (!FLAG_enable_one_shot_optimization) return false;

  if (loop_depth_ > 0) return false;

  return info()->literal()->is_toplevel() ||
         info()->literal()->is_oneshot_iife();
}

void BytecodeGenerator::BuildClassLiteral(ClassLiteral* expr, Register name) {
  size_t class_boilerplate_entry =
      builder()->AllocateDeferredConstantPoolEntry();
  class_literals_.push_back(std::make_pair(expr, class_boilerplate_entry));

  VisitDeclarations(expr->scope()->declarations());
  Register class_constructor = register_allocator()->NewRegister();

  // Create the class brand symbol and store it on the context during class
  // evaluation. This will be stored in the instance later in the constructor.
  // We do this early so that invalid access to private methods or accessors
  // in computed property keys throw.
  if (expr->scope()->brand() != nullptr) {
    Register brand = register_allocator()->NewRegister();
    const AstRawString* class_name =
        expr->scope()->class_variable() != nullptr
            ? expr->scope()->class_variable()->raw_name()
            : ast_string_constants()->empty_string();
    builder()
        ->LoadLiteral(class_name)
        .StoreAccumulatorInRegister(brand)
        .CallRuntime(Runtime::kCreatePrivateBrandSymbol, brand);
    BuildVariableAssignment(expr->scope()->brand(), Token::INIT,
                            HoleCheckMode::kElided);
  }

  AccessorTable<ClassLiteral::Property> private_accessors(zone());
  for (int i = 0; i < expr->private_members()->length(); i++) {
    ClassLiteral::Property* property = expr->private_members()->at(i);
    DCHECK(property->is_private());
    switch (property->kind()) {
      case ClassLiteral::Property::FIELD: {
        // Initialize the private field variables early.
        // Create the private name symbols for fields during class
        // evaluation and store them on the context. These will be
        // used as keys later during instance or static initialization.
        RegisterAllocationScope private_name_register_scope(this);
        Register private_name = register_allocator()->NewRegister();
        VisitForRegisterValue(property->key(), private_name);
        builder()
            ->LoadLiteral(property->key()->AsLiteral()->AsRawPropertyName())
            .StoreAccumulatorInRegister(private_name)
            .CallRuntime(Runtime::kCreatePrivateNameSymbol, private_name);
        DCHECK_NOT_NULL(property->private_name_var());
        BuildVariableAssignment(property->private_name_var(), Token::INIT,
                                HoleCheckMode::kElided);
        break;
      }
      case ClassLiteral::Property::METHOD: {
        // We can initialize the private methods and accessors later so that the
        // home objects can be assigned right after the creation of the
        // closures, and those are guarded by the brand checks.
        break;
      }
      // Collect private accessors into a table to merge the creation of
      // those closures later.
      case ClassLiteral::Property::GETTER: {
        Literal* key = property->key()->AsLiteral();
        DCHECK_NULL(private_accessors.LookupOrInsert(key)->getter);
        private_accessors.LookupOrInsert(key)->getter = property;
        break;
      }
      case ClassLiteral::Property::SETTER: {
        Literal* key = property->key()->AsLiteral();
        DCHECK_NULL(private_accessors.LookupOrInsert(key)->setter);
        private_accessors.LookupOrInsert(key)->setter = property;
        break;
      }
      default:
        UNREACHABLE();
    }
  }

  {
    RegisterAllocationScope register_scope(this);
    RegisterList args = register_allocator()->NewGrowableRegisterList();

    Register class_boilerplate = register_allocator()->GrowRegisterList(&args);
    Register class_constructor_in_args =
        register_allocator()->GrowRegisterList(&args);
    Register super_class = register_allocator()->GrowRegisterList(&args);
    DCHECK_EQ(ClassBoilerplate::kFirstDynamicArgumentIndex,
              args.register_count());

    VisitForAccumulatorValueOrTheHole(expr->extends());
    builder()->StoreAccumulatorInRegister(super_class);

    VisitFunctionLiteral(expr->constructor());
    builder()
        ->StoreAccumulatorInRegister(class_constructor)
        .MoveRegister(class_constructor, class_constructor_in_args)
        .LoadConstantPoolEntry(class_boilerplate_entry)
        .StoreAccumulatorInRegister(class_boilerplate);

    // Create computed names and method values nodes to store into the literal.
    for (int i = 0; i < expr->public_members()->length(); i++) {
      ClassLiteral::Property* property = expr->public_members()->at(i);
      if (property->is_computed_name()) {
        Register key = register_allocator()->GrowRegisterList(&args);

        builder()->SetExpressionAsStatementPosition(property->key());
        BuildLoadPropertyKey(property, key);
        if (property->is_static()) {
          // The static prototype property is read only. We handle the non
          // computed property name case in the parser. Since this is the only
          // case where we need to check for an own read only property we
          // special case this so we do not need to do this for every property.

          FeedbackSlot slot = GetDummyCompareICSlot();
          BytecodeLabel done;
          builder()
              ->LoadLiteral(ast_string_constants()->prototype_string())
              .CompareOperation(Token::Value::EQ_STRICT, key,
                                feedback_index(slot))
              .JumpIfFalse(ToBooleanMode::kAlreadyBoolean, &done)
              .CallRuntime(Runtime::kThrowStaticPrototypeError)
              .Bind(&done);
        }

        if (property->kind() == ClassLiteral::Property::FIELD) {
          DCHECK(!property->is_private());
          // Initialize field's name variable with the computed name.
          DCHECK_NOT_NULL(property->computed_name_var());
          builder()->LoadAccumulatorWithRegister(key);
          BuildVariableAssignment(property->computed_name_var(), Token::INIT,
                                  HoleCheckMode::kElided);
        }
      }

      DCHECK(!property->is_private());

      if (property->kind() == ClassLiteral::Property::FIELD) {
        // We don't compute field's value here, but instead do it in the
        // initializer function.
        continue;
      }

      Register value = register_allocator()->GrowRegisterList(&args);
      VisitForRegisterValue(property->value(), value);
    }

    builder()->CallRuntime(Runtime::kDefineClass, args);
  }
  Register prototype = register_allocator()->NewRegister();
  builder()->StoreAccumulatorInRegister(prototype);

  // Assign to class variable.
  Variable* class_variable = expr->scope()->class_variable();
  if (class_variable != nullptr && class_variable->is_used()) {
    DCHECK(class_variable->IsStackLocal() || class_variable->IsContextSlot());
    builder()->LoadAccumulatorWithRegister(class_constructor);
    BuildVariableAssignment(class_variable, Token::INIT,
                            HoleCheckMode::kElided);
  }

  // Create the closures of private methods, and store the home object for
  // any private methods that need them.
  if (expr->has_private_methods()) {
    for (int i = 0; i < expr->private_members()->length(); i++) {
      ClassLiteral::Property* property = expr->private_members()->at(i);
      if (property->kind() != ClassLiteral::Property::METHOD) {
        continue;
      }
      RegisterAllocationScope register_scope(this);
      VisitForAccumulatorValue(property->value());
      BuildVariableAssignment(property->private_name_var(), Token::INIT,
                              HoleCheckMode::kElided);
      Register home_object = property->private_name_var()->is_static()
                                 ? class_constructor
                                 : prototype;
      if (property->NeedsHomeObjectOnClassPrototype()) {
        Register func = register_allocator()->NewRegister();
        builder()->StoreAccumulatorInRegister(func);
        VisitSetHomeObject(func, home_object, property);
      }
    }
  }

  // Define private accessors, using only a single call to the runtime for
  // each pair of corresponding getters and setters, in the order the first
  // component is declared. Store the home objects if necessary.
  for (auto accessors : private_accessors.ordered_accessors()) {
    RegisterAllocationScope inner_register_scope(this);
    RegisterList accessors_reg = register_allocator()->NewRegisterList(2);
    ClassLiteral::Property* getter = accessors.second->getter;
    ClassLiteral::Property* setter = accessors.second->setter;
    bool is_static =
        getter != nullptr ? getter->is_static() : setter->is_static();
    Register home_object = is_static ? class_constructor : prototype;
    VisitLiteralAccessor(home_object, getter, accessors_reg[0]);
    VisitLiteralAccessor(home_object, setter, accessors_reg[1]);
    builder()->CallRuntime(Runtime::kCreatePrivateAccessors, accessors_reg);
    Variable* var = getter != nullptr ? getter->private_name_var()
                                      : setter->private_name_var();
    DCHECK_NOT_NULL(var);
    BuildVariableAssignment(var, Token::INIT, HoleCheckMode::kElided);
  }

  if (expr->instance_members_initializer_function() != nullptr) {
    Register initializer =
        VisitForRegisterValue(expr->instance_members_initializer_function());

    if (FunctionLiteral::NeedsHomeObject(
            expr->instance_members_initializer_function())) {
      FeedbackSlot slot = feedback_spec()->AddStoreICSlot(language_mode());
      builder()->LoadAccumulatorWithRegister(prototype).StoreHomeObjectProperty(
          initializer, feedback_index(slot), language_mode());
    }

    FeedbackSlot slot = feedback_spec()->AddStoreICSlot(language_mode());
    builder()
        ->LoadAccumulatorWithRegister(initializer)
        .StoreClassFieldsInitializer(class_constructor, feedback_index(slot))
        .LoadAccumulatorWithRegister(class_constructor);
  }

  if (expr->static_fields_initializer() != nullptr) {
    // TODO(gsathya): This can be optimized away to be a part of the
    // class boilerplate in the future. The name argument can be
    // passed to the DefineClass runtime function and have it set
    // there.
    if (name.is_valid()) {
      Register key = register_allocator()->NewRegister();
      builder()
          ->LoadLiteral(ast_string_constants()->name_string())
          .StoreAccumulatorInRegister(key);

      DataPropertyInLiteralFlags data_property_flags =
          DataPropertyInLiteralFlag::kNoFlags;
      FeedbackSlot slot =
          feedback_spec()->AddStoreDataPropertyInLiteralICSlot();
      builder()->LoadAccumulatorWithRegister(name).StoreDataPropertyInLiteral(
          class_constructor, key, data_property_flags, feedback_index(slot));
    }

    RegisterList args = register_allocator()->NewRegisterList(1);
    Register initializer =
        VisitForRegisterValue(expr->static_fields_initializer());

    if (FunctionLiteral::NeedsHomeObject(expr->static_fields_initializer())) {
      FeedbackSlot slot = feedback_spec()->AddStoreICSlot(language_mode());
      builder()
          ->LoadAccumulatorWithRegister(class_constructor)
          .StoreHomeObjectProperty(initializer, feedback_index(slot),
                                   language_mode());
    }

    builder()
        ->MoveRegister(class_constructor, args[0])
        .CallProperty(initializer, args,
                      feedback_index(feedback_spec()->AddCallICSlot()));
  }
  builder()->LoadAccumulatorWithRegister(class_constructor);
}

void BytecodeGenerator::VisitClassLiteral(ClassLiteral* expr) {
  VisitClassLiteral(expr, Register::invalid_value());
}

void BytecodeGenerator::VisitClassLiteral(ClassLiteral* expr, Register name) {
  CurrentScope current_scope(this, expr->scope());
  DCHECK_NOT_NULL(expr->scope());
  if (expr->scope()->NeedsContext()) {
    BuildNewLocalBlockContext(expr->scope());
    ContextScope scope(this, expr->scope());
    BuildClassLiteral(expr, name);
  } else {
    BuildClassLiteral(expr, name);
  }
}

void BytecodeGenerator::VisitInitializeClassMembersStatement(
    InitializeClassMembersStatement* stmt) {
  RegisterList args = register_allocator()->NewRegisterList(3);
  Register constructor = args[0], key = args[1], value = args[2];
  builder()->MoveRegister(builder()->Receiver(), constructor);

  for (int i = 0; i < stmt->fields()->length(); i++) {
    ClassLiteral::Property* property = stmt->fields()->at(i);
    // Private methods are not initialized in the
    // InitializeClassMembersStatement.
    DCHECK_IMPLIES(property->is_private(),
                   property->kind() == ClassLiteral::Property::FIELD);

    if (property->is_computed_name()) {
      DCHECK_EQ(property->kind(), ClassLiteral::Property::FIELD);
      DCHECK(!property->is_private());
      Variable* var = property->computed_name_var();
      DCHECK_NOT_NULL(var);
      // The computed name is already evaluated and stored in a
      // variable at class definition time.
      BuildVariableLoad(var, HoleCheckMode::kElided);
      builder()->StoreAccumulatorInRegister(key);
    } else if (property->is_private()) {
      Variable* private_name_var = property->private_name_var();
      DCHECK_NOT_NULL(private_name_var);
      BuildVariableLoad(private_name_var, HoleCheckMode::kElided);
      builder()->StoreAccumulatorInRegister(key);
    } else {
      BuildLoadPropertyKey(property, key);
    }

    builder()->SetExpressionAsStatementPosition(property->value());
    VisitForRegisterValue(property->value(), value);
    VisitSetHomeObject(value, constructor, property);

    Runtime::FunctionId function_id =
        property->kind() == ClassLiteral::Property::FIELD &&
                !property->is_private()
            ? Runtime::kCreateDataProperty
            : Runtime::kAddPrivateField;
    builder()->CallRuntime(function_id, args);
  }
}

void BytecodeGenerator::BuildInvalidPropertyAccess(MessageTemplate tmpl,
                                                   Property* property) {
  RegisterAllocationScope register_scope(this);
  const AstRawString* name = property->key()->AsVariableProxy()->raw_name();
  RegisterList args = register_allocator()->NewRegisterList(2);
  builder()
      ->LoadLiteral(Smi::FromEnum(tmpl))
      .StoreAccumulatorInRegister(args[0])
      .LoadLiteral(name)
      .StoreAccumulatorInRegister(args[1])
      .CallRuntime(Runtime::kNewTypeError, args)
      .Throw();
}

void BytecodeGenerator::BuildPrivateBrandInitialization(Register receiver) {
  RegisterList brand_args = register_allocator()->NewRegisterList(3);
  Variable* brand = info()->scope()->outer_scope()->AsClassScope()->brand();
  int depth = execution_context()->ContextChainDepth(brand->scope());
  ContextScope* class_context = execution_context()->Previous(depth);

  BuildVariableLoad(brand, HoleCheckMode::kElided);
  builder()
      ->StoreAccumulatorInRegister(brand_args[1])
      .MoveRegister(receiver, brand_args[0])
      .MoveRegister(class_context->reg(), brand_args[2])
      .CallRuntime(Runtime::kAddPrivateBrand, brand_args);
}

void BytecodeGenerator::BuildInstanceMemberInitialization(Register constructor,
                                                          Register instance) {
  RegisterList args = register_allocator()->NewRegisterList(1);
  Register initializer = register_allocator()->NewRegister();

  FeedbackSlot slot = feedback_spec()->AddLoadICSlot();
  BytecodeLabel done;

  builder()
      ->LoadClassFieldsInitializer(constructor, feedback_index(slot))
      // TODO(gsathya): This jump can be elided for the base
      // constructor and derived constructor. This is only required
      // when called from an arrow function.
      .JumpIfUndefined(&done)
      .StoreAccumulatorInRegister(initializer)
      .MoveRegister(instance, args[0])
      .CallProperty(initializer, args,
                    feedback_index(feedback_spec()->AddCallICSlot()))
      .Bind(&done);
}

void BytecodeGenerator::VisitNativeFunctionLiteral(
    NativeFunctionLiteral* expr) {
  size_t entry = builder()->AllocateDeferredConstantPoolEntry();
  int index = feedback_spec()->AddCreateClosureSlot();
  uint8_t flags = CreateClosureFlags::Encode(false, false, false);
  builder()->CreateClosure(entry, index, flags);
  native_function_literals_.push_back(std::make_pair(expr, entry));
}

void BytecodeGenerator::VisitConditional(Conditional* expr) {
  ConditionalControlFlowBuilder conditional_builder(
      builder(), block_coverage_builder_, expr);

  if (expr->condition()->ToBooleanIsTrue()) {
    // Generate then block unconditionally as always true.
    conditional_builder.Then();
    VisitForAccumulatorValue(expr->then_expression());
  } else if (expr->condition()->ToBooleanIsFalse()) {
    // Generate else block unconditionally if it exists.
    conditional_builder.Else();
    VisitForAccumulatorValue(expr->else_expression());
  } else {
    VisitForTest(expr->condition(), conditional_builder.then_labels(),
                 conditional_builder.else_labels(), TestFallthrough::kThen);

    conditional_builder.Then();
    VisitForAccumulatorValue(expr->then_expression());
    conditional_builder.JumpToEnd();

    conditional_builder.Else();
    VisitForAccumulatorValue(expr->else_expression());
  }
}

void BytecodeGenerator::VisitLiteral(Literal* expr) {
  if (execution_result()->IsEffect()) return;
  switch (expr->type()) {
    case Literal::kSmi:
      builder()->LoadLiteral(expr->AsSmiLiteral());
      break;
    case Literal::kHeapNumber:
      builder()->LoadLiteral(expr->AsNumber());
      break;
    case Literal::kUndefined:
      builder()->LoadUndefined();
      break;
    case Literal::kBoolean:
      builder()->LoadBoolean(expr->ToBooleanIsTrue());
      execution_result()->SetResultIsBoolean();
      break;
    case Literal::kNull:
      builder()->LoadNull();
      break;
    case Literal::kTheHole:
      builder()->LoadTheHole();
      break;
    case Literal::kString:
      builder()->LoadLiteral(expr->AsRawString());
      execution_result()->SetResultIsString();
      break;
    case Literal::kSymbol:
      builder()->LoadLiteral(expr->AsSymbol());
      break;
    case Literal::kBigInt:
      builder()->LoadLiteral(expr->AsBigInt());
      break;
  }
}

void BytecodeGenerator::VisitRegExpLiteral(RegExpLiteral* expr) {
  // Materialize a regular expression literal.
  builder()->CreateRegExpLiteral(
      expr->raw_pattern(), feedback_index(feedback_spec()->AddLiteralSlot()),
      expr->flags());
}

void BytecodeGenerator::BuildCreateObjectLiteral(Register literal,
                                                 uint8_t flags, size_t entry) {
  if (ShouldOptimizeAsOneShot()) {
    RegisterList args = register_allocator()->NewRegisterList(2);
    builder()
        ->LoadConstantPoolEntry(entry)
        .StoreAccumulatorInRegister(args[0])
        .LoadLiteral(Smi::FromInt(flags))
        .StoreAccumulatorInRegister(args[1])
        .CallRuntime(Runtime::kCreateObjectLiteralWithoutAllocationSite, args)
        .StoreAccumulatorInRegister(literal);

  } else {
    // TODO(cbruni): Directly generate runtime call for literals we cannot
    // optimize once the CreateShallowObjectLiteral stub is in sync with the TF
    // optimizations.
    int literal_index = feedback_index(feedback_spec()->AddLiteralSlot());
    builder()
        ->CreateObjectLiteral(entry, literal_index, flags)
        .StoreAccumulatorInRegister(literal);
  }
}

void BytecodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
  expr->InitDepthAndFlags();

  // Fast path for the empty object literal which doesn't need an
  // AllocationSite.
  if (expr->IsEmptyObjectLiteral()) {
    DCHECK(expr->IsFastCloningSupported());
    builder()->CreateEmptyObjectLiteral();
    return;
  }

  // Deep-copy the literal boilerplate.
  uint8_t flags = CreateObjectLiteralFlags::Encode(
      expr->ComputeFlags(), expr->IsFastCloningSupported());

  Register literal = register_allocator()->NewRegister();

  // Create literal object.
  int property_index = 0;
  bool clone_object_spread =
      expr->properties()->first()->kind() == ObjectLiteral::Property::SPREAD;
  if (clone_object_spread) {
    // Avoid the slow path for spreads in the following common cases:
    //   1) `let obj = { ...source }`
    //   2) `let obj = { ...source, override: 1 }`
    //   3) `let obj = { ...source, ...overrides }`
    RegisterAllocationScope register_scope(this);
    Expression* property = expr->properties()->first()->value();
    Register from_value = VisitForRegisterValue(property);
    int clone_index = feedback_index(feedback_spec()->AddCloneObjectSlot());
    builder()->CloneObject(from_value, flags, clone_index);
    builder()->StoreAccumulatorInRegister(literal);
    property_index++;
  } else {
    size_t entry;
    // If constant properties is an empty fixed array, use a cached empty fixed
    // array to ensure it's only added to the constant pool once.
    if (expr->properties_count() == 0) {
      entry = builder()->EmptyObjectBoilerplateDescriptionConstantPoolEntry();
    } else {
      entry = builder()->AllocateDeferredConstantPoolEntry();
      object_literals_.push_back(std::make_pair(expr, entry));
    }
    BuildCreateObjectLiteral(literal, flags, entry);
  }

  // Store computed values into the literal.
  AccessorTable<ObjectLiteral::Property> accessor_table(zone());
  for (; property_index < expr->properties()->length(); property_index++) {
    ObjectLiteral::Property* property = expr->properties()->at(property_index);
    if (property->is_computed_name()) break;
    if (!clone_object_spread && property->IsCompileTimeValue()) continue;

    RegisterAllocationScope inner_register_scope(this);
    Literal* key = property->key()->AsLiteral();
    switch (property->kind()) {
      case ObjectLiteral::Property::SPREAD:
        UNREACHABLE();
      case ObjectLiteral::Property::CONSTANT:
      case ObjectLiteral::Property::MATERIALIZED_LITERAL:
        DCHECK(clone_object_spread || !property->value()->IsCompileTimeValue());
        V8_FALLTHROUGH;
      case ObjectLiteral::Property::COMPUTED: {
        // It is safe to use [[Put]] here because the boilerplate already
        // contains computed properties with an uninitialized value.
        if (key->IsStringLiteral()) {
          DCHECK(key->IsPropertyName());
          if (property->emit_store()) {
            builder()->SetExpressionPosition(property->value());
            VisitForAccumulatorValue(property->value());
            FeedbackSlot slot = feedback_spec()->AddStoreOwnICSlot();
            if (FunctionLiteral::NeedsHomeObject(property->value())) {
              RegisterAllocationScope register_scope(this);
              Register value = register_allocator()->NewRegister();
              builder()->StoreAccumulatorInRegister(value);
              builder()->StoreNamedOwnProperty(
                  literal, key->AsRawPropertyName(), feedback_index(slot));
              VisitSetHomeObject(value, literal, property);
            } else {
              builder()->StoreNamedOwnProperty(
                  literal, key->AsRawPropertyName(), feedback_index(slot));
            }
          } else {
            builder()->SetExpressionPosition(property->value());
            VisitForEffect(property->value());
          }
        } else {
          RegisterList args = register_allocator()->NewRegisterList(3);

          builder()->MoveRegister(literal, args[0]);
          builder()->SetExpressionPosition(property->key());
          VisitForRegisterValue(property->key(), args[1]);
          builder()->SetExpressionPosition(property->value());
          VisitForRegisterValue(property->value(), args[2]);
          if (property->emit_store()) {
            builder()->CallRuntime(Runtime::kSetKeyedProperty, args);
            Register value = args[2];
            VisitSetHomeObject(value, literal, property);
          }
        }
        break;
      }
      case ObjectLiteral::Property::PROTOTYPE: {
        // __proto__:null is handled by CreateObjectLiteral.
        if (property->IsNullPrototype()) break;
        DCHECK(property->emit_store());
        DCHECK(!property->NeedsSetFunctionName());
        RegisterList args = register_allocator()->NewRegisterList(2);
        builder()->MoveRegister(literal, args[0]);
        builder()->SetExpressionPosition(property->value());
        VisitForRegisterValue(property->value(), args[1]);
        builder()->CallRuntime(Runtime::kInternalSetPrototype, args);
        break;
      }
      case ObjectLiteral::Property::GETTER:
        if (property->emit_store()) {
          accessor_table.LookupOrInsert(key)->getter = property;
        }
        break;
      case ObjectLiteral::Property::SETTER:
        if (property->emit_store()) {
          accessor_table.LookupOrInsert(key)->setter = property;
        }
        break;
    }
  }

  // Define accessors, using only a single call to the runtime for each pair of
  // corresponding getters and setters.
  for (auto accessors : accessor_table.ordered_accessors()) {
    RegisterAllocationScope inner_register_scope(this);
    RegisterList args = register_allocator()->NewRegisterList(5);
    builder()->MoveRegister(literal, args[0]);
    VisitForRegisterValue(accessors.first, args[1]);
    VisitLiteralAccessor(literal, accessors.second->getter, args[2]);
    VisitLiteralAccessor(literal, accessors.second->setter, args[3]);
    builder()
        ->LoadLiteral(Smi::FromInt(NONE))
        .StoreAccumulatorInRegister(args[4])
        .CallRuntime(Runtime::kDefineAccessorPropertyUnchecked, args);
  }

  // Object literals have two parts. The "static" part on the left contains no
  // computed property names, and so we can compute its map ahead of time; see
  // Runtime_CreateObjectLiteralBoilerplate. The second "dynamic" part starts
  // with the first computed property name and continues with all properties to
  // its right. All the code from above initializes the static component of the
  // object literal, and arranges for the map of the result to reflect the
  // static order in which the keys appear. For the dynamic properties, we
  // compile them into a series of "SetOwnProperty" runtime calls. This will
  // preserve insertion order.
  for (; property_index < expr->properties()->length(); property_index++) {
    ObjectLiteral::Property* property = expr->properties()->at(property_index);
    RegisterAllocationScope inner_register_scope(this);

    if (property->IsPrototype()) {
      // __proto__:null is handled by CreateObjectLiteral.
      if (property->IsNullPrototype()) continue;
      DCHECK(property->emit_store());
      DCHECK(!property->NeedsSetFunctionName());
      RegisterList args = register_allocator()->NewRegisterList(2);
      builder()->MoveRegister(literal, args[0]);
      builder()->SetExpressionPosition(property->value());
      VisitForRegisterValue(property->value(), args[1]);
      builder()->CallRuntime(Runtime::kInternalSetPrototype, args);
      continue;
    }

    switch (property->kind()) {
      case ObjectLiteral::Property::CONSTANT:
      case ObjectLiteral::Property::COMPUTED:
      case ObjectLiteral::Property::MATERIALIZED_LITERAL: {
        Register key = register_allocator()->NewRegister();
        BuildLoadPropertyKey(property, key);
        builder()->SetExpressionPosition(property->value());
        Register value;

        // Static class fields require the name property to be set on
        // the class, meaning we can't wait until the
        // StoreDataPropertyInLiteral call later to set the name.
        if (property->value()->IsClassLiteral() &&
            property->value()->AsClassLiteral()->static_fields_initializer() !=
                nullptr) {
          value = register_allocator()->NewRegister();
          VisitClassLiteral(property->value()->AsClassLiteral(), key);
          builder()->StoreAccumulatorInRegister(value);
        } else {
          value = VisitForRegisterValue(property->value());
        }
        VisitSetHomeObject(value, literal, property);

        DataPropertyInLiteralFlags data_property_flags =
            DataPropertyInLiteralFlag::kNoFlags;
        if (property->NeedsSetFunctionName()) {
          data_property_flags |= DataPropertyInLiteralFlag::kSetFunctionName;
        }

        FeedbackSlot slot =
            feedback_spec()->AddStoreDataPropertyInLiteralICSlot();
        builder()
            ->LoadAccumulatorWithRegister(value)
            .StoreDataPropertyInLiteral(literal, key, data_property_flags,
                                        feedback_index(slot));
        break;
      }
      case ObjectLiteral::Property::GETTER:
      case ObjectLiteral::Property::SETTER: {
        RegisterList args = register_allocator()->NewRegisterList(4);
        builder()->MoveRegister(literal, args[0]);
        BuildLoadPropertyKey(property, args[1]);
        builder()->SetExpressionPosition(property->value());
        VisitForRegisterValue(property->value(), args[2]);
        VisitSetHomeObject(args[2], literal, property);
        builder()
            ->LoadLiteral(Smi::FromInt(NONE))
            .StoreAccumulatorInRegister(args[3]);
        Runtime::FunctionId function_id =
            property->kind() == ObjectLiteral::Property::GETTER
                ? Runtime::kDefineGetterPropertyUnchecked
                : Runtime::kDefineSetterPropertyUnchecked;
        builder()->CallRuntime(function_id, args);
        break;
      }
      case ObjectLiteral::Property::SPREAD: {
        RegisterList args = register_allocator()->NewRegisterList(2);
        builder()->MoveRegister(literal, args[0]);
        builder()->SetExpressionPosition(property->value());
        VisitForRegisterValue(property->value(), args[1]);
        builder()->CallRuntime(Runtime::kInlineCopyDataProperties, args