text: // Copyright 2012 the V8 project authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #include "src/full-codegen/full-codegen.h"
  
  #include "src/ast/ast-numbering.h"
  #include "src/ast/ast.h"
  #include "src/ast/prettyprinter.h"
  #include "src/ast/scopeinfo.h"
  #include "src/ast/scopes.h"
  #include "src/code-factory.h"
  #include "src/codegen.h"
  #include "src/compiler.h"
  #include "src/debug/debug.h"
  #include "src/debug/liveedit.h"
  #include "src/frames-inl.h"
  #include "src/isolate-inl.h"
  #include "src/macro-assembler.h"
  #include "src/snapshot/snapshot.h"
  #include "src/tracing/trace-event.h"
  
  namespace v8 {
  namespace internal {
  
  #define __ ACCESS_MASM(masm())
  
  bool FullCodeGenerator::MakeCode(CompilationInfo* info) {
    Isolate* isolate = info->isolate();
  
    RuntimeCallTimerScope runtimeTimer(isolate,
                                       &RuntimeCallStats::CompileFullCode);
    TimerEventScope<TimerEventCompileFullCode> timer(info->isolate());
    TRACE_EVENT0("v8", "V8.CompileFullCode");
  
    Handle<Script> script = info->script();
    if (!script->IsUndefined() && !script->source()->IsUndefined()) {
      int len = String::cast(script->source())->length();
      isolate->counters()->total_full_codegen_source_size()->Increment(len);
    }
    CodeGenerator::MakeCodePrologue(info, "full");
    const int kInitialBufferSize = 4 * KB;
    MacroAssembler masm(info->isolate(), NULL, kInitialBufferSize,
                        CodeObjectRequired::kYes);
    if (info->will_serialize()) masm.enable_serializer();
  
    LOG_CODE_EVENT(isolate,
                   CodeStartLinePosInfoRecordEvent(masm.positions_recorder()));
  
    FullCodeGenerator cgen(&masm, info);
    cgen.Generate();
    if (cgen.HasStackOverflow()) {
      DCHECK(!isolate->has_pending_exception());
      return false;
    }
    unsigned table_offset = cgen.EmitBackEdgeTable();
  
    Handle<Code> code = CodeGenerator::MakeCodeEpilogue(&masm, info);
    cgen.PopulateDeoptimizationData(code);
    cgen.PopulateTypeFeedbackInfo(code);
    cgen.PopulateHandlerTable(code);
    code->set_has_deoptimization_support(info->HasDeoptimizationSupport());
    code->set_has_reloc_info_for_serialization(info->will_serialize());
    code->set_allow_osr_at_loop_nesting_level(0);
    code->set_profiler_ticks(0);
    code->set_back_edge_table_offset(table_offset);
    CodeGenerator::PrintCode(code, info);
    info->SetCode(code);
    void* line_info = masm.positions_recorder()->DetachJITHandlerData();
    LOG_CODE_EVENT(isolate, CodeEndLinePosInfoRecordEvent(
                                AbstractCode::cast(*code), line_info));
  
  #ifdef DEBUG
    // Check that no context-specific object has been embedded.
    code->VerifyEmbeddedObjects(Code::kNoContextSpecificPointers);
  #endif  // DEBUG
    return true;
  }
  
  
  unsigned FullCodeGenerator::EmitBackEdgeTable() {
    // The back edge table consists of a length (in number of entries)
    // field, and then a sequence of entries.  Each entry is a pair of AST id
    // and code-relative pc offset.
    masm()->Align(kPointerSize);
    unsigned offset = masm()->pc_offset();
    unsigned length = back_edges_.length();
    __ dd(length);
    for (unsigned i = 0; i < length; ++i) {
      __ dd(back_edges_[i].id.ToInt());
      __ dd(back_edges_[i].pc);
      __ dd(back_edges_[i].loop_depth);
    }
    return offset;
  }
  
  
  void FullCodeGenerator::PopulateDeoptimizationData(Handle<Code> code) {
    // Fill in the deoptimization information.
    DCHECK(info_->HasDeoptimizationSupport() || bailout_entries_.is_empty());
    if (!info_->HasDeoptimizationSupport()) return;
    int length = bailout_entries_.length();
    Handle<DeoptimizationOutputData> data =
        DeoptimizationOutputData::New(isolate(), length, TENURED);
    for (int i = 0; i < length; i++) {
      data->SetAstId(i, bailout_entries_[i].id);
      data->SetPcAndState(i, Smi::FromInt(bailout_entries_[i].pc_and_state));
    }
    code->set_deoptimization_data(*data);
  }
  
  
  void FullCodeGenerator::PopulateTypeFeedbackInfo(Handle<Code> code) {
    Handle<TypeFeedbackInfo> info = isolate()->factory()->NewTypeFeedbackInfo();
    info->set_ic_total_count(ic_total_count_);
    DCHECK(!isolate()->heap()->InNewSpace(*info));
    code->set_type_feedback_info(*info);
  }
  
  
  void FullCodeGenerator::PopulateHandlerTable(Handle<Code> code) {
    int handler_table_size = static_cast<int>(handler_table_.size());
    Handle<HandlerTable> table =
        Handle<HandlerTable>::cast(isolate()->factory()->NewFixedArray(
            HandlerTable::LengthForRange(handler_table_size), TENURED));
    for (int i = 0; i < handler_table_size; ++i) {
      HandlerTable::CatchPrediction prediction =
          handler_table_[i].try_catch_depth > 0 ? HandlerTable::CAUGHT
                                                : HandlerTable::UNCAUGHT;
      table->SetRangeStart(i, handler_table_[i].range_start);
      table->SetRangeEnd(i, handler_table_[i].range_end);
      table->SetRangeHandler(i, handler_table_[i].handler_offset, prediction);
      table->SetRangeData(i, handler_table_[i].stack_depth);
    }
    code->set_handler_table(*table);
  }
  
  
  int FullCodeGenerator::NewHandlerTableEntry() {
    int index = static_cast<int>(handler_table_.size());
    HandlerTableEntry entry = {0, 0, 0, 0, 0};
    handler_table_.push_back(entry);
    return index;
  }
  
  
  bool FullCodeGenerator::MustCreateObjectLiteralWithRuntime(
      ObjectLiteral* expr) const {
    return masm()->serializer_enabled() ||
           !FastCloneShallowObjectStub::IsSupported(expr);
  }
  
  
  bool FullCodeGenerator::MustCreateArrayLiteralWithRuntime(
      ArrayLiteral* expr) const {
    return expr->depth() > 1 ||
           expr->values()->length() > JSArray::kInitialMaxFastElementArray;
  }
  
  
  void FullCodeGenerator::Initialize() {
    InitializeAstVisitor(info_->isolate());
    masm_->set_emit_debug_code(FLAG_debug_code);
    masm_->set_predictable_code_size(true);
  }
  
  void FullCodeGenerator::PrepareForBailout(Expression* node,
                                            BailoutState state) {
    PrepareForBailoutForId(node->id(), state);
  }
  
  
  void FullCodeGenerator::CallLoadIC(TypeofMode typeof_mode,
                                     TypeFeedbackId id) {
    Handle<Code> ic = CodeFactory::LoadIC(isolate(), typeof_mode).code();
    CallIC(ic, id);
  }
  
  
  void FullCodeGenerator::CallStoreIC(TypeFeedbackId id) {
    Handle<Code> ic = CodeFactory::StoreIC(isolate(), language_mode()).code();
    CallIC(ic, id);
  }
  
  
  void FullCodeGenerator::RecordJSReturnSite(Call* call) {
    // We record the offset of the function return so we can rebuild the frame
    // if the function was inlined, i.e., this is the return address in the
    // inlined function's frame.
    //
    // The bailout state is ignored.  We defensively set it to TOS_REGISTER, which
    // is the real state of the unoptimized code at the return site.
    PrepareForBailoutForId(call->ReturnId(), BailoutState::TOS_REGISTER);
  #ifdef DEBUG
    // In debug builds, mark the return so we can verify that this function
    // was called.
    DCHECK(!call->return_is_recorded_);
    call->return_is_recorded_ = true;
  #endif
  }
  
  void FullCodeGenerator::PrepareForBailoutForId(BailoutId id,
                                                 BailoutState state) {
    // There's no need to prepare this code for bailouts from already optimized
    // code or code that can't be optimized.
    if (!info_->HasDeoptimizationSupport()) return;
    unsigned pc_and_state =
        BailoutStateField::encode(state) | PcField::encode(masm_->pc_offset());
    DCHECK(Smi::IsValid(pc_and_state));
  #ifdef DEBUG
    for (int i = 0; i < bailout_entries_.length(); ++i) {
      DCHECK(bailout_entries_[i].id != id);
    }
  #endif
    BailoutEntry entry = { id, pc_and_state };
    bailout_entries_.Add(entry, zone());
  }
  
  
  void FullCodeGenerator::RecordBackEdge(BailoutId ast_id) {
    // The pc offset does not need to be encoded and packed together with a state.
    DCHECK(masm_->pc_offset() > 0);
    DCHECK(loop_depth() > 0);
    uint8_t depth = Min(loop_depth(), Code::kMaxLoopNestingMarker);
    BackEdgeEntry entry =
        { ast_id, static_cast<unsigned>(masm_->pc_offset()), depth };
    back_edges_.Add(entry, zone());
  }
  
  
  bool FullCodeGenerator::ShouldInlineSmiCase(Token::Value op) {
    // Inline smi case inside loops, but not division and modulo which
    // are too complicated and take up too much space.
    if (op == Token::DIV ||op == Token::MOD) return false;
    if (FLAG_always_inline_smi_code) return true;
    return loop_depth_ > 0;
  }
  
  
  void FullCodeGenerator::EffectContext::Plug(Variable* var) const {
    DCHECK(var->IsStackAllocated() || var->IsContextSlot());
  }
  
  
  void FullCodeGenerator::AccumulatorValueContext::Plug(Variable* var) const {
    DCHECK(var->IsStackAllocated() || var->IsContextSlot());
    codegen()->GetVar(result_register(), var);
  }
  
  
  void FullCodeGenerator::TestContext::Plug(Variable* var) const {
    DCHECK(var->IsStackAllocated() || var->IsContextSlot());
    // For simplicity we always test the accumulator register.
    codegen()->GetVar(result_register(), var);
    codegen()->PrepareForBailoutBeforeSplit(condition(), false, NULL, NULL);
    codegen()->DoTest(this);
  }
  
  
  void FullCodeGenerator::EffectContext::Plug(Register reg) const {
  }
  
  
  void FullCodeGenerator::AccumulatorValueContext::Plug(Register reg) const {
    __ Move(result_register(), reg);
  }
  
  
  void FullCodeGenerator::StackValueContext::Plug(Register reg) const {
    codegen()->PushOperand(reg);
  }
  
  
  void FullCodeGenerator::TestContext::Plug(Register reg) const {
    // For simplicity we always test the accumulator register.
    __ Move(result_register(), reg);
    codegen()->PrepareForBailoutBeforeSplit(condition(), false, NULL, NULL);
    codegen()->DoTest(this);
  }
  
  
  void FullCodeGenerator::EffectContext::Plug(bool flag) const {}
  
  void FullCodeGenerator::EffectContext::DropAndPlug(int count,
                                                     Register reg) const {
    DCHECK(count > 0);
    codegen()->DropOperands(count);
  }
  
  void FullCodeGenerator::AccumulatorValueContext::DropAndPlug(
      int count, Register reg) const {
    DCHECK(count > 0);
    codegen()->DropOperands(count);
    __ Move(result_register(), reg);
  }
  
  void FullCodeGenerator::TestContext::DropAndPlug(int count,
                                                   Register reg) const {
    DCHECK(count > 0);
    // For simplicity we always test the accumulator register.
    codegen()->DropOperands(count);
    __ Move(result_register(), reg);
    codegen()->PrepareForBailoutBeforeSplit(condition(), false, NULL, NULL);
    codegen()->DoTest(this);
  }
  
  void FullCodeGenerator::EffectContext::PlugTOS() const {
    codegen()->DropOperands(1);
  }
  
  
  void FullCodeGenerator::AccumulatorValueContext::PlugTOS() const {
    codegen()->PopOperand(result_register());
  }
  
  
  void FullCodeGenerator::StackValueContext::PlugTOS() const {
  }
  
  
  void FullCodeGenerator::TestContext::PlugTOS() const {
    // For simplicity we always test the accumulator register.
    codegen()->PopOperand(result_register());
    codegen()->PrepareForBailoutBeforeSplit(condition(), false, NULL, NULL);
    codegen()->DoTest(this);
  }
  
  
  void FullCodeGenerator::EffectContext::PrepareTest(
      Label* materialize_true,
      Label* materialize_false,
      Label** if_true,
      Label** if_false,
      Label** fall_through) const {
    // In an effect context, the true and the false case branch to the
    // same label.
    *if_true = *if_false = *fall_through = materialize_true;
  }
  
  
  void FullCodeGenerator::AccumulatorValueContext::PrepareTest(
      Label* materialize_true,
      Label* materialize_false,
      Label** if_true,
      Label** if_false,
      Label** fall_through) const {
    *if_true = *fall_through = materialize_true;
    *if_false = materialize_false;
  }
  
  
  void FullCodeGenerator::StackValueContext::PrepareTest(
      Label* materialize_true,
      Label* materialize_false,
      Label** if_true,
      Label** if_false,
      Label** fall_through) const {
    *if_true = *fall_through = materialize_true;
    *if_false = materialize_false;
  }
  
  
  void FullCodeGenerator::TestContext::PrepareTest(
      Label* materialize_true,
      Label* materialize_false,
      Label** if_true,
      Label** if_false,
      Label** fall_through) const {
    *if_true = true_label_;
    *if_false = false_label_;
    *fall_through = fall_through_;
  }
  
  
  void FullCodeGenerator::DoTest(const TestContext* context) {
    DoTest(context->condition(),
           context->true_label(),
           context->false_label(),
           context->fall_through());
  }
  
  
  void FullCodeGenerator::VisitDeclarations(
      ZoneList<Declaration*>* declarations) {
    ZoneList<Handle<Object> >* saved_globals = globals_;
    ZoneList<Handle<Object> > inner_globals(10, zone());
    globals_ = &inner_globals;
  
    AstVisitor::VisitDeclarations(declarations);
  
    if (!globals_->is_empty()) {
      // Invoke the platform-dependent code generator to do the actual
      // declaration of the global functions and variables.
      Handle<FixedArray> array =
         isolate()->factory()->NewFixedArray(globals_->length(), TENURED);
      for (int i = 0; i < globals_->length(); ++i)
        array->set(i, *globals_->at(i));
      DeclareGlobals(array);
    }
  
    globals_ = saved_globals;
  }
  
  
  void FullCodeGenerator::VisitImportDeclaration(ImportDeclaration* declaration) {
    VariableProxy* proxy = declaration->proxy();
    Variable* variable = proxy->var();
    switch (variable->location()) {
      case VariableLocation::GLOBAL:
      case VariableLocation::UNALLOCATED:
        // TODO(rossberg)
        break;
  
      case VariableLocation::CONTEXT: {
        Comment cmnt(masm_, "[ ImportDeclaration");
        EmitDebugCheckDeclarationContext(variable);
        // TODO(rossberg)
        break;
      }
  
      case VariableLocation::PARAMETER:
      case VariableLocation::LOCAL:
      case VariableLocation::LOOKUP:
        UNREACHABLE();
    }
  }
  
  
  void FullCodeGenerator::VisitExportDeclaration(ExportDeclaration* declaration) {
    // TODO(rossberg)
  }
  
  
  void FullCodeGenerator::VisitVariableProxy(VariableProxy* expr) {
    Comment cmnt(masm_, "[ VariableProxy");
    EmitVariableLoad(expr);
  }
  
  
  void FullCodeGenerator::VisitSloppyBlockFunctionStatement(
      SloppyBlockFunctionStatement* declaration) {
    Visit(declaration->statement());
  }
  
  
  int FullCodeGenerator::DeclareGlobalsFlags() {
    return info_->GetDeclareGlobalsFlags();
  }
  
  void FullCodeGenerator::PushOperand(Handle<Object> handle) {
    OperandStackDepthIncrement(1);
    __ Push(handle);
  }
  
  void FullCodeGenerator::PushOperand(Smi* smi) {
    OperandStackDepthIncrement(1);
    __ Push(smi);
  }
  
  void FullCodeGenerator::PushOperand(Register reg) {
    OperandStackDepthIncrement(1);
    __ Push(reg);
  }
  
  void FullCodeGenerator::PopOperand(Register reg) {
    OperandStackDepthDecrement(1);
    __ Pop(reg);
  }
  
  void FullCodeGenerator::DropOperands(int count) {
    OperandStackDepthDecrement(count);
    __ Drop(count);
  }
  
  void FullCodeGenerator::CallRuntimeWithOperands(Runtime::FunctionId id) {
    OperandStackDepthDecrement(Runtime::FunctionForId(id)->nargs);
    __ CallRuntime(id);
  }
  
  void FullCodeGenerator::OperandStackDepthIncrement(int count) {
    DCHECK_IMPLIES(!HasStackOverflow(), operand_stack_depth_ >= 0);
    DCHECK_GE(count, 0);
    operand_stack_depth_ += count;
  }
  
  void FullCodeGenerator::OperandStackDepthDecrement(int count) {
    DCHECK_IMPLIES(!HasStackOverflow(), operand_stack_depth_ >= count);
    DCHECK_GE(count, 0);
    operand_stack_depth_ -= count;
  }
  
  void FullCodeGenerator::EmitSubString(CallRuntime* expr) {
    // Load the arguments on the stack and call the stub.
    SubStringStub stub(isolate());
    ZoneList<Expression*>* args = expr->arguments();
    DCHECK(args->length() == 3);
    VisitForStackValue(args->at(0));
    VisitForStackValue(args->at(1));
    VisitForStackValue(args->at(2));
    __ CallStub(&stub);
    OperandStackDepthDecrement(3);
    context()->Plug(result_register());
  }
  
  
  void FullCodeGenerator::EmitRegExpExec(CallRuntime* expr) {
    // Load the arguments on the stack and call the stub.
    RegExpExecStub stub(isolate());
    ZoneList<Expression*>* args = expr->arguments();
    DCHECK(args->length() == 4);
    VisitForStackValue(args->at(0));
    VisitForStackValue(args->at(1));
    VisitForStackValue(args->at(2));
    VisitForStackValue(args->at(3));
    __ CallStub(&stub);
    OperandStackDepthDecrement(4);
    context()->Plug(result_register());
  }
  
  
  void FullCodeGenerator::EmitMathPow(CallRuntime* expr) {
    // Load the arguments on the stack and call the runtime function.
    MathPowStub stub(isolate(), MathPowStub::ON_STACK);
    ZoneList<Expression*>* args = expr->arguments();
    DCHECK(args->length() == 2);
    VisitForStackValue(args->at(0));
    VisitForStackValue(args->at(1));
    __ CallStub(&stub);
    OperandStackDepthDecrement(2);
    context()->Plug(result_register());
  }
  
  
  void FullCodeGenerator::EmitIntrinsicAsStubCall(CallRuntime* expr,
                                                  const Callable& callable) {
    ZoneList<Expression*>* args = expr->arguments();
    int param_count = callable.descriptor().GetRegisterParameterCount();
    DCHECK_EQ(args->length(), param_count);
  
    if (param_count > 0) {
      int last = param_count - 1;
      // Put all but last arguments on stack.
      for (int i = 0; i < last; i++) {
        VisitForStackValue(args->at(i));
      }
      // The last argument goes to the accumulator.
      VisitForAccumulatorValue(args->at(last));
  
      // Move the arguments to the registers, as required by the stub.
      __ Move(callable.descriptor().GetRegisterParameter(last),
              result_register());
      for (int i = last; i-- > 0;) {
        PopOperand(callable.descriptor().GetRegisterParameter(i));
      }
    }
    __ Call(callable.code(), RelocInfo::CODE_TARGET);
  
    // Reload the context register after the call as i.e. TurboFan code stubs
    // won't preserve the context register.
    LoadFromFrameField(StandardFrameConstants::kContextOffset,
                       context_register());
    context()->Plug(result_register());
  }
  
  void FullCodeGenerator::EmitNewObject(CallRuntime* expr) {
    EmitIntrinsicAsStubCall(expr, CodeFactory::FastNewObject(isolate()));
  }
  
  void FullCodeGenerator::EmitNumberToString(CallRuntime* expr) {
    EmitIntrinsicAsStubCall(expr, CodeFactory::NumberToString(isolate()));
  }
  
  
  void FullCodeGenerator::EmitToString(CallRuntime* expr) {
    EmitIntrinsicAsStubCall(expr, CodeFactory::ToString(isolate()));
  }
  
  
  void FullCodeGenerator::EmitToName(CallRuntime* expr) {
    EmitIntrinsicAsStubCall(expr, CodeFactory::ToName(isolate()));
  }
  
  
  void FullCodeGenerator::EmitToLength(CallRuntime* expr) {
    EmitIntrinsicAsStubCall(expr, CodeFactory::ToLength(isolate()));
  }
  
  void FullCodeGenerator::EmitToInteger(CallRuntime* expr) {
    EmitIntrinsicAsStubCall(expr, CodeFactory::ToInteger(isolate()));
  }
  
  void FullCodeGenerator::EmitToNumber(CallRuntime* expr) {
    EmitIntrinsicAsStubCall(expr, CodeFactory::ToNumber(isolate()));
  }
  
  
  void FullCodeGenerator::EmitToObject(CallRuntime* expr) {
    EmitIntrinsicAsStubCall(expr, CodeFactory::ToObject(isolate()));
  }
  
  
  void FullCodeGenerator::EmitRegExpConstructResult(CallRuntime* expr) {
    EmitIntrinsicAsStubCall(expr, CodeFactory::RegExpConstructResult(isolate()));
  }
  
  void FullCodeGenerator::EmitHasProperty() {
    Callable callable = CodeFactory::HasProperty(isolate());
    PopOperand(callable.descriptor().GetRegisterParameter(1));
    PopOperand(callable.descriptor().GetRegisterParameter(0));
    __ Call(callable.code(), RelocInfo::CODE_TARGET);
    RestoreContext();
  }
  
  bool RecordStatementPosition(MacroAssembler* masm, int pos) {
    if (pos == RelocInfo::kNoPosition) return false;
    masm->positions_recorder()->RecordStatementPosition(pos);
    masm->positions_recorder()->RecordPosition(pos);
    return masm->positions_recorder()->WriteRecordedPositions();
  }
  
  
  bool RecordPosition(MacroAssembler* masm, int pos) {
    if (pos == RelocInfo::kNoPosition) return false;
    masm->positions_recorder()->RecordPosition(pos);
    return masm->positions_recorder()->WriteRecordedPositions();
  }
  
  
  void FullCodeGenerator::SetFunctionPosition(FunctionLiteral* fun) {
    RecordPosition(masm_, fun->start_position());
  }
  
  
  void FullCodeGenerator::SetReturnPosition(FunctionLiteral* fun) {
    // For default constructors, start position equals end position, and there
    // is no source code besides the class literal.
    int pos = std::max(fun->start_position(), fun->end_position() - 1);
    RecordStatementPosition(masm_, pos);
    if (info_->is_debug()) {
      // Always emit a debug break slot before a return.
      DebugCodegen::GenerateSlot(masm_, RelocInfo::DEBUG_BREAK_SLOT_AT_RETURN);
    }
  }
  
  
  void FullCodeGenerator::SetStatementPosition(
      Statement* stmt, FullCodeGenerator::InsertBreak insert_break) {
    if (stmt->position() == RelocInfo::kNoPosition) return;
    bool recorded = RecordStatementPosition(masm_, stmt->position());
    if (recorded && insert_break == INSERT_BREAK && info_->is_debug() &&
        !stmt->IsDebuggerStatement()) {
      DebugCodegen::GenerateSlot(masm_, RelocInfo::DEBUG_BREAK_SLOT_AT_POSITION);
    }
  }
  
  void FullCodeGenerator::SetExpressionPosition(Expression* expr) {
    if (expr->position() == RelocInfo::kNoPosition) return;
    RecordPosition(masm_, expr->position());
  }
  
  
  void FullCodeGenerator::SetExpressionAsStatementPosition(Expression* expr) {
    if (expr->position() == RelocInfo::kNoPosition) return;
    bool recorded = RecordStatementPosition(masm_, expr->position());
    if (recorded && info_->is_debug()) {
      DebugCodegen::GenerateSlot(masm_, RelocInfo::DEBUG_BREAK_SLOT_AT_POSITION);
    }
  }
  
  void FullCodeGenerator::SetCallPosition(Expression* expr,
                                          TailCallMode tail_call_mode) {
    if (expr->position() == RelocInfo::kNoPosition) return;
    RecordPosition(masm_, expr->position());
    if (info_->is_debug()) {
      RelocInfo::Mode mode = (tail_call_mode == TailCallMode::kAllow)
                                 ? RelocInfo::DEBUG_BREAK_SLOT_AT_TAIL_CALL
                                 : RelocInfo::DEBUG_BREAK_SLOT_AT_CALL;
      // Always emit a debug break slot before a call.
      DebugCodegen::GenerateSlot(masm_, mode);
    }
  }
  
  
  void FullCodeGenerator::VisitSuperPropertyReference(
      SuperPropertyReference* super) {
    __ CallRuntime(Runtime::kThrowUnsupportedSuperError);
    // Even though this expression doesn't produce a value, we need to simulate
    // plugging of the value context to ensure stack depth tracking is in sync.
    if (context()->IsStackValue()) OperandStackDepthIncrement(1);
  }
  
  
  void FullCodeGenerator::VisitSuperCallReference(SuperCallReference* super) {
    // Handled by VisitCall
    UNREACHABLE();
  }
  
  
  void FullCodeGenerator::EmitDebugBreakInOptimizedCode(CallRuntime* expr) {
    context()->Plug(handle(Smi::FromInt(0), isolate()));
  }
  
  
  void FullCodeGenerator::VisitBinaryOperation(BinaryOperation* expr) {
    switch (expr->op()) {
      case Token::COMMA:
        return VisitComma(expr);
      case Token::OR:
      case Token::AND:
        return VisitLogicalExpression(expr);
      default:
        return VisitArithmeticExpression(expr);
    }
  }
  
  
  void FullCodeGenerator::VisitInDuplicateContext(Expression* expr) {
    if (context()->IsEffect()) {
      VisitForEffect(expr);
    } else if (context()->IsAccumulatorValue()) {
      VisitForAccumulatorValue(expr);
    } else if (context()->IsStackValue()) {
      VisitForStackValue(expr);
    } else if (context()->IsTest()) {
      const TestContext* test = TestContext::cast(context());
      VisitForControl(expr, test->true_label(), test->false_label(),
                      test->fall_through());
    }
  }
  
  
  void FullCodeGenerator::VisitComma(BinaryOperation* expr) {
    Comment cmnt(masm_, "[ Comma");
    VisitForEffect(expr->left());
    VisitInDuplicateContext(expr->right());
  }
  
  
  void FullCodeGenerator::VisitLogicalExpression(BinaryOperation* expr) {
    bool is_logical_and = expr->op() == Token::AND;
    Comment cmnt(masm_, is_logical_and ? "[ Logical AND" :  "[ Logical OR");
    Expression* left = expr->left();
    Expression* right = expr->right();
    BailoutId right_id = expr->RightId();
    Label done;
  
    if (context()->IsTest()) {
      Label eval_right;
      const TestContext* test = TestContext::cast(context());
      if (is_logical_and) {
        VisitForControl(left, &eval_right, test->false_label(), &eval_right);
      } else {
        VisitForControl(left, test->true_label(), &eval_right, &eval_right);
      }
      PrepareForBailoutForId(right_id, BailoutState::NO_REGISTERS);
      __ bind(&eval_right);
  
    } else if (context()->IsAccumulatorValue()) {
      VisitForAccumulatorValue(left);
      // We want the value in the accumulator for the test, and on the stack in
      // case we need it.
      __ Push(result_register());
      Label discard, restore;
      if (is_logical_and) {
        DoTest(left, &discard, &restore, &restore);
      } else {
        DoTest(left, &restore, &discard, &restore);
      }
      __ bind(&restore);
      __ Pop(result_register());
      __ jmp(&done);
      __ bind(&discard);
      __ Drop(1);
      PrepareForBailoutForId(right_id, BailoutState::NO_REGISTERS);
  
    } else if (context()->IsStackValue()) {
      VisitForAccumulatorValue(left);
      // We want the value in the accumulator for the test, and on the stack in
      // case we need it.
      __ Push(result_register());
      Label discard;
      if (is_logical_and) {
        DoTest(left, &discard, &done, &discard);
      } else {
        DoTest(left, &done, &discard, &discard);
      }
      __ bind(&discard);
      __ Drop(1);
      PrepareForBailoutForId(right_id, BailoutState::NO_REGISTERS);
  
    } else {
      DCHECK(context()->IsEffect());
      Label eval_right;
      if (is_logical_and) {
        VisitForControl(left, &eval_right, &done, &eval_right);
      } else {
        VisitForControl(left, &done, &eval_right, &eval_right);
      }
      PrepareForBailoutForId(right_id, BailoutState::NO_REGISTERS);
      __ bind(&eval_right);
    }
  
    VisitInDuplicateContext(right);
    __ bind(&done);
  }
  
  
  void FullCodeGenerator::VisitArithmeticExpression(BinaryOperation* expr) {
    Token::Value op = expr->op();
    Comment cmnt(masm_, "[ ArithmeticExpression");
    Expression* left = expr->left();
    Expression* right = expr->right();
  
    VisitForStackValue(left);
    VisitForAccumulatorValue(right);
  
    SetExpressionPosition(expr);
    if (ShouldInlineSmiCase(op)) {
      EmitInlineSmiBinaryOp(expr, op, left, right);
    } else {
      EmitBinaryOp(expr, op);
    }
  }
  
  void FullCodeGenerator::VisitProperty(Property* expr) {
    Comment cmnt(masm_, "[ Property");
    SetExpressionPosition(expr);
  
    Expression* key = expr->key();
  
    if (key->IsPropertyName()) {
      if (!expr->IsSuperAccess()) {
        VisitForAccumulatorValue(expr->obj());
        __ Move(LoadDescriptor::ReceiverRegister(), result_register());
        EmitNamedPropertyLoad(expr);
      } else {
        VisitForStackValue(expr->obj()->AsSuperPropertyReference()->this_var());
        VisitForStackValue(
            expr->obj()->AsSuperPropertyReference()->home_object());
        EmitNamedSuperPropertyLoad(expr);
      }
    } else {
      if (!expr->IsSuperAccess()) {
        VisitForStackValue(expr->obj());
        VisitForAccumulatorValue(expr->key());
        __ Move(LoadDescriptor::NameRegister(), result_register());
        PopOperand(LoadDescriptor::ReceiverRegister());
        EmitKeyedPropertyLoad(expr);
      } else {
        VisitForStackValue(expr->obj()->AsSuperPropertyReference()->this_var());
        VisitForStackValue(
            expr->obj()->AsSuperPropertyReference()->home_object());
        VisitForStackValue(expr->key());
        EmitKeyedSuperPropertyLoad(expr);
      }
    }
    PrepareForBailoutForId(expr->LoadId(), BailoutState::TOS_REGISTER);
    context()->Plug(result_register());
  }
  
  void FullCodeGenerator::VisitForTypeofValue(Expression* expr) {
    VariableProxy* proxy = expr->AsVariableProxy();
    DCHECK(!context()->IsEffect());
    DCHECK(!context()->IsTest());
  
    if (proxy != NULL && (proxy->var()->IsUnallocatedOrGlobalSlot() ||
                          proxy->var()->IsLookupSlot())) {
      EmitVariableLoad(proxy, INSIDE_TYPEOF);
      PrepareForBailout(proxy, BailoutState::TOS_REGISTER);
    } else {
      // This expression cannot throw a reference error at the top level.
      VisitInDuplicateContext(expr);
    }
  }
  
  
  void FullCodeGenerator::VisitBlock(Block* stmt) {
    Comment cmnt(masm_, "[ Block");
    NestedBlock nested_block(this, stmt);
  
    {
      EnterBlockScopeIfNeeded block_scope_state(
          this, stmt->scope(), stmt->EntryId(), stmt->DeclsId(), stmt->ExitId());
      VisitStatements(stmt->statements());
      __ bind(nested_block.break_label());
    }
  }
  
  
  void FullCodeGenerator::VisitDoExpression(DoExpression* expr) {
    Comment cmnt(masm_, "[ Do Expression");
    SetExpressionPosition(expr);
    VisitBlock(expr->block());
    EmitVariableLoad(expr->result());
  }
  
  
  void FullCodeGenerator::VisitExpressionStatement(ExpressionStatement* stmt) {
    Comment cmnt(masm_, "[ ExpressionStatement");
    SetStatementPosition(stmt);
    VisitForEffect(stmt->expression());
  }
  
  
  void FullCodeGenerator::VisitEmptyStatement(EmptyStatement* stmt) {
    Comment cmnt(masm_, "[ EmptyStatement");
  }
  
  
  void FullCodeGenerator::VisitIfStatement(IfStatement* stmt) {
    Comment cmnt(masm_, "[ IfStatement");
    SetStatementPosition(stmt);
    Label then_part, else_part, done;
  
    if (stmt->HasElseStatement()) {
      VisitForControl(stmt->condition(), &then_part, &else_part, &then_part);
      PrepareForBailoutForId(stmt->ThenId(), BailoutState::NO_REGISTERS);
      __ bind(&then_part);
      Visit(stmt->then_statement());
      __ jmp(&done);
  
      PrepareForBailoutForId(stmt->ElseId(), BailoutState::NO_REGISTERS);
      __ bind(&else_part);
      Visit(stmt->else_statement());
    } else {
      VisitForControl(stmt->condition(), &then_part, &done, &then_part);
      PrepareForBailoutForId(stmt->ThenId(), BailoutState::NO_REGISTERS);
      __ bind(&then_part);
      Visit(stmt->then_statement());
  
      PrepareForBailoutForId(stmt->ElseId(), BailoutState::NO_REGISTERS);
    }
    __ bind(&done);
    PrepareForBailoutForId(stmt->IfId(), BailoutState::NO_REGISTERS);
  }
  
  void FullCodeGenerator::EmitContinue(Statement* target) {
    NestedStatement* current = nesting_stack_;
    int context_length = 0;
    // When continuing, we clobber the unpredictable value in the accumulator
    // with one that's safe for GC.  If we hit an exit from the try block of
    // try...finally on our way out, we will unconditionally preserve the
    // accumulator on the stack.
    ClearAccumulator();
    while (!current->IsContinueTarget(target)) {
      if (current->IsTryFinally()) {
        Comment cmnt(masm(), "[ Deferred continue through finally");
        current->Exit(&context_length);
        DCHECK_EQ(-1, context_length);
        current->AsTryFinally()->deferred_commands()->RecordContinue(target);
        return;
      }
      current = current->Exit(&context_length);
    }
    int stack_depth = current->GetStackDepthAtTarget();
    int stack_drop = operand_stack_depth_ - stack_depth;
    DCHECK_GE(stack_drop, 0);
    __ Drop(stack_drop);
    if (context_length > 0) {
      while (context_length > 0) {
        LoadContextField(context_register(), Context::PREVIOUS_INDEX);
        --context_length;
      }
      StoreToFrameField(StandardFrameConstants::kContextOffset,
                        context_register());
    }
  
    __ jmp(current->AsIteration()->continue_label());
  }
  
  void FullCodeGenerator::VisitContinueStatement(ContinueStatement* stmt) {
    Comment cmnt(masm_, "[ ContinueStatement");
    SetStatementPosition(stmt);
    EmitContinue(stmt->target());
  }
  
  void FullCodeGenerator::EmitBreak(Statement* target) {
    NestedStatement* current = nesting_stack_;
    int context_length = 0;
    // When breaking, we clobber the unpredictable value in the accumulator
    // with one that's safe for GC.  If we hit an exit from the try block of
    // try...finally on our way out, we will unconditionally preserve the
    // accumulator on the stack.
    ClearAccumulator();
    while (!current->IsBreakTarget(target)) {
      if (current->IsTryFinally()) {
        Comment cmnt(masm(), "[ Deferred break through finally");
        current->Exit(&context_length);
        DCHECK_EQ(-1, context_length);
        current->AsTryFinally()->deferred_commands()->RecordBreak(target);
        return;
      }
      current = current->Exit(&context_length);
    }
    int stack_depth = current->GetStackDepthAtTarget();
    int stack_drop = operand_stack_depth_ - stack_depth;
    DCHECK_GE(stack_drop, 0);
    __ Drop(stack_drop);
    if (context_length > 0) {
      while (context_length > 0) {
        LoadContextField(context_register(), Context::PREVIOUS_INDEX);
        --context_length;
      }
      StoreToFrameField(StandardFrameConstants::kContextOffset,
                        context_register());
    }
  
    __ jmp(current->AsBreakable()->break_label());
  }
  
  void FullCodeGenerator::VisitBreakStatement(BreakStatement* stmt) {
    Comment cmnt(masm_, "[ BreakStatement");
    SetStatementPosition(stmt);
    EmitBreak(stmt->target());
  }
  
  void FullCodeGenerator::EmitUnwindAndReturn() {
    NestedStatement* current = nesting_stack_;
    int context_length = 0;
    while (current != NULL) {
      if (current->IsTryFinally()) {
        Comment cmnt(masm(), "[ Deferred return through finally");
        current->Exit(&context_length);
        DCHECK_EQ(-1, context_length);
        current->AsTryFinally()->deferred_commands()->RecordReturn();
        return;
      }
      current = current->Exit(&context_length);
    }
    EmitReturnSequence();
  }
  
  void FullCodeGenerator::EmitNewClosure(Handle<SharedFunctionInfo> info,
                                         bool pretenure) {
    // Use the fast case closure allocation code that allocates in new
    // space for nested functions that don't need literals cloning. If
    // we're running with the --always-opt or the --prepare-always-opt
    // flag, we need to use the runtime function so that the new function
    // we are creating here gets a chance to have its code optimized and
    // doesn't just get a copy of the existing unoptimized code.
    if (!FLAG_always_opt &&
        !FLAG_prepare_always_opt &&
        !pretenure &&
        scope()->is_function_scope() &&
        info->num_literals() == 0) {
      FastNewClosureStub stub(isolate(), info->language_mode(), info->kind());
      __ Move(stub.GetCallInterfaceDescriptor().GetRegisterParameter(0), info);
      __ CallStub(&stub);
    } else {
      __ Push(info);
      __ CallRuntime(pretenure ? Runtime::kNewClosure_Tenured
                               : Runtime::kNewClosure);
    }
    context()->Plug(result_register());
  }
  
  void FullCodeGenerator::EmitNamedPropertyLoad(Property* prop) {
    SetExpressionPosition(prop);
    Literal* key = prop->key()->AsLiteral();
    DCHECK(!key->value()->IsSmi());
    DCHECK(!prop->IsSuperAccess());
  
    __ Move(LoadDescriptor::NameRegister(), key->value());
    __ Move(LoadDescriptor::SlotRegister(),
            SmiFromSlot(prop->PropertyFeedbackSlot()));
    CallLoadIC(NOT_INSIDE_TYPEOF);
  }
  
  void FullCodeGenerator::EmitNamedSuperPropertyLoad(Property* prop) {
    // Stack: receiver, home_object
    SetExpressionPosition(prop);
    Literal* key = prop->key()->AsLiteral();
    DCHECK(!key->value()->IsSmi());
    DCHECK(prop->IsSuperAccess());
  
    PushOperand(key->value());
    CallRuntimeWithOperands(Runtime::kLoadFromSuper);
  }
  
  void FullCodeGenerator::EmitKeyedPropertyLoad(Property* prop) {
    SetExpressionPosition(prop);
    Handle<Code> ic = CodeFactory::KeyedLoadIC(isolate()).code();
    __ Move(LoadDescriptor::SlotRegister(),
            SmiFromSlot(prop->PropertyFeedbackSlot()));
    CallIC(ic);
  }
  
  void FullCodeGenerator::EmitKeyedSuperPropertyLoad(Property* prop) {
    // Stack: receiver, home_object, key.
    SetExpressionPosition(prop);
    CallRuntimeWithOperands(Runtime::kLoadKeyedFromSuper);
  }
  
  void FullCodeGenerator::EmitPropertyKey(ObjectLiteralProperty* property,
                                          BailoutId bailout_id) {
    VisitForStackValue(property->key());
    CallRuntimeWithOperands(Runtime::kToName);
    PrepareForBailoutForId(bailout_id, BailoutState::NO_REGISTERS);
    PushOperand(result_register());
  }
  
  void FullCodeGenerator::EmitLoadStoreICSlot(FeedbackVectorSlot slot) {
    DCHECK(!slot.IsInvalid());
    __ Move(VectorStoreICTrampolineDescriptor::SlotRegister(), SmiFromSlot(slot));
  }
  
  void FullCodeGenerator::VisitReturnStatement(ReturnStatement* stmt) {
    Comment cmnt(masm_, "[ ReturnStatement");
    SetStatementPosition(stmt);
    Expression* expr = stmt->expression();
    VisitForAccumulatorValue(expr);
    EmitUnwindAndReturn();
  }
  
  
  void FullCodeGenerator::VisitWithStatement(WithStatement* stmt) {
    Comment cmnt(masm_, "[ WithStatement");
    SetStatementPosition(stmt);
  
    VisitForAccumulatorValue(stmt->expression());
    Callable callable = CodeFactory::ToObject(isolate());
    __ Move(callable.descriptor().GetRegisterParameter(0), result_register());
    __ Call(callable.code(), RelocInfo::CODE_TARGET);
    PrepareForBailoutForId(stmt->ToObjectId(), BailoutState::NO_REGISTERS);
    PushOperand(result_register());
    PushFunctionArgumentForContextAllocation();
    CallRuntimeWithOperands(Runtime::kPushWithContext);
    StoreToFrameField(StandardFrameConstants::kContextOffset, context_register());
    PrepareForBailoutForId(stmt->EntryId(), BailoutState::NO_REGISTERS);
  
    Scope* saved_scope = scope();
    scope_ = stmt->scope();
    { WithOrCatch body(this);
      Visit(stmt->statement());
    }
    scope_ = saved_scope;
  
    // Pop context.
    LoadContextField(context_register(), Context::PREVIOUS_INDEX);
    // Update local stack frame context field.
    StoreToFrameField(StandardFrameConstants::kContextOffset, context_register());
  }
  
  
  void FullCodeGenerator::VisitDoWhileStatement(DoWhileStatement* stmt) {
    Comment cmnt(masm_, "[ DoWhileStatement");
    // Do not insert break location as we do that below.
    SetStatementPosition(stmt, SKIP_BREAK);
  
    Label body, book_keeping;
  
    Iteration loop_statement(this, stmt);
    increment_loop_depth();
  
    __ bind(&body);
    Visit(stmt->body());
  
    // Record the position of the do while condition and make sure it is
    // possible to break on the condition.
    __ bind(loop_statement.continue_label());
    PrepareForBailoutForId(stmt->ContinueId(), BailoutState::NO_REGISTERS);
  
    // Here is the actual 'while' keyword.
    SetExpressionAsStatementPosition(stmt->cond());
    VisitForControl(stmt->cond(),
                    &book_keeping,
                    loop_statement.break_label(),
                    &book_keeping);
  
    // Check stack before looping.
    PrepareForBailoutForId(stmt->BackEdgeId(), BailoutState::NO_REGISTERS);
    __ bind(&book_keeping);
    EmitBackEdgeBookkeeping(stmt, &body);
    __ jmp(&body);
  
    PrepareForBailoutForId(stmt->ExitId(), BailoutState::NO_REGISTERS);
    __ bind(loop_statement.break_label());
    decrement_loop_depth();
  }
  
  
  void FullCodeGenerator::VisitWhileStatement(WhileStatement* stmt) {
    Comment cmnt(masm_, "[ WhileStatement");
    Label loop, body;
  
    Iteration loop_statement(this, stmt);
    increment_loop_depth();
  
    __ bind(&loop);
  
    SetExpressionAsStatementPosition(stmt->cond());
    VisitForControl(stmt->cond(),
                    &body,
                    loop_statement.break_label(),
                    &body);
  
    PrepareForBailoutForId(stmt->BodyId(), BailoutState::NO_REGISTERS);
    __ bind(&body);
    Visit(stmt->body());
  
    __ bind(loop_statement.continue_label());
  
    // Check stack before looping.
    EmitBackEdgeBookkeeping(stmt, &loop);
    __ jmp(&loop);
  
    PrepareForBailoutForId(stmt->ExitId(), BailoutState::NO_REGISTERS);
    __ bind(loop_statement.break_label());
    decrement_loop_depth();
  }
  
  
  void FullCodeGenerator::VisitForStatement(ForStatement* stmt) {
    Comment cmnt(masm_, "[ ForStatement");
    // Do not insert break location as we do it below.
    SetStatementPosition(stmt, SKIP_BREAK);
  
    Label test, body;
  
    Iteration loop_statement(this, stmt);
  
    if (stmt->init() != NULL) {
      Visit(stmt->init());
    }
  
    increment_loop_depth();
    // Emit the test at the bottom of the loop (even if empty).
    __ jmp(&test);
  
    PrepareForBailoutForId(stmt->BodyId(), BailoutState::NO_REGISTERS);
    __ bind(&body);
    Visit(stmt->body());
  
    PrepareForBailoutForId(stmt->ContinueId(), BailoutState::NO_REGISTERS);
    __ bind(loop_statement.continue_label());
    if (stmt->next() != NULL) {
      SetStatementPosition(stmt->next());
      Visit(stmt->next());
    }
  
    // Check stack before looping.
    EmitBackEdgeBookkeeping(stmt, &body);
  
    __ bind(&test);
    if (stmt->cond() != NULL) {
      SetExpressionAsStatementPosition(stmt->cond());
      VisitForControl(stmt->cond(),
                      &body,
                      loop_statement.break_label(),
                      loop_statement.break_label());
    } else {
      __ jmp(&body);
    }
  
    PrepareForBailoutForId(stmt->ExitId(), BailoutState::NO_REGISTERS);
    __ bind(loop_statement.break_label());
    decrement_loop_depth();
  }
  
  
  void FullCodeGenerator::VisitForOfStatement(ForOfStatement* stmt) {
    Comment cmnt(masm_, "[ ForOfStatement");
  
    Iteration loop_statement(this, stmt);
    increment_loop_depth();
  
    // var iterator = iterable[Symbol.iterator]();
    SetExpressionAsStatementPosition(stmt->assign_iterator());
    VisitForEffect(stmt->assign_iterator());
  
    // Loop entry.
    __ bind(loop_statement.continue_label());
  
    // result = iterator.next()
    SetExpressionAsStatementPosition(stmt->next_result());
    VisitForEffect(stmt->next_result());
  
    // if (result.done) break;
    Label result_not_done;
    VisitForControl(stmt->result_done(), loop_statement.break_label(),
                    &result_not_done, &result_not_done);
    __ bind(&result_not_done);
  
    // each = result.value
    VisitForEffect(stmt->assign_each());
  
    // Generate code for the body of the loop.
    Visit(stmt->body());
  
    // Check stack before looping.
    PrepareForBailoutForId(stmt->BackEdgeId(), BailoutState::NO_REGISTERS);
    EmitBackEdgeBookkeeping(stmt, loop_statement.continue_label());
    __ jmp(loop_statement.continue_label());
  
    // Exit and decrement the loop depth.
    PrepareForBailoutForId(stmt->ExitId(), BailoutState::NO_REGISTERS);
    __ bind(loop_statement.break_label());
    decrement_loop_depth();
  }
  
  void FullCodeGenerator::VisitThisFunction(ThisFunction* expr) {
    LoadFromFrameField(JavaScriptFrameConstants::kFunctionOffset,
                       result_register());
    context()->Plug(result_register());
  }
  
  void FullCodeGenerator::VisitTryCatchStatement(TryCatchStatement* stmt) {
    Comment cmnt(masm_, "[ TryCatchStatement");
    SetStatementPosition(stmt, SKIP_BREAK);
  
    // The try block adds a handler to the exception handler chain before
    // entering, and removes it again when exiting normally.  If an exception
    // is thrown during execution of the try block, the handler is consumed
    // and control is passed to the catch block with the exception in the
    // result register.
  
    Label try_entry, handler_entry, exit;
    __ jmp(&try_entry);
    __ bind(&handler_entry);
    if (stmt->clear_pending_message()) ClearPendingMessage();
  
    // Exception handler code, the exception is in the result register.
    // Extend the context before executing the catch block.
    { Comment cmnt(masm_, "[ Extend catch context");
      PushOperand(stmt->variable()->name());
      PushOperand(result_register());
      PushFunctionArgumentForContextAllocation();
      CallRuntimeWithOperands(Runtime::kPushCatchContext);
      StoreToFrameField(StandardFrameConstants::kContextOffset,
                        context_register());
    }
  
    Scope* saved_scope = scope();
    scope_ = stmt->scope();
    DCHECK(scope_->declarations()->is_empty());
    { WithOrCatch catch_body(this);
      Visit(stmt->catch_block());
    }
    // Restore the context.
    LoadContextField(context_register(), Context::PREVIOUS_INDEX);
    StoreToFrameField(StandardFrameConstants::kContextOffset, context_register());
    scope_ = saved_scope;
    __ jmp(&exit);
  
    // Try block code. Sets up the exception handler chain.
    __ bind(&try_entry);
  
    try_catch_depth_++;
    int handler_index = NewHandlerTableEntry();
    EnterTryBlock(handler_index, &handler_entry);
    {
      Comment cmnt_try(masm(), "[ Try block");
      Visit(stmt->try_block());
    }
    ExitTryBlock(handler_index);
    try_catch_depth_--;
    __ bind(&exit);
  }
  
  
  void FullCodeGenerator::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
    Comment cmnt(masm_, "[ TryFinallyStatement");
    SetStatementPosition(stmt, SKIP_BREAK);
  
    // Try finally is compiled by setting up a try-handler on the stack while
    // executing the try body, and removing it again afterwards.
    //
    // The try-finally construct can enter the finally block in three ways:
    // 1. By exiting the try-block normally. This exits the try block,
    //    pushes the continuation token and falls through to the finally
    //    block.
    // 2. By exiting the try-block with a function-local control flow transfer
    //    (break/continue/return). The site of the, e.g., break exits the
    //    try block, pushes the continuation token and jumps to the
    //    finally block. After the finally block executes, the execution
    //    continues based on the continuation token to a block that
    //    continues with the control flow transfer.
    // 3. By exiting the try-block with a thrown exception. In the handler,
    //    we push the exception and continuation token and jump to the
    //    finally block (which will again dispatch based on the token once
    //    it is finished).
  
    Label try_entry, handler_entry, finally_entry;
    DeferredCommands deferred(this, &finally_entry);
  
    // Jump to try-handler setup and try-block code.
    __ jmp(&try_entry);
    __ bind(&handler_entry);
  
    // Exception handler code.  This code is only executed when an exception
    // is thrown.  Record the continuation and jump to the finally block.
    {
      Comment cmnt_handler(masm(), "[ Finally handler");
      deferred.RecordThrow();
    }
  
    // Set up try handler.
    __ bind(&try_entry);
    int handler_index = NewHandlerTableEntry();
    EnterTryBlock(handler_index, &handler_entry);
    {
      Comment cmnt_try(masm(), "[ Try block");
      TryFinally try_body(this, &deferred);
      Visit(stmt->try_block());
    }
    ExitTryBlock(handler_index);
    // Execute the finally block on the way out.  Clobber the unpredictable
    // value in the result register with one that's safe for GC because the
    // finally block will unconditionally preserve the result register on the
    // stack.
    ClearAccumulator();
    deferred.EmitFallThrough();
    // Fall through to the finally block.
  
    // Finally block implementation.
    __ bind(&finally_entry);
    {
      Comment cmnt_finally(masm(), "[ Finally block");
      OperandStackDepthIncrement(2);  // Token and accumulator are on stack.
      EnterFinallyBlock();
      Visit(stmt->finally_block());
      ExitFinallyBlock();
      OperandStackDepthDecrement(2);  // Token and accumulator were on stack.
    }
  
    {
      Comment cmnt_deferred(masm(), "[ Post-finally dispatch");
      deferred.EmitCommands();  // Return to the calling code.
    }
  }
  
  
  void FullCodeGenerator::VisitDebuggerStatement(DebuggerStatement* stmt) {
    Comment cmnt(masm_, "[ DebuggerStatement");
    SetStatementPosition(stmt);
  
    __ DebugBreak();
    // Ignore the return value.
  
    PrepareForBailoutForId(stmt->DebugBreakId(), BailoutState::NO_REGISTERS);
  }
  
  
  void FullCodeGenerator::VisitCaseClause(CaseClause* clause) {
    UNREACHABLE();
  }
  
  
  void FullCodeGenerator::VisitConditional(Conditional* expr) {
    Comment cmnt(masm_, "[ Conditional");
    Label true_case, false_case, done;
    VisitForControl(expr->condition(), &true_case, &false_case, &true_case);
  
    int original_stack_depth = operand_stack_depth_;
    PrepareForBailoutForId(expr->ThenId(), BailoutState::NO_REGISTERS);
    __ bind(&true_case);
    SetExpressionPosition(expr->then_expression());
    if (context()->IsTest()) {
      const TestContext* for_test = TestContext::cast(context());
      VisitForControl(expr->then_expression(),
                      for_test->true_label(),
                      for_test->false_label(),
                      NULL);
    } else {
      VisitInDuplicateContext(expr->then_expression());
      __ jmp(&done);
    }
  
    operand_stack_depth_ = original_stack_depth;
    PrepareForBailoutForId(expr->ElseId(), BailoutState::NO_REGISTERS);
    __ bind(&false_case);
    SetExpressionPosition(expr->else_expression());
    VisitInDuplicateContext(expr->else_expression());
    // If control flow falls through Visit, merge it with true case here.
    if (!context()->IsTest()) {
      __ bind(&done);
    }
  }
  
  
  void FullCodeGenerator::VisitLiteral(Literal* expr) {
    Comment cmnt(masm_, "[ Literal");
    context()->Plug(expr->value());
  }
  
  
  void FullCodeGenerator::VisitFunctionLiteral(FunctionLiteral* expr) {
    Comment cmnt(masm_, "[ FunctionLiteral");
  
    // Build the function boilerplate and instantiate it.
    Handle<SharedFunctionInfo> function_info =
        Compiler::GetSharedFunctionInfo(expr, script(), info_);
    if (function_info.is_null()) {
      SetStackOverflow();
      return;
    }
    EmitNewClosure(function_info, expr->pretenure());
  }
  
  
  void FullCodeGenerator::VisitClassLiteral(ClassLiteral* lit) {
    Comment cmnt(masm_, "[ ClassLiteral");
  
    {
      NestedClassLiteral nested_class_literal(this, lit);
      EnterBlockScopeIfNeeded block_scope_state(
          this, lit->scope(), lit->EntryId(), lit->DeclsId(), lit->ExitId());
  
      if (lit->extends() != NULL) {
        VisitForStackValue(lit->extends());
      } else {
        PushOperand(isolate()->factory()->the_hole_value());
      }
  
      VisitForStackValue(lit->constructor());
  
      PushOperand(Smi::FromInt(lit->start_position()));
      PushOperand(Smi::FromInt(lit->end_position()));
  
      CallRuntimeWithOperands(Runtime::kDefineClass);
      PrepareForBailoutForId(lit->CreateLiteralId(), BailoutState::TOS_REGISTER);
      PushOperand(result_register());
  
      // Load the "prototype" from the constructor.
      __ Move(LoadDescriptor::ReceiverRegister(), result_register());
      __ LoadRoot(LoadDescriptor::NameRegister(),
                  Heap::kprototype_stringRootIndex);
      __ Move(LoadDescriptor::SlotRegister(), SmiFromSlot(lit->PrototypeSlot()));
      CallLoadIC(NOT_INSIDE_TYPEOF);
      PrepareForBailoutForId(lit->PrototypeId(), BailoutState::TOS_REGISTER);
      PushOperand(result_register());
  
      EmitClassDefineProperties(lit);
      DropOperands(1);
  
      // Set the constructor to have fast properties.
      CallRuntimeWithOperands(Runtime::kToFastProperties);
  
      if (lit->class_variable_proxy() != nullptr) {
        EmitVariableAssignment(lit->class_variable_proxy()->var(), Token::INIT,
                               lit->ProxySlot());
      }
    }
  
    context()->Plug(result_register());
  }
  
  
  void FullCodeGenerator::VisitNativeFunctionLiteral(
      NativeFunctionLiteral* expr) {
    Comment cmnt(masm_, "[ NativeFunctionLiteral");
    Handle<SharedFunctionInfo> shared =
        Compiler::GetSharedFunctionInfoForNative(expr->extension(), expr->name());
    EmitNewClosure(shared, false);
  }
  
  
  void FullCodeGenerator::VisitThrow(Throw* expr) {
    Comment cmnt(masm_, "[ Throw");
    VisitForStackValue(expr->exception());
    SetExpressionPosition(expr);
    CallRuntimeWithOperands(Runtime::kThrow);
    // Never returns here.
  
    // Even though this expression doesn't produce a value, we need to simulate
    // plugging of the value context to ensure stack depth tracking is in sync.
    if (context()->IsStackValue()) OperandStackDepthIncrement(1);
  }
  
  
  void FullCodeGenerator::EnterTryBlock(int handler_index, Label* handler) {
    HandlerTableEntry* entry = &handler_table_[handler_index];
    entry->range_start = masm()->pc_offset();
    entry->handler_offset = handler->pos();
    entry->try_catch_depth = try_catch_depth_;
    entry->stack_depth = operand_stack_depth_;
  
    // We are using the operand stack depth, check for accuracy.
    EmitOperandStackDepthCheck();
  
    // Push context onto operand stack.
    STATIC_ASSERT(TryBlockConstant::kElementCount == 1);
    PushOperand(context_register());
  }
  
  
  void FullCodeGenerator::ExitTryBlock(int handler_index) {
    HandlerTableEntry* entry = &handler_table_[handler_index];
    entry->range_end = masm()->pc_offset();
  
    // Drop context from operand stack.
    DropOperands(TryBlockConstant::kElementCount);
  }
  
  
  void FullCodeGenerator::VisitCall(Call* expr) {
  #ifdef DEBUG
    // We want to verify that RecordJSReturnSite gets called on all paths
    // through this function.  Avoid early returns.
    expr->return_is_recorded_ = false;
  #endif
  
    Comment cmnt(masm_, (expr->tail_call_mode() == TailCallMode::kAllow)
                            ? "[ TailCall"
                            : "[ Call");
    Expression* callee = expr->expression();
    Call::CallType call_type = expr->GetCallType(isolate());
  
    switch (call_type) {
      case Call::POSSIBLY_EVAL_CALL:
        EmitPossiblyEvalCall(expr);
        break;
      case Call::GLOBAL_CALL:
        EmitCallWithLoadIC(expr);
        break;
      case Call::LOOKUP_SLOT_CALL:
        // Call to a lookup slot (dynamically introduced variable).
        PushCalleeAndWithBaseObject(expr);
        EmitCall(expr);
        break;
      case Call::NAMED_PROPERTY_CALL: {
        Property* property = callee->AsProperty();
        VisitForStackValue(property->obj());
        EmitCallWithLoadIC(expr);
        break;
      }
      case Call::KEYED_PROPERTY_CALL: {
        Property* property = callee->AsProperty();
        VisitForStackValue(property->obj());
        EmitKeyedCallWithLoadIC(expr, property->key());
        break;
      }
      case Call::NAMED_SUPER_PROPERTY_CALL:
        EmitSuperCallWithLoadIC(expr);
        break;
      case Call::KEYED_SUPER_PROPERTY_CALL:
        EmitKeyedSuperCallWithLoadIC(expr);
        break;
      case Call::SUPER_CALL:
        EmitSuperConstructorCall(expr);
        break;
      case Call::OTHER_CALL:
        // Call to an arbitrary expression not handled specially above.
        VisitForStackValue(callee);
        OperandStackDepthIncrement(1);
        __ PushRoot(Heap::kUndefinedValueRootIndex);
        // Emit function call.
        EmitCall(expr);
        break;
    }
  
  #ifdef DEBUG
    // RecordJSReturnSite should have been called.
    DCHECK(expr->return_is_recorded_);
  #endif
  }
  
  void FullCodeGenerator::VisitCallRuntime(CallRuntime* expr) {
    ZoneList<Expression*>* args = expr->arguments();
    int arg_count = args->length();
  
    if (expr->is_jsruntime()) {
      Comment cmnt(masm_, "[ CallRuntime");
      EmitLoadJSRuntimeFunction(expr);
  
      // Push the arguments ("left-to-right").
      for (int i = 0; i < arg_count; i++) {
        VisitForStackValue(args->at(i));
      }
  
      PrepareForBailoutForId(expr->CallId(), BailoutState::NO_REGISTERS);
      EmitCallJSRuntimeFunction(expr);
      context()->DropAndPlug(1, result_register());
  
    } else {
      const Runtime::Function* function = expr->function();
      switch (function->function_id) {
  #define CALL_INTRINSIC_GENERATOR(Name)     \
    case Runtime::kInline##Name: {           \
      Comment cmnt(masm_, "[ Inline" #Name); \
      return Emit##Name(expr);               \
    }
        FOR_EACH_FULL_CODE_INTRINSIC(CALL_INTRINSIC_GENERATOR)
  #undef CALL_INTRINSIC_GENERATOR
        default: {
          Comment cmnt(masm_, "[ CallRuntime for unhandled intrinsic");
          // Push the arguments ("left-to-right").
          for (int i = 0; i < arg_count; i++) {
            VisitForStackValue(args->at(i));
          }
  
          // Call the C runtime function.
          PrepareForBailoutForId(expr->CallId(), BailoutState::NO_REGISTERS);
          __ CallRuntime(expr->function(), arg_count);
          OperandStackDepthDecrement(arg_count);
          context()->Plug(result_register());
        }
      }
    }
  }
  
  void FullCodeGenerator::VisitSpread(Spread* expr) { UNREACHABLE(); }
  
  
  void FullCodeGenerator::VisitEmptyParentheses(EmptyParentheses* expr) {
    UNREACHABLE();
  }
  
  
  void FullCodeGenerator::VisitRewritableExpression(RewritableExpression* expr) {
    Visit(expr->expression());
  }
  
  FullCodeGenerator::NestedStatement* FullCodeGenerator::TryFinally::Exit(
      int* context_length) {
    // The macros used here must preserve the result register.
  
    // Calculate how many operands to drop to get down to handler block.
    int stack_drop = codegen_->operand_stack_depth_ - GetStackDepthAtTarget();
    DCHECK_GE(stack_drop, 0);
  
    // Because the handler block contains the context of the finally
    // code, we can restore it directly from there for the finally code
    // rather than iteratively unwinding contexts via their previous
    // links.
    if (*context_length > 0) {
      __ Drop(stack_drop);  // Down to the handler block.
      // Restore the context to its dedicated register and the stack.
      STATIC_ASSERT(TryBlockConstant::kElementCount == 1);
      __ Pop(codegen_->context_register());
      codegen_->StoreToFrameField(StandardFrameConstants::kContextOffset,
                                  codegen_->context_register());
    } else {
      // Down to the handler block and also drop context.
      __ Drop(stack_drop + TryBlockConstant::kElementCount);
    }
  
    // The caller will ignore outputs.
    *context_length = -1;
    return previous_;
  }
  
  void FullCodeGenerator::DeferredCommands::RecordBreak(Statement* target) {
    TokenId token = dispenser_.GetBreakContinueToken();
    commands_.push_back({kBreak, token, target});
    EmitJumpToFinally(token);
  }
  
  void FullCodeGenerator::DeferredCommands::RecordContinue(Statement* target) {
    TokenId token = dispenser_.GetBreakContinueToken();
    commands_.push_back({kContinue, token, target});
    EmitJumpToFinally(token);
  }
  
  void FullCodeGenerator::DeferredCommands::RecordReturn() {
    if (return_token_ == TokenDispenserForFinally::kInvalidToken) {
      return_token_ = TokenDispenserForFinally::kReturnToken;
      commands_.push_back({kReturn, return_token_, nullptr});
    }
    EmitJumpToFinally(return_token_);
  }
  
  void FullCodeGenerator::DeferredCommands::RecordThrow() {
    if (throw_token_ == TokenDispenserForFinally::kInvalidToken) {
      throw_token_ = TokenDispenserForFinally::kThrowToken;
      commands_.push_back({kThrow, throw_token_, nullptr});
    }
    EmitJumpToFinally(throw_token_);
  }
  
  void FullCodeGenerator::DeferredCommands::EmitFallThrough() {
    __ Push(Smi::FromInt(TokenDispenserForFinally::kFallThroughToken));
    __ Push(result_register());
  }
  
  void FullCodeGenerator::DeferredCommands::EmitJumpToFinally(TokenId token) {
    __ Push(Smi::FromInt(token));
    __ Push(result_register());
    __ jmp(finally_entry_);
  }
  
  bool FullCodeGenerator::TryLiteralCompare(CompareOperation* expr) {
    Expression* sub_expr;
    Handle<String> check;
    if (expr->IsLiteralCompareTypeof(&sub_expr, &check)) {
      SetExpressionPosition(expr);
      EmitLiteralCompareTypeof(expr, sub_expr, check);
      return true;
    }
  
    if (expr->IsLiteralCompareUndefined(&sub_expr)) {
      SetExpressionPosition(expr);
      EmitLiteralCompareNil(expr, sub_expr, kUndefinedValue);
      return true;
    }
  
    if (expr->IsLiteralCompareNull(&sub_expr)) {
      SetExpressionPosition(expr);
      EmitLiteralCompareNil(expr, sub_expr, kNullValue);
      return true;
    }
  
    return false;
  }
  
  
  void BackEdgeTable::Patch(Isolate* isolate, Code* unoptimized) {
    DisallowHeapAllocation no_gc;
    Code* patch = isolate->builtins()->builtin(Builtins::kOnStackReplacement);
  
    // Increment loop nesting level by one and iterate over the back edge table
    // to find the matching loops to patch the interrupt
    // call to an unconditional call to the replacement code.
    int loop_nesting_level = unoptimized->allow_osr_at_loop_nesting_level() + 1;
    if (loop_nesting_level > Code::kMaxLoopNestingMarker) return;
  
    BackEdgeTable back_edges(unoptimized, &no_gc);
    for (uint32_t i = 0; i < back_edges.length(); i++) {
      if (static_cast<int>(back_edges.loop_depth(i)) == loop_nesting_level) {
        DCHECK_EQ(INTERRUPT, GetBackEdgeState(isolate,
                                              unoptimized,
                                              back_edges.pc(i)));
        PatchAt(unoptimized, back_edges.pc(i), ON_STACK_REPLACEMENT, patch);
      }
    }
  
    unoptimized->set_allow_osr_at_loop_nesting_level(loop_nesting_level);
    DCHECK(Verify(isolate, unoptimized));
  }
  
  
  void BackEdgeTable::Revert(Isolate* isolate, Code* unoptimized) {
    DisallowHeapAllocation no_gc;
    Code* patch = isolate->builtins()->builtin(Builtins::kInterruptCheck);
  
    // Iterate over the back edge table and revert the patched interrupt calls.
    int loop_nesting_level = unoptimized->allow_osr_at_loop_nesting_level();
  
    BackEdgeTable back_edges(unoptimized, &no_gc);
    for (uint32_t i = 0; i < back_edges.length(); i++) {
      if (static_cast<int>(back_edges.loop_depth(i)) <= loop_nesting_level) {
        DCHECK_NE(INTERRUPT, GetBackEdgeState(isolate,
                                              unoptimized,
                                              back_edges.pc(i)));
        PatchAt(unoptimized, back_edges.pc(i), INTERRUPT, patch);
      }
    }
  
    unoptimized->set_allow_osr_at_loop_nesting_level(0);
    // Assert that none of the back edges are patched anymore.
    DCHECK(Verify(isolate, unoptimized));
  }
  
  
  #ifdef DEBUG
  bool BackEdgeTable::Verify(Isolate* isolate, Code* unoptimized) {
    DisallowHeapAllocation no_gc;
    int loop_nesting_level = unoptimized->allow_osr_at_loop_nesting_level();
    BackEdgeTable back_edges(unoptimized, &no_gc);
    for (uint32_t i = 0; i < back_edges.length(); i++) {
      uint32_t loop_depth = back_edges.loop_depth(i);
      CHECK_LE(static_cast<int>(loop_depth), Code::kMaxLoopNestingMarker);
      // Assert that all back edges for shallower loops (and only those)
      // have already been patched.
      CHECK_EQ((static_cast<int>(loop_depth) <= loop_nesting_level),
               GetBackEdgeState(isolate,
                                unoptimized,
                                back_edges.pc(i)) != INTERRUPT);
    }
    return true;
  }
  #endif  // DEBUG
  
  
  FullCodeGenerator::EnterBlockScopeIfNeeded::EnterBlockScopeIfNeeded(
      FullCodeGenerator* codegen, Scope* scope, BailoutId entry_id,
      BailoutId declarations_id, BailoutId exit_id)
      : codegen_(codegen), exit_id_(exit_id) {
    saved_scope_ = codegen_->scope();
  
    if (scope == NULL) {
      codegen_->PrepareForBailoutForId(entry_id, BailoutState::NO_REGISTERS);
      needs_block_context_ = false;
    } else {
      needs_block_context_ = scope->NeedsContext();
      codegen_->scope_ = scope;
      {
        if (needs_block_context_) {
          Comment cmnt(masm(), "[ Extend block context");
          codegen_->PushOperand(scope->GetScopeInfo(codegen->isolate()));
          codegen_->PushFunctionArgumentForContextAllocation();
          codegen_->CallRuntimeWithOperands(Runtime::kPushBlockContext);
  
          // Replace the context stored in the frame.
          codegen_->StoreToFrameField(StandardFrameConstants::kContextOffset,
                                      codegen_->context_register());
        }
        CHECK_EQ(0, scope->num_stack_slots());
        codegen_->PrepareForBailoutForId(entry_id, BailoutState::NO_REGISTERS);
      }
      {
        Comment cmnt(masm(), "[ Declarations");
        codegen_->VisitDeclarations(scope->declarations());
        codegen_->PrepareForBailoutForId(declarations_id,
                                         BailoutState::NO_REGISTERS);
      }
    }
  }
  
  
  FullCodeGenerator::EnterBlockScopeIfNeeded::~EnterBlockScopeIfNeeded() {
    if (needs_block_context_) {
      codegen_->LoadContextField(codegen_->context_register(),
                                 Context::PREVIOUS_INDEX);
      // Update local stack frame context field.
      codegen_->StoreToFrameField(StandardFrameConstants::kContextOffset,
                                  codegen_->context_register());
    }
    codegen_->PrepareForBailoutForId(exit_id_, BailoutState::NO_REGISTERS);
    codegen_->scope_ = saved_scope_;
  }
  
  
  bool FullCodeGenerator::NeedsHoleCheckForLoad(VariableProxy* proxy) {
    Variable* var = proxy->var();
  
    if (!var->binding_needs_init()) {
      return false;
    }
  
    // var->scope() may be NULL when the proxy is located in eval code and
    // refers to a potential outside binding. Currently those bindings are
    // always looked up dynamically, i.e. in that case
    //     var->location() == LOOKUP.
    // always holds.
    DCHECK(var->scope() != NULL);
    DCHECK(var->location() == VariableLocation::PARAMETER ||
           var->location() == VariableLocation::LOCAL ||
           var->location() == VariableLocation::CONTEXT);
  
    // Check if the binding really needs an initialization check. The check
    // can be skipped in the following situation: we have a LET or CONST
    // binding in harmony mode, both the Variable and the VariableProxy have
    // the same declaration scope (i.e. they are both in global code, in the
    // same function or in the same eval code), the VariableProxy is in
    // the source physically located after the initializer of the variable,
    // and that the initializer cannot be skipped due to a nonlinear scope.
    //
    // We cannot skip any initialization checks for CONST in non-harmony
    // mode because const variables may be declared but never initialized:
    //   if (false) { const x; }; var y = x;
    //
    // The condition on the declaration scopes is a conservative check for
    // nested functions that access a binding and are called before the
    // binding is initialized:
    //   function() { f(); let x = 1; function f() { x = 2; } }
    //
    // The check cannot be skipped on non-linear scopes, namely switch
    // scopes, to ensure tests are done in cases like the following:
    //   switch (1) { case 0: let x = 2; case 1: f(x); }
    // The scope of the variable needs to be checked, in case the use is
    // in a sub-block which may be linear.
    if (var->scope()->DeclarationScope() != scope()->DeclarationScope()) {
      return true;
    }
  
    if (var->is_this()) {
      DCHECK(literal() != nullptr &&
             (literal()->kind() & kSubclassConstructor) != 0);
      // TODO(littledan): implement 'this' hole check elimination.
      return true;
    }
  
    // Check that we always have valid source position.
    DCHECK(var->initializer_position() != RelocInfo::kNoPosition);
    DCHECK(proxy->position() != RelocInfo::kNoPosition);
  
    return var->scope()->is_nonlinear() ||
           var->initializer_position() >= proxy->position();
  }
  
  
  #undef __
  
  
  }  // namespace internal
  }  // namespace v8
  