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/ast/ast-numbering.h"
  
  #include "src/ast/ast.h"
  #include "src/ast/scopes.h"
  
  namespace v8 {
  namespace internal {
  
  class AstNumberingVisitor final : public AstVisitor<AstNumberingVisitor> {
   public:
    AstNumberingVisitor(Isolate* isolate, Zone* zone)
        : isolate_(isolate),
          zone_(zone),
          next_id_(BailoutId::FirstUsable().ToInt()),
          yield_count_(0),
          properties_(zone),
          slot_cache_(zone),
          dont_optimize_reason_(kNoReason),
          catch_prediction_(HandlerTable::UNCAUGHT) {
      InitializeAstVisitor(isolate);
    }
  
    bool Renumber(FunctionLiteral* node);
  
   private:
  // AST node visitor interface.
  #define DEFINE_VISIT(type) void Visit##type(type* node);
    AST_NODE_LIST(DEFINE_VISIT)
  #undef DEFINE_VISIT
  
    void VisitVariableProxyReference(VariableProxy* node);
    void VisitPropertyReference(Property* node);
    void VisitReference(Expression* expr);
  
    void VisitStatements(ZoneList<Statement*>* statements);
    void VisitDeclarations(Declaration::List* declarations);
    void VisitArguments(ZoneList<Expression*>* arguments);
    void VisitLiteralProperty(LiteralProperty* property);
  
    int ReserveIdRange(int n) {
      int tmp = next_id_;
      next_id_ += n;
      return tmp;
    }
  
    void IncrementNodeCount() { properties_.add_node_count(1); }
    void DisableSelfOptimization() {
      properties_.flags() |= AstProperties::kDontSelfOptimize;
    }
    void DisableOptimization(BailoutReason reason) {
      dont_optimize_reason_ = reason;
      DisableSelfOptimization();
    }
    void DisableCrankshaft(BailoutReason reason) {
      properties_.flags() |= AstProperties::kDontCrankshaft;
    }
  
    template <typename Node>
    void ReserveFeedbackSlots(Node* node) {
      node->AssignFeedbackVectorSlots(isolate_, properties_.get_spec(),
                                      &slot_cache_);
    }
  
    BailoutReason dont_optimize_reason() const { return dont_optimize_reason_; }
  
    Isolate* isolate_;
    Zone* zone_;
    int next_id_;
    int yield_count_;
    AstProperties properties_;
    // The slot cache allows us to reuse certain feedback vector slots.
    FeedbackVectorSlotCache slot_cache_;
    BailoutReason dont_optimize_reason_;
    HandlerTable::CatchPrediction catch_prediction_;
  
    DEFINE_AST_VISITOR_SUBCLASS_MEMBERS();
    DISALLOW_COPY_AND_ASSIGN(AstNumberingVisitor);
  };
  
  
  void AstNumberingVisitor::VisitVariableDeclaration(VariableDeclaration* node) {
    IncrementNodeCount();
    VisitVariableProxy(node->proxy());
  }
  
  
  void AstNumberingVisitor::VisitEmptyStatement(EmptyStatement* node) {
    IncrementNodeCount();
  }
  
  
  void AstNumberingVisitor::VisitSloppyBlockFunctionStatement(
      SloppyBlockFunctionStatement* node) {
    IncrementNodeCount();
    Visit(node->statement());
  }
  
  
  void AstNumberingVisitor::VisitContinueStatement(ContinueStatement* node) {
    IncrementNodeCount();
  }
  
  
  void AstNumberingVisitor::VisitBreakStatement(BreakStatement* node) {
    IncrementNodeCount();
  }
  
  
  void AstNumberingVisitor::VisitDebuggerStatement(DebuggerStatement* node) {
    IncrementNodeCount();
    DisableOptimization(kDebuggerStatement);
    node->set_base_id(ReserveIdRange(DebuggerStatement::num_ids()));
  }
  
  
  void AstNumberingVisitor::VisitNativeFunctionLiteral(
      NativeFunctionLiteral* node) {
    IncrementNodeCount();
    DisableOptimization(kNativeFunctionLiteral);
    node->set_base_id(ReserveIdRange(NativeFunctionLiteral::num_ids()));
  }
  
  
  void AstNumberingVisitor::VisitDoExpression(DoExpression* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(DoExpression::num_ids()));
    Visit(node->block());
    Visit(node->result());
  }
  
  
  void AstNumberingVisitor::VisitLiteral(Literal* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(Literal::num_ids()));
  }
  
  
  void AstNumberingVisitor::VisitRegExpLiteral(RegExpLiteral* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(RegExpLiteral::num_ids()));
  }
  
  
  void AstNumberingVisitor::VisitVariableProxyReference(VariableProxy* node) {
    IncrementNodeCount();
    switch (node->var()->location()) {
      case VariableLocation::LOOKUP:
        DisableCrankshaft(kReferenceToAVariableWhichRequiresDynamicLookup);
        break;
      case VariableLocation::MODULE:
        DisableCrankshaft(kReferenceToModuleVariable);
        break;
      default:
        break;
    }
    node->set_base_id(ReserveIdRange(VariableProxy::num_ids()));
  }
  
  
  void AstNumberingVisitor::VisitVariableProxy(VariableProxy* node) {
    VisitVariableProxyReference(node);
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitThisFunction(ThisFunction* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(ThisFunction::num_ids()));
  }
  
  
  void AstNumberingVisitor::VisitSuperPropertyReference(
      SuperPropertyReference* node) {
    IncrementNodeCount();
    DisableCrankshaft(kSuperReference);
    node->set_base_id(ReserveIdRange(SuperPropertyReference::num_ids()));
    Visit(node->this_var());
    Visit(node->home_object());
  }
  
  
  void AstNumberingVisitor::VisitSuperCallReference(SuperCallReference* node) {
    IncrementNodeCount();
    DisableCrankshaft(kSuperReference);
    node->set_base_id(ReserveIdRange(SuperCallReference::num_ids()));
    Visit(node->this_var());
    Visit(node->new_target_var());
    Visit(node->this_function_var());
  }
  
  
  void AstNumberingVisitor::VisitExpressionStatement(ExpressionStatement* node) {
    IncrementNodeCount();
    Visit(node->expression());
  }
  
  
  void AstNumberingVisitor::VisitReturnStatement(ReturnStatement* node) {
    IncrementNodeCount();
    Visit(node->expression());
  }
  
  
  void AstNumberingVisitor::VisitYield(Yield* node) {
    node->set_yield_id(yield_count_);
    yield_count_++;
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(Yield::num_ids()));
    Visit(node->generator_object());
    Visit(node->expression());
  }
  
  
  void AstNumberingVisitor::VisitThrow(Throw* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(Throw::num_ids()));
    Visit(node->exception());
  }
  
  
  void AstNumberingVisitor::VisitUnaryOperation(UnaryOperation* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(UnaryOperation::num_ids()));
    Visit(node->expression());
  }
  
  
  void AstNumberingVisitor::VisitCountOperation(CountOperation* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(CountOperation::num_ids()));
    Visit(node->expression());
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitBlock(Block* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(Block::num_ids()));
    if (node->scope() != NULL) VisitDeclarations(node->scope()->declarations());
    VisitStatements(node->statements());
  }
  
  
  void AstNumberingVisitor::VisitFunctionDeclaration(FunctionDeclaration* node) {
    IncrementNodeCount();
    VisitVariableProxy(node->proxy());
    VisitFunctionLiteral(node->fun());
  }
  
  
  void AstNumberingVisitor::VisitCallRuntime(CallRuntime* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(CallRuntime::num_ids()));
    VisitArguments(node->arguments());
    // To support catch prediction within async/await:
    //
    // The AstNumberingVisitor is when catch prediction currently occurs, and it
    // is the only common point that has access to this information. The parser
    // just doesn't know yet. Take the following two cases of catch prediction:
    //
    // try { await fn(); } catch (e) { }
    // try { await fn(); } finally { }
    //
    // When parsing the await that we want to mark as caught or uncaught, it's
    // not yet known whether it will be followed by a 'finally' or a 'catch.
    // The AstNumberingVisitor is what learns whether it is caught. To make
    // the information available later to the runtime, the AstNumberingVisitor
    // has to stash it somewhere. Changing the runtime function into another
    // one in ast-numbering seemed like a simple and straightforward solution to
    // that problem.
    if (node->is_jsruntime() &&
        node->context_index() == Context::ASYNC_FUNCTION_AWAIT_CAUGHT_INDEX &&
        catch_prediction_ == HandlerTable::ASYNC_AWAIT) {
      node->set_context_index(Context::ASYNC_FUNCTION_AWAIT_UNCAUGHT_INDEX);
    }
  }
  
  
  void AstNumberingVisitor::VisitWithStatement(WithStatement* node) {
    IncrementNodeCount();
    DisableCrankshaft(kWithStatement);
    node->set_base_id(ReserveIdRange(WithStatement::num_ids()));
    Visit(node->expression());
    Visit(node->statement());
  }
  
  
  void AstNumberingVisitor::VisitDoWhileStatement(DoWhileStatement* node) {
    IncrementNodeCount();
    DisableSelfOptimization();
    node->set_base_id(ReserveIdRange(DoWhileStatement::num_ids()));
    node->set_first_yield_id(yield_count_);
    Visit(node->body());
    Visit(node->cond());
    node->set_yield_count(yield_count_ - node->first_yield_id());
  }
  
  
  void AstNumberingVisitor::VisitWhileStatement(WhileStatement* node) {
    IncrementNodeCount();
    DisableSelfOptimization();
    node->set_base_id(ReserveIdRange(WhileStatement::num_ids()));
    node->set_first_yield_id(yield_count_);
    Visit(node->cond());
    Visit(node->body());
    node->set_yield_count(yield_count_ - node->first_yield_id());
  }
  
  
  void AstNumberingVisitor::VisitTryCatchStatement(TryCatchStatement* node) {
    IncrementNodeCount();
    DisableCrankshaft(kTryCatchStatement);
    {
      const HandlerTable::CatchPrediction old_prediction = catch_prediction_;
      // This node uses its own prediction, unless it's "uncaught", in which case
      // we adopt the prediction of the outer try-block.
      HandlerTable::CatchPrediction catch_prediction = node->catch_prediction();
      if (catch_prediction != HandlerTable::UNCAUGHT) {
        catch_prediction_ = catch_prediction;
      }
      node->set_catch_prediction(catch_prediction_);
      Visit(node->try_block());
      catch_prediction_ = old_prediction;
    }
    Visit(node->catch_block());
  }
  
  
  void AstNumberingVisitor::VisitTryFinallyStatement(TryFinallyStatement* node) {
    IncrementNodeCount();
    DisableCrankshaft(kTryFinallyStatement);
    // 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.
    node->set_catch_prediction(catch_prediction_);
    Visit(node->try_block());
    Visit(node->finally_block());
  }
  
  
  void AstNumberingVisitor::VisitPropertyReference(Property* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(Property::num_ids()));
    Visit(node->key());
    Visit(node->obj());
  }
  
  
  void AstNumberingVisitor::VisitReference(Expression* expr) {
    DCHECK(expr->IsProperty() || expr->IsVariableProxy());
    if (expr->IsProperty()) {
      VisitPropertyReference(expr->AsProperty());
    } else {
      VisitVariableProxyReference(expr->AsVariableProxy());
    }
  }
  
  
  void AstNumberingVisitor::VisitProperty(Property* node) {
    VisitPropertyReference(node);
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitAssignment(Assignment* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(Assignment::num_ids()));
  
    if (node->is_compound()) VisitBinaryOperation(node->binary_operation());
    VisitReference(node->target());
    Visit(node->value());
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitBinaryOperation(BinaryOperation* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(BinaryOperation::num_ids()));
    Visit(node->left());
    Visit(node->right());
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitCompareOperation(CompareOperation* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(CompareOperation::num_ids()));
    Visit(node->left());
    Visit(node->right());
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitSpread(Spread* node) { UNREACHABLE(); }
  
  
  void AstNumberingVisitor::VisitEmptyParentheses(EmptyParentheses* node) {
    UNREACHABLE();
  }
  
  
  void AstNumberingVisitor::VisitForInStatement(ForInStatement* node) {
    IncrementNodeCount();
    DisableSelfOptimization();
    node->set_base_id(ReserveIdRange(ForInStatement::num_ids()));
    Visit(node->enumerable());  // Not part of loop.
    node->set_first_yield_id(yield_count_);
    Visit(node->each());
    Visit(node->body());
    node->set_yield_count(yield_count_ - node->first_yield_id());
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitForOfStatement(ForOfStatement* node) {
    IncrementNodeCount();
    DisableCrankshaft(kForOfStatement);
    node->set_base_id(ReserveIdRange(ForOfStatement::num_ids()));
    Visit(node->assign_iterator());  // Not part of loop.
    node->set_first_yield_id(yield_count_);
    Visit(node->next_result());
    Visit(node->result_done());
    Visit(node->assign_each());
    Visit(node->body());
    node->set_yield_count(yield_count_ - node->first_yield_id());
  }
  
  
  void AstNumberingVisitor::VisitConditional(Conditional* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(Conditional::num_ids()));
    Visit(node->condition());
    Visit(node->then_expression());
    Visit(node->else_expression());
  }
  
  
  void AstNumberingVisitor::VisitIfStatement(IfStatement* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(IfStatement::num_ids()));
    Visit(node->condition());
    Visit(node->then_statement());
    if (node->HasElseStatement()) {
      Visit(node->else_statement());
    }
  }
  
  
  void AstNumberingVisitor::VisitSwitchStatement(SwitchStatement* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(SwitchStatement::num_ids()));
    Visit(node->tag());
    ZoneList<CaseClause*>* cases = node->cases();
    for (int i = 0; i < cases->length(); i++) {
      VisitCaseClause(cases->at(i));
    }
  }
  
  
  void AstNumberingVisitor::VisitCaseClause(CaseClause* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(CaseClause::num_ids()));
    if (!node->is_default()) Visit(node->label());
    VisitStatements(node->statements());
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitForStatement(ForStatement* node) {
    IncrementNodeCount();
    DisableSelfOptimization();
    node->set_base_id(ReserveIdRange(ForStatement::num_ids()));
    if (node->init() != NULL) Visit(node->init());  // Not part of loop.
    node->set_first_yield_id(yield_count_);
    if (node->cond() != NULL) Visit(node->cond());
    if (node->next() != NULL) Visit(node->next());
    Visit(node->body());
    node->set_yield_count(yield_count_ - node->first_yield_id());
  }
  
  
  void AstNumberingVisitor::VisitClassLiteral(ClassLiteral* node) {
    IncrementNodeCount();
    DisableCrankshaft(kClassLiteral);
    node->set_base_id(ReserveIdRange(node->num_ids()));
    if (node->extends()) Visit(node->extends());
    if (node->constructor()) Visit(node->constructor());
    if (node->class_variable_proxy()) {
      VisitVariableProxy(node->class_variable_proxy());
    }
    for (int i = 0; i < node->properties()->length(); i++) {
      VisitLiteralProperty(node->properties()->at(i));
    }
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitObjectLiteral(ObjectLiteral* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(node->num_ids()));
    for (int i = 0; i < node->properties()->length(); i++) {
      VisitLiteralProperty(node->properties()->at(i));
    }
    node->BuildConstantProperties(isolate_);
    // Mark all computed expressions that are bound to a key that
    // is shadowed by a later occurrence of the same key. For the
    // marked expressions, no store code will be is emitted.
    node->CalculateEmitStore(zone_);
    ReserveFeedbackSlots(node);
  }
  
  void AstNumberingVisitor::VisitLiteralProperty(LiteralProperty* node) {
    if (node->is_computed_name()) DisableCrankshaft(kComputedPropertyName);
    Visit(node->key());
    Visit(node->value());
  }
  
  void AstNumberingVisitor::VisitArrayLiteral(ArrayLiteral* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(node->num_ids()));
    for (int i = 0; i < node->values()->length(); i++) {
      Visit(node->values()->at(i));
    }
    node->BuildConstantElements(isolate_);
    ReserveFeedbackSlots(node);
  }
  
  
  void AstNumberingVisitor::VisitCall(Call* node) {
    IncrementNodeCount();
    ReserveFeedbackSlots(node);
    node->set_base_id(ReserveIdRange(Call::num_ids()));
    Visit(node->expression());
    VisitArguments(node->arguments());
  }
  
  
  void AstNumberingVisitor::VisitCallNew(CallNew* node) {
    IncrementNodeCount();
    ReserveFeedbackSlots(node);
    node->set_base_id(ReserveIdRange(CallNew::num_ids()));
    Visit(node->expression());
    VisitArguments(node->arguments());
  }
  
  
  void AstNumberingVisitor::VisitStatements(ZoneList<Statement*>* statements) {
    if (statements == NULL) return;
    for (int i = 0; i < statements->length(); i++) {
      Visit(statements->at(i));
    }
  }
  
  void AstNumberingVisitor::VisitDeclarations(Declaration::List* decls) {
    for (Declaration* decl : *decls) Visit(decl);
  }
  
  
  void AstNumberingVisitor::VisitArguments(ZoneList<Expression*>* arguments) {
    for (int i = 0; i < arguments->length(); i++) {
      Visit(arguments->at(i));
    }
  }
  
  
  void AstNumberingVisitor::VisitFunctionLiteral(FunctionLiteral* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(FunctionLiteral::num_ids()));
    // We don't recurse into the declarations or body of the function literal:
    // you have to separately Renumber() each FunctionLiteral that you compile.
  }
  
  
  void AstNumberingVisitor::VisitRewritableExpression(
      RewritableExpression* node) {
    IncrementNodeCount();
    node->set_base_id(ReserveIdRange(RewritableExpression::num_ids()));
    Visit(node->expression());
  }
  
  
  bool AstNumberingVisitor::Renumber(FunctionLiteral* node) {
    DeclarationScope* scope = node->scope();
    if (scope->new_target_var()) DisableCrankshaft(kSuperReference);
    if (scope->calls_eval()) DisableCrankshaft(kFunctionCallsEval);
    if (scope->arguments() != NULL && !scope->arguments()->IsStackAllocated()) {
      DisableCrankshaft(kContextAllocatedArguments);
    }
  
    if (scope->rest_parameter() != nullptr) {
      DisableCrankshaft(kRestParameter);
    }
  
    if (IsGeneratorFunction(node->kind()) || IsAsyncFunction(node->kind())) {
      DisableCrankshaft(kGenerator);
    }
  
    if (IsClassConstructor(node->kind())) {
      DisableCrankshaft(kClassConstructorFunction);
    }
  
    VisitDeclarations(scope->declarations());
    VisitStatements(node->body());
  
    node->set_ast_properties(&properties_);
    node->set_dont_optimize_reason(dont_optimize_reason());
    node->set_yield_count(yield_count_);
    return !HasStackOverflow();
  }
  
  
  bool AstNumbering::Renumber(Isolate* isolate, Zone* zone,
                              FunctionLiteral* function) {
    AstNumberingVisitor visitor(isolate, zone);
    return visitor.Renumber(function);
  }
  }  // namespace internal
  }  // namespace v8
  