v8/src/ast.cc

// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "ast.h"

#include <math.h>  // For isfinite.
#include "builtins.h"
#include "code-stubs.h"
#include "conversions.h"
#include "hashmap.h"
#include "parser.h"
#include "property-details.h"
#include "property.h"
#include "scopes.h"
#include "string-stream.h"
#include "type-info.h"

namespace v8 {
namespace internal {

// ----------------------------------------------------------------------------
// All the Accept member functions for each syntax tree node type.

#define DECL_ACCEPT(type)                                       \
  void type::Accept(AstVisitor* v) { v->Visit##type(this); }
AST_NODE_LIST(DECL_ACCEPT)
#undef DECL_ACCEPT


// ----------------------------------------------------------------------------
// Implementation of other node functionality.


bool Expression::IsSmiLiteral() {
  return AsLiteral() != NULL && AsLiteral()->handle()->IsSmi();
}


bool Expression::IsStringLiteral() {
  return AsLiteral() != NULL && AsLiteral()->handle()->IsString();
}


bool Expression::IsNullLiteral() {
  return AsLiteral() != NULL && AsLiteral()->handle()->IsNull();
}


VariableProxy::VariableProxy(Isolate* isolate, Variable* var)
    : Expression(isolate),
      name_(var->name()),
      var_(NULL),  // Will be set by the call to BindTo.
      is_this_(var->is_this()),
      is_trivial_(false),
      is_lvalue_(false),
      position_(RelocInfo::kNoPosition),
      interface_(var->interface()) {
  BindTo(var);
}


VariableProxy::VariableProxy(Isolate* isolate,
                             Handle<String> name,
                             bool is_this,
                             Interface* interface,
                             int position)
    : Expression(isolate),
      name_(name),
      var_(NULL),
      is_this_(is_this),
      is_trivial_(false),
      is_lvalue_(false),
      position_(position),
      interface_(interface) {
  // Names must be canonicalized for fast equality checks.
  ASSERT(name->IsInternalizedString());
}


void VariableProxy::BindTo(Variable* var) {
  ASSERT(var_ == NULL);  // must be bound only once
  ASSERT(var != NULL);  // must bind
  ASSERT(!FLAG_harmony_modules || interface_->IsUnified(var->interface()));
  ASSERT((is_this() && var->is_this()) || name_.is_identical_to(var->name()));
  // Ideally CONST-ness should match. However, this is very hard to achieve
  // because we don't know the exact semantics of conflicting (const and
  // non-const) multiple variable declarations, const vars introduced via
  // eval() etc.  Const-ness and variable declarations are a complete mess
  // in JS. Sigh...
  var_ = var;
  var->set_is_used(true);
}


Assignment::Assignment(Isolate* isolate,
                       Token::Value op,
                       Expression* target,
                       Expression* value,
                       int pos)
    : Expression(isolate),
      op_(op),
      target_(target),
      value_(value),
      pos_(pos),
      binary_operation_(NULL),
      assignment_id_(GetNextId(isolate)),
      is_monomorphic_(false) { }


Token::Value Assignment::binary_op() const {
  switch (op_) {
    case Token::ASSIGN_BIT_OR: return Token::BIT_OR;
    case Token::ASSIGN_BIT_XOR: return Token::BIT_XOR;
    case Token::ASSIGN_BIT_AND: return Token::BIT_AND;
    case Token::ASSIGN_SHL: return Token::SHL;
    case Token::ASSIGN_SAR: return Token::SAR;
    case Token::ASSIGN_SHR: return Token::SHR;
    case Token::ASSIGN_ADD: return Token::ADD;
    case Token::ASSIGN_SUB: return Token::SUB;
    case Token::ASSIGN_MUL: return Token::MUL;
    case Token::ASSIGN_DIV: return Token::DIV;
    case Token::ASSIGN_MOD: return Token::MOD;
    default: UNREACHABLE();
  }
  return Token::ILLEGAL;
}


bool FunctionLiteral::AllowsLazyCompilation() {
  return scope()->AllowsLazyCompilation();
}


bool FunctionLiteral::AllowsLazyCompilationWithoutContext() {
  return scope()->AllowsLazyCompilationWithoutContext();
}


int FunctionLiteral::start_position() const {
  return scope()->start_position();
}


int FunctionLiteral::end_position() const {
  return scope()->end_position();
}


LanguageMode FunctionLiteral::language_mode() const {
  return scope()->language_mode();
}


ObjectLiteral::Property::Property(Literal* key,
                                  Expression* value,
                                  Isolate* isolate) {
  emit_store_ = true;
  key_ = key;
  value_ = value;
  Object* k = *key->handle();
  if (k->IsInternalizedString() &&
      isolate->heap()->proto_string()->Equals(String::cast(k))) {
    kind_ = PROTOTYPE;
  } else if (value_->AsMaterializedLiteral() != NULL) {
    kind_ = MATERIALIZED_LITERAL;
  } else if (value_->AsLiteral() != NULL) {
    kind_ = CONSTANT;
  } else {
    kind_ = COMPUTED;
  }
}


ObjectLiteral::Property::Property(bool is_getter, FunctionLiteral* value) {
  emit_store_ = true;
  value_ = value;
  kind_ = is_getter ? GETTER : SETTER;
}


bool ObjectLiteral::Property::IsCompileTimeValue() {
  return kind_ == CONSTANT ||
      (kind_ == MATERIALIZED_LITERAL &&
       CompileTimeValue::IsCompileTimeValue(value_));
}


void ObjectLiteral::Property::set_emit_store(bool emit_store) {
  emit_store_ = emit_store;
}


bool ObjectLiteral::Property::emit_store() {
  return emit_store_;
}


bool IsEqualString(void* first, void* second) {
  ASSERT((*reinterpret_cast<String**>(first))->IsString());
  ASSERT((*reinterpret_cast<String**>(second))->IsString());
  Handle<String> h1(reinterpret_cast<String**>(first));
  Handle<String> h2(reinterpret_cast<String**>(second));
  return (*h1)->Equals(*h2);
}


bool IsEqualNumber(void* first, void* second) {
  ASSERT((*reinterpret_cast<Object**>(first))->IsNumber());
  ASSERT((*reinterpret_cast<Object**>(second))->IsNumber());

  Handle<Object> h1(reinterpret_cast<Object**>(first));
  Handle<Object> h2(reinterpret_cast<Object**>(second));
  if (h1->IsSmi()) {
    return h2->IsSmi() && *h1 == *h2;
  }
  if (h2->IsSmi()) return false;
  Handle<HeapNumber> n1 = Handle<HeapNumber>::cast(h1);
  Handle<HeapNumber> n2 = Handle<HeapNumber>::cast(h2);
  ASSERT(isfinite(n1->value()));
  ASSERT(isfinite(n2->value()));
  return n1->value() == n2->value();
}


void ObjectLiteral::CalculateEmitStore(Zone* zone) {
  ZoneAllocationPolicy allocator(zone);

  ZoneHashMap table(Literal::Match, ZoneHashMap::kDefaultHashMapCapacity,
                    allocator);
  for (int i = properties()->length() - 1; i >= 0; i--) {
    ObjectLiteral::Property* property = properties()->at(i);
    Literal* literal = property->key();
    if (literal->handle()->IsNull()) continue;
    uint32_t hash = literal->Hash();
    // If the key of a computed property is in the table, do not emit
    // a store for the property later.
    if (property->kind() == ObjectLiteral::Property::COMPUTED &&
        table.Lookup(literal, hash, false, allocator) != NULL) {
      property->set_emit_store(false);
    } else {
      // Add key to the table.
      table.Lookup(literal, hash, true, allocator);
    }
  }
}


void TargetCollector::AddTarget(Label* target, Zone* zone) {
  // Add the label to the collector, but discard duplicates.
  int length = targets_.length();
  for (int i = 0; i < length; i++) {
    if (targets_[i] == target) return;
  }
  targets_.Add(target, zone);
}


bool UnaryOperation::ResultOverwriteAllowed() {
  switch (op_) {
    case Token::BIT_NOT:
    case Token::SUB:
      return true;
    default:
      return false;
  }
}


bool BinaryOperation::ResultOverwriteAllowed() {
  switch (op_) {
    case Token::COMMA:
    case Token::OR:
    case Token::AND:
      return false;
    case Token::BIT_OR:
    case Token::BIT_XOR:
    case Token::BIT_AND:
    case Token::SHL:
    case Token::SAR:
    case Token::SHR:
    case Token::ADD:
    case Token::SUB:
    case Token::MUL:
    case Token::DIV:
    case Token::MOD:
      return true;
    default:
      UNREACHABLE();
  }
  return false;
}


static bool IsTypeof(Expression* expr) {
  UnaryOperation* maybe_unary = expr->AsUnaryOperation();
  return maybe_unary != NULL && maybe_unary->op() == Token::TYPEOF;
}


// Check for the pattern: typeof <expression> equals <string literal>.
static bool MatchLiteralCompareTypeof(Expression* left,
                                      Token::Value op,
                                      Expression* right,
                                      Expression** expr,
                                      Handle<String>* check) {
  if (IsTypeof(left) && right->IsStringLiteral() && Token::IsEqualityOp(op)) {
    *expr = left->AsUnaryOperation()->expression();
    *check = Handle<String>::cast(right->AsLiteral()->handle());
    return true;
  }
  return false;
}


bool CompareOperation::IsLiteralCompareTypeof(Expression** expr,
                                              Handle<String>* check) {
  return MatchLiteralCompareTypeof(left_, op_, right_, expr, check) ||
      MatchLiteralCompareTypeof(right_, op_, left_, expr, check);
}


static bool IsVoidOfLiteral(Expression* expr) {
  UnaryOperation* maybe_unary = expr->AsUnaryOperation();
  return maybe_unary != NULL &&
      maybe_unary->op() == Token::VOID &&
      maybe_unary->expression()->AsLiteral() != NULL;
}


// Check for the pattern: void <literal> equals <expression>
static bool MatchLiteralCompareUndefined(Expression* left,
                                         Token::Value op,
                                         Expression* right,
                                         Expression** expr) {
  if (IsVoidOfLiteral(left) && Token::IsEqualityOp(op)) {
    *expr = right;
    return true;
  }
  return false;
}


bool CompareOperation::IsLiteralCompareUndefined(Expression** expr) {
  return MatchLiteralCompareUndefined(left_, op_, right_, expr) ||
      MatchLiteralCompareUndefined(right_, op_, left_, expr);
}


// Check for the pattern: null equals <expression>
static bool MatchLiteralCompareNull(Expression* left,
                                    Token::Value op,
                                    Expression* right,
                                    Expression** expr) {
  if (left->IsNullLiteral() && Token::IsEqualityOp(op)) {
    *expr = right;
    return true;
  }
  return false;
}


bool CompareOperation::IsLiteralCompareNull(Expression** expr) {
  return MatchLiteralCompareNull(left_, op_, right_, expr) ||
      MatchLiteralCompareNull(right_, op_, left_, expr);
}


// ----------------------------------------------------------------------------
// Inlining support

bool Declaration::IsInlineable() const {
  return proxy()->var()->IsStackAllocated();
}

bool FunctionDeclaration::IsInlineable() const {
  return false;
}


// ----------------------------------------------------------------------------
// Recording of type feedback

void Property::RecordTypeFeedback(TypeFeedbackOracle* oracle,
                                  Zone* zone) {
  // Record type feedback from the oracle in the AST.
  is_uninitialized_ = oracle->LoadIsUninitialized(this);
  if (is_uninitialized_) return;

  is_monomorphic_ = oracle->LoadIsMonomorphicNormal(this);
  receiver_types_.Clear();
  if (key()->IsPropertyName()) {
    ArrayLengthStub array_stub(Code::LOAD_IC);
    FunctionPrototypeStub proto_stub(Code::LOAD_IC);
    StringLengthStub string_stub(Code::LOAD_IC, false);
    if (oracle->LoadIsStub(this, &array_stub)) {
      is_array_length_ = true;
    } else if (oracle->LoadIsStub(this, &string_stub)) {
      is_string_length_ = true;
    } else if (oracle->LoadIsStub(this, &proto_stub)) {
      is_function_prototype_ = true;
    } else {
      Literal* lit_key = key()->AsLiteral();
      ASSERT(lit_key != NULL && lit_key->handle()->IsString());
      Handle<String> name = Handle<String>::cast(lit_key->handle());
      oracle->LoadReceiverTypes(this, name, &receiver_types_);
    }
  } else if (oracle->LoadIsBuiltin(this, Builtins::kKeyedLoadIC_String)) {
    is_string_access_ = true;
  } else if (is_monomorphic_) {
    receiver_types_.Add(oracle->LoadMonomorphicReceiverType(this),
                        zone);
  } else if (oracle->LoadIsPolymorphic(this)) {
    receiver_types_.Reserve(kMaxKeyedPolymorphism, zone);
    oracle->CollectKeyedReceiverTypes(PropertyFeedbackId(), &receiver_types_);
  }
}


void Assignment::RecordTypeFeedback(TypeFeedbackOracle* oracle,
                                    Zone* zone) {
  Property* prop = target()->AsProperty();
  ASSERT(prop != NULL);
  TypeFeedbackId id = AssignmentFeedbackId();
  is_monomorphic_ = oracle->StoreIsMonomorphicNormal(id);
  receiver_types_.Clear();
  if (prop->key()->IsPropertyName()) {
    Literal* lit_key = prop->key()->AsLiteral();
    ASSERT(lit_key != NULL && lit_key->handle()->IsString());
    Handle<String> name = Handle<String>::cast(lit_key->handle());
    oracle->StoreReceiverTypes(this, name, &receiver_types_);
  } else if (is_monomorphic_) {
    // Record receiver type for monomorphic keyed stores.
    receiver_types_.Add(oracle->StoreMonomorphicReceiverType(id), zone);
  } else if (oracle->StoreIsPolymorphic(id)) {
    receiver_types_.Reserve(kMaxKeyedPolymorphism, zone);
    oracle->CollectKeyedReceiverTypes(id, &receiver_types_);
  }
}


void CountOperation::RecordTypeFeedback(TypeFeedbackOracle* oracle,
                                        Zone* zone) {
  TypeFeedbackId id = CountStoreFeedbackId();
  is_monomorphic_ = oracle->StoreIsMonomorphicNormal(id);
  receiver_types_.Clear();
  if (is_monomorphic_) {
    // Record receiver type for monomorphic keyed stores.
    receiver_types_.Add(
        oracle->StoreMonomorphicReceiverType(id), zone);
  } else if (oracle->StoreIsPolymorphic(id)) {
    receiver_types_.Reserve(kMaxKeyedPolymorphism, zone);
    oracle->CollectKeyedReceiverTypes(id, &receiver_types_);
  }
}


void CaseClause::RecordTypeFeedback(TypeFeedbackOracle* oracle) {
  TypeInfo info = oracle->SwitchType(this);
  if (info.IsUninitialized()) info = TypeInfo::Unknown();
  if (info.IsSmi()) {
    compare_type_ = SMI_ONLY;
  } else if (info.IsInternalizedString()) {
    compare_type_ = NAME_ONLY;
  } else if (info.IsNonInternalizedString()) {
    compare_type_ = STRING_ONLY;
  } else if (info.IsNonPrimitive()) {
    compare_type_ = OBJECT_ONLY;
  } else {
    ASSERT(compare_type_ == NONE);
  }
}


bool Call::ComputeTarget(Handle<Map> type, Handle<String> name) {
  // If there is an interceptor, we can't compute the target for a direct call.
  if (type->has_named_interceptor()) return false;

  if (check_type_ == RECEIVER_MAP_CHECK) {
    // For primitive checks the holder is set up to point to the corresponding
    // prototype object, i.e. one step of the algorithm below has been already
    // performed. For non-primitive checks we clear it to allow computing
    // targets for polymorphic calls.
    holder_ = Handle<JSObject>::null();
  }
  LookupResult lookup(type->GetIsolate());
  while (true) {
    type->LookupDescriptor(NULL, *name, &lookup);
    if (lookup.IsFound()) {
      switch (lookup.type()) {
        case CONSTANT_FUNCTION:
          // We surely know the target for a constant function.
          target_ =
              Handle<JSFunction>(lookup.GetConstantFunctionFromMap(*type));
          return true;
        case NORMAL:
        case FIELD:
        case CALLBACKS:
        case HANDLER:
        case INTERCEPTOR:
          // We don't know the target.
          return false;
        case TRANSITION:
        case NONEXISTENT:
          UNREACHABLE();
          break;
      }
    }
    // If we reach the end of the prototype chain, we don't know the target.
    if (!type->prototype()->IsJSObject()) return false;
    // Go up the prototype chain, recording where we are currently.
    holder_ = Handle<JSObject>(JSObject::cast(type->prototype()));
    if (!holder_->HasFastProperties()) return false;
    type = Handle<Map>(holder()->map());
  }
}


bool Call::ComputeGlobalTarget(Handle<GlobalObject> global,
                               LookupResult* lookup) {
  target_ = Handle<JSFunction>::null();
  cell_ = Handle<JSGlobalPropertyCell>::null();
  ASSERT(lookup->IsFound() &&
         lookup->type() == NORMAL &&
         lookup->holder() == *global);
  cell_ = Handle<JSGlobalPropertyCell>(global->GetPropertyCell(lookup));
  if (cell_->value()->IsJSFunction()) {
    Handle<JSFunction> candidate(JSFunction::cast(cell_->value()));
    // If the function is in new space we assume it's more likely to
    // change and thus prefer the general IC code.
    if (!HEAP->InNewSpace(*candidate)) {
      target_ = candidate;
      return true;
    }
  }
  return false;
}


void Call::RecordTypeFeedback(TypeFeedbackOracle* oracle,
                              CallKind call_kind) {
  is_monomorphic_ = oracle->CallIsMonomorphic(this);
  Property* property = expression()->AsProperty();
  if (property == NULL) {
    // Function call.  Specialize for monomorphic calls.
    if (is_monomorphic_) target_ = oracle->GetCallTarget(this);
  } else {
    // Method call.  Specialize for the receiver types seen at runtime.
    Literal* key = property->key()->AsLiteral();
    ASSERT(key != NULL && key->handle()->IsString());
    Handle<String> name = Handle<String>::cast(key->handle());
    receiver_types_.Clear();
    oracle->CallReceiverTypes(this, name, call_kind, &receiver_types_);
#ifdef DEBUG
    if (FLAG_enable_slow_asserts) {
      int length = receiver_types_.length();
      for (int i = 0; i < length; i++) {
        Handle<Map> map = receiver_types_.at(i);
        ASSERT(!map.is_null() && *map != NULL);
      }
    }
#endif
    check_type_ = oracle->GetCallCheckType(this);
    if (is_monomorphic_) {
      Handle<Map> map;
      if (receiver_types_.length() > 0) {
        ASSERT(check_type_ == RECEIVER_MAP_CHECK);
        map = receiver_types_.at(0);
      } else {
        ASSERT(check_type_ != RECEIVER_MAP_CHECK);
        holder_ = Handle<JSObject>(
            oracle->GetPrototypeForPrimitiveCheck(check_type_));
        map = Handle<Map>(holder_->map());
      }
      is_monomorphic_ = ComputeTarget(map, name);
    }
  }
}


void CallNew::RecordTypeFeedback(TypeFeedbackOracle* oracle) {
  is_monomorphic_ = oracle->CallNewIsMonomorphic(this);
  if (is_monomorphic_) {
    target_ = oracle->GetCallNewTarget(this);
    elements_kind_ = oracle->GetCallNewElementsKind(this);
  }
}


void ObjectLiteral::Property::RecordTypeFeedback(TypeFeedbackOracle* oracle) {
  receiver_type_ = oracle->ObjectLiteralStoreIsMonomorphic(this)
      ? oracle->GetObjectLiteralStoreMap(this)
      : Handle<Map>::null();
}


// ----------------------------------------------------------------------------
// Implementation of AstVisitor

void AstVisitor::VisitDeclarations(ZoneList<Declaration*>* declarations) {
  for (int i = 0; i < declarations->length(); i++) {
    Visit(declarations->at(i));
  }
}


void AstVisitor::VisitStatements(ZoneList<Statement*>* statements) {
  for (int i = 0; i < statements->length(); i++) {
    Visit(statements->at(i));
  }
}


void AstVisitor::VisitExpressions(ZoneList<Expression*>* expressions) {
  for (int i = 0; i < expressions->length(); i++) {
    // The variable statement visiting code may pass NULL expressions
    // to this code. Maybe this should be handled by introducing an
    // undefined expression or literal?  Revisit this code if this
    // changes
    Expression* expression = expressions->at(i);
    if (expression != NULL) Visit(expression);
  }
}


// ----------------------------------------------------------------------------
// Regular expressions

#define MAKE_ACCEPT(Name)                                            \
  void* RegExp##Name::Accept(RegExpVisitor* visitor, void* data) {   \
    return visitor->Visit##Name(this, data);                         \
  }
FOR_EACH_REG_EXP_TREE_TYPE(MAKE_ACCEPT)
#undef MAKE_ACCEPT

#define MAKE_TYPE_CASE(Name)                                         \
  RegExp##Name* RegExpTree::As##Name() {                             \
    return NULL;                                                     \
  }                                                                  \
  bool RegExpTree::Is##Name() { return false; }
FOR_EACH_REG_EXP_TREE_TYPE(MAKE_TYPE_CASE)
#undef MAKE_TYPE_CASE

#define MAKE_TYPE_CASE(Name)                                        \
  RegExp##Name* RegExp##Name::As##Name() {                          \
    return this;                                                    \
  }                                                                 \
  bool RegExp##Name::Is##Name() { return true; }
FOR_EACH_REG_EXP_TREE_TYPE(MAKE_TYPE_CASE)
#undef MAKE_TYPE_CASE


static Interval ListCaptureRegisters(ZoneList<RegExpTree*>* children) {
  Interval result = Interval::Empty();
  for (int i = 0; i < children->length(); i++)
    result = result.Union(children->at(i)->CaptureRegisters());
  return result;
}


Interval RegExpAlternative::CaptureRegisters() {
  return ListCaptureRegisters(nodes());
}


Interval RegExpDisjunction::CaptureRegisters() {
  return ListCaptureRegisters(alternatives());
}


Interval RegExpLookahead::CaptureRegisters() {
  return body()->CaptureRegisters();
}


Interval RegExpCapture::CaptureRegisters() {
  Interval self(StartRegister(index()), EndRegister(index()));
  return self.Union(body()->CaptureRegisters());
}


Interval RegExpQuantifier::CaptureRegisters() {
  return body()->CaptureRegisters();
}


bool RegExpAssertion::IsAnchoredAtStart() {
  return type() == RegExpAssertion::START_OF_INPUT;
}


bool RegExpAssertion::IsAnchoredAtEnd() {
  return type() == RegExpAssertion::END_OF_INPUT;
}


bool RegExpAlternative::IsAnchoredAtStart() {
  ZoneList<RegExpTree*>* nodes = this->nodes();
  for (int i = 0; i < nodes->length(); i++) {
    RegExpTree* node = nodes->at(i);
    if (node->IsAnchoredAtStart()) { return true; }
    if (node->max_match() > 0) { return false; }
  }
  return false;
}


bool RegExpAlternative::IsAnchoredAtEnd() {
  ZoneList<RegExpTree*>* nodes = this->nodes();
  for (int i = nodes->length() - 1; i >= 0; i--) {
    RegExpTree* node = nodes->at(i);
    if (node->IsAnchoredAtEnd()) { return true; }
    if (node->max_match() > 0) { return false; }
  }
  return false;
}


bool RegExpDisjunction::IsAnchoredAtStart() {
  ZoneList<RegExpTree*>* alternatives = this->alternatives();
  for (int i = 0; i < alternatives->length(); i++) {
    if (!alternatives->at(i)->IsAnchoredAtStart())
      return false;
  }
  return true;
}


bool RegExpDisjunction::IsAnchoredAtEnd() {
  ZoneList<RegExpTree*>* alternatives = this->alternatives();
  for (int i = 0; i < alternatives->length(); i++) {
    if (!alternatives->at(i)->IsAnchoredAtEnd())
      return false;
  }
  return true;
}


bool RegExpLookahead::IsAnchoredAtStart() {
  return is_positive() && body()->IsAnchoredAtStart();
}


bool RegExpCapture::IsAnchoredAtStart() {
  return body()->IsAnchoredAtStart();
}


bool RegExpCapture::IsAnchoredAtEnd() {
  return body()->IsAnchoredAtEnd();
}


// Convert regular expression trees to a simple sexp representation.
// This representation should be different from the input grammar
// in as many cases as possible, to make it more difficult for incorrect
// parses to look as correct ones which is likely if the input and
// output formats are alike.
class RegExpUnparser: public RegExpVisitor {
 public:
  explicit RegExpUnparser(Zone* zone);
  void VisitCharacterRange(CharacterRange that);
  SmartArrayPointer<const char> ToString() { return stream_.ToCString(); }
#define MAKE_CASE(Name) virtual void* Visit##Name(RegExp##Name*, void* data);
  FOR_EACH_REG_EXP_TREE_TYPE(MAKE_CASE)
#undef MAKE_CASE
 private:
  StringStream* stream() { return &stream_; }
  HeapStringAllocator alloc_;
  StringStream stream_;
  Zone* zone_;
};


RegExpUnparser::RegExpUnparser(Zone* zone) : stream_(&alloc_), zone_(zone) {
}


void* RegExpUnparser::VisitDisjunction(RegExpDisjunction* that, void* data) {
  stream()->Add("(|");
  for (int i = 0; i <  that->alternatives()->length(); i++) {
    stream()->Add(" ");
    that->alternatives()->at(i)->Accept(this, data);
  }
  stream()->Add(")");
  return NULL;
}


void* RegExpUnparser::VisitAlternative(RegExpAlternative* that, void* data) {
  stream()->Add("(:");
  for (int i = 0; i <  that->nodes()->length(); i++) {
    stream()->Add(" ");
    that->nodes()->at(i)->Accept(this, data);
  }
  stream()->Add(")");
  return NULL;
}


void RegExpUnparser::VisitCharacterRange(CharacterRange that) {
  stream()->Add("%k", that.from());
  if (!that.IsSingleton()) {
    stream()->Add("-%k", that.to());
  }
}



void* RegExpUnparser::VisitCharacterClass(RegExpCharacterClass* that,
                                          void* data) {
  if (that->is_negated())
    stream()->Add("^");
  stream()->Add("[");
  for (int i = 0; i < that->ranges(zone_)->length(); i++) {
    if (i > 0) stream()->Add(" ");
    VisitCharacterRange(that->ranges(zone_)->at(i));
  }
  stream()->Add("]");
  return NULL;
}


void* RegExpUnparser::VisitAssertion(RegExpAssertion* that, void* data) {
  switch (that->type()) {
    case RegExpAssertion::START_OF_INPUT:
      stream()->Add("@^i");
      break;
    case RegExpAssertion::END_OF_INPUT:
      stream()->Add("@$i");
      break;
    case RegExpAssertion::START_OF_LINE:
      stream()->Add("@^l");
      break;
    case RegExpAssertion::END_OF_LINE:
      stream()->Add("@$l");
       break;
    case RegExpAssertion::BOUNDARY:
      stream()->Add("@b");
      break;
    case RegExpAssertion::NON_BOUNDARY:
      stream()->Add("@B");
      break;
  }
  return NULL;
}


void* RegExpUnparser::VisitAtom(RegExpAtom* that, void* data) {
  stream()->Add("'");
  Vector<const uc16> chardata = that->data();
  for (int i = 0; i < chardata.length(); i++) {
    stream()->Add("%k", chardata[i]);
  }
  stream()->Add("'");
  return NULL;
}


void* RegExpUnparser::VisitText(RegExpText* that, void* data) {
  if (that->elements()->length() == 1) {
    that->elements()->at(0).data.u_atom->Accept(this, data);
  } else {
    stream()->Add("(!");
    for (int i = 0; i < that->elements()->length(); i++) {
      stream()->Add(" ");
      that->elements()->at(i).data.u_atom->Accept(this, data);
    }
    stream()->Add(")");
  }
  return NULL;
}


void* RegExpUnparser::VisitQuantifier(RegExpQuantifier* that, void* data) {
  stream()->Add("(# %i ", that->min());
  if (that->max() == RegExpTree::kInfinity) {
    stream()->Add("- ");
  } else {
    stream()->Add("%i ", that->max());
  }
  stream()->Add(that->is_greedy() ? "g " : that->is_possessive() ? "p " : "n ");
  that->body()->Accept(this, data);
  stream()->Add(")");
  return NULL;
}


void* RegExpUnparser::VisitCapture(RegExpCapture* that, void* data) {
  stream()->Add("(^ ");
  that->body()->Accept(this, data);
  stream()->Add(")");
  return NULL;
}


void* RegExpUnparser::VisitLookahead(RegExpLookahead* that, void* data) {
  stream()->Add("(-> ");
  stream()->Add(that->is_positive() ? "+ " : "- ");
  that->body()->Accept(this, data);
  stream()->Add(")");
  return NULL;
}


void* RegExpUnparser::VisitBackReference(RegExpBackReference* that,
                                         void* data) {
  stream()->Add("(<- %i)", that->index());
  return NULL;
}


void* RegExpUnparser::VisitEmpty(RegExpEmpty* that, void* data) {
  stream()->Put('%');
  return NULL;
}


SmartArrayPointer<const char> RegExpTree::ToString(Zone* zone) {
  RegExpUnparser unparser(zone);
  Accept(&unparser, NULL);
  return unparser.ToString();
}


RegExpDisjunction::RegExpDisjunction(ZoneList<RegExpTree*>* alternatives)
    : alternatives_(alternatives) {
  ASSERT(alternatives->length() > 1);
  RegExpTree* first_alternative = alternatives->at(0);
  min_match_ = first_alternative->min_match();
  max_match_ = first_alternative->max_match();
  for (int i = 1; i < alternatives->length(); i++) {
    RegExpTree* alternative = alternatives->at(i);
    min_match_ = Min(min_match_, alternative->min_match());
    max_match_ = Max(max_match_, alternative->max_match());
  }
}


static int IncreaseBy(int previous, int increase) {
  if (RegExpTree::kInfinity - previous < increase) {
    return RegExpTree::kInfinity;
  } else {
    return previous + increase;
  }
}

RegExpAlternative::RegExpAlternative(ZoneList<RegExpTree*>* nodes)
    : nodes_(nodes) {
  ASSERT(nodes->length() > 1);
  min_match_ = 0;
  max_match_ = 0;
  for (int i = 0; i < nodes->length(); i++) {
    RegExpTree* node = nodes->at(i);
    int node_min_match = node->min_match();
    min_match_ = IncreaseBy(min_match_, node_min_match);
    int node_max_match = node->max_match();
    max_match_ = IncreaseBy(max_match_, node_max_match);
  }
}


CaseClause::CaseClause(Isolate* isolate,
                       Expression* label,
                       ZoneList<Statement*>* statements,
                       int pos)
    : label_(label),
      statements_(statements),
      position_(pos),
      compare_type_(NONE),
      compare_id_(AstNode::GetNextId(isolate)),
      entry_id_(AstNode::GetNextId(isolate)) {
}


#define REGULAR_NODE(NodeType) \
  void AstConstructionVisitor::Visit##NodeType(NodeType* node) { \
    increase_node_count(); \
  }
#define DONT_OPTIMIZE_NODE(NodeType) \
  void AstConstructionVisitor::Visit##NodeType(NodeType* node) { \
    increase_node_count(); \
    add_flag(kDontOptimize); \
    add_flag(kDontInline); \
    add_flag(kDontSelfOptimize); \
  }
#define DONT_INLINE_NODE(NodeType) \
  void AstConstructionVisitor::Visit##NodeType(NodeType* node) { \
    increase_node_count(); \
    add_flag(kDontInline); \
  }
#define DONT_SELFOPTIMIZE_NODE(NodeType) \
  void AstConstructionVisitor::Visit##NodeType(NodeType* node) { \
    increase_node_count(); \
    add_flag(kDontSelfOptimize); \
  }
#define DONT_CACHE_NODE(NodeType) \
  void AstConstructionVisitor::Visit##NodeType(NodeType* node) { \
    increase_node_count(); \
    add_flag(kDontOptimize); \
    add_flag(kDontInline); \
    add_flag(kDontSelfOptimize); \
    add_flag(kDontCache); \
  }

REGULAR_NODE(VariableDeclaration)
REGULAR_NODE(FunctionDeclaration)
REGULAR_NODE(Block)
REGULAR_NODE(ExpressionStatement)
REGULAR_NODE(EmptyStatement)
REGULAR_NODE(IfStatement)
REGULAR_NODE(ContinueStatement)
REGULAR_NODE(BreakStatement)
REGULAR_NODE(ReturnStatement)
REGULAR_NODE(SwitchStatement)
REGULAR_NODE(Conditional)
REGULAR_NODE(Literal)
REGULAR_NODE(ObjectLiteral)
REGULAR_NODE(RegExpLiteral)
REGULAR_NODE(Assignment)
REGULAR_NODE(Throw)
REGULAR_NODE(Property)
REGULAR_NODE(UnaryOperation)
REGULAR_NODE(CountOperation)
REGULAR_NODE(BinaryOperation)
REGULAR_NODE(CompareOperation)
REGULAR_NODE(ThisFunction)
REGULAR_NODE(Call)
REGULAR_NODE(CallNew)
// In theory, for VariableProxy we'd have to add:
// if (node->var()->IsLookupSlot()) add_flag(kDontInline);
// But node->var() is usually not bound yet at VariableProxy creation time, and
// LOOKUP variables only result from constructs that cannot be inlined anyway.
REGULAR_NODE(VariableProxy)

// We currently do not optimize any modules.
DONT_OPTIMIZE_NODE(ModuleDeclaration)
DONT_OPTIMIZE_NODE(ImportDeclaration)
DONT_OPTIMIZE_NODE(ExportDeclaration)
DONT_OPTIMIZE_NODE(ModuleVariable)
DONT_OPTIMIZE_NODE(ModulePath)
DONT_OPTIMIZE_NODE(ModuleUrl)
DONT_OPTIMIZE_NODE(ModuleStatement)
DONT_OPTIMIZE_NODE(WithStatement)
DONT_OPTIMIZE_NODE(TryCatchStatement)
DONT_OPTIMIZE_NODE(TryFinallyStatement)
DONT_OPTIMIZE_NODE(DebuggerStatement)
DONT_OPTIMIZE_NODE(SharedFunctionInfoLiteral)

DONT_INLINE_NODE(ArrayLiteral)  // TODO(1322): Allow materialized literals.
DONT_INLINE_NODE(FunctionLiteral)

DONT_SELFOPTIMIZE_NODE(DoWhileStatement)
DONT_SELFOPTIMIZE_NODE(WhileStatement)
DONT_SELFOPTIMIZE_NODE(ForStatement)
DONT_SELFOPTIMIZE_NODE(ForInStatement)

DONT_CACHE_NODE(ModuleLiteral)

void AstConstructionVisitor::VisitCallRuntime(CallRuntime* node) {
  increase_node_count();
  if (node->is_jsruntime()) {
    // Don't try to inline JS runtime calls because we don't (currently) even
    // optimize them.
    add_flag(kDontInline);
  } else if (node->function()->intrinsic_type == Runtime::INLINE &&
      (node->name()->IsOneByteEqualTo(
          STATIC_ASCII_VECTOR("_ArgumentsLength")) ||
       node->name()->IsOneByteEqualTo(STATIC_ASCII_VECTOR("_Arguments")))) {
    // Don't inline the %_ArgumentsLength or %_Arguments because their
    // implementation will not work.  There is no stack frame to get them
    // from.
    add_flag(kDontInline);
  }
}

#undef REGULAR_NODE
#undef DONT_OPTIMIZE_NODE
#undef DONT_INLINE_NODE
#undef DONT_SELFOPTIMIZE_NODE
#undef DONT_CACHE_NODE


Handle<String> Literal::ToString() {
  if (handle_->IsString()) return Handle<String>::cast(handle_);
  ASSERT(handle_->IsNumber());
  char arr[100];
  Vector<char> buffer(arr, ARRAY_SIZE(arr));
  const char* str;
  if (handle_->IsSmi()) {
    // Optimization only, the heap number case would subsume this.
    OS::SNPrintF(buffer, "%d", Smi::cast(*handle_)->value());
    str = arr;
  } else {
    str = DoubleToCString(handle_->Number(), buffer);
  }
  return FACTORY->NewStringFromAscii(CStrVector(str));
}


} }  // namespace v8::internal