path: root/deps/v8/src/stub-cache.h

// 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.

#ifndef V8_STUB_CACHE_H_
#define V8_STUB_CACHE_H_

#include "src/allocation.h"
#include "src/arguments.h"
#include "src/code-stubs.h"
#include "src/ic-inl.h"
#include "src/macro-assembler.h"
#include "src/objects.h"
#include "src/zone-inl.h"

namespace v8 {
namespace internal {


// The stub cache is used for megamorphic property accesses.
// It maps (map, name, type) to property access handlers. The cache does not
// need explicit invalidation when a prototype chain is modified, since the
// handlers verify the chain.


class CallOptimization;
class SmallMapList;
class StubCache;


class SCTableReference {
 public:
  Address address() const { return address_; }

 private:
  explicit SCTableReference(Address address) : address_(address) {}

  Address address_;

  friend class StubCache;
};


class StubCache {
 public:
  struct Entry {
    Name* key;
    Code* value;
    Map* map;
  };

  void Initialize();
  // Access cache for entry hash(name, map).
  Code* Set(Name* name, Map* map, Code* code);
  Code* Get(Name* name, Map* map, Code::Flags flags);
  // Clear the lookup table (@ mark compact collection).
  void Clear();
  // Collect all maps that match the name and flags.
  void CollectMatchingMaps(SmallMapList* types,
                           Handle<Name> name,
                           Code::Flags flags,
                           Handle<Context> native_context,
                           Zone* zone);
  // Generate code for probing the stub cache table.
  // Arguments extra, extra2 and extra3 may be used to pass additional scratch
  // registers. Set to no_reg if not needed.
  void GenerateProbe(MacroAssembler* masm,
                     Code::Flags flags,
                     Register receiver,
                     Register name,
                     Register scratch,
                     Register extra,
                     Register extra2 = no_reg,
                     Register extra3 = no_reg);

  enum Table {
    kPrimary,
    kSecondary
  };

  SCTableReference key_reference(StubCache::Table table) {
    return SCTableReference(
        reinterpret_cast<Address>(&first_entry(table)->key));
  }

  SCTableReference map_reference(StubCache::Table table) {
    return SCTableReference(
        reinterpret_cast<Address>(&first_entry(table)->map));
  }

  SCTableReference value_reference(StubCache::Table table) {
    return SCTableReference(
        reinterpret_cast<Address>(&first_entry(table)->value));
  }

  StubCache::Entry* first_entry(StubCache::Table table) {
    switch (table) {
      case StubCache::kPrimary: return StubCache::primary_;
      case StubCache::kSecondary: return StubCache::secondary_;
    }
    UNREACHABLE();
    return NULL;
  }

  Isolate* isolate() { return isolate_; }

  // Setting the entry size such that the index is shifted by Name::kHashShift
  // is convenient; shifting down the length field (to extract the hash code)
  // automatically discards the hash bit field.
  static const int kCacheIndexShift = Name::kHashShift;

 private:
  explicit StubCache(Isolate* isolate);

  // The stub cache has a primary and secondary level.  The two levels have
  // different hashing algorithms in order to avoid simultaneous collisions
  // in both caches.  Unlike a probing strategy (quadratic or otherwise) the
  // update strategy on updates is fairly clear and simple:  Any existing entry
  // in the primary cache is moved to the secondary cache, and secondary cache
  // entries are overwritten.

  // Hash algorithm for the primary table.  This algorithm is replicated in
  // assembler for every architecture.  Returns an index into the table that
  // is scaled by 1 << kCacheIndexShift.
  static int PrimaryOffset(Name* name, Code::Flags flags, Map* map) {
    STATIC_ASSERT(kCacheIndexShift == Name::kHashShift);
    // Compute the hash of the name (use entire hash field).
    DCHECK(name->HasHashCode());
    uint32_t field = name->hash_field();
    // Using only the low bits in 64-bit mode is unlikely to increase the
    // risk of collision even if the heap is spread over an area larger than
    // 4Gb (and not at all if it isn't).
    uint32_t map_low32bits =
        static_cast<uint32_t>(reinterpret_cast<uintptr_t>(map));
    // We always set the in_loop bit to zero when generating the lookup code
    // so do it here too so the hash codes match.
    uint32_t iflags =
        (static_cast<uint32_t>(flags) & ~Code::kFlagsNotUsedInLookup);
    // Base the offset on a simple combination of name, flags, and map.
    uint32_t key = (map_low32bits + field) ^ iflags;
    return key & ((kPrimaryTableSize - 1) << kCacheIndexShift);
  }

  // Hash algorithm for the secondary table.  This algorithm is replicated in
  // assembler for every architecture.  Returns an index into the table that
  // is scaled by 1 << kCacheIndexShift.
  static int SecondaryOffset(Name* name, Code::Flags flags, int seed) {
    // Use the seed from the primary cache in the secondary cache.
    uint32_t name_low32bits =
        static_cast<uint32_t>(reinterpret_cast<uintptr_t>(name));
    // We always set the in_loop bit to zero when generating the lookup code
    // so do it here too so the hash codes match.
    uint32_t iflags =
        (static_cast<uint32_t>(flags) & ~Code::kFlagsNotUsedInLookup);
    uint32_t key = (seed - name_low32bits) + iflags;
    return key & ((kSecondaryTableSize - 1) << kCacheIndexShift);
  }

  // Compute the entry for a given offset in exactly the same way as
  // we do in generated code.  We generate an hash code that already
  // ends in Name::kHashShift 0s.  Then we multiply it so it is a multiple
  // of sizeof(Entry).  This makes it easier to avoid making mistakes
  // in the hashed offset computations.
  static Entry* entry(Entry* table, int offset) {
    const int multiplier = sizeof(*table) >> Name::kHashShift;
    return reinterpret_cast<Entry*>(
        reinterpret_cast<Address>(table) + offset * multiplier);
  }

  static const int kPrimaryTableBits = 11;
  static const int kPrimaryTableSize = (1 << kPrimaryTableBits);
  static const int kSecondaryTableBits = 9;
  static const int kSecondaryTableSize = (1 << kSecondaryTableBits);

  Entry primary_[kPrimaryTableSize];
  Entry secondary_[kSecondaryTableSize];
  Isolate* isolate_;

  friend class Isolate;
  friend class SCTableReference;

  DISALLOW_COPY_AND_ASSIGN(StubCache);
};


// ------------------------------------------------------------------------


// Support functions for IC stubs for callbacks.
DECLARE_RUNTIME_FUNCTION(StoreCallbackProperty);


// Support functions for IC stubs for interceptors.
DECLARE_RUNTIME_FUNCTION(LoadPropertyWithInterceptorOnly);
DECLARE_RUNTIME_FUNCTION(LoadPropertyWithInterceptor);
DECLARE_RUNTIME_FUNCTION(LoadElementWithInterceptor);
DECLARE_RUNTIME_FUNCTION(StorePropertyWithInterceptor);


enum PrototypeCheckType { CHECK_ALL_MAPS, SKIP_RECEIVER };
enum IcCheckType { ELEMENT, PROPERTY };


class PropertyAccessCompiler BASE_EMBEDDED {
 public:
  static Builtins::Name MissBuiltin(Code::Kind kind) {
    switch (kind) {
      case Code::LOAD_IC:
        return Builtins::kLoadIC_Miss;
      case Code::STORE_IC:
        return Builtins::kStoreIC_Miss;
      case Code::KEYED_LOAD_IC:
        return Builtins::kKeyedLoadIC_Miss;
      case Code::KEYED_STORE_IC:
        return Builtins::kKeyedStoreIC_Miss;
      default:
        UNREACHABLE();
    }
    return Builtins::kLoadIC_Miss;
  }

  static void TailCallBuiltin(MacroAssembler* masm, Builtins::Name name);

 protected:
  PropertyAccessCompiler(Isolate* isolate, Code::Kind kind,
                         CacheHolderFlag cache_holder)
      : registers_(GetCallingConvention(kind)),
        kind_(kind),
        cache_holder_(cache_holder),
        isolate_(isolate),
        masm_(isolate, NULL, 256) {}

  Code::Kind kind() const { return kind_; }
  CacheHolderFlag cache_holder() const { return cache_holder_; }
  MacroAssembler* masm() { return &masm_; }
  Isolate* isolate() const { return isolate_; }
  Heap* heap() const { return isolate()->heap(); }
  Factory* factory() const { return isolate()->factory(); }

  Register receiver() const { return registers_[0]; }
  Register name() const { return registers_[1]; }
  Register scratch1() const { return registers_[2]; }
  Register scratch2() const { return registers_[3]; }
  Register scratch3() const { return registers_[4]; }

  // Calling convention between indexed store IC and handler.
  Register transition_map() const { return scratch1(); }

  static Register* GetCallingConvention(Code::Kind);
  static Register* load_calling_convention();
  static Register* store_calling_convention();
  static Register* keyed_store_calling_convention();

  Register* registers_;

  static void GenerateTailCall(MacroAssembler* masm, Handle<Code> code);

  Handle<Code> GetCodeWithFlags(Code::Flags flags, const char* name);
  Handle<Code> GetCodeWithFlags(Code::Flags flags, Handle<Name> name);

 private:
  Code::Kind kind_;
  CacheHolderFlag cache_holder_;

  Isolate* isolate_;
  MacroAssembler masm_;
};


class PropertyICCompiler : public PropertyAccessCompiler {
 public:
  // Finds the Code object stored in the Heap::non_monomorphic_cache().
  static Code* FindPreMonomorphic(Isolate* isolate, Code::Kind kind,
                                  ExtraICState extra_ic_state);

  // Named
  static Handle<Code> ComputeLoad(Isolate* isolate, InlineCacheState ic_state,
                                  ExtraICState extra_state);
  static Handle<Code> ComputeStore(Isolate* isolate, InlineCacheState ic_state,
                                   ExtraICState extra_state);

  static Handle<Code> ComputeMonomorphic(Code::Kind kind, Handle<Name> name,
                                         Handle<HeapType> type,
                                         Handle<Code> handler,
                                         ExtraICState extra_ic_state);
  static Handle<Code> ComputePolymorphic(Code::Kind kind, TypeHandleList* types,
                                         CodeHandleList* handlers,
                                         int number_of_valid_maps,
                                         Handle<Name> name,
                                         ExtraICState extra_ic_state);

  // Keyed
  static Handle<Code> ComputeKeyedLoadMonomorphic(Handle<Map> receiver_map);

  static Handle<Code> ComputeKeyedStoreMonomorphic(
      Handle<Map> receiver_map, StrictMode strict_mode,
      KeyedAccessStoreMode store_mode);
  static Handle<Code> ComputeKeyedLoadPolymorphic(MapHandleList* receiver_maps);
  static Handle<Code> ComputeKeyedStorePolymorphic(
      MapHandleList* receiver_maps, KeyedAccessStoreMode store_mode,
      StrictMode strict_mode);

  // Compare nil
  static Handle<Code> ComputeCompareNil(Handle<Map> receiver_map,
                                        CompareNilICStub* stub);


 private:
  PropertyICCompiler(Isolate* isolate, Code::Kind kind,
                     ExtraICState extra_ic_state = kNoExtraICState,
                     CacheHolderFlag cache_holder = kCacheOnReceiver)
      : PropertyAccessCompiler(isolate, kind, cache_holder),
        extra_ic_state_(extra_ic_state) {}

  static Handle<Code> Find(Handle<Name> name, Handle<Map> stub_holder_map,
                           Code::Kind kind,
                           ExtraICState extra_ic_state = kNoExtraICState,
                           CacheHolderFlag cache_holder = kCacheOnReceiver);

  Handle<Code> CompileLoadInitialize(Code::Flags flags);
  Handle<Code> CompileLoadPreMonomorphic(Code::Flags flags);
  Handle<Code> CompileLoadMegamorphic(Code::Flags flags);
  Handle<Code> CompileStoreInitialize(Code::Flags flags);
  Handle<Code> CompileStorePreMonomorphic(Code::Flags flags);
  Handle<Code> CompileStoreGeneric(Code::Flags flags);
  Handle<Code> CompileStoreMegamorphic(Code::Flags flags);

  Handle<Code> CompileMonomorphic(Handle<HeapType> type, Handle<Code> handler,
                                  Handle<Name> name, IcCheckType check);
  Handle<Code> CompilePolymorphic(TypeHandleList* types,
                                  CodeHandleList* handlers, Handle<Name> name,
                                  Code::StubType type, IcCheckType check);

  Handle<Code> CompileKeyedStoreMonomorphic(Handle<Map> receiver_map,
                                            KeyedAccessStoreMode store_mode);
  Handle<Code> CompileKeyedStorePolymorphic(MapHandleList* receiver_maps,
                                            KeyedAccessStoreMode store_mode);
  Handle<Code> CompileKeyedStorePolymorphic(MapHandleList* receiver_maps,
                                            CodeHandleList* handler_stubs,
                                            MapHandleList* transitioned_maps);

  bool IncludesNumberType(TypeHandleList* types);

  Handle<Code> GetCode(Code::Kind kind, Code::StubType type, Handle<Name> name,
                       InlineCacheState state = MONOMORPHIC);

  Logger::LogEventsAndTags log_kind(Handle<Code> code) {
    if (kind() == Code::LOAD_IC) {
      return code->ic_state() == MONOMORPHIC ? Logger::LOAD_IC_TAG
                                             : Logger::LOAD_POLYMORPHIC_IC_TAG;
    } else if (kind() == Code::KEYED_LOAD_IC) {
      return code->ic_state() == MONOMORPHIC
                 ? Logger::KEYED_LOAD_IC_TAG
                 : Logger::KEYED_LOAD_POLYMORPHIC_IC_TAG;
    } else if (kind() == Code::STORE_IC) {
      return code->ic_state() == MONOMORPHIC ? Logger::STORE_IC_TAG
                                             : Logger::STORE_POLYMORPHIC_IC_TAG;
    } else {
      DCHECK_EQ(Code::KEYED_STORE_IC, kind());
      return code->ic_state() == MONOMORPHIC
                 ? Logger::KEYED_STORE_IC_TAG
                 : Logger::KEYED_STORE_POLYMORPHIC_IC_TAG;
    }
  }

  const ExtraICState extra_ic_state_;
};


class PropertyHandlerCompiler : public PropertyAccessCompiler {
 public:
  static Handle<Code> Find(Handle<Name> name, Handle<Map> map, Code::Kind kind,
                           CacheHolderFlag cache_holder, Code::StubType type);

 protected:
  PropertyHandlerCompiler(Isolate* isolate, Code::Kind kind,
                          Handle<HeapType> type, Handle<JSObject> holder,
                          CacheHolderFlag cache_holder)
      : PropertyAccessCompiler(isolate, kind, cache_holder),
        type_(type),
        holder_(holder) {}

  virtual ~PropertyHandlerCompiler() {}

  virtual Register FrontendHeader(Register object_reg, Handle<Name> name,
                                  Label* miss) {
    UNREACHABLE();
    return receiver();
  }

  virtual void FrontendFooter(Handle<Name> name, Label* miss) { UNREACHABLE(); }

  Register Frontend(Register object_reg, Handle<Name> name);
  void NonexistentFrontendHeader(Handle<Name> name, Label* miss,
                                 Register scratch1, Register scratch2);

  // TODO(verwaest): Make non-static.
  static void GenerateFastApiCall(MacroAssembler* masm,
                                  const CallOptimization& optimization,
                                  Handle<Map> receiver_map, Register receiver,
                                  Register scratch, bool is_store, int argc,
                                  Register* values);

  // Helper function used to check that the dictionary doesn't contain
  // the property. This function may return false negatives, so miss_label
  // must always call a backup property check that is complete.
  // This function is safe to call if the receiver has fast properties.
  // Name must be unique and receiver must be a heap object.
  static void GenerateDictionaryNegativeLookup(MacroAssembler* masm,
                                               Label* miss_label,
                                               Register receiver,
                                               Handle<Name> name,
                                               Register r0,
                                               Register r1);

  // Generate code to check that a global property cell is empty. Create
  // the property cell at compilation time if no cell exists for the
  // property.
  static void GenerateCheckPropertyCell(MacroAssembler* masm,
                                        Handle<JSGlobalObject> global,
                                        Handle<Name> name,
                                        Register scratch,
                                        Label* miss);

  // Generates code that verifies that the property holder has not changed
  // (checking maps of objects in the prototype chain for fast and global
  // objects or doing negative lookup for slow objects, ensures that the
  // property cells for global objects are still empty) and checks that the map
  // of the holder has not changed. If necessary the function also generates
  // code for security check in case of global object holders. Helps to make
  // sure that the current IC is still valid.
  //
  // The scratch and holder registers are always clobbered, but the object
  // register is only clobbered if it the same as the holder register. The
  // function returns a register containing the holder - either object_reg or
  // holder_reg.
  Register CheckPrototypes(Register object_reg, Register holder_reg,
                           Register scratch1, Register scratch2,
                           Handle<Name> name, Label* miss,
                           PrototypeCheckType check = CHECK_ALL_MAPS);

  Handle<Code> GetCode(Code::Kind kind, Code::StubType type, Handle<Name> name);
  void set_type_for_object(Handle<Object> object) {
    type_ = IC::CurrentTypeOf(object, isolate());
  }
  void set_holder(Handle<JSObject> holder) { holder_ = holder; }
  Handle<HeapType> type() const { return type_; }
  Handle<JSObject> holder() const { return holder_; }

 private:
  Handle<HeapType> type_;
  Handle<JSObject> holder_;
};


class NamedLoadHandlerCompiler : public PropertyHandlerCompiler {
 public:
  NamedLoadHandlerCompiler(Isolate* isolate, Handle<HeapType> type,
                           Handle<JSObject> holder,
                           CacheHolderFlag cache_holder)
      : PropertyHandlerCompiler(isolate, Code::LOAD_IC, type, holder,
                                cache_holder) {}

  virtual ~NamedLoadHandlerCompiler() {}

  Handle<Code> CompileLoadField(Handle<Name> name, FieldIndex index);

  Handle<Code> CompileLoadCallback(Handle<Name> name,
                                   Handle<ExecutableAccessorInfo> callback);

  Handle<Code> CompileLoadCallback(Handle<Name> name,
                                   const CallOptimization& call_optimization);

  Handle<Code> CompileLoadConstant(Handle<Name> name, int constant_index);

  Handle<Code> CompileLoadInterceptor(Handle<Name> name);

  Handle<Code> CompileLoadViaGetter(Handle<Name> name,
                                    Handle<JSFunction> getter);

  Handle<Code> CompileLoadGlobal(Handle<PropertyCell> cell, Handle<Name> name,
                                 bool is_configurable);

  // Static interface
  static Handle<Code> ComputeLoadNonexistent(Handle<Name> name,
                                             Handle<HeapType> type);

  static void GenerateLoadViaGetter(MacroAssembler* masm, Handle<HeapType> type,
                                    Register receiver,
                                    Handle<JSFunction> getter);

  static void GenerateLoadViaGetterForDeopt(MacroAssembler* masm) {
    GenerateLoadViaGetter(masm, Handle<HeapType>::null(), no_reg,
                          Handle<JSFunction>());
  }

  static void GenerateLoadFunctionPrototype(MacroAssembler* masm,
                                            Register receiver,
                                            Register scratch1,
                                            Register scratch2,
                                            Label* miss_label);

  // These constants describe the structure of the interceptor arguments on the
  // stack. The arguments are pushed by the (platform-specific)
  // PushInterceptorArguments and read by LoadPropertyWithInterceptorOnly and
  // LoadWithInterceptor.
  static const int kInterceptorArgsNameIndex = 0;
  static const int kInterceptorArgsInfoIndex = 1;
  static const int kInterceptorArgsThisIndex = 2;
  static const int kInterceptorArgsHolderIndex = 3;
  static const int kInterceptorArgsLength = 4;

 protected:
  virtual Register FrontendHeader(Register object_reg, Handle<Name> name,
                                  Label* miss);

  virtual void FrontendFooter(Handle<Name> name, Label* miss);

 private:
  Handle<Code> CompileLoadNonexistent(Handle<Name> name);
  void GenerateLoadConstant(Handle<Object> value);
  void GenerateLoadCallback(Register reg,
                            Handle<ExecutableAccessorInfo> callback);
  void GenerateLoadCallback(const CallOptimization& call_optimization,
                            Handle<Map> receiver_map);
  void GenerateLoadInterceptor(Register holder_reg,
                               LookupResult* lookup,
                               Handle<Name> name);
  void GenerateLoadPostInterceptor(Register reg,
                                   Handle<Name> name,
                                   LookupResult* lookup);

  // Generates prototype loading code that uses the objects from the
  // context we were in when this function was called. If the context
  // has changed, a jump to miss is performed. This ties the generated
  // code to a particular context and so must not be used in cases
  // where the generated code is not allowed to have references to
  // objects from a context.
  static void GenerateDirectLoadGlobalFunctionPrototype(MacroAssembler* masm,
                                                        int index,
                                                        Register prototype,
                                                        Label* miss);


  Register scratch4() { return registers_[5]; }
};


class NamedStoreHandlerCompiler : public PropertyHandlerCompiler {
 public:
  explicit NamedStoreHandlerCompiler(Isolate* isolate, Handle<HeapType> type,
                                     Handle<JSObject> holder)
      : PropertyHandlerCompiler(isolate, Code::STORE_IC, type, holder,
                                kCacheOnReceiver) {}

  virtual ~NamedStoreHandlerCompiler() {}

  Handle<Code> CompileStoreTransition(Handle<Map> transition,
                                      Handle<Name> name);
  Handle<Code> CompileStoreField(LookupResult* lookup, Handle<Name> name);
  Handle<Code> CompileStoreCallback(Handle<JSObject> object, Handle<Name> name,
                                    Handle<ExecutableAccessorInfo> callback);
  Handle<Code> CompileStoreCallback(Handle<JSObject> object, Handle<Name> name,
                                    const CallOptimization& call_optimization);
  Handle<Code> CompileStoreViaSetter(Handle<JSObject> object, Handle<Name> name,
                                     Handle<JSFunction> setter);
  Handle<Code> CompileStoreInterceptor(Handle<Name> name);

  static void GenerateStoreViaSetter(MacroAssembler* masm,
                                     Handle<HeapType> type, Register receiver,
                                     Handle<JSFunction> setter);

  static void GenerateStoreViaSetterForDeopt(MacroAssembler* masm) {
    GenerateStoreViaSetter(masm, Handle<HeapType>::null(), no_reg,
                           Handle<JSFunction>());
  }

 protected:
  virtual Register FrontendHeader(Register object_reg, Handle<Name> name,
                                  Label* miss);

  virtual void FrontendFooter(Handle<Name> name, Label* miss);
  void GenerateRestoreName(Label* label, Handle<Name> name);

 private:
  void GenerateStoreTransition(Handle<Map> transition, Handle<Name> name,
                               Register receiver_reg, Register name_reg,
                               Register value_reg, Register scratch1,
                               Register scratch2, Register scratch3,
                               Label* miss_label, Label* slow);

  void GenerateStoreField(LookupResult* lookup, Register value_reg,
                          Label* miss_label);

  static Builtins::Name SlowBuiltin(Code::Kind kind) {
    switch (kind) {
      case Code::STORE_IC: return Builtins::kStoreIC_Slow;
      case Code::KEYED_STORE_IC: return Builtins::kKeyedStoreIC_Slow;
      default: UNREACHABLE();
    }
    return Builtins::kStoreIC_Slow;
  }

  static Register value();
};


class ElementHandlerCompiler : public PropertyHandlerCompiler {
 public:
  explicit ElementHandlerCompiler(Isolate* isolate)
      : PropertyHandlerCompiler(isolate, Code::KEYED_LOAD_IC,
                                Handle<HeapType>::null(),
                                Handle<JSObject>::null(), kCacheOnReceiver) {}

  virtual ~ElementHandlerCompiler() {}

  void CompileElementHandlers(MapHandleList* receiver_maps,
                              CodeHandleList* handlers);

  static void GenerateLoadDictionaryElement(MacroAssembler* masm);
  static void GenerateStoreDictionaryElement(MacroAssembler* masm);
};


// Holds information about possible function call optimizations.
class CallOptimization BASE_EMBEDDED {
 public:
  explicit CallOptimization(LookupResult* lookup);

  explicit CallOptimization(Handle<JSFunction> function);

  bool is_constant_call() const {
    return !constant_function_.is_null();
  }

  Handle<JSFunction> constant_function() const {
    DCHECK(is_constant_call());
    return constant_function_;
  }

  bool is_simple_api_call() const {
    return is_simple_api_call_;
  }

  Handle<FunctionTemplateInfo> expected_receiver_type() const {
    DCHECK(is_simple_api_call());
    return expected_receiver_type_;
  }

  Handle<CallHandlerInfo> api_call_info() const {
    DCHECK(is_simple_api_call());
    return api_call_info_;
  }

  enum HolderLookup {
    kHolderNotFound,
    kHolderIsReceiver,
    kHolderFound
  };
  Handle<JSObject> LookupHolderOfExpectedType(
      Handle<Map> receiver_map,
      HolderLookup* holder_lookup) const;

  // Check if the api holder is between the receiver and the holder.
  bool IsCompatibleReceiver(Handle<Object> receiver,
                            Handle<JSObject> holder) const;

 private:
  void Initialize(Handle<JSFunction> function);

  // Determines whether the given function can be called using the
  // fast api call builtin.
  void AnalyzePossibleApiFunction(Handle<JSFunction> function);

  Handle<JSFunction> constant_function_;
  bool is_simple_api_call_;
  Handle<FunctionTemplateInfo> expected_receiver_type_;
  Handle<CallHandlerInfo> api_call_info_;
};


} }  // namespace v8::internal

#endif  // V8_STUB_CACHE_H_