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/ic/ic.h"
  
  #include "src/accessors.h"
  #include "src/api.h"
  #include "src/api-arguments.h"
  #include "src/arguments.h"
  #include "src/base/bits.h"
  #include "src/codegen.h"
  #include "src/conversions.h"
  #include "src/execution.h"
  #include "src/field-type.h"
  #include "src/frames-inl.h"
  #include "src/ic/call-optimization.h"
  #include "src/ic/handler-compiler.h"
  #include "src/ic/ic-inl.h"
  #include "src/ic/ic-compiler.h"
  #include "src/ic/stub-cache.h"
  #include "src/isolate-inl.h"
  #include "src/macro-assembler.h"
  #include "src/prototype.h"
  #include "src/runtime/runtime.h"
  #include "src/runtime/runtime-utils.h"
  #include "src/tracing/trace-event.h"
  
  namespace v8 {
  namespace internal {
  
  char IC::TransitionMarkFromState(IC::State state) {
    switch (state) {
      case UNINITIALIZED:
        return '0';
      case PREMONOMORPHIC:
        return '.';
      case MONOMORPHIC:
        return '1';
      case RECOMPUTE_HANDLER:
        return '^';
      case POLYMORPHIC:
        return 'P';
      case MEGAMORPHIC:
        return 'N';
      case GENERIC:
        return 'G';
  
      // We never see the debugger states here, because the state is
      // computed from the original code - not the patched code. Let
      // these cases fall through to the unreachable code below.
      case DEBUG_STUB:
        break;
    }
    UNREACHABLE();
    return 0;
  }
  
  
  const char* GetTransitionMarkModifier(KeyedAccessStoreMode mode) {
    if (mode == STORE_NO_TRANSITION_HANDLE_COW) return ".COW";
    if (mode == STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS) {
      return ".IGNORE_OOB";
    }
    if (IsGrowStoreMode(mode)) return ".GROW";
    return "";
  }
  
  
  #ifdef DEBUG
  
  #define TRACE_GENERIC_IC(isolate, type, reason)                \
    do {                                                         \
      if (FLAG_trace_ic) {                                       \
        PrintF("[%s patching generic stub in ", type);           \
        JavaScriptFrame::PrintTop(isolate, stdout, false, true); \
        PrintF(" (%s)]\n", reason);                              \
      }                                                          \
    } while (false)
  
  #else
  
  #define TRACE_GENERIC_IC(isolate, type, reason)      \
    do {                                               \
      if (FLAG_trace_ic) {                             \
        PrintF("[%s patching generic stub in ", type); \
        PrintF("(see below) (%s)]\n", reason);         \
      }                                                \
    } while (false)
  
  #endif  // DEBUG
  
  
  void IC::TraceIC(const char* type, Handle<Object> name) {
    if (FLAG_trace_ic) {
      if (AddressIsDeoptimizedCode()) return;
      DCHECK(UseVector());
      State new_state = nexus()->StateFromFeedback();
      TraceIC(type, name, state(), new_state);
    }
  }
  
  
  void IC::TraceIC(const char* type, Handle<Object> name, State old_state,
                   State new_state) {
    if (FLAG_trace_ic) {
      PrintF("[%s%s in ", is_keyed() ? "Keyed" : "", type);
  
      // TODO(jkummerow): Add support for "apply". The logic is roughly:
      // marker = [fp_ + kMarkerOffset];
      // if marker is smi and marker.value == INTERNAL and
      //     the frame's code == builtin(Builtins::kFunctionApply):
      // then print "apply from" and advance one frame
  
      Object* maybe_function =
          Memory::Object_at(fp_ + JavaScriptFrameConstants::kFunctionOffset);
      if (maybe_function->IsJSFunction()) {
        JSFunction* function = JSFunction::cast(maybe_function);
        JavaScriptFrame::PrintFunctionAndOffset(function, function->code(), pc(),
                                                stdout, true);
      }
  
      const char* modifier = "";
      if (kind() == Code::KEYED_STORE_IC) {
        KeyedAccessStoreMode mode =
            casted_nexus<KeyedStoreICNexus>()->GetKeyedAccessStoreMode();
        modifier = GetTransitionMarkModifier(mode);
      }
      PrintF(" (%c->%c%s) ", TransitionMarkFromState(old_state),
             TransitionMarkFromState(new_state), modifier);
  #ifdef OBJECT_PRINT
      OFStream os(stdout);
      name->Print(os);
  #else
      name->ShortPrint(stdout);
  #endif
      PrintF("]\n");
    }
  }
  
  
  #define TRACE_IC(type, name) TraceIC(type, name)
  
  
  IC::IC(FrameDepth depth, Isolate* isolate, FeedbackNexus* nexus)
      : isolate_(isolate),
        vector_set_(false),
        target_maps_set_(false),
        nexus_(nexus) {
    // To improve the performance of the (much used) IC code, we unfold a few
    // levels of the stack frame iteration code. This yields a ~35% speedup when
    // running DeltaBlue and a ~25% speedup of gbemu with the '--nouse-ic' flag.
    const Address entry = Isolate::c_entry_fp(isolate->thread_local_top());
    Address* constant_pool = NULL;
    if (FLAG_enable_embedded_constant_pool) {
      constant_pool = reinterpret_cast<Address*>(
          entry + ExitFrameConstants::kConstantPoolOffset);
    }
    Address* pc_address =
        reinterpret_cast<Address*>(entry + ExitFrameConstants::kCallerPCOffset);
    Address fp = Memory::Address_at(entry + ExitFrameConstants::kCallerFPOffset);
    // If there's another JavaScript frame on the stack or a
    // StubFailureTrampoline, we need to look one frame further down the stack to
    // find the frame pointer and the return address stack slot.
    if (depth == EXTRA_CALL_FRAME) {
      if (FLAG_enable_embedded_constant_pool) {
        constant_pool = reinterpret_cast<Address*>(
            fp + StandardFrameConstants::kConstantPoolOffset);
      }
      const int kCallerPCOffset = StandardFrameConstants::kCallerPCOffset;
      pc_address = reinterpret_cast<Address*>(fp + kCallerPCOffset);
      fp = Memory::Address_at(fp + StandardFrameConstants::kCallerFPOffset);
    }
  #ifdef DEBUG
    StackFrameIterator it(isolate);
    for (int i = 0; i < depth + 1; i++) it.Advance();
    StackFrame* frame = it.frame();
    DCHECK(fp == frame->fp() && pc_address == frame->pc_address());
  #endif
    fp_ = fp;
    if (FLAG_enable_embedded_constant_pool) {
      constant_pool_address_ = constant_pool;
    }
    pc_address_ = StackFrame::ResolveReturnAddressLocation(pc_address);
    Code* target = this->target();
    kind_ = target->kind();
    state_ = UseVector() ? nexus->StateFromFeedback() : target->ic_state();
    old_state_ = state_;
    extra_ic_state_ = target->extra_ic_state();
  }
  
  
  SharedFunctionInfo* IC::GetSharedFunctionInfo() const {
    // Compute the JavaScript frame for the frame pointer of this IC
    // structure. We need this to be able to find the function
    // corresponding to the frame.
    StackFrameIterator it(isolate());
    while (it.frame()->fp() != this->fp()) it.Advance();
    if (FLAG_ignition && it.frame()->type() == StackFrame::STUB) {
      // Advance over bytecode handler frame.
      // TODO(rmcilroy): Remove this once bytecode handlers don't need a frame.
      it.Advance();
    }
    JavaScriptFrame* frame = JavaScriptFrame::cast(it.frame());
    // Find the function on the stack and both the active code for the
    // function and the original code.
    JSFunction* function = frame->function();
    return function->shared();
  }
  
  
  Code* IC::GetCode() const {
    HandleScope scope(isolate());
    Handle<SharedFunctionInfo> shared(GetSharedFunctionInfo(), isolate());
    Code* code = shared->code();
    return code;
  }
  
  
  bool IC::AddressIsOptimizedCode() const {
    Code* host =
        isolate()->inner_pointer_to_code_cache()->GetCacheEntry(address())->code;
    return host->kind() == Code::OPTIMIZED_FUNCTION;
  }
  
  
  static void LookupForRead(LookupIterator* it) {
    for (; it->IsFound(); it->Next()) {
      switch (it->state()) {
        case LookupIterator::NOT_FOUND:
        case LookupIterator::TRANSITION:
          UNREACHABLE();
        case LookupIterator::JSPROXY:
          return;
        case LookupIterator::INTERCEPTOR: {
          // If there is a getter, return; otherwise loop to perform the lookup.
          Handle<JSObject> holder = it->GetHolder<JSObject>();
          if (!holder->GetNamedInterceptor()->getter()->IsUndefined()) {
            return;
          }
          break;
        }
        case LookupIterator::ACCESS_CHECK:
          // PropertyHandlerCompiler::CheckPrototypes() knows how to emit
          // access checks for global proxies.
          if (it->GetHolder<JSObject>()->IsJSGlobalProxy() && it->HasAccess()) {
            break;
          }
          return;
        case LookupIterator::ACCESSOR:
        case LookupIterator::INTEGER_INDEXED_EXOTIC:
        case LookupIterator::DATA:
          return;
      }
    }
  }
  
  bool IC::ShouldRecomputeHandler(Handle<Object> receiver, Handle<String> name) {
    if (!RecomputeHandlerForName(name)) return false;
    DCHECK(UseVector());
    maybe_handler_ = nexus()->FindHandlerForMap(receiver_map());
  
    // The current map wasn't handled yet. There's no reason to stay monomorphic,
    // *unless* we're moving from a deprecated map to its replacement, or
    // to a more general elements kind.
    // TODO(verwaest): Check if the current map is actually what the old map
    // would transition to.
    if (maybe_handler_.is_null()) {
      if (!receiver_map()->IsJSObjectMap()) return false;
      Map* first_map = FirstTargetMap();
      if (first_map == NULL) return false;
      Handle<Map> old_map(first_map);
      if (old_map->is_deprecated()) return true;
      return IsMoreGeneralElementsKindTransition(old_map->elements_kind(),
                                                 receiver_map()->elements_kind());
    }
  
    if (receiver->IsJSGlobalObject()) {
      Handle<JSGlobalObject> global = Handle<JSGlobalObject>::cast(receiver);
      LookupIterator it(global, name, LookupIterator::OWN_SKIP_INTERCEPTOR);
      if (it.state() == LookupIterator::ACCESS_CHECK) return false;
      if (!it.IsFound()) return false;
      if (!it.GetHolder<JSReceiver>()->IsJSGlobalObject()) return false;
      return it.property_details().cell_type() == PropertyCellType::kConstant;
    }
  
    return true;
  }
  
  bool IC::RecomputeHandlerForName(Handle<Object> name) {
    if (is_keyed()) {
      // Determine whether the failure is due to a name failure.
      if (!name->IsName()) return false;
      DCHECK(UseVector());
      Name* stub_name = nexus()->FindFirstName();
      if (*name != stub_name) return false;
    }
  
    return true;
  }
  
  
  void IC::UpdateState(Handle<Object> receiver, Handle<Object> name) {
    update_receiver_map(receiver);
    if (!name->IsString()) return;
    if (state() != MONOMORPHIC && state() != POLYMORPHIC) return;
    if (receiver->IsUndefined() || receiver->IsNull()) return;
  
    // Remove the target from the code cache if it became invalid
    // because of changes in the prototype chain to avoid hitting it
    // again.
    if (ShouldRecomputeHandler(receiver, Handle<String>::cast(name))) {
      MarkRecomputeHandler(name);
    }
  }
  
  
  MaybeHandle<Object> IC::TypeError(MessageTemplate::Template index,
                                    Handle<Object> object, Handle<Object> key) {
    HandleScope scope(isolate());
    THROW_NEW_ERROR(isolate(), NewTypeError(index, key, object), Object);
  }
  
  
  MaybeHandle<Object> IC::ReferenceError(Handle<Name> name) {
    HandleScope scope(isolate());
    THROW_NEW_ERROR(
        isolate(), NewReferenceError(MessageTemplate::kNotDefined, name), Object);
  }
  
  
  static void ComputeTypeInfoCountDelta(IC::State old_state, IC::State new_state,
                                        int* polymorphic_delta,
                                        int* generic_delta) {
    switch (old_state) {
      case UNINITIALIZED:
      case PREMONOMORPHIC:
        if (new_state == UNINITIALIZED || new_state == PREMONOMORPHIC) break;
        if (new_state == MONOMORPHIC || new_state == POLYMORPHIC) {
          *polymorphic_delta = 1;
        } else if (new_state == MEGAMORPHIC || new_state == GENERIC) {
          *generic_delta = 1;
        }
        break;
      case MONOMORPHIC:
      case POLYMORPHIC:
        if (new_state == MONOMORPHIC || new_state == POLYMORPHIC) break;
        *polymorphic_delta = -1;
        if (new_state == MEGAMORPHIC || new_state == GENERIC) {
          *generic_delta = 1;
        }
        break;
      case MEGAMORPHIC:
      case GENERIC:
        if (new_state == MEGAMORPHIC || new_state == GENERIC) break;
        *generic_delta = -1;
        if (new_state == MONOMORPHIC || new_state == POLYMORPHIC) {
          *polymorphic_delta = 1;
        }
        break;
      case RECOMPUTE_HANDLER:
      case DEBUG_STUB:
        UNREACHABLE();
    }
  }
  
  // static
  void IC::OnTypeFeedbackChanged(Isolate* isolate, Code* host) {
    if (host->kind() != Code::FUNCTION) return;
  
    TypeFeedbackInfo* info = TypeFeedbackInfo::cast(host->type_feedback_info());
    info->change_own_type_change_checksum();
    host->set_profiler_ticks(0);
    isolate->runtime_profiler()->NotifyICChanged();
    // TODO(2029): When an optimized function is patched, it would
    // be nice to propagate the corresponding type information to its
    // unoptimized version for the benefit of later inlining.
  }
  
  void IC::PostPatching(Address address, Code* target, Code* old_target) {
    // Type vector based ICs update these statistics at a different time because
    // they don't always patch on state change.
    if (ICUseVector(target->kind())) return;
  
    DCHECK(old_target->is_inline_cache_stub());
    DCHECK(target->is_inline_cache_stub());
    State old_state = old_target->ic_state();
    State new_state = target->ic_state();
  
    Isolate* isolate = target->GetIsolate();
    Code* host =
        isolate->inner_pointer_to_code_cache()->GetCacheEntry(address)->code;
    if (host->kind() != Code::FUNCTION) return;
  
    // Not all Code objects have TypeFeedbackInfo.
    if (host->type_feedback_info()->IsTypeFeedbackInfo()) {
      if (FLAG_type_info_threshold > 0) {
        int polymorphic_delta = 0;  // "Polymorphic" here includes monomorphic.
        int generic_delta = 0;      // "Generic" here includes megamorphic.
        ComputeTypeInfoCountDelta(old_state, new_state, &polymorphic_delta,
                                  &generic_delta);
        TypeFeedbackInfo* info =
            TypeFeedbackInfo::cast(host->type_feedback_info());
        info->change_ic_with_type_info_count(polymorphic_delta);
        info->change_ic_generic_count(generic_delta);
      }
      TypeFeedbackInfo* info = TypeFeedbackInfo::cast(host->type_feedback_info());
      info->change_own_type_change_checksum();
    }
    host->set_profiler_ticks(0);
    isolate->runtime_profiler()->NotifyICChanged();
    // TODO(2029): When an optimized function is patched, it would
    // be nice to propagate the corresponding type information to its
    // unoptimized version for the benefit of later inlining.
  }
  
  void IC::Clear(Isolate* isolate, Address address, Address constant_pool) {
    Code* target = GetTargetAtAddress(address, constant_pool);
  
    // Don't clear debug break inline cache as it will remove the break point.
    if (target->is_debug_stub()) return;
  
    if (target->kind() == Code::COMPARE_IC) {
      CompareIC::Clear(isolate, address, target, constant_pool);
    }
  }
  
  
  void KeyedLoadIC::Clear(Isolate* isolate, Code* host, KeyedLoadICNexus* nexus) {
    if (IsCleared(nexus)) return;
    // Make sure to also clear the map used in inline fast cases.  If we
    // do not clear these maps, cached code can keep objects alive
    // through the embedded maps.
    nexus->ConfigurePremonomorphic();
    OnTypeFeedbackChanged(isolate, host);
  }
  
  
  void CallIC::Clear(Isolate* isolate, Code* host, CallICNexus* nexus) {
    // Determine our state.
    Object* feedback = nexus->vector()->Get(nexus->slot());
    State state = nexus->StateFromFeedback();
  
    if (state != UNINITIALIZED && !feedback->IsAllocationSite()) {
      nexus->ConfigureUninitialized();
      // The change in state must be processed.
      OnTypeFeedbackChanged(isolate, host);
    }
  }
  
  
  void LoadIC::Clear(Isolate* isolate, Code* host, LoadICNexus* nexus) {
    if (IsCleared(nexus)) return;
    nexus->ConfigurePremonomorphic();
    OnTypeFeedbackChanged(isolate, host);
  }
  
  
  void StoreIC::Clear(Isolate* isolate, Code* host, StoreICNexus* nexus) {
    if (IsCleared(nexus)) return;
    nexus->ConfigurePremonomorphic();
    OnTypeFeedbackChanged(isolate, host);
  }
  
  
  void KeyedStoreIC::Clear(Isolate* isolate, Code* host,
                           KeyedStoreICNexus* nexus) {
    if (IsCleared(nexus)) return;
    nexus->ConfigurePremonomorphic();
    OnTypeFeedbackChanged(isolate, host);
  }
  
  
  void CompareIC::Clear(Isolate* isolate, Address address, Code* target,
                        Address constant_pool) {
    DCHECK(CodeStub::GetMajorKey(target) == CodeStub::CompareIC);
    CompareICStub stub(target->stub_key(), isolate);
    // Only clear CompareICs that can retain objects.
    if (stub.state() != CompareICState::KNOWN_RECEIVER) return;
    SetTargetAtAddress(address, GetRawUninitialized(isolate, stub.op()),
                       constant_pool);
    PatchInlinedSmiCode(isolate, address, DISABLE_INLINED_SMI_CHECK);
  }
  
  
  // static
  Handle<Code> KeyedLoadIC::ChooseMegamorphicStub(Isolate* isolate,
                                                  ExtraICState extra_state) {
    if (FLAG_compiled_keyed_generic_loads) {
      return KeyedLoadGenericStub(isolate, LoadICState(extra_state)).GetCode();
    } else {
      return isolate->builtins()->KeyedLoadIC_Megamorphic();
    }
  }
  
  
  static bool MigrateDeprecated(Handle<Object> object) {
    if (!object->IsJSObject()) return false;
    Handle<JSObject> receiver = Handle<JSObject>::cast(object);
    if (!receiver->map()->is_deprecated()) return false;
    JSObject::MigrateInstance(Handle<JSObject>::cast(object));
    return true;
  }
  
  void IC::ConfigureVectorState(IC::State new_state, Handle<Object> key) {
    DCHECK(UseVector());
    if (new_state == PREMONOMORPHIC) {
      nexus()->ConfigurePremonomorphic();
    } else if (new_state == MEGAMORPHIC) {
      if (kind() == Code::LOAD_IC || kind() == Code::STORE_IC) {
        nexus()->ConfigureMegamorphic();
      } else if (kind() == Code::KEYED_LOAD_IC) {
        KeyedLoadICNexus* nexus = casted_nexus<KeyedLoadICNexus>();
        nexus->ConfigureMegamorphicKeyed(key->IsName() ? PROPERTY : ELEMENT);
      } else {
        DCHECK(kind() == Code::KEYED_STORE_IC);
        KeyedStoreICNexus* nexus = casted_nexus<KeyedStoreICNexus>();
        nexus->ConfigureMegamorphicKeyed(key->IsName() ? PROPERTY : ELEMENT);
      }
    } else {
      UNREACHABLE();
    }
  
    vector_set_ = true;
    OnTypeFeedbackChanged(isolate(), get_host());
  }
  
  
  void IC::ConfigureVectorState(Handle<Name> name, Handle<Map> map,
                                Handle<Code> handler) {
    DCHECK(UseVector());
    if (kind() == Code::LOAD_IC) {
      LoadICNexus* nexus = casted_nexus<LoadICNexus>();
      nexus->ConfigureMonomorphic(map, handler);
    } else if (kind() == Code::KEYED_LOAD_IC) {
      KeyedLoadICNexus* nexus = casted_nexus<KeyedLoadICNexus>();
      nexus->ConfigureMonomorphic(name, map, handler);
    } else if (kind() == Code::STORE_IC) {
      StoreICNexus* nexus = casted_nexus<StoreICNexus>();
      nexus->ConfigureMonomorphic(map, handler);
    } else {
      DCHECK(kind() == Code::KEYED_STORE_IC);
      KeyedStoreICNexus* nexus = casted_nexus<KeyedStoreICNexus>();
      nexus->ConfigureMonomorphic(name, map, handler);
    }
  
    vector_set_ = true;
    OnTypeFeedbackChanged(isolate(), get_host());
  }
  
  
  void IC::ConfigureVectorState(Handle<Name> name, MapHandleList* maps,
                                CodeHandleList* handlers) {
    DCHECK(UseVector());
    if (kind() == Code::LOAD_IC) {
      LoadICNexus* nexus = casted_nexus<LoadICNexus>();
      nexus->ConfigurePolymorphic(maps, handlers);
    } else if (kind() == Code::KEYED_LOAD_IC) {
      KeyedLoadICNexus* nexus = casted_nexus<KeyedLoadICNexus>();
      nexus->ConfigurePolymorphic(name, maps, handlers);
    } else if (kind() == Code::STORE_IC) {
      StoreICNexus* nexus = casted_nexus<StoreICNexus>();
      nexus->ConfigurePolymorphic(maps, handlers);
    } else {
      DCHECK(kind() == Code::KEYED_STORE_IC);
      KeyedStoreICNexus* nexus = casted_nexus<KeyedStoreICNexus>();
      nexus->ConfigurePolymorphic(name, maps, handlers);
    }
  
    vector_set_ = true;
    OnTypeFeedbackChanged(isolate(), get_host());
  }
  
  
  void IC::ConfigureVectorState(MapHandleList* maps,
                                MapHandleList* transitioned_maps,
                                CodeHandleList* handlers) {
    DCHECK(UseVector());
    DCHECK(kind() == Code::KEYED_STORE_IC);
    KeyedStoreICNexus* nexus = casted_nexus<KeyedStoreICNexus>();
    nexus->ConfigurePolymorphic(maps, transitioned_maps, handlers);
  
    vector_set_ = true;
    OnTypeFeedbackChanged(isolate(), get_host());
  }
  
  
  MaybeHandle<Object> LoadIC::Load(Handle<Object> object, Handle<Name> name) {
    // If the object is undefined or null it's illegal to try to get any
    // of its properties; throw a TypeError in that case.
    if (object->IsUndefined() || object->IsNull()) {
      return TypeError(MessageTemplate::kNonObjectPropertyLoad, object, name);
    }
  
    // Check if the name is trivially convertible to an index and get
    // the element or char if so.
    uint32_t index;
    if (kind() == Code::KEYED_LOAD_IC && name->AsArrayIndex(&index)) {
      // Rewrite to the generic keyed load stub.
      if (FLAG_use_ic) {
        DCHECK(UseVector());
        ConfigureVectorState(MEGAMORPHIC, name);
        TRACE_GENERIC_IC(isolate(), "LoadIC", "name as array index");
        TRACE_IC("LoadIC", name);
      }
      Handle<Object> result;
      ASSIGN_RETURN_ON_EXCEPTION(isolate(), result,
                                 Object::GetElement(isolate(), object, index),
                                 Object);
      return result;
    }
  
    bool use_ic = MigrateDeprecated(object) ? false : FLAG_use_ic;
  
    if (object->IsJSGlobalObject() && name->IsString()) {
      // Look up in script context table.
      Handle<String> str_name = Handle<String>::cast(name);
      Handle<JSGlobalObject> global = Handle<JSGlobalObject>::cast(object);
      Handle<ScriptContextTable> script_contexts(
          global->native_context()->script_context_table());
  
      ScriptContextTable::LookupResult lookup_result;
      if (ScriptContextTable::Lookup(script_contexts, str_name, &lookup_result)) {
        Handle<Object> result =
            FixedArray::get(*ScriptContextTable::GetContext(
                                script_contexts, lookup_result.context_index),
                            lookup_result.slot_index, isolate());
        if (*result == *isolate()->factory()->the_hole_value()) {
          // Do not install stubs and stay pre-monomorphic for
          // uninitialized accesses.
          return ReferenceError(name);
        }
  
        if (use_ic && LoadScriptContextFieldStub::Accepted(&lookup_result)) {
          TRACE_HANDLER_STATS(isolate(), LoadIC_LoadScriptContextFieldStub);
          LoadScriptContextFieldStub stub(isolate(), &lookup_result);
          PatchCache(name, stub.GetCode());
        }
        return result;
      }
    }
  
    // Named lookup in the object.
    LookupIterator it(object, name);
    LookupForRead(&it);
  
    if (it.IsFound() || !ShouldThrowReferenceError(object)) {
      // Update inline cache and stub cache.
      if (use_ic) UpdateCaches(&it);
  
      // Get the property.
      Handle<Object> result;
  
      ASSIGN_RETURN_ON_EXCEPTION(isolate(), result, Object::GetProperty(&it),
                                 Object);
      if (it.IsFound()) {
        return result;
      } else if (!ShouldThrowReferenceError(object)) {
        LOG(isolate(), SuspectReadEvent(*name, *object));
        return result;
      }
    }
    return ReferenceError(name);
  }
  
  
  static bool AddOneReceiverMapIfMissing(MapHandleList* receiver_maps,
                                         Handle<Map> new_receiver_map) {
    DCHECK(!new_receiver_map.is_null());
    for (int current = 0; current < receiver_maps->length(); ++current) {
      if (!receiver_maps->at(current).is_null() &&
          receiver_maps->at(current).is_identical_to(new_receiver_map)) {
        return false;
      }
    }
    receiver_maps->Add(new_receiver_map);
    return true;
  }
  
  
  bool IC::UpdatePolymorphicIC(Handle<Name> name, Handle<Code> code) {
    if (!code->is_handler()) return false;
    if (is_keyed() && state() != RECOMPUTE_HANDLER) return false;
    Handle<Map> map = receiver_map();
    MapHandleList maps;
    CodeHandleList handlers;
  
    TargetMaps(&maps);
    int number_of_maps = maps.length();
    int deprecated_maps = 0;
    int handler_to_overwrite = -1;
  
    for (int i = 0; i < number_of_maps; i++) {
      Handle<Map> current_map = maps.at(i);
      if (current_map->is_deprecated()) {
        // Filter out deprecated maps to ensure their instances get migrated.
        ++deprecated_maps;
      } else if (map.is_identical_to(current_map)) {
        // If the receiver type is already in the polymorphic IC, this indicates
        // there was a prototoype chain failure. In that case, just overwrite the
        // handler.
        handler_to_overwrite = i;
      } else if (handler_to_overwrite == -1 &&
                 IsTransitionOfMonomorphicTarget(*current_map, *map)) {
        handler_to_overwrite = i;
      }
    }
  
    int number_of_valid_maps =
        number_of_maps - deprecated_maps - (handler_to_overwrite != -1);
  
    if (number_of_valid_maps >= 4) return false;
    if (number_of_maps == 0 && state() != MONOMORPHIC && state() != POLYMORPHIC) {
      return false;
    }
    DCHECK(UseVector());
    if (!nexus()->FindHandlers(&handlers, maps.length())) return false;
  
    number_of_valid_maps++;
    if (number_of_valid_maps > 1 && is_keyed()) return false;
    Handle<Code> ic;
    if (number_of_valid_maps == 1) {
      ConfigureVectorState(name, receiver_map(), code);
    } else {
      if (handler_to_overwrite >= 0) {
        handlers.Set(handler_to_overwrite, code);
        if (!map.is_identical_to(maps.at(handler_to_overwrite))) {
          maps.Set(handler_to_overwrite, map);
        }
      } else {
        maps.Add(map);
        handlers.Add(code);
      }
  
      ConfigureVectorState(name, &maps, &handlers);
    }
  
    return true;
  }
  
  
  void IC::UpdateMonomorphicIC(Handle<Code> handler, Handle<Name> name) {
    DCHECK(handler->is_handler());
    ConfigureVectorState(name, receiver_map(), handler);
  }
  
  
  void IC::CopyICToMegamorphicCache(Handle<Name> name) {
    MapHandleList maps;
    CodeHandleList handlers;
    TargetMaps(&maps);
    if (!nexus()->FindHandlers(&handlers, maps.length())) return;
    for (int i = 0; i < maps.length(); i++) {
      UpdateMegamorphicCache(*maps.at(i), *name, *handlers.at(i));
    }
  }
  
  
  bool IC::IsTransitionOfMonomorphicTarget(Map* source_map, Map* target_map) {
    if (source_map == NULL) return true;
    if (target_map == NULL) return false;
    ElementsKind target_elements_kind = target_map->elements_kind();
    bool more_general_transition = IsMoreGeneralElementsKindTransition(
        source_map->elements_kind(), target_elements_kind);
    Map* transitioned_map = nullptr;
    if (more_general_transition) {
      MapHandleList map_list;
      map_list.Add(handle(target_map));
      transitioned_map = source_map->FindElementsKindTransitionedMap(&map_list);
    }
    return transitioned_map == target_map;
  }
  
  
  void IC::PatchCache(Handle<Name> name, Handle<Code> code) {
    switch (state()) {
      case UNINITIALIZED:
      case PREMONOMORPHIC:
        UpdateMonomorphicIC(code, name);
        break;
      case RECOMPUTE_HANDLER:
      case MONOMORPHIC:
      case POLYMORPHIC:
        if (!is_keyed() || state() == RECOMPUTE_HANDLER) {
          if (UpdatePolymorphicIC(name, code)) break;
          // For keyed stubs, we can't know whether old handlers were for the
          // same key.
          CopyICToMegamorphicCache(name);
        }
        DCHECK(UseVector());
        ConfigureVectorState(MEGAMORPHIC, name);
      // Fall through.
      case MEGAMORPHIC:
        UpdateMegamorphicCache(*receiver_map(), *name, *code);
        // Indicate that we've handled this case.
        DCHECK(UseVector());
        vector_set_ = true;
        break;
      case DEBUG_STUB:
        break;
      case GENERIC:
        UNREACHABLE();
        break;
    }
  }
  
  Handle<Code> LoadIC::initialize_stub_in_optimized_code(
      Isolate* isolate, ExtraICState extra_state, State initialization_state) {
    return LoadICStub(isolate, LoadICState(extra_state)).GetCode();
  }
  
  Handle<Code> KeyedLoadIC::initialize_stub_in_optimized_code(
      Isolate* isolate, State initialization_state, ExtraICState extra_state) {
    if (initialization_state != MEGAMORPHIC) {
      return KeyedLoadICStub(isolate, LoadICState(extra_state)).GetCode();
    }
    return isolate->builtins()->KeyedLoadIC_Megamorphic();
  }
  
  
  Handle<Code> KeyedStoreIC::initialize_stub_in_optimized_code(
      Isolate* isolate, LanguageMode language_mode, State initialization_state) {
    StoreICState state = StoreICState(language_mode);
    if (initialization_state != MEGAMORPHIC) {
      return VectorKeyedStoreICStub(isolate, state).GetCode();
    }
    return ChooseMegamorphicStub(isolate, state.GetExtraICState());
  }
  
  
  Handle<Code> KeyedStoreIC::ChooseMegamorphicStub(Isolate* isolate,
                                                   ExtraICState extra_state) {
    LanguageMode mode = StoreICState::GetLanguageMode(extra_state);
    return is_strict(mode)
               ? isolate->builtins()->KeyedStoreIC_Megamorphic_Strict()
               : isolate->builtins()->KeyedStoreIC_Megamorphic();
  }
  
  
  Handle<Code> LoadIC::SimpleFieldLoad(FieldIndex index) {
    TRACE_HANDLER_STATS(isolate(), LoadIC_LoadFieldStub);
    LoadFieldStub stub(isolate(), index);
    return stub.GetCode();
  }
  
  
  bool IsCompatibleReceiver(LookupIterator* lookup, Handle<Map> receiver_map) {
    DCHECK(lookup->state() == LookupIterator::ACCESSOR);
    Isolate* isolate = lookup->isolate();
    Handle<Object> accessors = lookup->GetAccessors();
    if (accessors->IsAccessorInfo()) {
      Handle<AccessorInfo> info = Handle<AccessorInfo>::cast(accessors);
      if (info->getter() != NULL &&
          !AccessorInfo::IsCompatibleReceiverMap(isolate, info, receiver_map)) {
        return false;
      }
    } else if (accessors->IsAccessorPair()) {
      Handle<Object> getter(Handle<AccessorPair>::cast(accessors)->getter(),
                            isolate);
      if (!getter->IsJSFunction() && !getter->IsFunctionTemplateInfo()) {
        return false;
      }
      Handle<JSObject> holder = lookup->GetHolder<JSObject>();
      Handle<Object> receiver = lookup->GetReceiver();
      if (holder->HasFastProperties()) {
        if (getter->IsJSFunction()) {
          Handle<JSFunction> function = Handle<JSFunction>::cast(getter);
          if (!receiver->IsJSObject() && !function->shared()->IsBuiltin() &&
              is_sloppy(function->shared()->language_mode())) {
            // Calling sloppy non-builtins with a value as the receiver
            // requires boxing.
            return false;
          }
        }
        CallOptimization call_optimization(getter);
        if (call_optimization.is_simple_api_call() &&
            !call_optimization.IsCompatibleReceiverMap(receiver_map, holder)) {
          return false;
        }
      }
    }
    return true;
  }
  
  
  void LoadIC::UpdateCaches(LookupIterator* lookup) {
    if (state() == UNINITIALIZED) {
      // This is the first time we execute this inline cache. Set the target to
      // the pre monomorphic stub to delay setting the monomorphic state.
      ConfigureVectorState(PREMONOMORPHIC, Handle<Object>());
      TRACE_IC("LoadIC", lookup->name());
      return;
    }
  
    Handle<Code> code;
    if (lookup->state() == LookupIterator::JSPROXY ||
        lookup->state() == LookupIterator::ACCESS_CHECK) {
      code = slow_stub();
    } else if (!lookup->IsFound()) {
      if (kind() == Code::LOAD_IC) {
        code = NamedLoadHandlerCompiler::ComputeLoadNonexistent(lookup->name(),
                                                                receiver_map());
        // TODO(jkummerow/verwaest): Introduce a builtin that handles this case.
        if (code.is_null()) code = slow_stub();
      } else {
        code = slow_stub();
      }
    } else {
      if (lookup->state() == LookupIterator::ACCESSOR) {
        if (!IsCompatibleReceiver(lookup, receiver_map())) {
          TRACE_GENERIC_IC(isolate(), "LoadIC", "incompatible receiver type");
          code = slow_stub();
        }
      } else if (lookup->state() == LookupIterator::INTERCEPTOR) {
        // Perform a lookup behind the interceptor. Copy the LookupIterator since
        // the original iterator will be used to fetch the value.
        LookupIterator it = *lookup;
        it.Next();
        LookupForRead(&it);
        if (it.state() == LookupIterator::ACCESSOR &&
            !IsCompatibleReceiver(&it, receiver_map())) {
          TRACE_GENERIC_IC(isolate(), "LoadIC", "incompatible receiver type");
          code = slow_stub();
        }
      }
      if (code.is_null()) code = ComputeHandler(lookup);
    }
  
    PatchCache(lookup->name(), code);
    TRACE_IC("LoadIC", lookup->name());
  }
  
  
  void IC::UpdateMegamorphicCache(Map* map, Name* name, Code* code) {
    isolate()->stub_cache()->Set(name, map, code);
  }
  
  
  Handle<Code> IC::ComputeHandler(LookupIterator* lookup, Handle<Object> value) {
    // Try to find a globally shared handler stub.
    Handle<Code> code = GetMapIndependentHandler(lookup);
    if (!code.is_null()) return code;
  
    // Otherwise check the map's handler cache for a map-specific handler, and
    // compile one if the cache comes up empty.
    bool receiver_is_holder =
        lookup->GetReceiver().is_identical_to(lookup->GetHolder<JSObject>());
    CacheHolderFlag flag;
    Handle<Map> stub_holder_map;
    if (kind() == Code::LOAD_IC || kind() == Code::KEYED_LOAD_IC) {
      stub_holder_map = IC::GetHandlerCacheHolder(
          receiver_map(), receiver_is_holder, isolate(), &flag);
    } else {
      DCHECK(kind() == Code::STORE_IC || kind() == Code::KEYED_STORE_IC);
      // Store handlers cannot be cached on prototypes.
      flag = kCacheOnReceiver;
      stub_holder_map = receiver_map();
    }
  
    code = PropertyHandlerCompiler::Find(lookup->name(), stub_holder_map, kind(),
                                         flag);
    // Use the cached value if it exists, and if it is different from the
    // handler that just missed.
    if (!code.is_null()) {
      Handle<Code> handler;
      if (maybe_handler_.ToHandle(&handler)) {
        if (!handler.is_identical_to(code)) {
          TRACE_HANDLER_STATS(isolate(), IC_HandlerCacheHit);
          return code;
        }
      } else {
        // maybe_handler_ is only populated for MONOMORPHIC and POLYMORPHIC ICs.
        // In MEGAMORPHIC case, check if the handler in the megamorphic stub
        // cache (which just missed) is different from the cached handler.
        if (state() == MEGAMORPHIC && lookup->GetReceiver()->IsHeapObject()) {
          Map* map = Handle<HeapObject>::cast(lookup->GetReceiver())->map();
          Code* megamorphic_cached_code =
              isolate()->stub_cache()->Get(*lookup->name(), map, code->flags());
          if (megamorphic_cached_code != *code) {
            TRACE_HANDLER_STATS(isolate(), IC_HandlerCacheHit);
            return code;
          }
        } else {
          TRACE_HANDLER_STATS(isolate(), IC_HandlerCacheHit);
          return code;
        }
      }
    }
  
    code = CompileHandler(lookup, value, flag);
    DCHECK(code->is_handler());
    DCHECK(Code::ExtractCacheHolderFromFlags(code->flags()) == flag);
    Map::UpdateCodeCache(stub_holder_map, lookup->name(), code);
  
    return code;
  }
  
  Handle<Code> LoadIC::GetMapIndependentHandler(LookupIterator* lookup) {
    Handle<Object> receiver = lookup->GetReceiver();
    if (receiver->IsString() &&
        Name::Equals(isolate()->factory()->length_string(), lookup->name())) {
      FieldIndex index = FieldIndex::ForInObjectOffset(String::kLengthOffset);
      return SimpleFieldLoad(index);
    }
  
    if (receiver->IsStringWrapper() &&
        Name::Equals(isolate()->factory()->length_string(), lookup->name())) {
      TRACE_HANDLER_STATS(isolate(), LoadIC_StringLengthStub);
      StringLengthStub string_length_stub(isolate());
      return string_length_stub.GetCode();
    }
  
    // Use specialized code for getting prototype of functions.
    if (receiver->IsJSFunction() &&
        Name::Equals(isolate()->factory()->prototype_string(), lookup->name()) &&
        receiver->IsConstructor() &&
        !Handle<JSFunction>::cast(receiver)
             ->map()
             ->has_non_instance_prototype()) {
      Handle<Code> stub;
      TRACE_HANDLER_STATS(isolate(), LoadIC_FunctionPrototypeStub);
      FunctionPrototypeStub function_prototype_stub(isolate());
      return function_prototype_stub.GetCode();
    }
  
    Handle<Map> map = receiver_map();
    Handle<JSObject> holder = lookup->GetHolder<JSObject>();
    bool receiver_is_holder = receiver.is_identical_to(holder);
    switch (lookup->state()) {
      case LookupIterator::INTERCEPTOR:
        break;  // Custom-compiled handler.
  
      case LookupIterator::ACCESSOR: {
        // Use simple field loads for some well-known callback properties.
        // The method will only return true for absolute truths based on the
        // receiver maps.
        int object_offset;
        if (Accessors::IsJSObjectFieldAccessor(map, lookup->name(),
                                               &object_offset)) {
          FieldIndex index = FieldIndex::ForInObjectOffset(object_offset, *map);
          return SimpleFieldLoad(index);
        }
        if (Accessors::IsJSArrayBufferViewFieldAccessor(map, lookup->name(),
                                                        &object_offset)) {
          TRACE_HANDLER_STATS(isolate(), LoadIC_ArrayBufferViewLoadFieldStub);
          FieldIndex index = FieldIndex::ForInObjectOffset(object_offset, *map);
          ArrayBufferViewLoadFieldStub stub(isolate(), index);
          return stub.GetCode();
        }
  
        if (IsCompatibleReceiver(lookup, map)) {
          Handle<Object> accessors = lookup->GetAccessors();
          if (accessors->IsAccessorPair()) {
            if (!holder->HasFastProperties()) {
              TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
              return slow_stub();
            }
            // When debugging we need to go the slow path to flood the accessor.
            if (GetSharedFunctionInfo()->HasDebugInfo()) {
              TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
              return slow_stub();
            }
            break;  // Custom-compiled handler.
          } else if (accessors->IsAccessorInfo()) {
            Handle<AccessorInfo> info = Handle<AccessorInfo>::cast(accessors);
            if (v8::ToCData<Address>(info->getter()) == nullptr) {
              TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
              return slow_stub();
            }
            // Ruled out by IsCompatibleReceiver() above.
            DCHECK(AccessorInfo::IsCompatibleReceiverMap(isolate(), info, map));
            if (!holder->HasFastProperties()) return slow_stub();
            if (receiver_is_holder) {
              TRACE_HANDLER_STATS(isolate(), LoadIC_LoadApiGetterStub);
              int index = lookup->GetAccessorIndex();
              LoadApiGetterStub stub(isolate(), true, index);
              return stub.GetCode();
            }
            if (info->is_sloppy() && !receiver->IsJSReceiver()) {
              TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
              return slow_stub();
            }
            break;  // Custom-compiled handler.
          }
        }
        TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
        return slow_stub();
      }
  
      case LookupIterator::DATA: {
        if (lookup->is_dictionary_holder()) {
          if (kind() != Code::LOAD_IC) {
            TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
            return slow_stub();
          }
          if (holder->IsJSGlobalObject()) {
            break;  // Custom-compiled handler.
          }
          // There is only one shared stub for loading normalized
          // properties. It does not traverse the prototype chain, so the
          // property must be found in the object for the stub to be
          // applicable.
          if (!receiver_is_holder) {
            TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
            return slow_stub();
          }
          TRACE_HANDLER_STATS(isolate(), LoadIC_LoadNormal);
          return isolate()->builtins()->LoadIC_Normal();
        }
  
        // -------------- Fields --------------
        if (lookup->property_details().type() == DATA) {
          FieldIndex field = lookup->GetFieldIndex();
          if (receiver_is_holder) {
            return SimpleFieldLoad(field);
          }
          break;  // Custom-compiled handler.
        }
  
        // -------------- Constant properties --------------
        DCHECK(lookup->property_details().type() == DATA_CONSTANT);
        if (receiver_is_holder) {
          TRACE_HANDLER_STATS(isolate(), LoadIC_LoadConstantStub);
          LoadConstantStub stub(isolate(), lookup->GetConstantIndex());
          return stub.GetCode();
        }
        break;  // Custom-compiled handler.
      }
  
      case LookupIterator::INTEGER_INDEXED_EXOTIC:
        TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
        return slow_stub();
      case LookupIterator::ACCESS_CHECK:
      case LookupIterator::JSPROXY:
      case LookupIterator::NOT_FOUND:
      case LookupIterator::TRANSITION:
        UNREACHABLE();
    }
  
    return Handle<Code>::null();
  }
  
  Handle<Code> LoadIC::CompileHandler(LookupIterator* lookup,
                                      Handle<Object> unused,
                                      CacheHolderFlag cache_holder) {
    Handle<JSObject> holder = lookup->GetHolder<JSObject>();
  #ifdef DEBUG
    // Only used by DCHECKs below.
    Handle<Object> receiver = lookup->GetReceiver();
    bool receiver_is_holder = receiver.is_identical_to(holder);
  #endif
    // Non-map-specific handler stubs have already been selected.
    DCHECK(!receiver->IsString() ||
           !Name::Equals(isolate()->factory()->length_string(), lookup->name()));
    DCHECK(!receiver->IsStringWrapper() ||
           !Name::Equals(isolate()->factory()->length_string(), lookup->name()));
  
    DCHECK(!(
        receiver->IsJSFunction() &&
        Name::Equals(isolate()->factory()->prototype_string(), lookup->name()) &&
        receiver->IsConstructor() &&
        !Handle<JSFunction>::cast(receiver)
             ->map()
             ->has_non_instance_prototype()));
  
    Handle<Map> map = receiver_map();
    switch (lookup->state()) {
      case LookupIterator::INTERCEPTOR: {
        DCHECK(!holder->GetNamedInterceptor()->getter()->IsUndefined());
        TRACE_HANDLER_STATS(isolate(), LoadIC_LoadInterceptor);
        NamedLoadHandlerCompiler compiler(isolate(), map, holder, cache_holder);
        // Perform a lookup behind the interceptor. Copy the LookupIterator since
        // the original iterator will be used to fetch the value.
        LookupIterator it = *lookup;
        it.Next();
        LookupForRead(&it);
        return compiler.CompileLoadInterceptor(&it);
      }
  
      case LookupIterator::ACCESSOR: {
  #ifdef DEBUG
        int object_offset;
        DCHECK(!Accessors::IsJSObjectFieldAccessor(map, lookup->name(),
                                                   &object_offset));
        DCHECK(!Accessors::IsJSArrayBufferViewFieldAccessor(map, lookup->name(),
                                                            &object_offset));
  #endif
  
        DCHECK(IsCompatibleReceiver(lookup, map));
        Handle<Object> accessors = lookup->GetAccessors();
        if (accessors->IsAccessorPair()) {
          DCHECK(holder->HasFastProperties());
          DCHECK(!GetSharedFunctionInfo()->HasDebugInfo());
          Handle<Object> getter(Handle<AccessorPair>::cast(accessors)->getter(),
                                isolate());
          CallOptimization call_optimization(getter);
          NamedLoadHandlerCompiler compiler(isolate(), map, holder, cache_holder);
          if (call_optimization.is_simple_api_call()) {
            TRACE_HANDLER_STATS(isolate(), LoadIC_LoadCallback);
            int index = lookup->GetAccessorIndex();
            Handle<Code> code = compiler.CompileLoadCallback(
                lookup->name(), call_optimization, index);
            if (FLAG_runtime_call_stats) return slow_stub();
            return code;
          }
          TRACE_HANDLER_STATS(isolate(), LoadIC_LoadViaGetter);
          int expected_arguments = Handle<JSFunction>::cast(getter)
                                       ->shared()
                                       ->internal_formal_parameter_count();
          return compiler.CompileLoadViaGetter(
              lookup->name(), lookup->GetAccessorIndex(), expected_arguments);
        } else {
          DCHECK(accessors->IsAccessorInfo());
          Handle<AccessorInfo> info = Handle<AccessorInfo>::cast(accessors);
          DCHECK(v8::ToCData<Address>(info->getter()) != nullptr);
          DCHECK(AccessorInfo::IsCompatibleReceiverMap(isolate(), info, map));
          DCHECK(holder->HasFastProperties());
          DCHECK(!receiver_is_holder);
          DCHECK(!info->is_sloppy() || receiver->IsJSReceiver());
          TRACE_HANDLER_STATS(isolate(), LoadIC_LoadCallback);
          NamedLoadHandlerCompiler compiler(isolate(), map, holder, cache_holder);
          Handle<Code> code = compiler.CompileLoadCallback(lookup->name(), info);
          if (FLAG_runtime_call_stats) return slow_stub();
          return code;
        }
        UNREACHABLE();
      }
  
      case LookupIterator::DATA: {
        if (lookup->is_dictionary_holder()) {
          DCHECK(kind() == Code::LOAD_IC);
          DCHECK(holder->IsJSGlobalObject());
          TRACE_HANDLER_STATS(isolate(), LoadIC_LoadGlobal);
          NamedLoadHandlerCompiler compiler(isolate(), map, holder, cache_holder);
          Handle<PropertyCell> cell = lookup->GetPropertyCell();
          Handle<Code> code = compiler.CompileLoadGlobal(
              cell, lookup->name(), lookup->IsConfigurable());
          return code;
        }
  
        // -------------- Fields --------------
        if (lookup->property_details().type() == DATA) {
          FieldIndex field = lookup->GetFieldIndex();
          DCHECK(!receiver_is_holder);
          TRACE_HANDLER_STATS(isolate(), LoadIC_LoadField);
          NamedLoadHandlerCompiler compiler(isolate(), map, holder, cache_holder);
          return compiler.CompileLoadField(lookup->name(), field);
        }
  
        // -------------- Constant properties --------------
        DCHECK(lookup->property_details().type() == DATA_CONSTANT);
        DCHECK(!receiver_is_holder);
        TRACE_HANDLER_STATS(isolate(), LoadIC_LoadConstant);
        NamedLoadHandlerCompiler compiler(isolate(), map, holder, cache_holder);
        return compiler.CompileLoadConstant(lookup->name(),
                                            lookup->GetConstantIndex());
      }
  
      case LookupIterator::INTEGER_INDEXED_EXOTIC:
      case LookupIterator::ACCESS_CHECK:
      case LookupIterator::JSPROXY:
      case LookupIterator::NOT_FOUND:
      case LookupIterator::TRANSITION:
        UNREACHABLE();
    }
    UNREACHABLE();
    return slow_stub();
  }
  
  
  static Handle<Object> TryConvertKey(Handle<Object> key, Isolate* isolate) {
    // This helper implements a few common fast cases for converting
    // non-smi keys of keyed loads/stores to a smi or a string.
    if (key->IsHeapNumber()) {
      double value = Handle<HeapNumber>::cast(key)->value();
      if (std::isnan(value)) {
        key = isolate->factory()->nan_string();
      } else {
        int int_value = FastD2I(value);
        if (value == int_value && Smi::IsValid(int_value)) {
          key = handle(Smi::FromInt(int_value), isolate);
        }
      }
    } else if (key->IsUndefined()) {
      key = isolate->factory()->undefined_string();
    }
    return key;
  }
  
  void KeyedLoadIC::UpdateLoadElement(Handle<HeapObject> receiver) {
    Handle<Map> receiver_map(receiver->map(), isolate());
    DCHECK(receiver_map->instance_type() != JS_VALUE_TYPE &&
           receiver_map->instance_type() != JS_PROXY_TYPE);  // Checked by caller.
    MapHandleList target_receiver_maps;
    TargetMaps(&target_receiver_maps);
  
    if (target_receiver_maps.length() == 0) {
      Handle<Code> handler =
          PropertyICCompiler::ComputeKeyedLoadMonomorphicHandler(
              receiver_map, extra_ic_state());
      return ConfigureVectorState(Handle<Name>(), receiver_map, handler);
    }
  
    for (int i = 0; i < target_receiver_maps.length(); i++) {
      Handle<Map> map = target_receiver_maps.at(i);
      if (map.is_null()) continue;
      if (map->instance_type() == JS_VALUE_TYPE) {
        TRACE_GENERIC_IC(isolate(), "KeyedLoadIC", "JSValue");
        return;
      }
      if (map->instance_type() == JS_PROXY_TYPE) {
        TRACE_GENERIC_IC(isolate(), "KeyedLoadIC", "JSProxy");
        return;
      }
    }
  
    // The first time a receiver is seen that is a transitioned version of the
    // previous monomorphic receiver type, assume the new ElementsKind is the
    // monomorphic type. This benefits global arrays that only transition
    // once, and all call sites accessing them are faster if they remain
    // monomorphic. If this optimistic assumption is not true, the IC will
    // miss again and it will become polymorphic and support both the
    // untransitioned and transitioned maps.
    if (state() == MONOMORPHIC && !receiver->IsString() &&
        IsMoreGeneralElementsKindTransition(
            target_receiver_maps.at(0)->elements_kind(),
            Handle<JSObject>::cast(receiver)->GetElementsKind())) {
      Handle<Code> handler =
          PropertyICCompiler::ComputeKeyedLoadMonomorphicHandler(
              receiver_map, extra_ic_state());
      return ConfigureVectorState(Handle<Name>(), receiver_map, handler);
    }
  
    DCHECK(state() != GENERIC);
  
    // Determine the list of receiver maps that this call site has seen,
    // adding the map that was just encountered.
    if (!AddOneReceiverMapIfMissing(&target_receiver_maps, receiver_map)) {
      // If the miss wasn't due to an unseen map, a polymorphic stub
      // won't help, use the generic stub.
      TRACE_GENERIC_IC(isolate(), "KeyedLoadIC", "same map added twice");
      return;
    }
  
    // If the maximum number of receiver maps has been exceeded, use the generic
    // version of the IC.
    if (target_receiver_maps.length() > kMaxKeyedPolymorphism) {
      TRACE_GENERIC_IC(isolate(), "KeyedLoadIC", "max polymorph exceeded");
      return;
    }
  
    CodeHandleList handlers(target_receiver_maps.length());
    TRACE_HANDLER_STATS(isolate(), KeyedLoadIC_PolymorphicElement);
    ElementHandlerCompiler compiler(isolate());
    compiler.CompileElementHandlers(&target_receiver_maps, &handlers);
    ConfigureVectorState(Handle<Name>(), &target_receiver_maps, &handlers);
  }
  
  
  MaybeHandle<Object> KeyedLoadIC::Load(Handle<Object> object,
                                        Handle<Object> key) {
    if (MigrateDeprecated(object)) {
      Handle<Object> result;
      ASSIGN_RETURN_ON_EXCEPTION(
          isolate(), result, Runtime::GetObjectProperty(isolate(), object, key),
          Object);
      return result;
    }
  
    Handle<Object> load_handle;
  
    // Check for non-string values that can be converted into an
    // internalized string directly or is representable as a smi.
    key = TryConvertKey(key, isolate());
  
    if (key->IsInternalizedString() || key->IsSymbol()) {
      ASSIGN_RETURN_ON_EXCEPTION(isolate(), load_handle,
                                 LoadIC::Load(object, Handle<Name>::cast(key)),
                                 Object);
    } else if (FLAG_use_ic && !object->IsAccessCheckNeeded() &&
               !object->IsJSValue()) {
      if (object->IsJSObject() || (object->IsString() && key->IsNumber())) {
        Handle<HeapObject> receiver = Handle<HeapObject>::cast(object);
        if (object->IsString() || key->IsSmi()) UpdateLoadElement(receiver);
      }
    }
  
    if (!is_vector_set()) {
      ConfigureVectorState(MEGAMORPHIC, key);
      TRACE_GENERIC_IC(isolate(), "KeyedLoadIC", "set generic");
    }
    TRACE_IC("LoadIC", key);
  
    if (!load_handle.is_null()) return load_handle;
  
    Handle<Object> result;
    ASSIGN_RETURN_ON_EXCEPTION(isolate(), result,
                               Runtime::GetObjectProperty(isolate(), object, key),
                               Object);
    return result;
  }
  
  
  bool StoreIC::LookupForWrite(LookupIterator* it, Handle<Object> value,
                               JSReceiver::StoreFromKeyed store_mode) {
    // Disable ICs for non-JSObjects for now.
    Handle<Object> object = it->GetReceiver();
    if (!object->IsJSObject()) return false;
    Handle<JSObject> receiver = Handle<JSObject>::cast(object);
    DCHECK(!receiver->map()->is_deprecated());
  
    for (; it->IsFound(); it->Next()) {
      switch (it->state()) {
        case LookupIterator::NOT_FOUND:
        case LookupIterator::TRANSITION:
          UNREACHABLE();
        case LookupIterator::JSPROXY:
          return false;
        case LookupIterator::INTERCEPTOR: {
          Handle<JSObject> holder = it->GetHolder<JSObject>();
          InterceptorInfo* info = holder->GetNamedInterceptor();
          if (it->HolderIsReceiverOrHiddenPrototype()) {
            return !info->non_masking() && receiver.is_identical_to(holder) &&
                   !info->setter()->IsUndefined();
          } else if (!info->getter()->IsUndefined() ||
                     !info->query()->IsUndefined()) {
            return false;
          }
          break;
        }
        case LookupIterator::ACCESS_CHECK:
          if (it->GetHolder<JSObject>()->IsAccessCheckNeeded()) return false;
          break;
        case LookupIterator::ACCESSOR:
          return !it->IsReadOnly();
        case LookupIterator::INTEGER_INDEXED_EXOTIC:
          return false;
        case LookupIterator::DATA: {
          if (it->IsReadOnly()) return false;
          Handle<JSObject> holder = it->GetHolder<JSObject>();
          if (receiver.is_identical_to(holder)) {
            it->PrepareForDataProperty(value);
            // The previous receiver map might just have been deprecated,
            // so reload it.
            update_receiver_map(receiver);
            return true;
          }
  
          // Receiver != holder.
          if (receiver->IsJSGlobalProxy()) {
            PrototypeIterator iter(it->isolate(), receiver);
            return it->GetHolder<Object>().is_identical_to(
                PrototypeIterator::GetCurrent(iter));
          }
  
          if (it->HolderIsReceiverOrHiddenPrototype()) return false;
  
          if (it->ExtendingNonExtensible(receiver)) return false;
          it->PrepareTransitionToDataProperty(receiver, value, NONE, store_mode);
          return it->IsCacheableTransition();
        }
      }
    }
  
    receiver = it->GetStoreTarget();
    if (it->ExtendingNonExtensible(receiver)) return false;
    it->PrepareTransitionToDataProperty(receiver, value, NONE, store_mode);
    return it->IsCacheableTransition();
  }
  
  
  MaybeHandle<Object> StoreIC::Store(Handle<Object> object, Handle<Name> name,
                                     Handle<Object> value,
                                     JSReceiver::StoreFromKeyed store_mode) {
    // Check if the name is trivially convertible to an index and set the element.
    uint32_t index;
    if (kind() == Code::KEYED_STORE_IC && name->AsArrayIndex(&index)) {
      // Rewrite to the generic keyed store stub.
      if (FLAG_use_ic) {
        DCHECK(UseVector());
        ConfigureVectorState(MEGAMORPHIC, name);
        TRACE_IC("StoreIC", name);
        TRACE_GENERIC_IC(isolate(), "StoreIC", "name as array index");
      }
      Handle<Object> result;
      ASSIGN_RETURN_ON_EXCEPTION(
          isolate(), result,
          Object::SetElement(isolate(), object, index, value, language_mode()),
          Object);
      return result;
    }
  
    if (object->IsJSGlobalObject() && name->IsString()) {
      // Look up in script context table.
      Handle<String> str_name = Handle<String>::cast(name);
      Handle<JSGlobalObject> global = Handle<JSGlobalObject>::cast(object);
      Handle<ScriptContextTable> script_contexts(
          global->native_context()->script_context_table());
  
      ScriptContextTable::LookupResult lookup_result;
      if (ScriptContextTable::Lookup(script_contexts, str_name, &lookup_result)) {
        Handle<Context> script_context = ScriptContextTable::GetContext(
            script_contexts, lookup_result.context_index);
        if (lookup_result.mode == CONST) {
          return TypeError(MessageTemplate::kConstAssign, object, name);
        }
  
        Handle<Object> previous_value =
            FixedArray::get(*script_context, lookup_result.slot_index, isolate());
  
        if (*previous_value == *isolate()->factory()->the_hole_value()) {
          // Do not install stubs and stay pre-monomorphic for
          // uninitialized accesses.
          return ReferenceError(name);
        }
  
        if (FLAG_use_ic &&
            StoreScriptContextFieldStub::Accepted(&lookup_result)) {
          TRACE_HANDLER_STATS(isolate(), StoreIC_StoreScriptContextFieldStub);
          StoreScriptContextFieldStub stub(isolate(), &lookup_result);
          PatchCache(name, stub.GetCode());
        }
  
        script_context->set(lookup_result.slot_index, *value);
        return value;
      }
    }
  
    // TODO(verwaest): Let SetProperty do the migration, since storing a property
    // might deprecate the current map again, if value does not fit.
    if (MigrateDeprecated(object) || object->IsJSProxy()) {
      Handle<Object> result;
      ASSIGN_RETURN_ON_EXCEPTION(
          isolate(), result,
          Object::SetProperty(object, name, value, language_mode()), Object);
      return result;
    }
  
    // If the object is undefined or null it's illegal to try to set any
    // properties on it; throw a TypeError in that case.
    if (object->IsUndefined() || object->IsNull()) {
      return TypeError(MessageTemplate::kNonObjectPropertyStore, object, name);
    }
  
    LookupIterator it(object, name);
    if (FLAG_use_ic) UpdateCaches(&it, value, store_mode);
  
    MAYBE_RETURN_NULL(
        Object::SetProperty(&it, value, language_mode(), store_mode));
    return value;
  }
  
  Handle<Code> CallIC::initialize_stub_in_optimized_code(
      Isolate* isolate, int argc, ConvertReceiverMode mode,
      TailCallMode tail_call_mode) {
    CallICStub stub(isolate, CallICState(argc, mode, tail_call_mode));
    Handle<Code> code = stub.GetCode();
    return code;
  }
  
  
  Handle<Code> StoreIC::initialize_stub_in_optimized_code(
      Isolate* isolate, LanguageMode language_mode, State initialization_state) {
    DCHECK(initialization_state == UNINITIALIZED ||
           initialization_state == PREMONOMORPHIC ||
           initialization_state == MEGAMORPHIC);
    if (initialization_state != MEGAMORPHIC) {
      VectorStoreICStub stub(isolate, StoreICState(language_mode));
      return stub.GetCode();
    }
  
    return is_strict(language_mode)
               ? isolate->builtins()->StoreIC_Megamorphic_Strict()
               : isolate->builtins()->StoreIC_Megamorphic();
  }
  
  Handle<Code> StoreIC::slow_stub() const {
    return isolate()->builtins()->StoreIC_Slow();
  }
  
  
  void StoreIC::UpdateCaches(LookupIterator* lookup, Handle<Object> value,
                             JSReceiver::StoreFromKeyed store_mode) {
    if (state() == UNINITIALIZED) {
      // This is the first time we execute this inline cache. Set the target to
      // the pre monomorphic stub to delay setting the monomorphic state.
      ConfigureVectorState(PREMONOMORPHIC, Handle<Object>());
      TRACE_IC("StoreIC", lookup->name());
      return;
    }
  
    bool use_ic = LookupForWrite(lookup, value, store_mode);
    if (!use_ic) {
      TRACE_GENERIC_IC(isolate(), "StoreIC", "LookupForWrite said 'false'");
    }
    Handle<Code> code = use_ic ? ComputeHandler(lookup, value) : slow_stub();
  
    PatchCache(lookup->name(), code);
    TRACE_IC("StoreIC", lookup->name());
  }
  
  
  static Handle<Code> PropertyCellStoreHandler(
      Isolate* isolate, Handle<JSObject> receiver, Handle<JSGlobalObject> holder,
      Handle<Name> name, Handle<PropertyCell> cell, PropertyCellType type) {
    auto constant_type = Nothing<PropertyCellConstantType>();
    if (type == PropertyCellType::kConstantType) {
      constant_type = Just(cell->GetConstantType());
    }
    StoreGlobalStub stub(isolate, type, constant_type,
                         receiver->IsJSGlobalProxy());
    auto code = stub.GetCodeCopyFromTemplate(holder, cell);
    // TODO(verwaest): Move caching of these NORMAL stubs outside as well.
    HeapObject::UpdateMapCodeCache(receiver, name, code);
    return code;
  }
  
  Handle<Code> StoreIC::GetMapIndependentHandler(LookupIterator* lookup) {
    DCHECK_NE(LookupIterator::JSPROXY, lookup->state());
  
    // This is currently guaranteed by checks in StoreIC::Store.
    Handle<JSObject> receiver = Handle<JSObject>::cast(lookup->GetReceiver());
    Handle<JSObject> holder = lookup->GetHolder<JSObject>();
    DCHECK(!receiver->IsAccessCheckNeeded() || lookup->name()->IsPrivate());
  
    switch (lookup->state()) {
      case LookupIterator::TRANSITION: {
        auto store_target = lookup->GetStoreTarget();
        if (store_target->IsJSGlobalObject()) {
          break;  // Custom-compiled handler.
        }
        // Currently not handled by CompileStoreTransition.
        if (!holder->HasFastProperties()) {
          TRACE_GENERIC_IC(isolate(), "StoreIC", "transition from slow");
          TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
          return slow_stub();
        }
  
        DCHECK(lookup->IsCacheableTransition());
        break;  // Custom-compiled handler.
      }
  
      case LookupIterator::INTERCEPTOR: {
        DCHECK(!holder->GetNamedInterceptor()->setter()->IsUndefined());
        TRACE_HANDLER_STATS(isolate(), StoreIC_StoreInterceptorStub);
        StoreInterceptorStub stub(isolate());
        return stub.GetCode();
      }
  
      case LookupIterator::ACCESSOR: {
        if (!holder->HasFastProperties()) {
          TRACE_GENERIC_IC(isolate(), "StoreIC", "accessor on slow map");
          TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
          return slow_stub();
        }
        Handle<Object> accessors = lookup->GetAccessors();
        if (accessors->IsAccessorInfo()) {
          Handle<AccessorInfo> info = Handle<AccessorInfo>::cast(accessors);
          if (v8::ToCData<Address>(info->setter()) == nullptr) {
            TRACE_GENERIC_IC(isolate(), "StoreIC", "setter == nullptr");
            TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
            return slow_stub();
          }
          if (AccessorInfo::cast(*accessors)->is_special_data_property() &&
              !lookup->HolderIsReceiverOrHiddenPrototype()) {
            TRACE_GENERIC_IC(isolate(), "StoreIC",
                             "special data property in prototype chain");
            TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
            return slow_stub();
          }
          if (!AccessorInfo::IsCompatibleReceiverMap(isolate(), info,
                                                     receiver_map())) {
            TRACE_GENERIC_IC(isolate(), "StoreIC", "incompatible receiver type");
            TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
            return slow_stub();
          }
          if (info->is_sloppy() && !receiver->IsJSReceiver()) {
            TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
            return slow_stub();
          }
          break;  // Custom-compiled handler.
        } else if (accessors->IsAccessorPair()) {
          Handle<Object> setter(Handle<AccessorPair>::cast(accessors)->setter(),
                                isolate());
          if (!setter->IsJSFunction() && !setter->IsFunctionTemplateInfo()) {
            TRACE_GENERIC_IC(isolate(), "StoreIC", "setter not a function");
            TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
            return slow_stub();
          }
          CallOptimization call_optimization(setter);
          if (call_optimization.is_simple_api_call()) {
            if (call_optimization.IsCompatibleReceiver(receiver, holder)) {
              break;  // Custom-compiled handler.
            }
            TRACE_GENERIC_IC(isolate(), "StoreIC", "incompatible receiver");
            TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
            return slow_stub();
          }
          break;  // Custom-compiled handler.
        }
        TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
        return slow_stub();
      }
  
      case LookupIterator::DATA: {
        if (lookup->is_dictionary_holder()) {
          if (holder->IsJSGlobalObject()) {
            break;  // Custom-compiled handler.
          }
          TRACE_HANDLER_STATS(isolate(), StoreIC_StoreNormal);
          DCHECK(holder.is_identical_to(receiver));
          return isolate()->builtins()->StoreIC_Normal();
        }
  
        // -------------- Fields --------------
        if (lookup->property_details().type() == DATA) {
          bool use_stub = true;
          if (lookup->representation().IsHeapObject()) {
            // Only use a generic stub if no types need to be tracked.
            Handle<FieldType> field_type = lookup->GetFieldType();
            use_stub = !field_type->IsClass();
          }
          if (use_stub) {
            TRACE_HANDLER_STATS(isolate(), StoreIC_StoreFieldStub);
            StoreFieldStub stub(isolate(), lookup->GetFieldIndex(),
                                lookup->representation());
            return stub.GetCode();
          }
          break;  // Custom-compiled handler.
        }
  
        // -------------- Constant properties --------------
        DCHECK(lookup->property_details().type() == DATA_CONSTANT);
        TRACE_GENERIC_IC(isolate(), "StoreIC", "constant property");
        TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
        return slow_stub();
      }
  
      case LookupIterator::INTEGER_INDEXED_EXOTIC:
      case LookupIterator::ACCESS_CHECK:
      case LookupIterator::JSPROXY:
      case LookupIterator::NOT_FOUND:
        UNREACHABLE();
    }
    return Handle<Code>::null();
  }
  
  Handle<Code> StoreIC::CompileHandler(LookupIterator* lookup,
                                       Handle<Object> value,
                                       CacheHolderFlag cache_holder) {
    DCHECK_NE(LookupIterator::JSPROXY, lookup->state());
  
    // This is currently guaranteed by checks in StoreIC::Store.
    Handle<JSObject> receiver = Handle<JSObject>::cast(lookup->GetReceiver());
    Handle<JSObject> holder = lookup->GetHolder<JSObject>();
    DCHECK(!receiver->IsAccessCheckNeeded() || lookup->name()->IsPrivate());
  
    switch (lookup->state()) {
      case LookupIterator::TRANSITION: {
        auto store_target = lookup->GetStoreTarget();
        if (store_target->IsJSGlobalObject()) {
          // TODO(dcarney): this currently just deopts. Use the transition cell.
          TRACE_HANDLER_STATS(isolate(), StoreIC_StoreGlobalTransition);
          auto cell = isolate()->factory()->NewPropertyCell();
          cell->set_value(*value);
          auto code = PropertyCellStoreHandler(
              isolate(), store_target, Handle<JSGlobalObject>::cast(store_target),
              lookup->name(), cell, PropertyCellType::kConstant);
          cell->set_value(isolate()->heap()->the_hole_value());
          return code;
        }
        Handle<Map> transition = lookup->transition_map();
        // Currently not handled by CompileStoreTransition.
        DCHECK(holder->HasFastProperties());
  
        DCHECK(lookup->IsCacheableTransition());
        TRACE_HANDLER_STATS(isolate(), StoreIC_StoreTransition);
        NamedStoreHandlerCompiler compiler(isolate(), receiver_map(), holder);
        return compiler.CompileStoreTransition(transition, lookup->name());
      }
  
      case LookupIterator::INTERCEPTOR:
        UNREACHABLE();
  
      case LookupIterator::ACCESSOR: {
        DCHECK(holder->HasFastProperties());
        Handle<Object> accessors = lookup->GetAccessors();
        if (accessors->IsAccessorInfo()) {
          Handle<AccessorInfo> info = Handle<AccessorInfo>::cast(accessors);
          DCHECK(v8::ToCData<Address>(info->setter()) != 0);
          DCHECK(!AccessorInfo::cast(*accessors)->is_special_data_property() ||
                 lookup->HolderIsReceiverOrHiddenPrototype());
          DCHECK(AccessorInfo::IsCompatibleReceiverMap(isolate(), info,
                                                       receiver_map()));
          DCHECK(!info->is_sloppy() || receiver->IsJSReceiver());
          TRACE_HANDLER_STATS(isolate(), StoreIC_StoreCallback);
          NamedStoreHandlerCompiler compiler(isolate(), receiver_map(), holder);
          Handle<Code> code = compiler.CompileStoreCallback(
              receiver, lookup->name(), info, language_mode());
          if (FLAG_runtime_call_stats) return slow_stub();
          return code;
        } else {
          DCHECK(accessors->IsAccessorPair());
          Handle<Object> setter(Handle<AccessorPair>::cast(accessors)->setter(),
                                isolate());
          DCHECK(setter->IsJSFunction() || setter->IsFunctionTemplateInfo());
          CallOptimization call_optimization(setter);
          NamedStoreHandlerCompiler compiler(isolate(), receiver_map(), holder);
          if (call_optimization.is_simple_api_call()) {
            DCHECK(call_optimization.IsCompatibleReceiver(receiver, holder));
            TRACE_HANDLER_STATS(isolate(), StoreIC_StoreCallback);
            Handle<Code> code = compiler.CompileStoreCallback(
                receiver, lookup->name(), call_optimization,
                lookup->GetAccessorIndex());
            if (FLAG_runtime_call_stats) return slow_stub();
            return code;
          }
          TRACE_HANDLER_STATS(isolate(), StoreIC_StoreViaSetter);
          int expected_arguments = JSFunction::cast(*setter)
                                       ->shared()
                                       ->internal_formal_parameter_count();
          return compiler.CompileStoreViaSetter(receiver, lookup->name(),
                                                lookup->GetAccessorIndex(),
                                                expected_arguments);
        }
      }
  
      case LookupIterator::DATA: {
        if (lookup->is_dictionary_holder()) {
          DCHECK(holder->IsJSGlobalObject());
          TRACE_HANDLER_STATS(isolate(), StoreIC_StoreGlobal);
          DCHECK(holder.is_identical_to(receiver) ||
                 receiver->map()->prototype() == *holder);
          auto cell = lookup->GetPropertyCell();
          auto updated_type =
              PropertyCell::UpdatedType(cell, value, lookup->property_details());
          auto code = PropertyCellStoreHandler(
              isolate(), receiver, Handle<JSGlobalObject>::cast(holder),
              lookup->name(), cell, updated_type);
          return code;
        }
  
        // -------------- Fields --------------
        if (lookup->property_details().type() == DATA) {
  #ifdef DEBUG
          bool use_stub = true;
          if (lookup->representation().IsHeapObject()) {
            // Only use a generic stub if no types need to be tracked.
            Handle<FieldType> field_type = lookup->GetFieldType();
            use_stub = !field_type->IsClass();
          }
          DCHECK(!use_stub);
  #endif
          TRACE_HANDLER_STATS(isolate(), StoreIC_StoreField);
          NamedStoreHandlerCompiler compiler(isolate(), receiver_map(), holder);
          return compiler.CompileStoreField(lookup);
        }
  
        // -------------- Constant properties --------------
        DCHECK(lookup->property_details().type() == DATA_CONSTANT);
        UNREACHABLE();
      }
  
      case LookupIterator::INTEGER_INDEXED_EXOTIC:
      case LookupIterator::ACCESS_CHECK:
      case LookupIterator::JSPROXY:
      case LookupIterator::NOT_FOUND:
        UNREACHABLE();
    }
    UNREACHABLE();
    return slow_stub();
  }
  
  void KeyedStoreIC::UpdateStoreElement(Handle<Map> receiver_map,
                                        KeyedAccessStoreMode store_mode) {
    MapHandleList target_receiver_maps;
    TargetMaps(&target_receiver_maps);
    if (target_receiver_maps.length() == 0) {
      Handle<Map> monomorphic_map =
          ComputeTransitionedMap(receiver_map, store_mode);
      store_mode = GetNonTransitioningStoreMode(store_mode);
      Handle<Code> handler =
          PropertyICCompiler::ComputeKeyedStoreMonomorphicHandler(monomorphic_map,
                                                                  store_mode);
      return ConfigureVectorState(Handle<Name>(), monomorphic_map, handler);
    }
  
    for (int i = 0; i < target_receiver_maps.length(); i++) {
      if (!target_receiver_maps.at(i).is_null() &&
          target_receiver_maps.at(i)->instance_type() == JS_VALUE_TYPE) {
        TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "JSValue");
        return;
      }
    }
  
    // There are several special cases where an IC that is MONOMORPHIC can still
    // transition to a different GetNonTransitioningStoreMode IC that handles a
    // superset of the original IC. Handle those here if the receiver map hasn't
    // changed or it has transitioned to a more general kind.
    KeyedAccessStoreMode old_store_mode = GetKeyedAccessStoreMode();
    Handle<Map> previous_receiver_map = target_receiver_maps.at(0);
    if (state() == MONOMORPHIC) {
      Handle<Map> transitioned_receiver_map = receiver_map;
      if (IsTransitionStoreMode(store_mode)) {
        transitioned_receiver_map =
            ComputeTransitionedMap(receiver_map, store_mode);
      }
      if ((receiver_map.is_identical_to(previous_receiver_map) &&
           IsTransitionStoreMode(store_mode)) ||
          IsTransitionOfMonomorphicTarget(*previous_receiver_map,
                                          *transitioned_receiver_map)) {
        // If the "old" and "new" maps are in the same elements map family, or
        // if they at least come from the same origin for a transitioning store,
        // stay MONOMORPHIC and use the map for the most generic ElementsKind.
        store_mode = GetNonTransitioningStoreMode(store_mode);
        Handle<Code> handler =
            PropertyICCompiler::ComputeKeyedStoreMonomorphicHandler(
                transitioned_receiver_map, store_mode);
        ConfigureVectorState(Handle<Name>(), transitioned_receiver_map, handler);
        return;
      }
      if (receiver_map.is_identical_to(previous_receiver_map) &&
          old_store_mode == STANDARD_STORE &&
          (store_mode == STORE_AND_GROW_NO_TRANSITION ||
           store_mode == STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS ||
           store_mode == STORE_NO_TRANSITION_HANDLE_COW)) {
        // A "normal" IC that handles stores can switch to a version that can
        // grow at the end of the array, handle OOB accesses or copy COW arrays
        // and still stay MONOMORPHIC.
        Handle<Code> handler =
            PropertyICCompiler::ComputeKeyedStoreMonomorphicHandler(receiver_map,
                                                                    store_mode);
        return ConfigureVectorState(Handle<Name>(), receiver_map, handler);
      }
    }
  
    DCHECK(state() != GENERIC);
  
    bool map_added =
        AddOneReceiverMapIfMissing(&target_receiver_maps, receiver_map);
  
    if (IsTransitionStoreMode(store_mode)) {
      Handle<Map> transitioned_receiver_map =
          ComputeTransitionedMap(receiver_map, store_mode);
      map_added |= AddOneReceiverMapIfMissing(&target_receiver_maps,
                                              transitioned_receiver_map);
    }
  
    if (!map_added) {
      // If the miss wasn't due to an unseen map, a polymorphic stub
      // won't help, use the megamorphic stub which can handle everything.
      TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "same map added twice");
      return;
    }
  
    // If the maximum number of receiver maps has been exceeded, use the
    // megamorphic version of the IC.
    if (target_receiver_maps.length() > kMaxKeyedPolymorphism) return;
  
    // Make sure all polymorphic handlers have the same store mode, otherwise the
    // megamorphic stub must be used.
    store_mode = GetNonTransitioningStoreMode(store_mode);
    if (old_store_mode != STANDARD_STORE) {
      if (store_mode == STANDARD_STORE) {
        store_mode = old_store_mode;
      } else if (store_mode != old_store_mode) {
        TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "store mode mismatch");
        return;
      }
    }
  
    // If the store mode isn't the standard mode, make sure that all polymorphic
    // receivers are either external arrays, or all "normal" arrays. Otherwise,
    // use the megamorphic stub.
    if (store_mode != STANDARD_STORE) {
      int external_arrays = 0;
      for (int i = 0; i < target_receiver_maps.length(); ++i) {
        if (target_receiver_maps[i]->has_fixed_typed_array_elements()) {
          external_arrays++;
        }
      }
      if (external_arrays != 0 &&
          external_arrays != target_receiver_maps.length()) {
        TRACE_GENERIC_IC(isolate(), "KeyedStoreIC",
                         "unsupported combination of external and normal arrays");
        return;
      }
    }
  
    TRACE_HANDLER_STATS(isolate(), KeyedStoreIC_Polymorphic);
    MapHandleList transitioned_maps(target_receiver_maps.length());
    CodeHandleList handlers(target_receiver_maps.length());
    PropertyICCompiler::ComputeKeyedStorePolymorphicHandlers(
        &target_receiver_maps, &transitioned_maps, &handlers, store_mode);
    ConfigureVectorState(&target_receiver_maps, &transitioned_maps, &handlers);
  }
  
  
  Handle<Map> KeyedStoreIC::ComputeTransitionedMap(
      Handle<Map> map, KeyedAccessStoreMode store_mode) {
    switch (store_mode) {
      case STORE_TRANSITION_TO_OBJECT:
      case STORE_AND_GROW_TRANSITION_TO_OBJECT: {
        ElementsKind kind = IsFastHoleyElementsKind(map->elements_kind())
                                ? FAST_HOLEY_ELEMENTS
                                : FAST_ELEMENTS;
        return Map::TransitionElementsTo(map, kind);
      }
      case STORE_TRANSITION_TO_DOUBLE:
      case STORE_AND_GROW_TRANSITION_TO_DOUBLE: {
        ElementsKind kind = IsFastHoleyElementsKind(map->elements_kind())
                                ? FAST_HOLEY_DOUBLE_ELEMENTS
                                : FAST_DOUBLE_ELEMENTS;
        return Map::TransitionElementsTo(map, kind);
      }
      case STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS:
        DCHECK(map->has_fixed_typed_array_elements());
      // Fall through
      case STORE_NO_TRANSITION_HANDLE_COW:
      case STANDARD_STORE:
      case STORE_AND_GROW_NO_TRANSITION:
        return map;
    }
    UNREACHABLE();
    return MaybeHandle<Map>().ToHandleChecked();
  }
  
  
  bool IsOutOfBoundsAccess(Handle<JSObject> receiver, uint32_t index) {
    uint32_t length = 0;
    if (receiver->IsJSArray()) {
      JSArray::cast(*receiver)->length()->ToArrayLength(&length);
    } else {
      length = static_cast<uint32_t>(receiver->elements()->length());
    }
    return index >= length;
  }
  
  
  static KeyedAccessStoreMode GetStoreMode(Handle<JSObject> receiver,
                                           uint32_t index, Handle<Object> value) {
    bool oob_access = IsOutOfBoundsAccess(receiver, index);
    // Don't consider this a growing store if the store would send the receiver to
    // dictionary mode.
    bool allow_growth = receiver->IsJSArray() && oob_access &&
                        !receiver->WouldConvertToSlowElements(index);
    if (allow_growth) {
      // Handle growing array in stub if necessary.
      if (receiver->HasFastSmiElements()) {
        if (value->IsHeapNumber()) {
          return STORE_AND_GROW_TRANSITION_TO_DOUBLE;
        }
        if (value->IsHeapObject()) {
          return STORE_AND_GROW_TRANSITION_TO_OBJECT;
        }
      } else if (receiver->HasFastDoubleElements()) {
        if (!value->IsSmi() && !value->IsHeapNumber()) {
          return STORE_AND_GROW_TRANSITION_TO_OBJECT;
        }
      }
      return STORE_AND_GROW_NO_TRANSITION;
    } else {
      // Handle only in-bounds elements accesses.
      if (receiver->HasFastSmiElements()) {
        if (value->IsHeapNumber()) {
          return STORE_TRANSITION_TO_DOUBLE;
        } else if (value->IsHeapObject()) {
          return STORE_TRANSITION_TO_OBJECT;
        }
      } else if (receiver->HasFastDoubleElements()) {
        if (!value->IsSmi() && !value->IsHeapNumber()) {
          return STORE_TRANSITION_TO_OBJECT;
        }
      }
      if (!FLAG_trace_external_array_abuse &&
          receiver->map()->has_fixed_typed_array_elements() && oob_access) {
        return STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS;
      }
      Heap* heap = receiver->GetHeap();
      if (receiver->elements()->map() == heap->fixed_cow_array_map()) {
        return STORE_NO_TRANSITION_HANDLE_COW;
      } else {
        return STANDARD_STORE;
      }
    }
  }
  
  
  MaybeHandle<Object> KeyedStoreIC::Store(Handle<Object> object,
                                          Handle<Object> key,
                                          Handle<Object> value) {
    // TODO(verwaest): Let SetProperty do the migration, since storing a property
    // might deprecate the current map again, if value does not fit.
    if (MigrateDeprecated(object)) {
      Handle<Object> result;
      ASSIGN_RETURN_ON_EXCEPTION(
          isolate(), result, Runtime::SetObjectProperty(isolate(), object, key,
                                                        value, language_mode()),
          Object);
      return result;
    }
  
    // Check for non-string values that can be converted into an
    // internalized string directly or is representable as a smi.
    key = TryConvertKey(key, isolate());
  
    Handle<Object> store_handle;
  
    uint32_t index;
    if ((key->IsInternalizedString() &&
         !String::cast(*key)->AsArrayIndex(&index)) ||
        key->IsSymbol()) {
      ASSIGN_RETURN_ON_EXCEPTION(
          isolate(), store_handle,
          StoreIC::Store(object, Handle<Name>::cast(key), value,
                         JSReceiver::MAY_BE_STORE_FROM_KEYED),
          Object);
      if (!is_vector_set()) {
        ConfigureVectorState(MEGAMORPHIC, key);
        TRACE_GENERIC_IC(isolate(), "KeyedStoreIC",
                         "unhandled internalized string key");
        TRACE_IC("StoreIC", key);
      }
      return store_handle;
    }
  
    bool use_ic = FLAG_use_ic && !object->IsStringWrapper() &&
                  !object->IsAccessCheckNeeded() && !object->IsJSGlobalProxy();
    if (use_ic && !object->IsSmi()) {
      // Don't use ICs for maps of the objects in Array's prototype chain. We
      // expect to be able to trap element sets to objects with those maps in
      // the runtime to enable optimization of element hole access.
      Handle<HeapObject> heap_object = Handle<HeapObject>::cast(object);
      if (heap_object->map()->IsMapInArrayPrototypeChain()) {
        TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "map in array prototype");
        use_ic = false;
      }
    }
  
    Handle<Map> old_receiver_map;
    bool sloppy_arguments_elements = false;
    bool key_is_valid_index = false;
    KeyedAccessStoreMode store_mode = STANDARD_STORE;
    if (use_ic && object->IsJSObject()) {
      Handle<JSObject> receiver = Handle<JSObject>::cast(object);
      old_receiver_map = handle(receiver->map(), isolate());
      sloppy_arguments_elements =
          !is_sloppy(language_mode()) &&
          receiver->elements()->map() ==
              isolate()->heap()->sloppy_arguments_elements_map();
      if (!sloppy_arguments_elements) {
        key_is_valid_index = key->IsSmi() && Smi::cast(*key)->value() >= 0;
        if (key_is_valid_index) {
          uint32_t index = static_cast<uint32_t>(Smi::cast(*key)->value());
          store_mode = GetStoreMode(receiver, index, value);
        }
      }
    }
  
    DCHECK(store_handle.is_null());
    ASSIGN_RETURN_ON_EXCEPTION(isolate(), store_handle,
                               Runtime::SetObjectProperty(isolate(), object, key,
                                                          value, language_mode()),
                               Object);
  
    if (use_ic) {
      if (!old_receiver_map.is_null()) {
        if (sloppy_arguments_elements) {
          TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "arguments receiver");
        } else if (key_is_valid_index) {
          // We should go generic if receiver isn't a dictionary, but our
          // prototype chain does have dictionary elements. This ensures that
          // other non-dictionary receivers in the polymorphic case benefit
          // from fast path keyed stores.
          if (!old_receiver_map->DictionaryElementsInPrototypeChainOnly()) {
            UpdateStoreElement(old_receiver_map, store_mode);
          } else {
            TRACE_GENERIC_IC(isolate(), "KeyedStoreIC",
                             "dictionary or proxy prototype");
          }
        } else {
          TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "non-smi-like key");
        }
      } else {
        TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "non-JSObject receiver");
      }
    }
  
    if (!is_vector_set()) {
      ConfigureVectorState(MEGAMORPHIC, key);
      TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "set generic");
    }
    TRACE_IC("StoreIC", key);
  
    return store_handle;
  }
  
  
  void CallIC::HandleMiss(Handle<Object> function) {
    Handle<Object> name = isolate()->factory()->empty_string();
    CallICNexus* nexus = casted_nexus<CallICNexus>();
    Object* feedback = nexus->GetFeedback();
  
    // Hand-coded MISS handling is easier if CallIC slots don't contain smis.
    DCHECK(!feedback->IsSmi());
  
    if (feedback->IsWeakCell() || !function->IsJSFunction() ||
        feedback->IsAllocationSite()) {
      // We are going generic.
      nexus->ConfigureMegamorphic();
    } else {
      DCHECK(feedback == *TypeFeedbackVector::UninitializedSentinel(isolate()));
      Handle<JSFunction> js_function = Handle<JSFunction>::cast(function);
  
      Handle<JSFunction> array_function =
          Handle<JSFunction>(isolate()->native_context()->array_function());
      if (array_function.is_identical_to(js_function)) {
        // Alter the slot.
        nexus->ConfigureMonomorphicArray();
      } else if (js_function->context()->native_context() !=
                 *isolate()->native_context()) {
        // Don't collect cross-native context feedback for the CallIC.
        // TODO(bmeurer): We should collect the SharedFunctionInfo as
        // feedback in this case instead.
        nexus->ConfigureMegamorphic();
      } else {
        nexus->ConfigureMonomorphic(js_function);
      }
    }
  
    if (function->IsJSFunction()) {
      Handle<JSFunction> js_function = Handle<JSFunction>::cast(function);
      name = handle(js_function->shared()->name(), isolate());
    }
  
    OnTypeFeedbackChanged(isolate(), get_host());
    TRACE_IC("CallIC", name);
  }
  
  
  #undef TRACE_IC
  
  
  // ----------------------------------------------------------------------------
  // Static IC stub generators.
  //
  
  // Used from ic-<arch>.cc.
  RUNTIME_FUNCTION(Runtime_CallIC_Miss) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    DCHECK(args.length() == 3);
    Handle<Object> function = args.at<Object>(0);
    Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(1);
    Handle<Smi> slot = args.at<Smi>(2);
    FeedbackVectorSlot vector_slot = vector->ToSlot(slot->value());
    CallICNexus nexus(vector, vector_slot);
    CallIC ic(isolate, &nexus);
    ic.HandleMiss(function);
    return *function;
  }
  
  
  // Used from ic-<arch>.cc.
  RUNTIME_FUNCTION(Runtime_LoadIC_Miss) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    Handle<Object> receiver = args.at<Object>(0);
    Handle<Name> key = args.at<Name>(1);
    Handle<Object> result;
  
    DCHECK(args.length() == 4);
    Handle<Smi> slot = args.at<Smi>(2);
    Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(3);
    FeedbackVectorSlot vector_slot = vector->ToSlot(slot->value());
    // A monomorphic or polymorphic KeyedLoadIC with a string key can call the
    // LoadIC miss handler if the handler misses. Since the vector Nexus is
    // set up outside the IC, handle that here.
    if (vector->GetKind(vector_slot) == FeedbackVectorSlotKind::LOAD_IC) {
      LoadICNexus nexus(vector, vector_slot);
      LoadIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
      ic.UpdateState(receiver, key);
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, ic.Load(receiver, key));
    } else {
      DCHECK_EQ(FeedbackVectorSlotKind::KEYED_LOAD_IC,
                vector->GetKind(vector_slot));
      KeyedLoadICNexus nexus(vector, vector_slot);
      KeyedLoadIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
      ic.UpdateState(receiver, key);
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, ic.Load(receiver, key));
    }
    return *result;
  }
  
  
  // Used from ic-<arch>.cc
  RUNTIME_FUNCTION(Runtime_KeyedLoadIC_Miss) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    Handle<Object> receiver = args.at<Object>(0);
    Handle<Object> key = args.at<Object>(1);
    Handle<Object> result;
  
    DCHECK(args.length() == 4);
    Handle<Smi> slot = args.at<Smi>(2);
    Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(3);
    FeedbackVectorSlot vector_slot = vector->ToSlot(slot->value());
    KeyedLoadICNexus nexus(vector, vector_slot);
    KeyedLoadIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
    ic.UpdateState(receiver, key);
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, ic.Load(receiver, key));
    return *result;
  }
  
  
  RUNTIME_FUNCTION(Runtime_KeyedLoadIC_MissFromStubFailure) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    Handle<Object> receiver = args.at<Object>(0);
    Handle<Object> key = args.at<Object>(1);
    Handle<Object> result;
  
    DCHECK(args.length() == 4);
    Handle<Smi> slot = args.at<Smi>(2);
    Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(3);
    FeedbackVectorSlot vector_slot = vector->ToSlot(slot->value());
    KeyedLoadICNexus nexus(vector, vector_slot);
    KeyedLoadIC ic(IC::EXTRA_CALL_FRAME, isolate, &nexus);
    ic.UpdateState(receiver, key);
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, ic.Load(receiver, key));
  
    return *result;
  }
  
  
  // Used from ic-<arch>.cc.
  RUNTIME_FUNCTION(Runtime_StoreIC_Miss) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    Handle<Object> receiver = args.at<Object>(0);
    Handle<Name> key = args.at<Name>(1);
    Handle<Object> value = args.at<Object>(2);
    Handle<Object> result;
  
    DCHECK(args.length() == 5 || args.length() == 6);
    Handle<Smi> slot = args.at<Smi>(3);
    Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(4);
    FeedbackVectorSlot vector_slot = vector->ToSlot(slot->value());
    if (vector->GetKind(vector_slot) == FeedbackVectorSlotKind::STORE_IC) {
      StoreICNexus nexus(vector, vector_slot);
      StoreIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
      ic.UpdateState(receiver, key);
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                         ic.Store(receiver, key, value));
    } else {
      DCHECK_EQ(FeedbackVectorSlotKind::KEYED_STORE_IC,
                vector->GetKind(vector_slot));
      KeyedStoreICNexus nexus(vector, vector_slot);
      KeyedStoreIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
      ic.UpdateState(receiver, key);
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                         ic.Store(receiver, key, value));
    }
    return *result;
  }
  
  
  RUNTIME_FUNCTION(Runtime_StoreIC_MissFromStubFailure) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    Handle<Object> receiver = args.at<Object>(0);
    Handle<Name> key = args.at<Name>(1);
    Handle<Object> value = args.at<Object>(2);
    Handle<Object> result;
  
    int length = args.length();
    DCHECK(length == 5 || length == 6);
    // We might have slot and vector, for a normal miss (slot(3), vector(4)).
    // Or, map and vector for a transitioning store miss (map(3), vector(4)).
    // In this case, we need to recover the slot from a virtual register.
    // If length == 6, then a map is included (map(3), slot(4), vector(5)).
    Handle<Smi> slot;
    Handle<TypeFeedbackVector> vector;
    if (length == 5) {
      if (args.at<Object>(3)->IsMap()) {
        vector = args.at<TypeFeedbackVector>(4);
        slot = handle(
            *reinterpret_cast<Smi**>(isolate->virtual_slot_register_address()),
            isolate);
      } else {
        vector = args.at<TypeFeedbackVector>(4);
        slot = args.at<Smi>(3);
      }
    } else {
      vector = args.at<TypeFeedbackVector>(5);
      slot = args.at<Smi>(4);
    }
  
    FeedbackVectorSlot vector_slot = vector->ToSlot(slot->value());
    if (vector->GetKind(vector_slot) == FeedbackVectorSlotKind::STORE_IC) {
      StoreICNexus nexus(vector, vector_slot);
      StoreIC ic(IC::EXTRA_CALL_FRAME, isolate, &nexus);
      ic.UpdateState(receiver, key);
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                         ic.Store(receiver, key, value));
    } else {
      DCHECK_EQ(FeedbackVectorSlotKind::KEYED_STORE_IC,
                vector->GetKind(vector_slot));
      KeyedStoreICNexus nexus(vector, vector_slot);
      KeyedStoreIC ic(IC::EXTRA_CALL_FRAME, isolate, &nexus);
      ic.UpdateState(receiver, key);
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                         ic.Store(receiver, key, value));
    }
    return *result;
  }
  
  
  // Used from ic-<arch>.cc.
  RUNTIME_FUNCTION(Runtime_KeyedStoreIC_Miss) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    Handle<Object> receiver = args.at<Object>(0);
    Handle<Object> key = args.at<Object>(1);
    Handle<Object> value = args.at<Object>(2);
    Handle<Object> result;
  
    DCHECK(args.length() == 5);
    Handle<Smi> slot = args.at<Smi>(3);
    Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(4);
    FeedbackVectorSlot vector_slot = vector->ToSlot(slot->value());
    KeyedStoreICNexus nexus(vector, vector_slot);
    KeyedStoreIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
    ic.UpdateState(receiver, key);
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                       ic.Store(receiver, key, value));
    return *result;
  }
  
  
  RUNTIME_FUNCTION(Runtime_KeyedStoreIC_MissFromStubFailure) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    Handle<Object> receiver = args.at<Object>(0);
    Handle<Object> key = args.at<Object>(1);
    Handle<Object> value = args.at<Object>(2);
    Handle<Object> result;
  
    DCHECK(args.length() == 5);
    Handle<Smi> slot = args.at<Smi>(3);
    Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(4);
    FeedbackVectorSlot vector_slot = vector->ToSlot(slot->value());
    KeyedStoreICNexus nexus(vector, vector_slot);
    KeyedStoreIC ic(IC::EXTRA_CALL_FRAME, isolate, &nexus);
    ic.UpdateState(receiver, key);
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                       ic.Store(receiver, key, value));
    return *result;
  }
  
  
  RUNTIME_FUNCTION(Runtime_StoreIC_Slow) {
    HandleScope scope(isolate);
    DCHECK(args.length() == 5);
    Handle<Object> object = args.at<Object>(0);
    Handle<Object> key = args.at<Object>(1);
    Handle<Object> value = args.at<Object>(2);
    LanguageMode language_mode;
    StoreICNexus nexus(isolate);
    StoreIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
    language_mode = ic.language_mode();
    Handle<Object> result;
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
        isolate, result,
        Runtime::SetObjectProperty(isolate, object, key, value, language_mode));
    return *result;
  }
  
  
  RUNTIME_FUNCTION(Runtime_KeyedStoreIC_Slow) {
    HandleScope scope(isolate);
    DCHECK(args.length() == 5);
    Handle<Object> object = args.at<Object>(0);
    Handle<Object> key = args.at<Object>(1);
    Handle<Object> value = args.at<Object>(2);
    LanguageMode language_mode;
    KeyedStoreICNexus nexus(isolate);
    KeyedStoreIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
    language_mode = ic.language_mode();
    Handle<Object> result;
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
        isolate, result,
        Runtime::SetObjectProperty(isolate, object, key, value, language_mode));
    return *result;
  }
  
  
  RUNTIME_FUNCTION(Runtime_ElementsTransitionAndStoreIC_Miss) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    // Length == 5 or 6, depending on whether the vector slot
    // is passed in a virtual register or not.
    DCHECK(args.length() == 5 || args.length() == 6);
    Handle<Object> object = args.at<Object>(0);
    Handle<Object> key = args.at<Object>(1);
    Handle<Object> value = args.at<Object>(2);
    Handle<Map> map = args.at<Map>(3);
    LanguageMode language_mode;
    KeyedStoreICNexus nexus(isolate);
    KeyedStoreIC ic(IC::EXTRA_CALL_FRAME, isolate, &nexus);
    language_mode = ic.language_mode();
    if (object->IsJSObject()) {
      JSObject::TransitionElementsKind(Handle<JSObject>::cast(object),
                                       map->elements_kind());
    }
    Handle<Object> result;
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
        isolate, result,
        Runtime::SetObjectProperty(isolate, object, key, value, language_mode));
    return *result;
  }
  
  
  MaybeHandle<Object> BinaryOpIC::Transition(
      Handle<AllocationSite> allocation_site, Handle<Object> left,
      Handle<Object> right) {
    BinaryOpICState state(isolate(), extra_ic_state());
  
  #ifdef V8_TARGET_ARCH_X64
    // Crash instrumentation for crbug.com/621147.
    uintptr_t left_raw = reinterpret_cast<uintptr_t>(*left);
    uintptr_t hole_raw =
        reinterpret_cast<uintptr_t>(isolate()->heap()->the_hole_value());
    if ((hole_raw & ((1ull << 32) - 1)) == (left_raw & ((1ull << 32) - 1))) {
      Code* c = GetCode();
      Code::Kind kind = c->kind();
      int instruction_size = c->instruction_size() + 2 * sizeof(Address);
      byte* instructions = static_cast<byte*>(alloca(instruction_size));
      Address* start = reinterpret_cast<Address*>(instructions);
      start[0] = fp();
      start[1] = pc();
      for (int i = 2 * sizeof(Address); i < instruction_size; i++) {
        instructions[i] = c->instruction_start()[i];
      }
      isolate()->PushStackTraceAndDie(0xBAAAAAAD, instructions, fp(),
                                      static_cast<unsigned int>(kind));
    }
  #endif  // V8_TARGET_ARCH_X64
  
    // Compute the actual result using the builtin for the binary operation.
    Handle<Object> result;
    switch (state.op()) {
      default:
        UNREACHABLE();
      case Token::ADD:
        ASSIGN_RETURN_ON_EXCEPTION(isolate(), result,
                                   Object::Add(isolate(), left, right), Object);
        break;
      case Token::SUB:
        ASSIGN_RETURN_ON_EXCEPTION(
            isolate(), result, Object::Subtract(isolate(), left, right), Object);
        break;
      case Token::MUL:
        ASSIGN_RETURN_ON_EXCEPTION(
            isolate(), result, Object::Multiply(isolate(), left, right), Object);
        break;
      case Token::DIV:
        ASSIGN_RETURN_ON_EXCEPTION(
            isolate(), result, Object::Divide(isolate(), left, right), Object);
        break;
      case Token::MOD:
        ASSIGN_RETURN_ON_EXCEPTION(
            isolate(), result, Object::Modulus(isolate(), left, right), Object);
        break;
      case Token::BIT_OR:
        ASSIGN_RETURN_ON_EXCEPTION(
            isolate(), result, Object::BitwiseOr(isolate(), left, right), Object);
        break;
      case Token::BIT_AND:
        ASSIGN_RETURN_ON_EXCEPTION(isolate(), result,
                                   Object::BitwiseAnd(isolate(), left, right),
                                   Object);
        break;
      case Token::BIT_XOR:
        ASSIGN_RETURN_ON_EXCEPTION(isolate(), result,
                                   Object::BitwiseXor(isolate(), left, right),
                                   Object);
        break;
      case Token::SAR:
        ASSIGN_RETURN_ON_EXCEPTION(isolate(), result,
                                   Object::ShiftRight(isolate(), left, right),
                                   Object);
        break;
      case Token::SHR:
        ASSIGN_RETURN_ON_EXCEPTION(
            isolate(), result, Object::ShiftRightLogical(isolate(), left, right),
            Object);
        break;
      case Token::SHL:
        ASSIGN_RETURN_ON_EXCEPTION(
            isolate(), result, Object::ShiftLeft(isolate(), left, right), Object);
        break;
    }
  
    // Do not try to update the target if the code was marked for lazy
    // deoptimization. (Since we do not relocate addresses in these
    // code objects, an attempt to access the target could fail.)
    if (AddressIsDeoptimizedCode()) {
      return result;
    }
  
    // Compute the new state.
    BinaryOpICState old_state(isolate(), target()->extra_ic_state());
    state.Update(left, right, result);
  
    // Check if we have a string operation here.
    Handle<Code> new_target;
    if (!allocation_site.is_null() || state.ShouldCreateAllocationMementos()) {
      // Setup the allocation site on-demand.
      if (allocation_site.is_null()) {
        allocation_site = isolate()->factory()->NewAllocationSite();
      }
  
      // Install the stub with an allocation site.
      BinaryOpICWithAllocationSiteStub stub(isolate(), state);
      new_target = stub.GetCodeCopyFromTemplate(allocation_site);
  
      // Sanity check the trampoline stub.
      DCHECK_EQ(*allocation_site, new_target->FindFirstAllocationSite());
    } else {
      // Install the generic stub.
      BinaryOpICStub stub(isolate(), state);
      new_target = stub.GetCode();
  
      // Sanity check the generic stub.
      DCHECK_NULL(new_target->FindFirstAllocationSite());
    }
    set_target(*new_target);
  
    if (FLAG_trace_ic) {
      OFStream os(stdout);
      os << "[BinaryOpIC" << old_state << " => " << state << " @ "
         << static_cast<void*>(*new_target) << " <- ";
      JavaScriptFrame::PrintTop(isolate(), stdout, false, true);
      if (!allocation_site.is_null()) {
        os << " using allocation site " << static_cast<void*>(*allocation_site);
      }
      os << "]" << std::endl;
    }
  
    // Patch the inlined smi code as necessary.
    if (!old_state.UseInlinedSmiCode() && state.UseInlinedSmiCode()) {
      PatchInlinedSmiCode(isolate(), address(), ENABLE_INLINED_SMI_CHECK);
    } else if (old_state.UseInlinedSmiCode() && !state.UseInlinedSmiCode()) {
      PatchInlinedSmiCode(isolate(), address(), DISABLE_INLINED_SMI_CHECK);
    }
  
    return result;
  }
  
  
  RUNTIME_FUNCTION(Runtime_BinaryOpIC_Miss) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    DCHECK_EQ(2, args.length());
    Handle<Object> left = args.at<Object>(BinaryOpICStub::kLeft);
    Handle<Object> right = args.at<Object>(BinaryOpICStub::kRight);
    BinaryOpIC ic(isolate);
    Handle<Object> result;
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
        isolate, result,
        ic.Transition(Handle<AllocationSite>::null(), left, right));
    return *result;
  }
  
  
  RUNTIME_FUNCTION(Runtime_BinaryOpIC_MissWithAllocationSite) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    DCHECK_EQ(3, args.length());
    Handle<AllocationSite> allocation_site =
        args.at<AllocationSite>(BinaryOpWithAllocationSiteStub::kAllocationSite);
    Handle<Object> left = args.at<Object>(BinaryOpWithAllocationSiteStub::kLeft);
    Handle<Object> right =
        args.at<Object>(BinaryOpWithAllocationSiteStub::kRight);
    BinaryOpIC ic(isolate);
    Handle<Object> result;
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
        isolate, result, ic.Transition(allocation_site, left, right));
    return *result;
  }
  
  Code* CompareIC::GetRawUninitialized(Isolate* isolate, Token::Value op) {
    CompareICStub stub(isolate, op, CompareICState::UNINITIALIZED,
                       CompareICState::UNINITIALIZED,
                       CompareICState::UNINITIALIZED);
    Code* code = NULL;
    CHECK(stub.FindCodeInCache(&code));
    return code;
  }
  
  Handle<Code> CompareIC::GetUninitialized(Isolate* isolate, Token::Value op) {
    CompareICStub stub(isolate, op, CompareICState::UNINITIALIZED,
                       CompareICState::UNINITIALIZED,
                       CompareICState::UNINITIALIZED);
    return stub.GetCode();
  }
  
  
  Code* CompareIC::UpdateCaches(Handle<Object> x, Handle<Object> y) {
    HandleScope scope(isolate());
    CompareICStub old_stub(target()->stub_key(), isolate());
    CompareICState::State new_left =
        CompareICState::NewInputState(old_stub.left(), x);
    CompareICState::State new_right =
        CompareICState::NewInputState(old_stub.right(), y);
    CompareICState::State state = CompareICState::TargetState(
        old_stub.state(), old_stub.left(), old_stub.right(), op_,
        HasInlinedSmiCode(address()), x, y);
    CompareICStub stub(isolate(), op_, new_left, new_right, state);
    if (state == CompareICState::KNOWN_RECEIVER) {
      stub.set_known_map(
          Handle<Map>(Handle<JSReceiver>::cast(x)->map(), isolate()));
    }
    Handle<Code> new_target = stub.GetCode();
    set_target(*new_target);
  
    if (FLAG_trace_ic) {
      PrintF("[CompareIC in ");
      JavaScriptFrame::PrintTop(isolate(), stdout, false, true);
      PrintF(" ((%s+%s=%s)->(%s+%s=%s))#%s @ %p]\n",
             CompareICState::GetStateName(old_stub.left()),
             CompareICState::GetStateName(old_stub.right()),
             CompareICState::GetStateName(old_stub.state()),
             CompareICState::GetStateName(new_left),
             CompareICState::GetStateName(new_right),
             CompareICState::GetStateName(state), Token::Name(op_),
             static_cast<void*>(*stub.GetCode()));
    }
  
    // Activate inlined smi code.
    if (old_stub.state() == CompareICState::UNINITIALIZED) {
      PatchInlinedSmiCode(isolate(), address(), ENABLE_INLINED_SMI_CHECK);
    }
  
    return *new_target;
  }
  
  
  // Used from CompareICStub::GenerateMiss in code-stubs-<arch>.cc.
  RUNTIME_FUNCTION(Runtime_CompareIC_Miss) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    DCHECK(args.length() == 3);
    CompareIC ic(isolate, static_cast<Token::Value>(args.smi_at(2)));
    return ic.UpdateCaches(args.at<Object>(0), args.at<Object>(1));
  }
  
  
  RUNTIME_FUNCTION(Runtime_Unreachable) {
    UNREACHABLE();
    CHECK(false);
    return isolate->heap()->undefined_value();
  }
  
  
  Handle<Object> ToBooleanIC::ToBoolean(Handle<Object> object) {
    ToBooleanICStub stub(isolate(), extra_ic_state());
    bool to_boolean_value = stub.UpdateStatus(object);
    Handle<Code> code = stub.GetCode();
    set_target(*code);
    return isolate()->factory()->ToBoolean(to_boolean_value);
  }
  
  
  RUNTIME_FUNCTION(Runtime_ToBooleanIC_Miss) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    DCHECK(args.length() == 1);
    HandleScope scope(isolate);
    Handle<Object> object = args.at<Object>(0);
    ToBooleanIC ic(isolate);
    return *ic.ToBoolean(object);
  }
  
  
  RUNTIME_FUNCTION(Runtime_StoreCallbackProperty) {
    Handle<JSObject> receiver = args.at<JSObject>(0);
    Handle<JSObject> holder = args.at<JSObject>(1);
    Handle<HeapObject> callback_or_cell = args.at<HeapObject>(2);
    Handle<Name> name = args.at<Name>(3);
    Handle<Object> value = args.at<Object>(4);
    CONVERT_LANGUAGE_MODE_ARG_CHECKED(language_mode, 5);
    HandleScope scope(isolate);
  
    Handle<AccessorInfo> callback(
        callback_or_cell->IsWeakCell()
            ? AccessorInfo::cast(WeakCell::cast(*callback_or_cell)->value())
            : AccessorInfo::cast(*callback_or_cell));
  
    DCHECK(callback->IsCompatibleReceiver(*receiver));
  
    Address setter_address = v8::ToCData<Address>(callback->setter());
    v8::AccessorNameSetterCallback fun =
        FUNCTION_CAST<v8::AccessorNameSetterCallback>(setter_address);
    DCHECK(fun != NULL);
  
    Object::ShouldThrow should_throw =
        is_sloppy(language_mode) ? Object::DONT_THROW : Object::THROW_ON_ERROR;
    PropertyCallbackArguments custom_args(isolate, callback->data(), *receiver,
                                          *holder, should_throw);
    custom_args.Call(fun, name, value);
    RETURN_FAILURE_IF_SCHEDULED_EXCEPTION(isolate);
    return *value;
  }
  
  
  /**
   * Attempts to load a property with an interceptor (which must be present),
   * but doesn't search the prototype chain.
   *
   * Returns |Heap::no_interceptor_result_sentinel()| if interceptor doesn't
   * provide any value for the given name.
   */
  RUNTIME_FUNCTION(Runtime_LoadPropertyWithInterceptorOnly) {
    DCHECK(args.length() == NamedLoadHandlerCompiler::kInterceptorArgsLength);
    Handle<Name> name =
        args.at<Name>(NamedLoadHandlerCompiler::kInterceptorArgsNameIndex);
    Handle<Object> receiver =
        args.at<Object>(NamedLoadHandlerCompiler::kInterceptorArgsThisIndex);
    Handle<JSObject> holder =
        args.at<JSObject>(NamedLoadHandlerCompiler::kInterceptorArgsHolderIndex);
    HandleScope scope(isolate);
  
    if (!receiver->IsJSReceiver()) {
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
          isolate, receiver, Object::ConvertReceiver(isolate, receiver));
    }
  
    InterceptorInfo* interceptor = holder->GetNamedInterceptor();
    PropertyCallbackArguments arguments(isolate, interceptor->data(), *receiver,
                                        *holder, Object::DONT_THROW);
  
    v8::GenericNamedPropertyGetterCallback getter =
        v8::ToCData<v8::GenericNamedPropertyGetterCallback>(
            interceptor->getter());
    Handle<Object> result = arguments.Call(getter, name);
  
    RETURN_FAILURE_IF_SCHEDULED_EXCEPTION(isolate);
  
    if (!result.is_null()) return *result;
    return isolate->heap()->no_interceptor_result_sentinel();
  }
  
  
  /**
   * Loads a property with an interceptor performing post interceptor
   * lookup if interceptor failed.
   */
  RUNTIME_FUNCTION(Runtime_LoadPropertyWithInterceptor) {
    HandleScope scope(isolate);
    DCHECK(args.length() == NamedLoadHandlerCompiler::kInterceptorArgsLength);
    Handle<Name> name =
        args.at<Name>(NamedLoadHandlerCompiler::kInterceptorArgsNameIndex);
    Handle<Object> receiver =
        args.at<Object>(NamedLoadHandlerCompiler::kInterceptorArgsThisIndex);
    Handle<JSObject> holder =
        args.at<JSObject>(NamedLoadHandlerCompiler::kInterceptorArgsHolderIndex);
  
    if (!receiver->IsJSReceiver()) {
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
          isolate, receiver, Object::ConvertReceiver(isolate, receiver));
    }
  
    InterceptorInfo* interceptor = holder->GetNamedInterceptor();
    PropertyCallbackArguments arguments(isolate, interceptor->data(), *receiver,
                                        *holder, Object::DONT_THROW);
  
    v8::GenericNamedPropertyGetterCallback getter =
        v8::ToCData<v8::GenericNamedPropertyGetterCallback>(
            interceptor->getter());
    Handle<Object> result = arguments.Call(getter, name);
  
    RETURN_FAILURE_IF_SCHEDULED_EXCEPTION(isolate);
  
    if (!result.is_null()) return *result;
  
    LookupIterator it(receiver, name, holder);
    // Skip any lookup work until we hit the (possibly non-masking) interceptor.
    while (it.state() != LookupIterator::INTERCEPTOR ||
           !it.GetHolder<JSObject>().is_identical_to(holder)) {
      DCHECK(it.state() != LookupIterator::ACCESS_CHECK || it.HasAccess());
      it.Next();
    }
    // Skip past the interceptor.
    it.Next();
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, Object::GetProperty(&it));
  
    if (it.IsFound()) return *result;
  
    LoadICNexus nexus(isolate);
    LoadIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
    if (!ic.ShouldThrowReferenceError(it.GetReceiver())) {
      return isolate->heap()->undefined_value();
    }
  
    // Throw a reference error.
    THROW_NEW_ERROR_RETURN_FAILURE(
        isolate, NewReferenceError(MessageTemplate::kNotDefined, it.name()));
  }
  
  
  RUNTIME_FUNCTION(Runtime_StorePropertyWithInterceptor) {
    HandleScope scope(isolate);
    DCHECK(args.length() == 3);
    StoreICNexus nexus(isolate);
    StoreIC ic(IC::NO_EXTRA_FRAME, isolate, &nexus);
    Handle<JSObject> receiver = args.at<JSObject>(0);
    Handle<Name> name = args.at<Name>(1);
    Handle<Object> value = args.at<Object>(2);
  
    DCHECK(receiver->HasNamedInterceptor());
    InterceptorInfo* interceptor = receiver->GetNamedInterceptor();
    DCHECK(!interceptor->non_masking());
    PropertyCallbackArguments arguments(isolate, interceptor->data(), *receiver,
                                        *receiver, Object::DONT_THROW);
  
    v8::GenericNamedPropertySetterCallback setter =
        v8::ToCData<v8::GenericNamedPropertySetterCallback>(
            interceptor->setter());
    Handle<Object> result = arguments.Call(setter, name, value);
    RETURN_FAILURE_IF_SCHEDULED_EXCEPTION(isolate);
    if (!result.is_null()) return *value;
  
    LookupIterator it(receiver, name, receiver);
    // Skip past any access check on the receiver.
    if (it.state() == LookupIterator::ACCESS_CHECK) {
      DCHECK(it.HasAccess());
      it.Next();
    }
    // Skip past the interceptor on the receiver.
    DCHECK_EQ(LookupIterator::INTERCEPTOR, it.state());
    it.Next();
  
    MAYBE_RETURN(Object::SetProperty(&it, value, ic.language_mode(),
                                     JSReceiver::CERTAINLY_NOT_STORE_FROM_KEYED),
                 isolate->heap()->exception());
    return *value;
  }
  
  
  RUNTIME_FUNCTION(Runtime_LoadElementWithInterceptor) {
    // TODO(verwaest): This should probably get the holder and receiver as input.
    HandleScope scope(isolate);
    Handle<JSObject> receiver = args.at<JSObject>(0);
    DCHECK(args.smi_at(1) >= 0);
    uint32_t index = args.smi_at(1);
  
    InterceptorInfo* interceptor = receiver->GetIndexedInterceptor();
    PropertyCallbackArguments arguments(isolate, interceptor->data(), *receiver,
                                        *receiver, Object::DONT_THROW);
  
    v8::IndexedPropertyGetterCallback getter =
        v8::ToCData<v8::IndexedPropertyGetterCallback>(interceptor->getter());
    Handle<Object> result = arguments.Call(getter, index);
  
    RETURN_FAILURE_IF_SCHEDULED_EXCEPTION(isolate);
  
    if (result.is_null()) {
      LookupIterator it(isolate, receiver, index, receiver);
      DCHECK_EQ(LookupIterator::INTERCEPTOR, it.state());
      it.Next();
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                         Object::GetProperty(&it));
    }
  
    return *result;
  }
  
  
  RUNTIME_FUNCTION(Runtime_LoadIC_MissFromStubFailure) {
    TimerEventScope<TimerEventIcMiss> timer(isolate);
    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.IcMiss");
    HandleScope scope(isolate);
    Handle<Object> receiver = args.at<Object>(0);
    Handle<Name> key = args.at<Name>(1);
    Handle<Object> result;
  
    DCHECK(args.length() == 4);
    Handle<Smi> slot = args.at<Smi>(2);
    Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(3);
    FeedbackVectorSlot vector_slot = vector->ToSlot(slot->value());
    // A monomorphic or polymorphic KeyedLoadIC with a string key can call the
    // LoadIC miss handler if the handler misses. Since the vector Nexus is
    // set up outside the IC, handle that here.
    if (vector->GetKind(vector_slot) == FeedbackVectorSlotKind::LOAD_IC) {
      LoadICNexus nexus(vector, vector_slot);
      LoadIC ic(IC::EXTRA_CALL_FRAME, isolate, &nexus);
      ic.UpdateState(receiver, key);
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, ic.Load(receiver, key));
    } else {
      DCHECK_EQ(FeedbackVectorSlotKind::KEYED_LOAD_IC,
                vector->GetKind(vector_slot));
      KeyedLoadICNexus nexus(vector, vector_slot);
      KeyedLoadIC ic(IC::EXTRA_CALL_FRAME, isolate, &nexus);
      ic.UpdateState(receiver, key);
      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, ic.Load(receiver, key));
    }
  
    return *result;
  }
  }  // namespace internal
  }  // namespace v8
  