Customized support for feedback on calls to Array.

src/ic.cc

 // 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 "v8.h"
 
 #include "accessors.h"
 #include "api.h"
 #include "arguments.h"
 #include "codegen.h"
@@ skipping 483 matching lines @@
   // through the embedded maps.
   SetTargetAtAddress(address, *pre_monomorphic_stub(isolate), constant_pool);
 }
 
 
 void CallIC::Clear(Isolate* isolate,
                    Address address,
                    Code* target,
                    ConstantPoolArray* constant_pool) {
   // Currently, CallIC doesn't have state changes.
-  ASSERT(target->ic_state() == v8::internal::GENERIC);
+  if (target->ic_state() != v8::internal::MONOMORPHIC) return;
+  CallIC::State existing_state(target->extra_ic_state());
+
+  // Monomorphic array stubs don't need to be cleared because
+  // 1) the stub doesn't store information that should be cleared, and
+  // 2) the AllocationSite stored in the type feedback vector is immune
+  //    from gc type feedback clearing.
+  ASSERT(existing_state.stub_type() == MONOMORPHIC_ARRAY);
+  return;

[danno, 2014/05/22 08:20:43]

nit: you don't need the return at the end.

[mvstanton, 2014/05/22 09:29:47]

Done.

 }
 
 
 void LoadIC::Clear(Isolate* isolate,
                    Address address,
                    Code* target,
                    ConstantPoolArray* constant_pool) {
   if (IsCleared(target)) return;
   Code* code = target->GetIsolate()->stub_cache()->FindPreMonomorphicIC(
       Code::LOAD_IC, target->extra_ic_state());
@@ skipping 1295 matching lines @@
       result,
       Runtime::SetObjectProperty(
           isolate(), object, key, value,  NONE, strict_mode()),
       Object);
   return result;
 }
 
 
 CallIC::State::State(ExtraICState extra_ic_state)
     : argc_(ArgcBits::decode(extra_ic_state)),
-      call_type_(CallTypeBits::decode(extra_ic_state)) {
+      call_type_(CallTypeBits::decode(extra_ic_state)),
+      stub_type_(StubTypeBits::decode(extra_ic_state)) {
 }
 
 
 ExtraICState CallIC::State::GetExtraICState() const {
   ExtraICState extra_ic_state =
       ArgcBits::encode(argc_) |
-      CallTypeBits::encode(call_type_);
+      CallTypeBits::encode(call_type_) |
+      StubTypeBits::encode(stub_type_);
   return extra_ic_state;
 }
 
 
+bool CallIC::DoCustomHandler(Handle<Object> receiver,
+                             Handle<Object> function,
+                             Handle<FixedArray> vector,
+                             Handle<Smi> slot,
+                             const State& state) {
+  ASSERT(function->IsJSFunction());
+  // Are we the array function?
+  Handle<JSFunction> array_function = Handle<JSFunction>(
+          isolate()->context()->native_context()->array_function(),

[danno, 2014/05/22 08:20:43]

nit: strange indentations

[mvstanton, 2014/05/22 09:29:47]

Done.

+          isolate());
+  if (array_function.is_identical_to(Handle<JSFunction>::cast(function))) {
+    // Alter the slot.
+    vector->set(slot->value(), *isolate()->factory()->NewAllocationSite());
+    State new_state = state.ToMonomorphicArrayCallState();
+    CallICStub stub(isolate(), new_state);
+    set_target(*stub.GetCode());
+    Handle<String> name;
+    if (array_function->shared()->name()->IsString()) {
+      name = Handle<String>(String::cast(array_function->shared()->name()),
+                            isolate());
+    }
+
+    TRACE_IC("CallIC (Array call)", name);
+    return true;
+  }
+  return false;
+}
+
+
 void CallIC::HandleMiss(Handle<Object> receiver,
                         Handle<Object> function,
                         Handle<FixedArray> vector,
                         Handle<Smi> slot) {
   State state(target()->extra_ic_state());
   Object* feedback = vector->get(slot->value());
 
-  if (feedback->IsJSFunction() || !function->IsJSFunction()) {
+  if (feedback->IsJSFunction() || !function->IsJSFunction() ||
+      state.stub_type() != DEFAULT) {
     // We are going generic.
-    ASSERT(!function->IsJSFunction() || *function != feedback);
-
     vector->set(slot->value(),
                 *TypeFeedbackInfo::MegamorphicSentinel(isolate()),
                 SKIP_WRITE_BARRIER);
+
+    State new_state = state.ToGenericState();
+    if (new_state != state) {
+      // Only happens when the array ic goes generic.
+      ASSERT(state.stub_type() == MONOMORPHIC_ARRAY);
+      CallICStub stub(isolate(), new_state);
+      Handle<Code> code = stub.GetCode();
+      set_target(*code);
+    }
+
     TRACE_GENERIC_IC(isolate(), "CallIC", "megamorphic");
   } else {
     // If we came here feedback must be the uninitialized sentinel,
     // and we are going monomorphic.
     ASSERT(feedback == *TypeFeedbackInfo::UninitializedSentinel(isolate()));
+
+    // Do we want to install a custom handler?
+    if (DoCustomHandler(receiver, function, vector, slot, state)) {
+      return;
+    }
+
     Handle<JSFunction> js_function = Handle<JSFunction>::cast(function);
     Handle<Object> name(js_function->shared()->name(), isolate());
     TRACE_IC("CallIC", name);
     vector->set(slot->value(), *function);
   }
 }
 
 
 #undef TRACE_IC
 
@@ skipping 1124 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal