Introduce FeedbackNexus for vector-based ics.

src/type-feedback-vector.cc

 // Copyright 2014 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/v8.h"
 
+#include "src/ic/ic.h"
 #include "src/ic/ic-state.h"
 #include "src/objects.h"
 #include "src/type-feedback-vector-inl.h"
 
 namespace v8 {
 namespace internal {
 
 // static
 TypeFeedbackVector::VectorICKind TypeFeedbackVector::FromCodeKind(
     Code::Kind kind) {
@@ skipping 121 matching lines @@
   slots = ICSlots();
   if (slots == 0) return;
 
   // Now clear vector-based ICs. They are all CallICs.
   // Try and pass the containing code (the "host").
   Code* host = shared->code();
   for (int i = 0; i < slots; i++) {
     FeedbackVectorICSlot slot(i);
     Object* obj = Get(slot);
     if (obj != uninitialized_sentinel) {
-      ICUtility::Clear(isolate, Code::CALL_IC, host, this, slot);
+      // TODO(mvstanton): To make this code work with --vector-ics,
+      // additional Nexus types must be created.
+      DCHECK(!FLAG_vector_ics);
+      DCHECK(GetKind(slot) == Code::CALL_IC);
+      CallICNexus nexus(this, slot);
+      ICUtility::Clear(isolate, Code::CALL_IC, host, &nexus);
     }
   }
 }
+
+
+Handle<FixedArray> FeedbackNexus::EnsureArrayOfSize(int length) {
+  Isolate* isolate = GetIsolate();
+  Handle<Object> feedback = handle(GetFeedback(), isolate);
+  if (!feedback->IsFixedArray() ||
+      FixedArray::cast(*feedback)->length() != length) {

[Igor Sheludko, 2014/10/28 11:12:36]

Do we need to allocate another array if existing one is longer than requested?
Does it make sense to right-trim and reuse the existing one?

[mvstanton, 2014/10/28 13:23:28]

Hmm, the only case that would happen would be if the IC is in POLYMORPHIC state
and it's going to a POLYMORPHIC state of lower degree or it's going to
MONOMORPHIC.

Neither of those happen in practice...we only go MONO->POLY, and to climb back
down to MONO there would be intervening states like UNINITIALIZED and/or
PREMONOMORPHIC, which are sentinels, so we'd lose the array in the meantime.

I think an optimization we may really want to do here soon is to share the
monomorphic arrays if possible between different sites.

+    Handle<FixedArray> array = isolate->factory()->NewFixedArray(length);
+    SetFeedback(*array);
+    return array;
+  }
+  return Handle<FixedArray>::cast(feedback);
+}
+
+
+void FeedbackNexus::InstallHandlers(int start_index, TypeHandleList* types,
+                                    CodeHandleList* handlers) {
+  Isolate* isolate = GetIsolate();
+  FixedArray* array = FixedArray::cast(GetFeedback());
+  int receiver_count = types->length();
+  for (int current = 0; current < receiver_count; ++current) {
+    Handle<HeapType> type = types->at(current);
+    Handle<Map> map = IC::TypeToMap(*type, isolate);
+    array->set(start_index + (current * 2), *map);
+    array->set(start_index + (current * 2 + 1), *handlers->at(current));
+  }
+}
+
+
+InlineCacheState CallICNexus::StateFromFeedback() const {
+  Isolate* isolate = GetIsolate();
+  InlineCacheState state = UNINITIALIZED;
+  Object* feedback = GetFeedback();
+
+  if (feedback == *vector()->MegamorphicSentinel(isolate)) {
+    state = GENERIC;
+  } else if (feedback->IsAllocationSite() || feedback->IsJSFunction()) {
+    state = MONOMORPHIC;
+  } else {
+    CHECK(feedback == *vector()->UninitializedSentinel(isolate));
+  }
+
+  return state;
+}
+
+
+void CallICNexus::ConfigureGeneric() {
+  SetFeedback(*vector()->MegamorphicSentinel(GetIsolate()));
+}
+
+
+void CallICNexus::ConfigureMonomorphicArray() {
+  Object* feedback = GetFeedback();
+  if (!feedback->IsAllocationSite()) {
+    Handle<AllocationSite> new_site =
+        GetIsolate()->factory()->NewAllocationSite();
+    SetFeedback(*new_site);
+  }
+}
+
+
+void CallICNexus::ConfigureUninitialized() {
+  SetFeedback(*vector()->UninitializedSentinel(GetIsolate()));
+}
+
+
+void CallICNexus::ConfigureMonomorphic(Handle<JSFunction> function) {
+  SetFeedback(*function);
+}
+

[Igor Sheludko, 2014/10/28 11:12:36]

Empty line is missing.

[mvstanton, 2014/10/28 13:23:28]

Done.

+int FeedbackNexus::ExtractMaps(int start_index, MapHandleList* maps) const {
+  Isolate* isolate = GetIsolate();
+  Object* feedback = GetFeedback();
+  if (feedback->IsFixedArray()) {
+    FixedArray* array = FixedArray::cast(feedback);
+    // The array should be of the form [<optional name>], then
+    // [map, handler, map, handler, ... ]
+    DCHECK(array->length() >= (2 + start_index));
+    for (int i = start_index; i < array->length(); i += 2) {
+      Map* map = Map::cast(array->get(i));
+      maps->Add(handle(map, isolate));
+    }
+    return (array->length() - start_index) / 2;
+  }
+
+  return 0;
+}
+
+
+MaybeHandle<Code> FeedbackNexus::FindHandlerForMap(int start_index,
+                                                   Handle<Map> map) const {
+  Object* feedback = GetFeedback();
+  if (feedback->IsFixedArray()) {
+    FixedArray* array = FixedArray::cast(feedback);
+    for (int i = start_index; i < array->length(); i += 2) {
+      Map* array_map = Map::cast(array->get(i));
+      if (array_map == *map) {
+        Code* code = Code::cast(array->get(i + 1));
+        DCHECK(code->kind() == Code::HANDLER);
+        return handle(code);
+      }
+    }
+  }
+
+  return MaybeHandle<Code>();
+}
+
+
+bool FeedbackNexus::FindHandlers(int start_index, CodeHandleList* code_list,
+                                 int length) const {
+  Object* feedback = GetFeedback();
+  int count = 0;
+  if (feedback->IsFixedArray()) {
+    FixedArray* array = FixedArray::cast(feedback);
+    // The array should be of the form [<optional name>], then
+    // [map, handler, map, handler, ... ]
+    DCHECK(array->length() >= (2 + start_index));
+    for (int i = start_index; i < array->length(); i += 2) {
+      Code* code = Code::cast(array->get(i + 1));
+      DCHECK(code->kind() == Code::HANDLER);
+      code_list->Add(handle(code));
+      count++;
+    }
+  }
+  return count == length;
+}
 }
 }  // namespace v8::internal