[TypeFeedbackVector] Root literal arrays in function literals slots

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/type-feedback-vector.h"
 
 #include "src/code-stubs.h"
 #include "src/ic/ic-inl.h"
 #include "src/ic/ic-state.h"
 #include "src/objects.h"
@@ skipping 19 matching lines @@
 }
 
 
 FeedbackVectorSlotKind TypeFeedbackMetadata::GetKind(
     FeedbackVectorSlot slot) const {
   int index = VectorICComputer::index(kReservedIndexCount, slot.ToInt());
   int data = Smi::cast(get(index))->value();
   return VectorICComputer::decode(data, slot.ToInt());
 }
 
+int TypeFeedbackMetadata::GetParameter(int parameter_index) const {
+  FixedArray* parameters = FixedArray::cast(get(kParametersTableIndex));
+  return Smi::cast(parameters->get(parameter_index))->value();
+}
+
 void TypeFeedbackMetadata::SetKind(FeedbackVectorSlot slot,
                                    FeedbackVectorSlotKind kind) {
   int index = VectorICComputer::index(kReservedIndexCount, slot.ToInt());
   int data = Smi::cast(get(index))->value();
   int new_data = VectorICComputer::encode(data, slot.ToInt(), kind);
   set(index, Smi::FromInt(new_data));
 }
 
 
 template Handle<TypeFeedbackMetadata> TypeFeedbackMetadata::New(
@@ skipping 34 matching lines @@
   }
 
   Handle<TypeFeedbackMetadata> metadata =
       Handle<TypeFeedbackMetadata>::cast(array);
 
   for (int i = 0; i < slot_count; i++) {
     FeedbackVectorSlotKind kind = spec->GetKind(i);
     metadata->SetKind(FeedbackVectorSlot(i), kind);
   }
 
+  if (spec->parameters_count() > 0) {
+    const int parameters_count = spec->parameters_count();
+    Handle<FixedArray> params_array =
+        factory->NewFixedArray(parameters_count, TENURED);
+    for (int i = 0; i < parameters_count; i++) {
+      params_array->set(i, Smi::FromInt(spec->GetParameter(i)));
+    }
+    metadata->set(kParametersTableIndex, *params_array);
+  } else {
+    metadata->set(kParametersTableIndex, *factory->empty_fixed_array());
+  }
+
   // It's important that the TypeFeedbackMetadata have a COW map, since it's
   // pointed to by both a SharedFunctionInfo and indirectly by closures through
   // the TypeFeedbackVector. The serializer uses the COW map type to decide
   // this object belongs in the startup snapshot and not the partial
   // snapshot(s).
   metadata->set_map(isolate->heap()->fixed_cow_array_map());
 
   return metadata;
 }
 
 
 bool TypeFeedbackMetadata::SpecDiffersFrom(
     const FeedbackVectorSpec* other_spec) const {
   if (other_spec->slots() != slot_count()) {
     return true;
   }
 
   int slots = slot_count();
+  int parameter_index = 0;
   for (int i = 0; i < slots;) {
     FeedbackVectorSlot slot(i);
     FeedbackVectorSlotKind kind = GetKind(slot);
     int entry_size = TypeFeedbackMetadata::GetSlotSize(kind);
 
     if (kind != other_spec->GetKind(i)) {
       return true;
     }
+    if (SlotRequiresParameter(kind)) {
+      int parameter = GetParameter(parameter_index);
+      int other_parameter = other_spec->GetParameter(parameter_index);
+      if (parameter != other_parameter) {
+        return true;
+      }
+      parameter_index++;
+    }
     i += entry_size;
   }
   return false;
 }
 
 bool TypeFeedbackMetadata::DiffersFrom(
     const TypeFeedbackMetadata* other_metadata) const {
   if (other_metadata->slot_count() != slot_count()) {
     return true;
   }
 
   int slots = slot_count();
+  int parameter_index = 0;
   for (int i = 0; i < slots;) {
     FeedbackVectorSlot slot(i);
     FeedbackVectorSlotKind kind = GetKind(slot);
     int entry_size = TypeFeedbackMetadata::GetSlotSize(kind);
     if (GetKind(slot) != other_metadata->GetKind(slot)) {
       return true;
     }
+    if (SlotRequiresParameter(kind)) {
+      if (GetParameter(parameter_index) !=
+          other_metadata->GetParameter(parameter_index)) {
+        return true;
+      }
+      parameter_index++;
+    }
     i += entry_size;
   }
   return false;
 }
 
 const char* TypeFeedbackMetadata::Kind2String(FeedbackVectorSlotKind kind) {
   switch (kind) {
     case FeedbackVectorSlotKind::INVALID:
       return "INVALID";
     case FeedbackVectorSlotKind::CALL_IC:
       return "CALL_IC";
     case FeedbackVectorSlotKind::LOAD_IC:
       return "LOAD_IC";
     case FeedbackVectorSlotKind::LOAD_GLOBAL_IC:
       return "LOAD_GLOBAL_IC";
     case FeedbackVectorSlotKind::KEYED_LOAD_IC:
       return "KEYED_LOAD_IC";
     case FeedbackVectorSlotKind::STORE_IC:
       return "STORE_IC";
     case FeedbackVectorSlotKind::KEYED_STORE_IC:
       return "KEYED_STORE_IC";
     case FeedbackVectorSlotKind::INTERPRETER_BINARYOP_IC:
       return "INTERPRETER_BINARYOP_IC";
     case FeedbackVectorSlotKind::INTERPRETER_COMPARE_IC:
       return "INTERPRETER_COMPARE_IC";
+    case FeedbackVectorSlotKind::CREATE_CLOSURE:
+      return "CREATE_CLOSURE";
     case FeedbackVectorSlotKind::GENERAL:
       return "STUB";
     case FeedbackVectorSlotKind::KINDS_NUMBER:
       break;
   }
   UNREACHABLE();
   return "?";
 }
 
 FeedbackVectorSlotKind TypeFeedbackVector::GetKind(
     FeedbackVectorSlot slot) const {
   DCHECK(!is_empty());
   return metadata()->GetKind(slot);
 }
 
+int TypeFeedbackVector::GetParameter(FeedbackVectorSlot slot) const {
+  DCHECK(!is_empty());
+  DCHECK(
+      TypeFeedbackMetadata::SlotRequiresParameter(metadata()->GetKind(slot)));
+  return FixedArray::cast(Get(slot))->length();
+}
+
 // static
 Handle<TypeFeedbackVector> TypeFeedbackVector::New(
     Isolate* isolate, Handle<TypeFeedbackMetadata> metadata) {
   Factory* factory = isolate->factory();
 
   const int slot_count = metadata->slot_count();
   const int length = slot_count + kReservedIndexCount;
   if (length == kReservedIndexCount) {
     return Handle<TypeFeedbackVector>::cast(
         factory->empty_type_feedback_vector());
   }
 
   Handle<FixedArray> array = factory->NewFixedArray(length, TENURED);
   array->set(kMetadataIndex, *metadata);
   array->set(kInvocationCountIndex, Smi::kZero);
+  int parameter_index = 0;
+  for (int i = 0; i < slot_count;) {

[Benedikt Meurer, 2016/12/11 17:58:09]

Hm, this looks expensive. Did you measure the perf impact?

[mvstanton, 2016/12/21 13:09:13]

The performance does seem to be okay.

+    FeedbackVectorSlot slot(i);
+    FeedbackVectorSlotKind kind = metadata->GetKind(slot);
+    int index = TypeFeedbackVector::GetIndex(slot);
+    int entry_size = TypeFeedbackMetadata::GetSlotSize(kind);
+
+    if (kind == FeedbackVectorSlotKind::CREATE_CLOSURE) {
+      // This fixed array is filled with undefined.
+      int length = metadata->GetParameter(parameter_index++);
+      if (length == 0) {
+        // This is a native function literal. We can always point to
+        // the empty literals array here.
+        array->set(index, *factory->empty_literals_array(), SKIP_WRITE_BARRIER);
+      } else {
+        Handle<FixedArray> value = factory->NewFixedArray(length);
+        array->set(index, *value);
+      }
+    }
+    i += entry_size;
+  }
 
   DisallowHeapAllocation no_gc;
 
   // Ensure we can skip the write barrier
   Handle<Object> uninitialized_sentinel = UninitializedSentinel(isolate);
   DCHECK_EQ(isolate->heap()->uninitialized_symbol(), *uninitialized_sentinel);
   for (int i = 0; i < slot_count;) {
     FeedbackVectorSlot slot(i);
     FeedbackVectorSlotKind kind = metadata->GetKind(slot);
     int index = TypeFeedbackVector::GetIndex(slot);
     int entry_size = TypeFeedbackMetadata::GetSlotSize(kind);
 
     Object* value;
     if (kind == FeedbackVectorSlotKind::LOAD_GLOBAL_IC) {
       value = isolate->heap()->empty_weak_cell();
     } else if (kind == FeedbackVectorSlotKind::INTERPRETER_COMPARE_IC ||
                kind == FeedbackVectorSlotKind::INTERPRETER_BINARYOP_IC) {
       value = Smi::kZero;
     } else {
       value = *uninitialized_sentinel;
     }
-    array->set(index, value, SKIP_WRITE_BARRIER);
 
-    value = kind == FeedbackVectorSlotKind::CALL_IC ? Smi::kZero
-                                                    : *uninitialized_sentinel;
-    for (int j = 1; j < entry_size; j++) {
-      array->set(index + j, value, SKIP_WRITE_BARRIER);
+    if (kind != FeedbackVectorSlotKind::CREATE_CLOSURE) {
+      array->set(index, value, SKIP_WRITE_BARRIER);
+      value = kind == FeedbackVectorSlotKind::CALL_IC ? Smi::kZero
+                                                      : *uninitialized_sentinel;
+      for (int j = 1; j < entry_size; j++) {
+        array->set(index + j, value, SKIP_WRITE_BARRIER);
+      }
     }
     i += entry_size;
   }
   return Handle<TypeFeedbackVector>::cast(array);
 }
 
 
 // static
 int TypeFeedbackVector::GetIndexFromSpec(const FeedbackVectorSpec* spec,
                                          FeedbackVectorSlot slot) {
@@ skipping 14 matching lines @@
 // This logic is copied from
 // StaticMarkingVisitor<StaticVisitor>::VisitCodeTarget.
 static bool ClearLogic(Isolate* isolate) {
   return FLAG_cleanup_code_caches_at_gc && isolate->serializer_enabled();
 }
 
 
 void TypeFeedbackVector::ClearSlotsImpl(SharedFunctionInfo* shared,
                                         bool force_clear) {
   Isolate* isolate = GetIsolate();
+  if (!force_clear && !ClearLogic(isolate)) return;
 
-  if (!force_clear && !ClearLogic(isolate)) return;
+  if (this == isolate->heap()->empty_type_feedback_vector()) return;
 
   Object* uninitialized_sentinel =
       TypeFeedbackVector::RawUninitializedSentinel(isolate);
 
   TypeFeedbackMetadataIterator iter(metadata());
   while (iter.HasNext()) {
     FeedbackVectorSlot slot = iter.Next();
     FeedbackVectorSlotKind kind = iter.kind();
 
     Object* obj = Get(slot);
@@ skipping 29 matching lines @@
           nexus.Clear(shared->code());
           break;
         }
         case FeedbackVectorSlotKind::INTERPRETER_BINARYOP_IC:
         case FeedbackVectorSlotKind::INTERPRETER_COMPARE_IC: {
           DCHECK(Get(slot)->IsSmi());
           // don't clear these smi slots.
           // Set(slot, Smi::kZero);
           break;
         }
+        case FeedbackVectorSlotKind::CREATE_CLOSURE: {
+          // Fill the array with undefined.
+          FixedArray* array = FixedArray::cast(Get(slot));
+          for (int i = 0; i < array->length(); i++) {
+            array->set_undefined(i);
+          }
+          break;
+        }
         case FeedbackVectorSlotKind::GENERAL: {
           if (obj->IsHeapObject()) {
             InstanceType instance_type =
                 HeapObject::cast(obj)->map()->instance_type();
             // AllocationSites are exempt from clearing. They don't store Maps
             // or Code pointers which can cause memory leaks if not cleared
             // regularly.
             if (instance_type != ALLOCATION_SITE_TYPE) {
               Set(slot, uninitialized_sentinel, SKIP_WRITE_BARRIER);
             }
@@ skipping 666 matching lines @@
   return BinaryOperationHintFromFeedback(feedback);
 }
 
 CompareOperationHint CompareICNexus::GetCompareOperationFeedback() const {
   int feedback = Smi::cast(GetFeedback())->value();
   return CompareOperationHintFromFeedback(feedback);
 }
 
 }  // namespace internal
 }  // namespace v8