[Interpreter] Add bytecode aging and use it enable CompilationCache for bytecode

src/objects.cc

 // Copyright 2015 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/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 15157 matching lines @@
             from->length());
 }
 
 int BytecodeArray::LookupRangeInHandlerTable(
     int code_offset, int* data, HandlerTable::CatchPrediction* prediction) {
   HandlerTable* table = HandlerTable::cast(handler_table());
   code_offset++;  // Point after current bytecode.
   return table->LookupRange(code_offset, data, prediction);
 }
 
+void BytecodeArray::MakeOlder() {
+  Age age = bytecode_age();
+  if (age < kLastBytecodeAge) {
+    set_bytecode_age(static_cast<Age>(age + 1));
+  }
+  DCHECK_GE(age, kFirstBytecodeAge);
+  DCHECK_LE(age, kLastBytecodeAge);

[Michael Starzinger, 2016/11/28 14:21:30]

nit: Shouldn't these DCHECKs be applied on the _new_ age? Or alternatively I
would vote for moving them 3 lines up to before the new value is stored (for
readability).

[rmcilroy, 2016/11/28 14:29:04]

Yes the should, updated to check bytecode_age() instead

+}
+
+bool BytecodeArray::IsOld() const {
+  return bytecode_age() >= kIsOldBytecodeAge;
+}
+
 // static
 void JSArray::Initialize(Handle<JSArray> array, int capacity, int length) {
   DCHECK(capacity >= 0);
   array->GetIsolate()->factory()->NewJSArrayStorage(
       array, length, capacity, INITIALIZE_ARRAY_ELEMENTS_WITH_HOLE);
 }
 
 void JSArray::SetLength(Handle<JSArray> array, uint32_t new_length) {
   // We should never end in here with a pixel or external array.
   DCHECK(array->AllowsSetLength());
@@ skipping 2775 matching lines @@
       count = Smi::FromInt(count->value() - 1);
       if (count->value() == 0) {
         NoWriteBarrierSet(this, entry_index, the_hole_value);
         NoWriteBarrierSet(this, value_index, the_hole_value);
         ElementRemoved();
       } else {
         NoWriteBarrierSet(this, value_index, count);
       }
     } else if (get(entry_index)->IsFixedArray()) {
       SharedFunctionInfo* info = SharedFunctionInfo::cast(get(value_index));
-      if (info->code()->kind() != Code::FUNCTION || info->code()->IsOld()) {
+      bool is_old =
+          info->IsInterpreted()
+              ? info->bytecode_array()->IsOld()
+              : info->code()->kind() != Code::FUNCTION || info->code()->IsOld();
+      if (is_old) {
         NoWriteBarrierSet(this, entry_index, the_hole_value);
         NoWriteBarrierSet(this, value_index, the_hole_value);
         ElementRemoved();
       }
     }
   }
 }
 
 
 void CompilationCacheTable::Remove(Object* value) {
@@ skipping 2455 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8