- Create isolate specific resuable handles and use them in the hot lookup paths.

runtime/vm/object.h

Index: runtime/vm/object.h
===================================================================
--- runtime/vm/object.h	(revision 24061)
+++ runtime/vm/object.h	(working copy)
@@ -169,6 +169,7 @@
     return raw()->ptr();                                                       \
   }                                                                            \
   SNAPSHOT_READER_SUPPORT(object)                                              \
+  friend class Isolate;                                                        \
   friend class StackFrame;                                                     \
 
 // This macro is used to denote types that do not have a sub-type.
@@ -190,6 +191,7 @@
     return raw()->ptr();                                                       \
   }                                                                            \
   SNAPSHOT_READER_SUPPORT(object)                                              \
+  friend class Isolate;                                                        \
   friend class StackFrame;                                                     \
 
 class Object {
@@ -591,6 +593,7 @@
   friend class TwoByteString;
   friend class ExternalOneByteString;
   friend class ExternalTwoByteString;
+  friend class Isolate;
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(Object);
@@ -2354,7 +2357,6 @@
   friend class Class;
   friend class Debugger;
   friend class DictionaryIterator;
-  friend class Isolate;
   friend class Namespace;
   friend class Object;
 };
@@ -2390,7 +2392,6 @@
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(LibraryPrefix, Object);
   friend class Class;
-  friend class Isolate;
 };
 
 
@@ -5808,20 +5809,22 @@
 }
 
 
-void Object::SetRaw(RawObject* value) {
+inline void Object::SetRaw(RawObject* value) {
   // NOTE: The assignment "raw_ = value" should be the first statement in
   // this function. Also do not use 'value' in this function after the
   // assignment (use 'raw_' instead).
   raw_ = value;
-  if ((reinterpret_cast<uword>(raw_) & kSmiTagMask) == kSmiTag) {
-    set_vtable(Smi::handle_vtable_);
-    return;
-  }
-  intptr_t cid = raw_->GetClassId();
-  if (cid >= kNumPredefinedCids) {
+  cpp_vtable vtable_ptr;
+  if ((reinterpret_cast<uword>(value) & kSmiTagMask) == kSmiTag) {
+    vtable_ptr = Smi::handle_vtable_;
+  } else {
+    intptr_t cid = value->GetClassId();
+    if (cid >= kNumPredefinedCids) {
       cid = kInstanceCid;
+    }
+    vtable_ptr = builtin_vtables_[cid];
   }
-  set_vtable(builtin_vtables_[cid]);
+  set_vtable(vtable_ptr);
 #if defined(DEBUG)
   if (FLAG_verify_handles) {
     Isolate* isolate = Isolate::Current();