Canonicalize handles for optimized compilation.

src/handles-inl.h

Index: src/handles-inl.h
diff --git a/src/handles-inl.h b/src/handles-inl.h
index 8c547e1b9c3eddbcc7f7955e4fefc355962eec61..cfaf4fb6eb68084ccad4051c9627ffd2da91473a 100644
--- a/src/handles-inl.h
+++ b/src/handles-inl.h
@@ -14,15 +14,23 @@ namespace v8 {
 namespace internal {
 
 HandleBase::HandleBase(Object* object, Isolate* isolate)
-    : location_(HandleScope::CreateHandle(isolate, object)) {}
+    : location_(HandleScope::GetHandle(isolate, object)) {}
+
+
+template <typename T>
+// Allocate a new handle for the object, do not canonicalize.
+Handle<T> Handle<T>::New(T* object, Isolate* isolate) {
+  return Handle(
+      reinterpret_cast<T**>(HandleScope::CreateHandle(isolate, object)));
+}
 
 
 HandleScope::HandleScope(Isolate* isolate) {
-  HandleScopeData* current = isolate->handle_scope_data();
+  HandleScopeData* data = isolate->handle_scope_data();
   isolate_ = isolate;
-  prev_next_ = current->next;
-  prev_limit_ = current->limit;
-  current->level++;
+  prev_next_ = data->next;
+  prev_limit_ = data->limit;
+  data->level++;
 }
 
 
@@ -76,7 +84,7 @@ Handle<T> HandleScope::CloseAndEscape(Handle<T> handle_value) {
   // Throw away all handles in the current scope.
   CloseScope(isolate_, prev_next_, prev_limit_);
   // Allocate one handle in the parent scope.
-  DCHECK(current->level > 0);
+  DCHECK(current->level > current->sealed_level);
   Handle<T> result(value, isolate_);
   // Reinitialize the current scope (so that it's ready
   // to be used or closed again).
@@ -87,24 +95,30 @@ Handle<T> HandleScope::CloseAndEscape(Handle<T> handle_value) {
 }
 
 
-template <typename T>
-T** HandleScope::CreateHandle(Isolate* isolate, T* value) {
+Object** HandleScope::CreateHandle(Isolate* isolate, Object* value) {
   DCHECK(AllowHandleAllocation::IsAllowed());
-  HandleScopeData* current = isolate->handle_scope_data();
+  HandleScopeData* data = isolate->handle_scope_data();
 
-  Object** cur = current->next;
-  if (cur == current->limit) cur = Extend(isolate);
+  Object** result = data->next;
+  if (result == data->limit) result = Extend(isolate);
   // Update the current next field, set the value in the created
   // handle, and return the result.
-  DCHECK(cur < current->limit);
-  current->next = cur + 1;
+  DCHECK(result < data->limit);
+  data->next = result + 1;
 
-  T** result = reinterpret_cast<T**>(cur);
   *result = value;
   return result;
 }
 
 
+Object** HandleScope::GetHandle(Isolate* isolate, Object* value) {
+  DCHECK(AllowHandleAllocation::IsAllowed());
+  HandleScopeData* data = isolate->handle_scope_data();
+  CanonicalHandleScope* canonical = data->canonical_scope;
+  return canonical ? canonical->Lookup(value) : CreateHandle(isolate, value);
+}
+
+
 #ifdef DEBUG
 inline SealHandleScope::SealHandleScope(Isolate* isolate) : isolate_(isolate) {
   // Make sure the current thread is allowed to create handles to begin with.
@@ -112,10 +126,10 @@ inline SealHandleScope::SealHandleScope(Isolate* isolate) : isolate_(isolate) {
   HandleScopeData* current = isolate_->handle_scope_data();
   // Shrink the current handle scope to make it impossible to do
   // handle allocations without an explicit handle scope.
-  limit_ = current->limit;
+  prev_limit_ = current->limit;
   current->limit = current->next;
-  level_ = current->level;
-  current->level = 0;
+  prev_sealed_level_ = current->sealed_level;
+  current->sealed_level = current->level;
 }
 
 
@@ -123,10 +137,10 @@ inline SealHandleScope::~SealHandleScope() {
   // Restore state in current handle scope to re-enable handle
   // allocations.
   HandleScopeData* current = isolate_->handle_scope_data();
-  DCHECK_EQ(0, current->level);
-  current->level = level_;
   DCHECK_EQ(current->next, current->limit);
-  current->limit = limit_;
+  current->limit = prev_limit_;
+  DCHECK_EQ(current->level, current->sealed_level);
+  current->sealed_level = prev_sealed_level_;
 }
 
 #endif