Create optimized versions of the Map/Set clear method

src/hydrogen.cc

 // Copyright 2013 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/hydrogen.h"
 
 #include <sstream>
 
 #include "src/v8.h"
 
@@ skipping 12709 matching lines @@
   CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
   HValue* receiver = Pop();
 
   NoObservableSideEffectsScope no_effects(this);
   HValue* table = BuildAllocateOrderedHashTable<OrderedHashMap>();
   Add<HStoreNamedField>(receiver, HObjectAccess::ForJSCollectionTable(), table);
   return ast_context()->ReturnValue(receiver);
 }
 
 
+template <typename CollectionType>
+void HOptimizedGraphBuilder::BuildOrderedHashTableClear(HValue* receiver) {
+  HValue* old_table =
+      Add<HLoadNamedField>(receiver, static_cast<HValue*>(NULL),
+                           HObjectAccess::ForJSCollectionTable());
+  HValue* new_table = BuildAllocateOrderedHashTable<CollectionType>();
+  Add<HStoreNamedField>(
+      old_table, HObjectAccess::ForOrderedHashTableNextTable<CollectionType>(),
+      new_table);
+  Add<HStoreNamedField>(
+      old_table, HObjectAccess::ForOrderedHashTableNumberOfDeletedElements<
+                     CollectionType>(),
+      Add<HConstant>(CollectionType::kClearedTableSentinel));
+  Add<HStoreNamedField>(receiver, HObjectAccess::ForJSCollectionTable(),
+                        new_table);
+}
+
+
+void HOptimizedGraphBuilder::GenerateSetClear(CallRuntime* call) {
+  DCHECK(call->arguments()->length() == 1);
+  CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
+  HValue* receiver = Pop();
+
+  NoObservableSideEffectsScope no_effects(this);
+  BuildOrderedHashTableClear<OrderedHashSet>(receiver);
+  return ast_context()->ReturnValue(graph()->GetConstantUndefined());
+}
+
+
+void HOptimizedGraphBuilder::GenerateMapClear(CallRuntime* call) {
+  DCHECK(call->arguments()->length() == 1);
+  CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
+  HValue* receiver = Pop();
+
+  NoObservableSideEffectsScope no_effects(this);
+  BuildOrderedHashTableClear<OrderedHashMap>(receiver);
+  return ast_context()->ReturnValue(graph()->GetConstantUndefined());
+}
+
+
 void HOptimizedGraphBuilder::GenerateGetCachedArrayIndex(CallRuntime* call) {
   DCHECK(call->arguments()->length() == 1);
   CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
   HValue* value = Pop();
   HGetCachedArrayIndex* result = New<HGetCachedArrayIndex>(value);
   return ast_context()->ReturnInstruction(result, call->id());
 }
 
 
 void HOptimizedGraphBuilder::GenerateFastOneByteArrayJoin(CallRuntime* call) {
@@ skipping 707 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal