Revert of Migrate FastCloneShallowObjectStub to TurboFan

src/code-stubs-hydrogen.cc

Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index 320799db4a79128173b5f1c657a623372e4d134b..50337ad6344ef3e4d97a0dc04cee8a8080d49046 100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -550,6 +550,79 @@
 
 
 template <>
+HValue* CodeStubGraphBuilder<FastCloneShallowObjectStub>::BuildCodeStub() {
+  HValue* undefined = graph()->GetConstantUndefined();
+  HValue* closure = GetParameter(0);
+  HValue* literal_index = GetParameter(1);
+
+  HValue* literals_array = Add<HLoadNamedField>(
+      closure, nullptr, HObjectAccess::ForLiteralsPointer());
+
+  HInstruction* allocation_site = Add<HLoadKeyed>(
+      literals_array, literal_index, nullptr, nullptr, FAST_ELEMENTS,
+      NEVER_RETURN_HOLE, LiteralsArray::kOffsetToFirstLiteral - kHeapObjectTag);
+
+  IfBuilder checker(this);
+  checker.IfNot<HCompareObjectEqAndBranch, HValue*>(allocation_site,
+                                                    undefined);
+  checker.And();
+
+  HObjectAccess access = HObjectAccess::ForAllocationSiteOffset(
+      AllocationSite::kTransitionInfoOffset);
+  HInstruction* boilerplate =
+      Add<HLoadNamedField>(allocation_site, nullptr, access);
+
+  int length = casted_stub()->length();
+  if (length == 0) {
+    // Empty objects have some slack added to them.
+    length = JSObject::kInitialGlobalObjectUnusedPropertiesCount;
+  }
+  int size = JSObject::kHeaderSize + length * kPointerSize;
+  int object_size = size;
+  if (FLAG_allocation_site_pretenuring) {
+    size += AllocationMemento::kSize;
+  }
+
+  HValue* boilerplate_map =
+      Add<HLoadNamedField>(boilerplate, nullptr, HObjectAccess::ForMap());
+  HValue* boilerplate_size = Add<HLoadNamedField>(
+      boilerplate_map, nullptr, HObjectAccess::ForMapInstanceSize());
+  HValue* size_in_words = Add<HConstant>(object_size >> kPointerSizeLog2);
+  checker.If<HCompareNumericAndBranch>(boilerplate_size,
+                                       size_in_words, Token::EQ);
+  checker.Then();
+
+  HValue* size_in_bytes = Add<HConstant>(size);
+
+  HInstruction* object = Add<HAllocate>(size_in_bytes, HType::JSObject(),
+      NOT_TENURED, JS_OBJECT_TYPE);
+
+  for (int i = 0; i < object_size; i += kPointerSize) {
+    HObjectAccess access = HObjectAccess::ForObservableJSObjectOffset(i);
+    Add<HStoreNamedField>(object, access,
+                          Add<HLoadNamedField>(boilerplate, nullptr, access));
+  }
+
+  DCHECK(FLAG_allocation_site_pretenuring || (size == object_size));
+  if (FLAG_allocation_site_pretenuring) {
+    BuildCreateAllocationMemento(
+        object, Add<HConstant>(object_size), allocation_site);
+  }
+
+  environment()->Push(object);
+  checker.ElseDeopt(Deoptimizer::kUninitializedBoilerplateInFastClone);
+  checker.End();
+
+  return environment()->Pop();
+}
+
+
+Handle<Code> FastCloneShallowObjectStub::GenerateCode() {
+  return DoGenerateCode(this);
+}
+
+
+template <>
 HValue* CodeStubGraphBuilder<CreateAllocationSiteStub>::BuildCodeStub() {
   // This stub is performance sensitive, the generated code must be tuned
   // so that it doesn't build an eager frame.