[turbofan] First step towards sanitizing for-in and making it optimizable.

src/runtime/runtime-forin.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/arguments.h"
+#include "src/runtime/runtime-utils.h"
+#include "src/v8.h"
+
+namespace v8 {
+namespace internal {
+
+RUNTIME_FUNCTION(Runtime_ForInDone) {
+  SealHandleScope scope(isolate);
+  DCHECK_EQ(2, args.length());
+  CONVERT_SMI_ARG_CHECKED(index, 0);
+  CONVERT_SMI_ARG_CHECKED(length, 1);
+  DCHECK_LE(0, index);
+  DCHECK_LE(index, length);
+  return isolate->heap()->ToBoolean(index == length);
+}
+
+
+RUNTIME_FUNCTION(Runtime_ForInFilter) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(2, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, receiver, 0);
+  CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
+  // TODO(turbofan): Fast case for array indices.
+  Handle<Name> name = Runtime::ToName(isolate, key).ToHandleChecked();
+  Maybe<bool> result = JSReceiver::HasProperty(receiver, name);
+  if (result.IsJust() && result.FromJust()) return *name;
+  return isolate->heap()->undefined_value();
+}
+
+
+RUNTIME_FUNCTION(Runtime_ForInNext) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(4, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, receiver, 0);
+  CONVERT_ARG_HANDLE_CHECKED(FixedArray, cache_array, 1);
+  CONVERT_ARG_HANDLE_CHECKED(Object, cache_type, 2);
+  CONVERT_SMI_ARG_CHECKED(index, 3);
+  Handle<Object> key = handle(cache_array->get(index), isolate);
+  // Don't need filtering if expected map still matches that of the receiver,
+  // and neither for proxies.
+  if (receiver->map() == *cache_type || *cache_type == Smi::FromInt(0)) {
+    return *key;
+  }
+  // TODO(turbofan): Fast case for array indices.
+  Handle<Name> name = Runtime::ToName(isolate, key).ToHandleChecked();
+  Maybe<bool> result = JSReceiver::HasProperty(receiver, name);
+  if (result.IsJust() && result.FromJust()) return *name;
+  return isolate->heap()->undefined_value();
+}
+
+
+RUNTIME_FUNCTION(Runtime_ForInStep) {
+  SealHandleScope scope(isolate);
+  DCHECK_EQ(1, args.length());
+  CONVERT_SMI_ARG_CHECKED(index, 0);
+  DCHECK_LE(0, index);
+  DCHECK_LT(index, Smi::kMaxValue);
+  return Smi::FromInt(index + 1);
+}
+
+}  // namespace internal
+}  // namespace v8