Re-land FastAccessorBuilder.

... using the RawMachineAssembler and the work in crrev.com/1407313004.

The original change collided with crrev.com/1513543003.

BUG=chromium:508898
LOG=Y

Committed: https://crrev.com/515d9ccd8e6df7bf2ca01e2a55aaad30226399e1
Cr-Commit-Position: refs/heads/master@{#32742}

patch from issue 1474543004 at patchset 260001 (http://crrev.com/1474543004#ps260001)

Review URL: https://codereview.chromium.org/1504713012

Cr-Commit-Position: refs/heads/master@{#32753}

BUILD.gn

@@ -596,6 +596,7 @@ source_set("v8_base") {
 
   sources = [
     "include/v8-debug.h",
+    "include/v8-experimental.h",
     "include/v8-platform.h",
     "include/v8-profiler.h",
     "include/v8-testing.h",
@@ -613,6 +614,8 @@ source_set("v8_base") {
     "src/allocation-site-scopes.h",
     "src/api.cc",
     "src/api.h",
+    "src/api-experimental.cc",
+    "src/api-experimental.h",
     "src/api-natives.cc",
     "src/api-natives.h",
     "src/arguments.cc",
@@ -724,6 +727,8 @@ source_set("v8_base") {
     "src/compiler/escape-analysis.h",
     "src/compiler/escape-analysis-reducer.cc",
     "src/compiler/escape-analysis-reducer.h",
+    "src/compiler/fast-accessor-assembler.cc",
+    "src/compiler/fast-accessor-assembler.h",
     "src/compiler/frame.cc",
     "src/compiler/frame.h",
     "src/compiler/frame-elider.cc",

include/v8-experimental.h

+// 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.
+
+/**
+ * This header contains a set of experimental V8 APIs. We hope these will
+ * become a part of standard V8, but they may also be removed if we deem the
+ * experiment to not be successul.
+ */
+#ifndef V8_INCLUDE_V8_EXPERIMENTAL_H_
+#define V8_INCLUDE_V8_EXPERIMENTAL_H_
+
+#include "include/v8.h"
+
+namespace v8 {
+namespace experimental {
+
+// Allow the embedder to construct accessors that V8 can compile and use
+// directly, without jumping into the runtime.
+class V8_EXPORT FastAccessorBuilder {
+ public:
+  struct ValueId {
+    size_t value_id;
+  };
+  struct LabelId {
+    size_t label_id;
+  };
+
+  static FastAccessorBuilder* New(Isolate* isolate);
+
+  ValueId IntegerConstant(int int_constant);
+  ValueId GetReceiver();
+  ValueId LoadInternalField(ValueId value_id, int field_no);
+  ValueId LoadValue(ValueId value_id, int offset);
+  ValueId LoadObject(ValueId value_id, int offset);
+  void ReturnValue(ValueId value_id);
+  void CheckFlagSetOrReturnNull(ValueId value_id, int mask);
+  void CheckNotZeroOrReturnNull(ValueId value_id);
+  LabelId MakeLabel();
+  void SetLabel(LabelId label_id);
+  void CheckNotZeroOrJump(ValueId value_id, LabelId label_id);
+
+ private:
+  FastAccessorBuilder() = delete;
+  FastAccessorBuilder(const FastAccessorBuilder&) = delete;
+  ~FastAccessorBuilder() = delete;
+  void operator=(const FastAccessorBuilder&) = delete;
+};
+
+}  // namespace experimental
+}  // namespace v8
+
+#endif  // V8_INCLUDE_V8_EXPERIMENTAL_H_

include/v8.h

@@ -136,6 +136,10 @@ class CallHandlerHelper;
 class EscapableHandleScope;
 template<typename T> class ReturnValue;
 
+namespace experimental {
+class FastAccessorBuilder;
+}  // namespace experimental
+
 namespace internal {
 class Arguments;
 class Heap;
@@ -4419,7 +4423,8 @@ class V8_EXPORT FunctionTemplate : public Template {
    * the callback cannot be null.
    */
   static Local<FunctionTemplate> NewWithFastHandler(
-      Isolate* isolate, FunctionCallback callback, Local<Value> fast_handler,
+      Isolate* isolate, FunctionCallback callback,
+      experimental::FastAccessorBuilder* fast_handler = nullptr,
       Local<Value> data = Local<Value>(),
       Local<Signature> signature = Local<Signature>(), int length = 0);
 
@@ -4433,9 +4438,9 @@ class V8_EXPORT FunctionTemplate : public Template {
    * callback is called whenever the function created from this
    * FunctionTemplate is called.
    */
-  void SetCallHandler(FunctionCallback callback,
-                      Local<Value> data = Local<Value>(),
-                      Local<Value> fast_handler = Local<Value>());
+  void SetCallHandler(
+      FunctionCallback callback, Local<Value> data = Local<Value>(),
+      experimental::FastAccessorBuilder* fast_handler = nullptr);
 
   /** Set the predefined length property for the FunctionTemplate. */
   void SetLength(int length);

src/DEPS

@@ -25,4 +25,7 @@ specific_include_rules = {
   "d8\.cc": [
     "+include/libplatform/libplatform.h",
   ],
+  "api-experimental\.cc": [
+    "+src/compiler/fast-accessor-assembler.h",
+  ],
 }

src/api-experimental.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.
+
+/**
+ * Implementation for v8-experimental.h.
+ */
+
+#include "src/api-experimental.h"
+
+#include "include/v8.h"
+#include "include/v8-experimental.h"
+#include "src/api.h"
+#include "src/compiler/fast-accessor-assembler.h"
+
+namespace {
+
+
+v8::internal::compiler::FastAccessorAssembler* FromApi(
+    v8::experimental::FastAccessorBuilder* builder) {
+  return reinterpret_cast<v8::internal::compiler::FastAccessorAssembler*>(
+      builder);
+}
+
+
+v8::experimental::FastAccessorBuilder* FromInternal(
+    v8::internal::compiler::FastAccessorAssembler* fast_accessor_assembler) {
+  return reinterpret_cast<v8::experimental::FastAccessorBuilder*>(
+      fast_accessor_assembler);
+}
+
+}  // namespace
+
+namespace v8 {
+namespace internal {
+namespace experimental {
+
+
+MaybeHandle<Code> BuildCodeFromFastAccessorBuilder(
+    v8::experimental::FastAccessorBuilder* fast_handler) {
+  i::MaybeHandle<i::Code> code;
+  if (fast_handler != nullptr) {
+    auto faa = FromApi(fast_handler);
+    code = faa->Build();
+    CHECK(!code.is_null());
+    delete faa;
+  }
+  return code;
+}
+
+}  // namespace experimental
+}  // namespace internal
+
+
+namespace experimental {
+
+
+FastAccessorBuilder* FastAccessorBuilder::New(Isolate* isolate) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  internal::compiler::FastAccessorAssembler* faa =
+      new internal::compiler::FastAccessorAssembler(i_isolate);
+  return FromInternal(faa);
+}
+
+
+FastAccessorBuilder::ValueId FastAccessorBuilder::IntegerConstant(
+    int const_value) {
+  return FromApi(this)->IntegerConstant(const_value);
+}
+
+
+FastAccessorBuilder::ValueId FastAccessorBuilder::GetReceiver() {
+  return FromApi(this)->GetReceiver();
+}
+
+
+FastAccessorBuilder::ValueId FastAccessorBuilder::LoadInternalField(
+    ValueId value, int field_no) {
+  return FromApi(this)->LoadInternalField(value, field_no);
+}
+
+
+FastAccessorBuilder::ValueId FastAccessorBuilder::LoadValue(ValueId value_id,
+                                                            int offset) {
+  return FromApi(this)->LoadValue(value_id, offset);
+}
+
+
+FastAccessorBuilder::ValueId FastAccessorBuilder::LoadObject(ValueId value_id,
+                                                             int offset) {
+  return FromApi(this)->LoadObject(value_id, offset);
+}
+
+
+void FastAccessorBuilder::ReturnValue(ValueId value) {
+  FromApi(this)->ReturnValue(value);
+}
+
+
+void FastAccessorBuilder::CheckFlagSetOrReturnNull(ValueId value_id, int mask) {
+  FromApi(this)->CheckFlagSetOrReturnNull(value_id, mask);
+}
+
+
+void FastAccessorBuilder::CheckNotZeroOrReturnNull(ValueId value_id) {
+  FromApi(this)->CheckNotZeroOrReturnNull(value_id);
+}
+
+
+FastAccessorBuilder::LabelId FastAccessorBuilder::MakeLabel() {
+  return FromApi(this)->MakeLabel();
+}
+
+
+void FastAccessorBuilder::SetLabel(LabelId label_id) {
+  FromApi(this)->SetLabel(label_id);
+}
+
+
+void FastAccessorBuilder::CheckNotZeroOrJump(ValueId value_id,
+                                             LabelId label_id) {
+  FromApi(this)->CheckNotZeroOrJump(value_id, label_id);
+}
+
+}  // namespace experimental
+}  // namespace v8

src/api-experimental.h

+// 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.
+
+#ifndef V8_API_EXPERIMENTAL_H_
+#define V8_API_EXPERIMENTAL_H_
+
+#include "src/handles.h"
+
+namespace v8 {
+namespace internal {
+class Code;
+}  // internal;
+namespace experimental {
+class FastAccessorBuilder;
+}  // experimental
+
+namespace internal {
+namespace experimental {
+
+v8::internal::MaybeHandle<v8::internal::Code> BuildCodeFromFastAccessorBuilder(
+    v8::experimental::FastAccessorBuilder* fast_handler);
+
+}  // namespace experimental
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_API_EXPERIMENTAL_H_

src/api.cc

@@ -12,8 +12,10 @@
 #include <limits>
 #include <vector>
 #include "include/v8-debug.h"
+#include "include/v8-experimental.h"
 #include "include/v8-profiler.h"
 #include "include/v8-testing.h"
+#include "src/api-experimental.h"
 #include "src/api-natives.h"
 #include "src/assert-scope.h"
 #include "src/background-parsing-task.h"
@@ -999,7 +1001,7 @@ void FunctionTemplate::Inherit(v8::Local<FunctionTemplate> value) {
 
 static Local<FunctionTemplate> FunctionTemplateNew(
     i::Isolate* isolate, FunctionCallback callback,
-    v8::Local<Value> fast_handler, v8::Local<Value> data,
+    experimental::FastAccessorBuilder* fast_handler, v8::Local<Value> data,
     v8::Local<Signature> signature, int length, bool do_not_cache) {
   i::Handle<i::Struct> struct_obj =
       isolate->factory()->NewStruct(i::FUNCTION_TEMPLATE_INFO_TYPE);
@@ -1040,14 +1042,15 @@ Local<FunctionTemplate> FunctionTemplate::New(Isolate* isolate,
   DCHECK(!i_isolate->serializer_enabled());
   LOG_API(i_isolate, "FunctionTemplate::New");
   ENTER_V8(i_isolate);
-  return FunctionTemplateNew(i_isolate, callback, v8::Local<Value>(), data,
-                             signature, length, false);
+  return FunctionTemplateNew(i_isolate, callback, nullptr, data, signature,
+                             length, false);
 }
 
 
 Local<FunctionTemplate> FunctionTemplate::NewWithFastHandler(
-    Isolate* isolate, FunctionCallback callback, v8::Local<Value> fast_handler,
-    v8::Local<Value> data, v8::Local<Signature> signature, int length) {
+    Isolate* isolate, FunctionCallback callback,
+    experimental::FastAccessorBuilder* fast_handler, v8::Local<Value> data,
+    v8::Local<Signature> signature, int length) {
   // TODO(vogelheim): 'fast_handler' should have a more specific type than
   // Local<Value>.
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
@@ -1077,9 +1080,9 @@ Local<AccessorSignature> AccessorSignature::New(
   } while (false)
 
 
-void FunctionTemplate::SetCallHandler(FunctionCallback callback,
-                                      v8::Local<Value> data,
-                                      v8::Local<Value> fast_handler) {
+void FunctionTemplate::SetCallHandler(
+    FunctionCallback callback, v8::Local<Value> data,
+    experimental::FastAccessorBuilder* fast_handler) {
   auto info = Utils::OpenHandle(this);
   EnsureNotInstantiated(info, "v8::FunctionTemplate::SetCallHandler");
   i::Isolate* isolate = info->GetIsolate();
@@ -1090,10 +1093,10 @@ void FunctionTemplate::SetCallHandler(FunctionCallback callback,
   i::Handle<i::CallHandlerInfo> obj =
       i::Handle<i::CallHandlerInfo>::cast(struct_obj);
   SET_FIELD_WRAPPED(obj, set_callback, callback);
-  if (!fast_handler.IsEmpty()) {
-    i::Handle<i::Object> code = Utils::OpenHandle(*fast_handler);
-    CHECK(code->IsCode());
-    obj->set_fast_handler(*code);
+  i::MaybeHandle<i::Code> code =
+      i::experimental::BuildCodeFromFastAccessorBuilder(fast_handler);
+  if (!code.is_null()) {
+    obj->set_fast_handler(*code.ToHandleChecked());
   }
   if (data.IsEmpty()) {
     data = v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
@@ -4368,7 +4371,7 @@ MaybeLocal<Function> Function::New(Local<Context> context,
   i::Isolate* isolate = Utils::OpenHandle(*context)->GetIsolate();
   LOG_API(isolate, "Function::New");
   ENTER_V8(isolate);
-  return FunctionTemplateNew(isolate, callback, Local<Value>(), data,
+  return FunctionTemplateNew(isolate, callback, nullptr, data,
                              Local<Signature>(), length, true)
       ->GetFunction(context);
 }

src/compiler/fast-accessor-assembler.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/compiler/fast-accessor-assembler.h"
+
+#include "src/base/logging.h"
+#include "src/compiler/graph.h"
+#include "src/compiler/linkage.h"
+#include "src/compiler/pipeline.h"
+#include "src/compiler/raw-machine-assembler.h"
+#include "src/compiler/schedule.h"
+#include "src/compiler/verifier.h"
+#include "src/handles-inl.h"
+#include "src/objects.h"  // For FAA::GetInternalField impl.
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+FastAccessorAssembler::FastAccessorAssembler(Isolate* isolate)
+    : zone_(),
+      assembler_(new RawMachineAssembler(
+          isolate, new (zone()) Graph(zone()),
+          Linkage::GetJSCallDescriptor(&zone_, false, 1,
+                                       CallDescriptor::kNoFlags))),
+      state_(kBuilding) {}
+
+
+FastAccessorAssembler::~FastAccessorAssembler() {}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::IntegerConstant(
+    int const_value) {
+  CHECK_EQ(kBuilding, state_);
+  return FromRaw(assembler_->NumberConstant(const_value));
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::GetReceiver() {
+  CHECK_EQ(kBuilding, state_);
+
+  // For JS call descriptor, the receiver is parameter 0. If we use other
+  // call descriptors, this may or may not hold. So let's check.
+  CHECK(assembler_->call_descriptor()->IsJSFunctionCall());
+  return FromRaw(assembler_->Parameter(0));
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::LoadInternalField(
+    ValueId value, int field_no) {
+  CHECK_EQ(kBuilding, state_);
+  // Determine the 'value' object's instance type.
+  Node* object_map =
+      assembler_->Load(MachineType::Pointer(), FromId(value),
+                       assembler_->IntPtrConstant(
+                           Internals::kHeapObjectMapOffset - kHeapObjectTag));
+  Node* instance_type = assembler_->WordAnd(
+      assembler_->Load(
+          MachineType::Uint16(), object_map,
+          assembler_->IntPtrConstant(
+              Internals::kMapInstanceTypeAndBitFieldOffset - kHeapObjectTag)),
+      assembler_->IntPtrConstant(0xff));
+
+  // Check whether we have a proper JSObject.
+  RawMachineLabel is_jsobject, is_not_jsobject, merge;
+  assembler_->Branch(
+      assembler_->WordEqual(
+          instance_type, assembler_->IntPtrConstant(Internals::kJSObjectType)),
+      &is_jsobject, &is_not_jsobject);
+
+  // JSObject? Then load the internal field field_no.
+  assembler_->Bind(&is_jsobject);
+  Node* internal_field = assembler_->Load(
+      MachineType::Pointer(), FromId(value),
+      assembler_->IntPtrConstant(JSObject::kHeaderSize - kHeapObjectTag +
+                                 kPointerSize * field_no));
+  assembler_->Goto(&merge);
+
+  // No JSObject? Return undefined.
+  // TODO(vogelheim): Check whether this is the appropriate action, or whether
+  //                  the method should take a label instead.
+  assembler_->Bind(&is_not_jsobject);
+  Node* fail_value = assembler_->UndefinedConstant();
+  assembler_->Goto(&merge);
+
+  // Return.
+  assembler_->Bind(&merge);
+  Node* phi = assembler_->Phi(MachineRepresentation::kTagged, internal_field,
+                              fail_value);
+  return FromRaw(phi);
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::LoadValue(ValueId value,
+                                                                int offset) {
+  CHECK_EQ(kBuilding, state_);
+  return FromRaw(assembler_->Load(MachineType::IntPtr(), FromId(value),
+                                  assembler_->IntPtrConstant(offset)));
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::LoadObject(ValueId value,
+                                                                 int offset) {
+  CHECK_EQ(kBuilding, state_);
+  return FromRaw(
+      assembler_->Load(MachineType::AnyTagged(),
+                       assembler_->Load(MachineType::Pointer(), FromId(value),
+                                        assembler_->IntPtrConstant(offset))));
+}
+
+
+void FastAccessorAssembler::ReturnValue(ValueId value) {
+  CHECK_EQ(kBuilding, state_);
+  assembler_->Return(FromId(value));
+}
+
+
+void FastAccessorAssembler::CheckFlagSetOrReturnNull(ValueId value, int mask) {
+  CHECK_EQ(kBuilding, state_);
+  RawMachineLabel pass, fail;
+  assembler_->Branch(
+      assembler_->Word32Equal(
+          assembler_->Word32And(FromId(value), assembler_->Int32Constant(mask)),
+          assembler_->Int32Constant(0)),
+      &pass, &fail);
+  assembler_->Bind(&fail);
+  assembler_->Return(assembler_->NullConstant());
+  assembler_->Bind(&pass);
+}
+
+
+void FastAccessorAssembler::CheckNotZeroOrReturnNull(ValueId value) {
+  CHECK_EQ(kBuilding, state_);
+  RawMachineLabel is_null, not_null;
+  assembler_->Branch(
+      assembler_->IntPtrEqual(FromId(value), assembler_->IntPtrConstant(0)),
+      &is_null, &not_null);
+  assembler_->Bind(&is_null);
+  assembler_->Return(assembler_->NullConstant());
+  assembler_->Bind(&not_null);
+}
+
+
+FastAccessorAssembler::LabelId FastAccessorAssembler::MakeLabel() {
+  CHECK_EQ(kBuilding, state_);
+  RawMachineLabel* label =
+      new (zone()->New(sizeof(RawMachineLabel))) RawMachineLabel;
+  return FromRaw(label);
+}
+
+
+void FastAccessorAssembler::SetLabel(LabelId label_id) {
+  CHECK_EQ(kBuilding, state_);
+  assembler_->Bind(FromId(label_id));
+}
+
+
+void FastAccessorAssembler::CheckNotZeroOrJump(ValueId value_id,
+                                               LabelId label_id) {
+  CHECK_EQ(kBuilding, state_);
+  RawMachineLabel pass;
+  assembler_->Branch(
+      assembler_->IntPtrEqual(FromId(value_id), assembler_->IntPtrConstant(0)),
+      &pass, FromId(label_id));
+  assembler_->Bind(&pass);
+}
+
+
+MaybeHandle<Code> FastAccessorAssembler::Build() {
+  CHECK_EQ(kBuilding, state_);
+
+  // Cleanup: We no longer need this.
+  nodes_.clear();
+  labels_.clear();
+
+  // Export the schedule and call the compiler.
+  CompilationInfo info("FastAccessorAssembler", assembler_->isolate(), zone());
+  Schedule* schedule = assembler_->Export();
+
+  // TODO(vogelheim): Pipeline should have a dedicated entry point for this
+  //                  assembler.
+  MaybeHandle<Code> code = Pipeline::GenerateCodeForTesting(
+      &info, assembler_->call_descriptor(), assembler_->graph(), schedule);
+
+  // Update state & return.
+  state_ = !code.is_null() ? kBuilt : kError;
+  return code;
+}
+
+
+FastAccessorAssembler::ValueId FastAccessorAssembler::FromRaw(Node* node) {
+  nodes_.push_back(node);
+  ValueId value = {nodes_.size() - 1};
+  return value;
+}
+
+
+FastAccessorAssembler::LabelId FastAccessorAssembler::FromRaw(
+    RawMachineLabel* label) {
+  labels_.push_back(label);
+  LabelId label_id = {labels_.size() - 1};
+  return label_id;
+}
+
+
+Node* FastAccessorAssembler::FromId(ValueId value) const {
+  CHECK_LT(value.value_id, nodes_.size());
+  CHECK_NOT_NULL(nodes_.at(value.value_id));
+  return nodes_.at(value.value_id);
+}
+
+
+RawMachineLabel* FastAccessorAssembler::FromId(LabelId label) const {
+  CHECK_LT(label.label_id, labels_.size());
+  CHECK_NOT_NULL(labels_.at(label.label_id));
+  return labels_.at(label.label_id);
+}
+
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8

src/compiler/fast-accessor-assembler.h

+// 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.
+
+#ifndef V8_COMPILER_FAST_ACCESSOR_ASSEMBLER_H_
+#define V8_COMPILER_FAST_ACCESSOR_ASSEMBLER_H_
+
+#include <stdint.h>
+#include <vector>
+
+// Clients of this interface shouldn't depend on lots of compiler internals.
+// Do not include anything from src/compiler here!
+#include "include/v8-experimental.h"
+#include "src/base/macros.h"
+#include "src/base/smart-pointers.h"
+#include "src/handles.h"
+
+
+namespace v8 {
+namespace internal {
+
+class Code;
+class Isolate;
+class Zone;
+
+namespace compiler {
+
+class Node;
+class RawMachineAssembler;
+class RawMachineLabel;
+
+
+// This interface "exports" an aggregated subset of RawMachineAssembler, for
+// use by the API to implement Fast Dom Accessors.
+//
+// This interface is made for this single purpose only and does not attempt
+// to implement a general purpose solution. If you need one, please look at
+// RawMachineAssembler instead.
+//
+// The life cycle of a FastAccessorAssembler has two phases:
+// - After creating the instance, you can call an arbitrary sequence of
+//   builder functions to build the desired function.
+// - When done, you can Build() the accessor and query for the build results.
+//
+// You cannot call any result getters before Build() was called & successful;
+// and you cannot call any builder functions after Build() was called.
+class FastAccessorAssembler {
+ public:
+  typedef v8::experimental::FastAccessorBuilder::ValueId ValueId;
+  typedef v8::experimental::FastAccessorBuilder::LabelId LabelId;
+
+  explicit FastAccessorAssembler(Isolate* isolate);
+  ~FastAccessorAssembler();
+
+  // Builder / assembler functions:
+  ValueId IntegerConstant(int int_constant);
+  ValueId GetReceiver();
+  ValueId LoadInternalField(ValueId value_id, int field_no);
+  ValueId LoadValue(ValueId value_id, int offset);
+  ValueId LoadObject(ValueId value_id, int offset);
+
+  // Builder / assembler functions for control flow.
+  void ReturnValue(ValueId value_id);
+  void CheckFlagSetOrReturnNull(ValueId value_id, int mask);
+  void CheckNotZeroOrReturnNull(ValueId value_id);
+
+  // TODO(vogelheim): Implement a C++ callback.
+  //  void CheckNotNullOrCallback(ValueId value_id, ..c++-callback type...,
+  //     ValueId arg1, ValueId arg2, ...);
+
+  LabelId MakeLabel();
+  void SetLabel(LabelId label_id);
+  void CheckNotZeroOrJump(ValueId value_id, LabelId label_id);
+
+  // Assemble the code.
+  MaybeHandle<Code> Build();
+
+ private:
+  ValueId FromRaw(Node* node);
+  LabelId FromRaw(RawMachineLabel* label);
+  Node* FromId(ValueId value) const;
+  RawMachineLabel* FromId(LabelId value) const;
+
+  Zone* zone() { return &zone_; }
+
+  Zone zone_;
+  base::SmartPointer<RawMachineAssembler> assembler_;
+
+  // To prevent exposing the RMA internals to the outside world, we'll map
+  // Node + Label pointers integers wrapped in ValueId and LabelId instances.
+  // These vectors maintain this mapping.
+  std::vector<Node*> nodes_;
+  std::vector<RawMachineLabel*> labels_;
+
+  // Remember the current state for easy error checking. (We prefer to be
+  // strict as this class will be exposed at the API.)
+  enum { kBuilding, kBuilt, kError } state_;
+
+  DISALLOW_COPY_AND_ASSIGN(FastAccessorAssembler);
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_FAST_ACCESSOR_ASSEMBLER_H_

test/cctest/cctest.gyp

@@ -110,6 +110,7 @@
         # checked in.
         # 'test-api-accessors.cc',
         'test-api-interceptors.cc',
+        'test-api-fast-accessor-builder.cc',
         'test-array-list.cc',
         'test-ast.cc',
         'test-ast-expression-visitor.cc',

test/cctest/cctest.h

@@ -550,6 +550,12 @@ static inline void ExpectUndefined(const char* code) {
 }
 
 
+static inline void ExpectNull(const char* code) {
+  v8::Local<v8::Value> result = CompileRun(code);
+  CHECK(result->IsNull());
+}
+
+
 static inline void CheckDoubleEquals(double expected, double actual) {
   const double kEpsilon = 1e-10;
   CHECK_LE(expected, actual + kEpsilon);

tools/gyp/v8.gyp

@@ -374,6 +374,7 @@
       ],
       'sources': [  ### gcmole(all) ###
         '../../include/v8-debug.h',
+        '../../include/v8-experimental.h',
         '../../include/v8-platform.h',
         '../../include/v8-profiler.h',
         '../../include/v8-testing.h',
@@ -389,6 +390,8 @@
         '../../src/allocation.h',
         '../../src/allocation-site-scopes.cc',
         '../../src/allocation-site-scopes.h',
+        '../../src/api-experimental.cc',
+        '../../src/api-experimental.h',
         '../../src/api.cc',
         '../../src/api.h',
         '../../src/api-natives.cc',
@@ -502,6 +505,8 @@
         '../../src/compiler/escape-analysis.h',
         "../../src/compiler/escape-analysis-reducer.cc",
         "../../src/compiler/escape-analysis-reducer.h",
+        '../../src/compiler/fast-accessor-assembler.cc',
+        '../../src/compiler/fast-accessor-assembler.h',
         '../../src/compiler/frame.cc',
         '../../src/compiler/frame.h',
         '../../src/compiler/frame-elider.cc',