[builtins] Properly optimize TypedArray/DataView accessors.

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index c596a9ca67d78858b52bf4ed98d27b058cd571ba..a6c8964f467cbc1ab14748672c3d30b5aa496dc0 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -3064,6 +3064,119 @@ BUILTIN(DataViewConstructor_ConstructStub) {
   return *result;
 }
 
+// ES6 section 24.2.4.1 get DataView.prototype.buffer
+BUILTIN(DataViewPrototypeGetBuffer) {
+  HandleScope scope(isolate);
+  CHECK_RECEIVER(JSDataView, data_view, "get DataView.prototype.buffer");
+  return data_view->buffer();
+}
+
+// ES6 section 24.2.4.2 get DataView.prototype.byteLength
+BUILTIN(DataViewPrototypeGetByteLength) {
+  HandleScope scope(isolate);
+  CHECK_RECEIVER(JSDataView, data_view, "get DataView.prototype.byteLength");
+  // TODO(bmeurer): According to the ES6 spec, we should throw a TypeError
+  // here if the JSArrayBuffer of the {data_view} was neutered.
+  return data_view->byte_length();
+}
+
+// ES6 section 24.2.4.3 get DataView.prototype.byteOffset
+BUILTIN(DataViewPrototypeGetByteOffset) {
+  HandleScope scope(isolate);
+  CHECK_RECEIVER(JSDataView, data_view, "get DataView.prototype.byteOffset");
+  // TODO(bmeurer): According to the ES6 spec, we should throw a TypeError
+  // here if the JSArrayBuffer of the {data_view} was neutered.
+  return data_view->byte_offset();
+}
+
+// -----------------------------------------------------------------------------
+// ES6 section 22.2 TypedArray Objects
+
+// ES6 section 22.2.3.1 get %TypedArray%.prototype.buffer
+BUILTIN(TypedArrayPrototypeBuffer) {
+  HandleScope scope(isolate);
+  CHECK_RECEIVER(JSTypedArray, typed_array, "get TypedArray.prototype.buffer");
+  return *typed_array->GetBuffer();
+}
+
+namespace {
+
+void Generate_TypedArrayProtoypeGetter(CodeStubAssembler* assembler,
+                                       const char* method_name,
+                                       int object_offset) {
+  typedef CodeStubAssembler::Label Label;
+  typedef compiler::Node Node;
+
+  Node* receiver = assembler->Parameter(0);
+  Node* context = assembler->Parameter(3);
+
+  // Check if the {receiver} is actually a JSTypedArray.
+  Label if_receiverisincompatible(assembler, Label::kDeferred);
+  assembler->GotoIf(assembler->WordIsSmi(receiver), &if_receiverisincompatible);
+  Node* receiver_instance_type = assembler->LoadInstanceType(receiver);
+  assembler->GotoUnless(
+      assembler->Word32Equal(receiver_instance_type,
+                             assembler->Int32Constant(JS_TYPED_ARRAY_TYPE)),
+      &if_receiverisincompatible);
+
+  // Check if the {receiver}'s JSArrayBuffer was neutered.
+  Node* receiver_buffer =
+      assembler->LoadObjectField(receiver, JSTypedArray::kBufferOffset);
+  Node* receiver_buffer_bit_field = assembler->LoadObjectField(
+      receiver_buffer, JSArrayBuffer::kBitFieldOffset, MachineType::Int8());
+  Label if_receiverisneutered(assembler, Label::kDeferred);
+  assembler->GotoUnless(
+      assembler->Word32Equal(
+          assembler->Word32And(
+              receiver_buffer_bit_field,
+              assembler->Int32Constant(JSArrayBuffer::WasNeutered::kMask)),
+          assembler->Int32Constant(0)),
+      &if_receiverisneutered);
+  assembler->Return(assembler->LoadObjectField(receiver, object_offset));
+
+  assembler->Bind(&if_receiverisneutered);
+  {
+    // The {receiver}s buffer was neutered, default to zero.
+    assembler->Return(assembler->SmiConstant(0));
+  }
+
+  assembler->Bind(&if_receiverisincompatible);
+  {
+    // The {receiver} is not a valid JSGeneratorObject.
+    Node* result = assembler->CallRuntime(
+        Runtime::kThrowIncompatibleMethodReceiver, context,
+        assembler->HeapConstant(assembler->factory()->NewStringFromAsciiChecked(
+            method_name, TENURED)),
+        receiver);
+    assembler->Return(result);  // Never reached.
+  }
+}
+
+}  // namespace
+
+// ES6 section 22.2.3.2 get %TypedArray%.prototype.byteLength
+void Builtins::Generate_TypedArrayPrototypeByteLength(
+    CodeStubAssembler* assembler) {
+  Generate_TypedArrayProtoypeGetter(assembler,
+                                    "get TypedArray.prototype.byteLength",
+                                    JSTypedArray::kByteLengthOffset);
+}
+
+// ES6 section 22.2.3.3 get %TypedArray%.prototype.byteOffset
+void Builtins::Generate_TypedArrayPrototypeByteOffset(
+    CodeStubAssembler* assembler) {
+  Generate_TypedArrayProtoypeGetter(assembler,
+                                    "get TypedArray.prototype.byteOffset",
+                                    JSTypedArray::kByteOffsetOffset);
+}
+
+// ES6 section 22.2.3.18 get %TypedArray%.prototype.length
+void Builtins::Generate_TypedArrayPrototypeLength(
+    CodeStubAssembler* assembler) {
+  Generate_TypedArrayProtoypeGetter(assembler,
+                                    "get TypedArray.prototype.length",
+                                    JSTypedArray::kLengthOffset);
+}
 
 // -----------------------------------------------------------------------------
 // ES6 section 20.3 Date Objects