Prototype CL for faster DOM accessors.

src/runtime/runtime-ptr.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.
+
+// Implmement runtime functions for Ptr* intrinsics, which are meant for
+// direct access of API object in embedder-supplied code.
+//
+// These intrinsics in this file are rather experimental and not included in
+// any default builds.
+#ifdef V8_JS_ACCESSORS
+
+#include "src/v8.h"
+
+#include "src/arguments.h"
+#include "src/runtime/runtime-utils.h"
+
+namespace v8 {
+namespace internal {
+
+namespace {
+
+// Helper functions & definitions to handle our 'external pointer' pseudo
+// type. Essentially, we're using the "aligned pointer in Smi" hack to
+// transport a C++ pointer between our intrinsics below.
+
+#define CONVERT_PTR_ARG_CHECKED(name, index) \
+  RUNTIME_ASSERT(args[index]->IsSmi());      \
+  intptr_t name = fromObject(args.arguments()[index]);
+
+typedef intptr_t aligned_ptr_t;
+
+
+static aligned_ptr_t fromObject(Object* value) {
+  DCHECK(value->IsSmi());
+  return reinterpret_cast<aligned_ptr_t>(value);
+}
+
+
+static Object* fromAlignedPtr(aligned_ptr_t value) {

[Toon Verwaest, 2015/09/30 13:57:19]

Camelcase function names should start with uppercase.

+  Object* object = reinterpret_cast<Object*>(value);
+  DCHECK(object->IsSmi());
+  return object;
+}
+
+
+static aligned_ptr_t loadAsPtr(aligned_ptr_t value) {
+  return *reinterpret_cast<aligned_ptr_t*>(value);
+}
+
+
+static int32_t loadAsInt32(aligned_ptr_t value) {
+  return *reinterpret_cast<int32_t*>(value);
+}
+
+
+static void checkAlignedOffset(int offset) { DCHECK((offset % 4) == 0); }
+
+
+static Object* objectFromAlignedPtr(aligned_ptr_t value) {
+  Object* object = reinterpret_cast<Object*>(value);
+  DCHECK(!object->IsSmi());
+  return object;
+}
+
+}  // anonymous namespace
+
+
+RUNTIME_FUNCTION(Runtime_PtrGetFromInternalField) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_ARG_HANDLE_CHECKED(JSObject, wrapper, 0);
+  CONVERT_SMI_ARG_CHECKED(field_number, 1);
+  Object* object = wrapper->GetInternalField(field_number);
+  DCHECK(object->IsSmi());
+  return object;
+}
+
+
+RUNTIME_FUNCTION(Runtime_PtrLoadOffset) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_PTR_ARG_CHECKED(ptr, 0);
+  CONVERT_SMI_ARG_CHECKED(offset, 1);
+  checkAlignedOffset(offset);
+  return fromAlignedPtr(loadAsPtr(ptr + offset));
+}
+
+
+RUNTIME_FUNCTION(Runtime_PtrLoadOffsetInt) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_PTR_ARG_CHECKED(ptr, 0);
+  CONVERT_SMI_ARG_CHECKED(offset, 1);
+  checkAlignedOffset(offset);
+  return Smi::FromInt(loadAsInt32(ptr + offset));
+}
+
+
+RUNTIME_FUNCTION(Runtime_PtrLoadOffsetObj) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_PTR_ARG_CHECKED(ptr, 0);
+  return objectFromAlignedPtr(loadAsPtr(ptr));
+}
+
+
+RUNTIME_FUNCTION(Runtime_PtrIsNull) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_PTR_ARG_CHECKED(ptr, 0);
+  return (ptr == 0) ? isolate->heap()->true_value()

[Toon Verwaest, 2015/09/30 13:57:18]

return isolate->heap()->ToBoolean(ptr == nullptr);

+                    : isolate->heap()->false_value();
+}
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_JS_ACCESSORS