WIP SharedArrayBuffer implementation

src/runtime/runtime-typedarray.cc

Index: src/runtime/runtime-typedarray.cc
diff --git a/src/runtime/runtime-typedarray.cc b/src/runtime/runtime-typedarray.cc
index 59c417f5b7c92ef548e2370703f94109dc670a66..6e2406010915ae4b93dddd92cfd4eaadd1345d69 100644
--- a/src/runtime/runtime-typedarray.cc
+++ b/src/runtime/runtime-typedarray.cc
@@ -26,16 +26,22 @@ void Runtime::FreeArrayBuffer(Isolate* isolate,
   reinterpret_cast<v8::Isolate*>(isolate)
       ->AdjustAmountOfExternalAllocatedMemory(
           -static_cast<int64_t>(allocated_length));
-  CHECK(V8::ArrayBufferAllocator() != NULL);
-  V8::ArrayBufferAllocator()->Free(phantom_array_buffer->backing_store(),
-                                   allocated_length);
+  if (phantom_array_buffer->is_shared()) {
+    CHECK(V8::SharedArrayBufferAllocator() != NULL);
+    V8::SharedArrayBufferAllocator()->Free(
+        phantom_array_buffer->backing_store(), allocated_length);
+  } else {
+    CHECK(V8::ArrayBufferAllocator() != NULL);
+    V8::ArrayBufferAllocator()->Free(phantom_array_buffer->backing_store(),
+                                     allocated_length);
+  }
 }
 
 
 void Runtime::SetupArrayBuffer(Isolate* isolate,
                                Handle<JSArrayBuffer> array_buffer,
                                bool is_external, void* data,
-                               size_t allocated_length) {
+                               size_t allocated_length, bool is_shared) {
   DCHECK(array_buffer->GetInternalFieldCount() ==
          v8::ArrayBuffer::kInternalFieldCount);
   for (int i = 0; i < v8::ArrayBuffer::kInternalFieldCount; i++) {
@@ -45,6 +51,7 @@ void Runtime::SetupArrayBuffer(Isolate* isolate,
   array_buffer->set_flag(Smi::FromInt(0));
   array_buffer->set_is_external(is_external);
   array_buffer->set_is_neuterable(true);
+  array_buffer->set_is_shared(is_shared);
 
   Handle<Object> byte_length =
       isolate->factory()->NewNumberFromSize(allocated_length);
@@ -60,24 +67,35 @@ void Runtime::SetupArrayBuffer(Isolate* isolate,
 bool Runtime::SetupArrayBufferAllocatingData(Isolate* isolate,
                                              Handle<JSArrayBuffer> array_buffer,
                                              size_t allocated_length,
-                                             bool initialize) {
+                                             bool initialize, bool is_shared) {
   void* data;
-  CHECK(V8::ArrayBufferAllocator() != NULL);
+  CHECK(is_shared ? V8::SharedArrayBufferAllocator() != NULL
+                  : V8::ArrayBufferAllocator() != NULL);
   // Prevent creating array buffers when serializing.
   DCHECK(!isolate->serializer_enabled());
   if (allocated_length != 0) {
-    if (initialize) {
-      data = V8::ArrayBufferAllocator()->Allocate(allocated_length);
+    if (is_shared) {
+      if (initialize) {
+        data = V8::SharedArrayBufferAllocator()->Allocate(allocated_length);
+      } else {
+        data = V8::SharedArrayBufferAllocator()->AllocateUninitialized(
+            allocated_length);
+      }
     } else {
-      data =
-          V8::ArrayBufferAllocator()->AllocateUninitialized(allocated_length);
+      if (initialize) {
+        data = V8::ArrayBufferAllocator()->Allocate(allocated_length);
+      } else {
+        data =
+            V8::ArrayBufferAllocator()->AllocateUninitialized(allocated_length);
+      }
     }
     if (data == NULL) return false;
   } else {
     data = NULL;
   }
 
-  SetupArrayBuffer(isolate, array_buffer, false, data, allocated_length);
+  SetupArrayBuffer(isolate, array_buffer, false, data, allocated_length,
+                   is_shared);
 
   reinterpret_cast<v8::Isolate*>(isolate)
       ->AdjustAmountOfExternalAllocatedMemory(allocated_length);
@@ -126,9 +144,10 @@ void Runtime::NeuterArrayBuffer(Handle<JSArrayBuffer> array_buffer) {
 
 RUNTIME_FUNCTION(Runtime_ArrayBufferInitialize) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
+  DCHECK(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(JSArrayBuffer, holder, 0);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(byteLength, 1);
+  CONVERT_BOOLEAN_ARG_CHECKED(isShared, 2);
   if (!holder->byte_length()->IsUndefined()) {
     // ArrayBuffer is already initialized; probably a fuzz test.
     return *holder;
@@ -139,8 +158,8 @@ RUNTIME_FUNCTION(Runtime_ArrayBufferInitialize) {
         isolate, NewRangeError("invalid_array_buffer_length",
                                HandleVector<Object>(NULL, 0)));
   }
-  if (!Runtime::SetupArrayBufferAllocatingData(isolate, holder,
-                                               allocated_length)) {
+  if (!Runtime::SetupArrayBufferAllocatingData(
+          isolate, holder, allocated_length, true, isShared)) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewRangeError("invalid_array_buffer_length",
                                HandleVector<Object>(NULL, 0)));
@@ -157,6 +176,14 @@ RUNTIME_FUNCTION(Runtime_ArrayBufferGetByteLength) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_ArrayBufferIsShared) {
+  SealHandleScope shs(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_CHECKED(JSArrayBuffer, holder, 0);
+  return isolate->heap()->ToBoolean(holder->is_shared());
+}
+
+
 RUNTIME_FUNCTION(Runtime_ArrayBufferSliceImpl) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
@@ -196,6 +223,8 @@ RUNTIME_FUNCTION(Runtime_ArrayBufferNeuter) {
     CHECK(Smi::FromInt(0) == array_buffer->byte_length());
     return isolate->heap()->undefined_value();
   }
+  // Shared array buffers should never be neutered.
+  DCHECK(!array_buffer->is_shared());
   DCHECK(!array_buffer->is_external());
   void* backing_store = array_buffer->backing_store();
   size_t byte_length = NumberToSize(isolate, array_buffer->byte_length());
@@ -230,12 +259,13 @@ void Runtime::ArrayIdToTypeAndSize(int arrayId, ExternalArrayType* array_type,
 
 RUNTIME_FUNCTION(Runtime_TypedArrayInitialize) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 5);
+  DCHECK(args.length() == 6);
   CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, holder, 0);
   CONVERT_SMI_ARG_CHECKED(arrayId, 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, maybe_buffer, 2);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(byte_offset_object, 3);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(byte_length_object, 4);
+  CONVERT_BOOLEAN_ARG_CHECKED(isShared, 5);
 
   RUNTIME_ASSERT(arrayId >= Runtime::ARRAY_ID_FIRST &&
                  arrayId <= Runtime::ARRAY_ID_LAST);
@@ -260,6 +290,7 @@ RUNTIME_FUNCTION(Runtime_TypedArrayInitialize) {
         NumberToSize(isolate, buffer->byte_length());
     RUNTIME_ASSERT(byte_offset <= array_buffer_byte_length);
     RUNTIME_ASSERT(array_buffer_byte_length - byte_offset >= byte_length);
+    RUNTIME_ASSERT(isShared == buffer->is_shared());
   } else {
     RUNTIME_ASSERT(maybe_buffer->IsNull());
   }
@@ -284,6 +315,7 @@ RUNTIME_FUNCTION(Runtime_TypedArrayInitialize) {
   holder->set_length(*length_obj);
   holder->set_byte_offset(*byte_offset_object);
   holder->set_byte_length(*byte_length_object);
+  holder->set_is_shared(isShared);
 
   Heap* heap = isolate->heap();
   if (!maybe_buffer->IsNull()) {