WIP SharedArrayBuffer implementation

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 7ba625442369de1f1f0dd57ac262c03196c90bae..beba791f5cfbec8af27f5af19450a3b8df6975a5 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -444,6 +444,8 @@ const int kStubMinorKeyBits = kSmiValueSize - kStubMajorKeyBits - 1;
   V(JS_ARRAY_BUFFER_TYPE)                                       \
   V(JS_TYPED_ARRAY_TYPE)                                        \
   V(JS_DATA_VIEW_TYPE)                                          \
+  V(JS_SHARED_ARRAY_BUFFER_TYPE)                                \
+  V(JS_SHARED_TYPED_ARRAY_TYPE)                                 \
   V(JS_PROXY_TYPE)                                              \
   V(JS_SET_TYPE)                                                \
   V(JS_MAP_TYPE)                                                \
@@ -745,6 +747,8 @@ enum InstanceType {
   JS_ARRAY_BUFFER_TYPE,
   JS_TYPED_ARRAY_TYPE,
   JS_DATA_VIEW_TYPE,
+  JS_SHARED_ARRAY_BUFFER_TYPE,
+  JS_SHARED_TYPED_ARRAY_TYPE,
   JS_SET_TYPE,
   JS_MAP_TYPE,
   JS_SET_ITERATOR_TYPE,
@@ -10225,6 +10229,9 @@ class JSArrayBuffer: public JSObject {
   inline bool is_neuterable();
   inline void set_is_neuterable(bool value);
 
+  inline bool is_shared();
+  inline void set_is_shared(bool value);
+
   // [weak_next]: linked list of array buffers.
   DECL_ACCESSORS(weak_next, Object)
 
@@ -10255,6 +10262,7 @@ class JSArrayBuffer: public JSObject {
   static const int kIsExternalBit = 0;
   static const int kShouldBeFreed = 1;
   static const int kIsNeuterableBit = 2;
+  static const int kIsSharedBit = 3;

[Jarin, 2015/04/16 14:55:28]

Why do you need the bit? Cannot you get the sharedness from the map?

[binji, 2015/04/16 21:00:34]

Do you mean from the ExternalArrayType? I currently share that enumeration value
between TypedArrays and SharedTypedArrays. I could add new shared types, but I'm
not sure how much code would need to be duplicated then. Also, I think that will
only work for TypedArrays, not for the SharedArrayBuffer.

Or am I missing something? (quite likely :)

[Jarin, 2015/04/17 07:49:27]

I was just wondering why you could not define is_shared()
{ return map()->instance_type() == JS_SHARED_ARRAY_BUFFER_TYPE; }

[binji, 2015/04/17 09:06:44]

Thanks, that works. I knew I was missing something. :)

 
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSArrayBuffer);
 };
@@ -10297,6 +10305,11 @@ class JSTypedArray: public JSArrayBufferView {
   // [length]: length of typed array in elements.
   DECL_ACCESSORS(length, Object)
 
+  // TODO(binji): How to make this a flags array and access it via hydrogen?
+  // See hydrogen.cc:HOptimizedGraphBuilder::GenerateTypedArrayInitialize
+  // [is_shared]
+  DECL_BOOLEAN_ACCESSORS(is_shared)
+
   // Neutering. Only neuters this typed array.
   void Neuter();
 
@@ -10312,7 +10325,8 @@ class JSTypedArray: public JSArrayBufferView {
   DECLARE_VERIFIER(JSTypedArray)
 
   static const int kLengthOffset = kViewSize + kPointerSize;
-  static const int kSize = kLengthOffset + kPointerSize;
+  static const int kIsSharedOffset = kLengthOffset + kPointerSize;

[Jarin, 2015/04/16 14:55:28]

Again, why do you need the shared flag? Don't you have it on the map already?

[binji, 2015/04/16 21:00:34]

see above

+  static const int kSize = kIsSharedOffset + kPointerSize;
 
   static const int kSizeWithInternalFields =
       kSize + v8::ArrayBufferView::kInternalFieldCount * kPointerSize;