WIP [esnext] implement async iteration proposal

src/objects.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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 #include <memory>
 
@@ skipping 372 matching lines @@
   V(ALLOCATION_SITE_TYPE)                                       \
   V(ALLOCATION_MEMENTO_TYPE)                                    \
   V(SCRIPT_TYPE)                                                \
   V(TYPE_FEEDBACK_INFO_TYPE)                                    \
   V(ALIASED_ARGUMENTS_ENTRY_TYPE)                               \
   V(BOX_TYPE)                                                   \
   V(PROMISE_RESOLVE_THENABLE_JOB_INFO_TYPE)                     \
   V(PROMISE_REACTION_JOB_INFO_TYPE)                             \
   V(DEBUG_INFO_TYPE)                                            \
   V(BREAK_POINT_INFO_TYPE)                                      \
+  V(ASYNC_GENERATOR_REQUEST_TYPE)                               \
   V(PROTOTYPE_INFO_TYPE)                                        \
   V(TUPLE2_TYPE)                                                \
   V(TUPLE3_TYPE)                                                \
   V(CONTEXT_EXTENSION_TYPE)                                     \
   V(CONSTANT_ELEMENTS_PAIR_TYPE)                                \
   V(MODULE_TYPE)                                                \
   V(MODULE_INFO_ENTRY_TYPE)                                     \
   V(FIXED_ARRAY_TYPE)                                           \
   V(TRANSITION_ARRAY_TYPE)                                      \
   V(SHARED_FUNCTION_INFO_TYPE)                                  \
   V(CELL_TYPE)                                                  \
   V(WEAK_CELL_TYPE)                                             \
   V(PROPERTY_CELL_TYPE)                                         \
                                                                 \
   V(JS_PROXY_TYPE)                                              \
   V(JS_GLOBAL_OBJECT_TYPE)                                      \
   V(JS_GLOBAL_PROXY_TYPE)                                       \
   V(JS_SPECIAL_API_OBJECT_TYPE)                                 \
   V(JS_VALUE_TYPE)                                              \
   V(JS_MESSAGE_OBJECT_TYPE)                                     \
   V(JS_DATE_TYPE)                                               \
   V(JS_API_OBJECT_TYPE)                                         \
   V(JS_OBJECT_TYPE)                                             \
   V(JS_ARGUMENTS_TYPE)                                          \
   V(JS_CONTEXT_EXTENSION_OBJECT_TYPE)                           \
   V(JS_GENERATOR_OBJECT_TYPE)                                   \
+  V(JS_ASYNC_GENERATOR_OBJECT_TYPE)                             \
+  V(JS_ASYNC_FROM_SYNC_ITERATOR_TYPE)                           \
   V(JS_MODULE_NAMESPACE_TYPE)                                   \
   V(JS_ARRAY_TYPE)                                              \
   V(JS_ARRAY_BUFFER_TYPE)                                       \
   V(JS_TYPED_ARRAY_TYPE)                                        \
   V(JS_DATA_VIEW_TYPE)                                          \
   V(JS_SET_TYPE)                                                \
   V(JS_MAP_TYPE)                                                \
   V(JS_SET_ITERATOR_TYPE)                                       \
   V(JS_MAP_ITERATOR_TYPE)                                       \
   V(JS_WEAK_MAP_TYPE)                                           \
@@ skipping 129 matching lines @@
   V(PROMISE_REACTION_JOB_INFO, PromiseReactionJobInfo,                       \
     promise_reaction_job_info)                                               \
   V(DEBUG_INFO, DebugInfo, debug_info)                                       \
   V(BREAK_POINT_INFO, BreakPointInfo, break_point_info)                      \
   V(PROTOTYPE_INFO, PrototypeInfo, prototype_info)                           \
   V(TUPLE2, Tuple2, tuple2)                                                  \
   V(TUPLE3, Tuple3, tuple3)                                                  \
   V(CONTEXT_EXTENSION, ContextExtension, context_extension)                  \
   V(CONSTANT_ELEMENTS_PAIR, ConstantElementsPair, constant_elements_pair)    \
   V(MODULE, Module, module)                                                  \
-  V(MODULE_INFO_ENTRY, ModuleInfoEntry, module_info_entry)
+  V(MODULE_INFO_ENTRY, ModuleInfoEntry, module_info_entry)                   \
+  V(ASYNC_GENERATOR_REQUEST, AsyncGeneratorRequest, async_generator_request)
 
 // We use the full 8 bits of the instance_type field to encode heap object
 // instance types.  The high-order bit (bit 7) is set if the object is not a
 // string, and cleared if it is a string.
 const uint32_t kIsNotStringMask = 0x80;
 const uint32_t kStringTag = 0x0;
 const uint32_t kNotStringTag = 0x80;
 
 // Bit 6 indicates that the object is an internalized string (if set) or not.
 // Bit 7 has to be clear as well.
@@ skipping 143 matching lines @@
   FUNCTION_TEMPLATE_INFO_TYPE,
   OBJECT_TEMPLATE_INFO_TYPE,
   ALLOCATION_SITE_TYPE,
   ALLOCATION_MEMENTO_TYPE,
   SCRIPT_TYPE,
   TYPE_FEEDBACK_INFO_TYPE,
   ALIASED_ARGUMENTS_ENTRY_TYPE,
   BOX_TYPE,
   PROMISE_RESOLVE_THENABLE_JOB_INFO_TYPE,
   PROMISE_REACTION_JOB_INFO_TYPE,
+  ASYNC_GENERATOR_REQUEST_TYPE,
   DEBUG_INFO_TYPE,
   BREAK_POINT_INFO_TYPE,
   PROTOTYPE_INFO_TYPE,
   TUPLE2_TYPE,
   TUPLE3_TYPE,
   CONTEXT_EXTENSION_TYPE,
   CONSTANT_ELEMENTS_PAIR_TYPE,
   MODULE_TYPE,
   MODULE_INFO_ENTRY_TYPE,
   FIXED_ARRAY_TYPE,
@@ skipping 15 matching lines @@
   JS_SPECIAL_API_OBJECT_TYPE,  // LAST_SPECIAL_RECEIVER_TYPE
   JS_VALUE_TYPE,               // LAST_CUSTOM_ELEMENTS_RECEIVER
   JS_MESSAGE_OBJECT_TYPE,
   JS_DATE_TYPE,
   // Like JS_OBJECT_TYPE, but created from API function.
   JS_API_OBJECT_TYPE,
   JS_OBJECT_TYPE,
   JS_ARGUMENTS_TYPE,
   JS_CONTEXT_EXTENSION_OBJECT_TYPE,
   JS_GENERATOR_OBJECT_TYPE,
+  JS_ASYNC_GENERATOR_OBJECT_TYPE,
+  JS_ASYNC_FROM_SYNC_ITERATOR_TYPE,
   JS_MODULE_NAMESPACE_TYPE,
   JS_ARRAY_TYPE,
   JS_ARRAY_BUFFER_TYPE,
   JS_TYPED_ARRAY_TYPE,
   JS_DATA_VIEW_TYPE,
   JS_SET_TYPE,
   JS_MAP_TYPE,
   JS_SET_ITERATOR_TYPE,
   JS_MAP_ITERATOR_TYPE,
   JS_WEAK_MAP_TYPE,
@@ skipping 270 matching lines @@
   V(FixedInt32Array)             \
   V(FixedFloat32Array)           \
   V(FixedFloat64Array)           \
   V(FixedUint8ClampedArray)      \
   V(ByteArray)                   \
   V(BytecodeArray)               \
   V(FreeSpace)                   \
   V(JSReceiver)                  \
   V(JSObject)                    \
   V(JSArgumentsObject)           \
+  V(JSAsyncFromSyncIterator)     \
   V(JSContextExtensionObject)    \
   V(JSGeneratorObject)           \
+  V(JSAsyncGeneratorObject)      \
   V(JSModuleNamespace)           \
   V(Map)                         \
   V(DescriptorArray)             \
   V(FrameArray)                  \
   V(TransitionArray)             \
   V(LiteralsArray)               \
   V(TypeFeedbackMetadata)        \
   V(TypeFeedbackVector)          \
   V(DeoptimizationInputData)     \
   V(DeoptimizationOutputData)    \
@@ skipping 1687 matching lines @@
   static const int kDoneOffset = kValueOffset + kPointerSize;
   static const int kSize = kDoneOffset + kPointerSize;
   // Indices of in-object properties.
   static const int kValueIndex = 0;
   static const int kDoneIndex = 1;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSIteratorResult);
 };
 
+class JSAsyncFromSyncIterator : public JSObject {
+ public:
+  DECLARE_CAST(JSAsyncFromSyncIterator)
+
+  DECLARE_PRINTER(JSAsyncFromSyncIterator)
+  DECLARE_VERIFIER(JSAsyncFromSyncIterator)
+
+  // Async-from-Sync Iterator instances are ordinary objects that inherit
+  // properties from the %AsyncFromSyncIteratorPrototype% intrinsic object.
+  // Async-from-Sync Iterator instances are initially created with the internal
+  // slots listed in Table 4.
+  // (proposal-async-iteration/#table-async-from-sync-iterator-internal-slots)
+  DECL_ACCESSORS(sync_iterator, HeapObject)
+
+  // Offsets of object fields.
+  static const int kSyncIteratorOffset = JSObject::kHeaderSize;
+  static const int kSize = kSyncIteratorOffset + kPointerSize;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSAsyncFromSyncIterator);
+};
 
 // Common superclass for JSSloppyArgumentsObject and JSStrictArgumentsObject.
 class JSArgumentsObject: public JSObject {
  public:
   // Offsets of object fields.
   static const int kLengthOffset = JSObject::kHeaderSize;
   static const int kHeaderSize = kLengthOffset + kPointerSize;
   // Indices of in-object properties.
   static const int kLengthIndex = 0;
 
@@ skipping 3859 matching lines @@
   static const int kSize = kContextOffset + kPointerSize;
 
   DECLARE_CAST(PromiseReactionJobInfo)
   DECLARE_PRINTER(PromiseReactionJobInfo)
   DECLARE_VERIFIER(PromiseReactionJobInfo)
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PromiseReactionJobInfo);
 };
 
+class AsyncGeneratorRequest : public Struct {
+ public:
+  // Holds an AsyncGeneratorRequest, or Undefined.
+  DECL_ACCESSORS(next, Object)
+  DECL_INT_ACCESSORS(resume_mode)
+  DECL_ACCESSORS(value, Object)
+  DECL_ACCESSORS(promise, Object)
+  DECL_ACCESSORS(awaited_promise, Object)
+
+  static const int kNextOffset = Struct::kHeaderSize;
+  static const int kResumeModeOffset = kNextOffset + kPointerSize;
+  static const int kValueOffset = kResumeModeOffset + kPointerSize;
+  static const int kPromiseOffset = kValueOffset + kPointerSize;
+  static const int kAwaitedPromiseOffset = kPromiseOffset + kPointerSize;
+  static const int kSize = kAwaitedPromiseOffset + kPointerSize;
+
+  DECLARE_CAST(AsyncGeneratorRequest)
+  DECLARE_PRINTER(AsyncGeneratorRequest)
+  DECLARE_VERIFIER(AsyncGeneratorRequest)
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(AsyncGeneratorRequest);
+};
+
 // A simple one-element struct, useful where smis need to be boxed.
 class Box : public Struct {
  public:
   // [value]: the boxed contents.
   DECL_ACCESSORS(value, Object)
 
   DECLARE_CAST(Box)
 
   // Dispatched behavior.
   DECLARE_PRINTER(Box)
@@ skipping 1224 matching lines @@
 
   // [context]: The context of the suspended computation.
   DECL_ACCESSORS(context, Context)
 
   // [receiver]: The receiver of the suspended computation.
   DECL_ACCESSORS(receiver, Object)
 
   // [input_or_debug_pos]
   // For executing generators: the most recent input value.
   // For suspended generators: debug information (bytecode offset).
-  // There is currently no need to remember the most recent input value for a
-  // suspended generator.
+  // If a generator has been suspended via Await(), then the previous input
+  // value is moved to the Await value register, and restored on resume.
   DECL_ACCESSORS(input_or_debug_pos, Object)
+  DECL_ACCESSORS(await_input, Object)

[Dan Ehrenberg, 2017/01/13 19:41:09]

Why is this added to JSGeneratorObject? I would expect it to only be added to
JSAsyncGeneratorObject.

[caitp, 2017/01/13 20:11:52]

I don't think it matters a whole lot, but OK, will move it

 
   // [resume_mode]: The most recent resume mode.
   enum ResumeMode { kNext, kReturn, kThrow };
   DECL_INT_ACCESSORS(resume_mode)
 
   // [continuation]
   //
   // A positive value indicates a suspended generator.  The special
   // kGeneratorExecuting and kGeneratorClosed values indicate that a generator
   // cannot be resumed.
@@ skipping 17 matching lines @@
 
   // Magic sentinel values for the continuation.
   static const int kGeneratorExecuting = -2;
   static const int kGeneratorClosed = -1;
 
   // Layout description.
   static const int kFunctionOffset = JSObject::kHeaderSize;
   static const int kContextOffset = kFunctionOffset + kPointerSize;
   static const int kReceiverOffset = kContextOffset + kPointerSize;
   static const int kInputOrDebugPosOffset = kReceiverOffset + kPointerSize;
-  static const int kResumeModeOffset = kInputOrDebugPosOffset + kPointerSize;
+  static const int kAwaitInputOffset = kInputOrDebugPosOffset + kPointerSize;
+  static const int kResumeModeOffset = kAwaitInputOffset + kPointerSize;
   static const int kContinuationOffset = kResumeModeOffset + kPointerSize;
   static const int kRegisterFileOffset = kContinuationOffset + kPointerSize;
   static const int kSize = kRegisterFileOffset + kPointerSize;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSGeneratorObject);
 };
 
+class JSAsyncGeneratorObject : public JSGeneratorObject {
+ public:
+  DECLARE_CAST(JSAsyncGeneratorObject)
+
+  // Dispatched behavior.
+  DECLARE_VERIFIER(JSAsyncGeneratorObject)
+
+  // [queue]
+  // Pointer to the head of a singly linked list of AsyncGeneratorRequest, or
+  // undefined.
+  DECL_ACCESSORS(queue, HeapObject)
+
+  // [awaited_promise]
+  // A reference to the Promise of an AwaitExpression.
+  DECL_ACCESSORS(awaited_promise, HeapObject)
+
+  // Layout description.
+  static const int kQueueOffset = JSGeneratorObject::kSize;
+  static const int kSize = kQueueOffset + kPointerSize;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSAsyncGeneratorObject);
+};
+
 class ModuleInfoEntry : public Struct {
  public:
   DECLARE_CAST(ModuleInfoEntry)
   DECLARE_PRINTER(ModuleInfoEntry)
   DECLARE_VERIFIER(ModuleInfoEntry)
 
   DECL_ACCESSORS(export_name, Object)
   DECL_ACCESSORS(local_name, Object)
   DECL_ACCESSORS(import_name, Object)
   DECL_INT_ACCESSORS(module_request)
@@ skipping 3800 matching lines @@
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #include "src/objects/object-macros-undef.h"
 
 #endif  // V8_OBJECTS_H_