WIP [esnext] implement async iteration proposal

src/code-stub-assembler.h

 // Copyright 2016 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_CODE_STUB_ASSEMBLER_H_
 #define V8_CODE_STUB_ASSEMBLER_H_
 
 #include <functional>
 
 #include "src/compiler/code-assembler.h"
@@ skipping 519 matching lines @@
   Node* AllocateFixedArray(ElementsKind kind, Node* capacity,
                            ParameterMode mode = INTPTR_PARAMETERS,
                            AllocationFlags flags = kNone);
 
   // Perform CreateArrayIterator (ES6 #sec-createarrayiterator).
   Node* CreateArrayIterator(Node* array, Node* array_map, Node* array_type,
                             Node* context, IterationKind mode);
 
   Node* AllocateJSArrayIterator(Node* array, Node* array_map, Node* map);
 
+  Node* AllocateJSIteratorResult(Node* context, Node* value, Node* done);
+  Node* AllocateJSIteratorResult(Node* context, Node* value, bool done) {
+    return AllocateJSIteratorResult(context, value, BooleanConstant(done));
+  }
+
   void FillFixedArrayWithValue(ElementsKind kind, Node* array, Node* from_index,
                                Node* to_index,
                                Heap::RootListIndex value_root_index,
                                ParameterMode mode = INTPTR_PARAMETERS);
 
   // Copies all elements from |from_array| of |length| size to
   // |to_array| of the same size respecting the elements kind.
   void CopyFixedArrayElements(
       ElementsKind kind, Node* from_array, Node* to_array, Node* length,
       WriteBarrierMode barrier_mode = UPDATE_WRITE_BARRIER,
@@ skipping 559 matching lines @@
 
   Node* Typeof(Node* value, Node* context);
 
   Node* GetSuperConstructor(Node* value, Node* context);
 
   Node* InstanceOf(Node* object, Node* callable, Node* context);
 
   // Debug helpers
   Node* IsDebugActive();
 
+  // Useful tools for PrintF-style debugging CSA builtins.
+  void ReleasePrint(const char* c_str) {

[caitp, 2017/01/10 04:13:41]

I find myself writing these helpers for builtins an awful lot, in order to trace
through control flow of builtins easier. I think it makes sense to just have
them in CSA.

+    std::string std_str(c_str);
+    std_str += '\n';
+    Handle<String> str =
+        factory()->NewStringFromAsciiChecked(std_str.c_str(), TENURED);
+    CallRuntime(Runtime::kGlobalPrint, NoContextConstant(), HeapConstant(str));
+  }
+
+  void ReleaseDebugPrint(Node* object) {
+    CallRuntime(Runtime::kDebugPrint, NoContextConstant(), object);
+  }
+
+  void Print(const char* c_str) {
+#ifdef DEBUG
+    ReleasePrint(c_str);
+#endif
+  }
+
+  void DebugPrint(Node* object) {
+#ifdef DEBUG
+    ReleaseDebugPrint(object);
+#endif
+  }
+
   // TypedArray/ArrayBuffer helpers
   Node* IsDetachedBuffer(Node* buffer);
 
   Node* ElementOffsetFromIndex(Node* index, ElementsKind kind,
                                ParameterMode mode, int base_size = 0);
 
   Node* AllocateFunctionWithMapAndContext(Node* map, Node* shared_info,
                                           Node* context);
 
   // Promise helpers
@@ skipping 123 matching lines @@
   }
 #else
 #define CSA_SLOW_ASSERT(csa, x) ((void)0)
 #endif
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_