WIP [esnext] implement async iteration proposal

src/compiler/bytecode-graph-builder.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.
 
 #include "src/compiler/bytecode-graph-builder.h"
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/compilation-info.h"
 #include "src/compiler/compiler-source-position-table.h"
@@ skipping 1856 matching lines @@
 
   Node** value_inputs = local_zone()->NewArray<Node*>(value_input_count);
   value_inputs[0] = generator;
   value_inputs[1] = state;
   value_inputs[2] = offset;
   for (int i = 0; i < register_count; ++i) {
     value_inputs[3 + i] =
         environment()->LookupRegister(interpreter::Register(i));
   }
 
-  MakeNode(javascript()->GeneratorStore(register_count), value_input_count,
-           value_inputs, false);
+  MakeNode(javascript()->GeneratorStore(register_count, SuspendType::kYield),
+           value_input_count, value_inputs, false);
+}
+
+void BytecodeGraphBuilder::VisitAwaitGenerator() {
+  Node* state = environment()->LookupAccumulator();
+  Node* generator =
+      environment()->LookupRegister(bytecode_iterator().GetRegisterOperand(0));
+  // The offsets used by the bytecode iterator are relative to a different base
+  // than what is used in the interpreter, hence the addition.
+  Node* offset =
+      jsgraph()->Constant(bytecode_iterator().current_offset() +
+                          (BytecodeArray::kHeaderSize - kHeapObjectTag));
+
+  int register_count = environment()->register_count();
+  int value_input_count = 3 + register_count;
+
+  Node** value_inputs = local_zone()->NewArray<Node*>(value_input_count);
+  value_inputs[0] = generator;
+  value_inputs[1] = state;
+  value_inputs[2] = offset;
+  for (int i = 0; i < register_count; ++i) {
+    value_inputs[3 + i] =
+        environment()->LookupRegister(interpreter::Register(i));
+  }
+
+  MakeNode(javascript()->GeneratorStore(register_count, SuspendType::kAwait),
+           value_input_count, value_inputs, false);
 }
 
 void BytecodeGraphBuilder::VisitResumeGenerator() {
   PrepareEagerCheckpoint();
 
   Node* generator = environment()->LookupRegister(
       bytecode_iterator().GetRegisterOperand(0));
 
   // Bijection between registers and array indices must match that used in
   // InterpreterAssembler::ExportRegisterFile.
@@ skipping 383 matching lines @@
         it->source_position().ScriptOffset(), start_position_.InliningId()));
     it->Advance();
   } else {
     DCHECK_GT(it->code_offset(), offset);
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8