WIP [esnext] implement async iteration proposal

src/compiler/bytecode-graph-builder.cc

Index: src/compiler/bytecode-graph-builder.cc
diff --git a/src/compiler/bytecode-graph-builder.cc b/src/compiler/bytecode-graph-builder.cc
index d22746d9ecbfa8378621b4eef81d13f8da7c09cf..53b013040a6ad76a41bbe4f6a0c349fdc123e8d6 100644
--- a/src/compiler/bytecode-graph-builder.cc
+++ b/src/compiler/bytecode-graph-builder.cc
@@ -1874,8 +1874,34 @@ void BytecodeGraphBuilder::VisitSuspendGenerator() {
         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() {