Allow Turbofan optimization of Ignition generators

src/interpreter/interpreter-assembler.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/interpreter/interpreter-assembler.h"
 
 #include <limits>
 #include <ostream>
 
 #include "src/code-factory.h"
@@ skipping 708 matching lines @@
   if (FLAG_debug_code) {
     Node* array_size = SmiUntag(LoadFixedArrayBaseLength(array));
     AbortIfWordNotEqual(
         array_size, RegisterCount(), kInvalidRegisterFileInGenerator);
   }
 
   Variable var_index(this, MachineRepresentation::kWord32);
   var_index.Bind(Int32Constant(0));
 
   // Iterate over register file and write values into array.
+  // The mapping of register to array index must match that used in
+  // BytecodeGraphBuilder::VisitResumeGenerator.
   Label loop(this, &var_index), done_loop(this);
   Goto(&loop);
   Bind(&loop);
   {
     Node* index = var_index.value();
     Node* condition = Int32LessThan(index, RegisterCount());
     GotoUnless(condition, &done_loop);
 
     Node* reg_index =
         Int32Sub(Int32Constant(Register(0).ToOperand()), index);
@@ skipping 41 matching lines @@
     Goto(&loop);
   }
   Bind(&done_loop);
 
   return array;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8