[turbofan] Make Node::set_op safer via wrapper.

src/compiler/control-flow-optimizer.cc

Index: src/compiler/control-flow-optimizer.cc
diff --git a/src/compiler/control-flow-optimizer.cc b/src/compiler/control-flow-optimizer.cc
index 25e183e1f65b1d66ad4abd630bcec7e2fcbc6159..f3b92638622065b7407d4a9b0f7d46758a9f471e 100644
--- a/src/compiler/control-flow-optimizer.cc
+++ b/src/compiler/control-flow-optimizer.cc
@@ -245,7 +245,7 @@ bool ControlFlowOptimizer::TryBuildSwitch(Node* node) {
       branch->NullAllInputs();
       if_true->ReplaceInput(0, node);
     }
-    if_true->set_op(common()->IfValue(value));
+    NodeProperties::ChangeOp(if_true, common()->IfValue(value));
     if_false->NullAllInputs();
     Enqueue(if_true);
 
@@ -261,12 +261,12 @@ bool ControlFlowOptimizer::TryBuildSwitch(Node* node) {
     return false;
   }
   DCHECK_LT(1u, values.size());
-  node->set_op(common()->Switch(values.size() + 1));
+  NodeProperties::ChangeOp(node, common()->Switch(values.size() + 1));

[Jarin, 2015/09/24 14:00:41]

I am wondering whether ChangeOp should not be the last operation in any sequence
(so that if we check any consistency, we do not get spurious errors).

[Michael Starzinger, 2015/09/24 14:21:28]

Done.

   node->ReplaceInput(0, index);
-  if_true->set_op(common()->IfValue(value));
+  NodeProperties::ChangeOp(if_true, common()->IfValue(value));
   if_true->ReplaceInput(0, node);
   Enqueue(if_true);
-  if_false->set_op(common()->IfDefault());
+  NodeProperties::ChangeOp(if_false, common()->IfDefault());
   if_false->ReplaceInput(0, node);
   Enqueue(if_false);
   branch->NullAllInputs();