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

src/compiler/ast-graph-builder.cc

 // Copyright 2014 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/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 4201 matching lines @@
   return graph()->NewNode(phi_op, count + 1, buffer, true);
 }
 
 
 Node* AstGraphBuilder::MergeControl(Node* control, Node* other) {
   int inputs = control->op()->ControlInputCount() + 1;
   if (control->opcode() == IrOpcode::kLoop) {
     // Control node for loop exists, add input.
     const Operator* op = common()->Loop(inputs);
     control->AppendInput(graph_zone(), other);
-    control->set_op(op);
+    NodeProperties::ChangeOp(control, op);
   } else if (control->opcode() == IrOpcode::kMerge) {
     // Control node for merge exists, add input.
     const Operator* op = common()->Merge(inputs);
     control->AppendInput(graph_zone(), other);
-    control->set_op(op);
+    NodeProperties::ChangeOp(control, op);
   } else {
     // Control node is a singleton, introduce a merge.
     const Operator* op = common()->Merge(inputs);
     Node* inputs[] = {control, other};
     control = graph()->NewNode(op, arraysize(inputs), inputs, true);
   }
   return control;
 }
 
 
 Node* AstGraphBuilder::MergeEffect(Node* value, Node* other, Node* control) {
   int inputs = control->op()->ControlInputCount();
   if (value->opcode() == IrOpcode::kEffectPhi &&
       NodeProperties::GetControlInput(value) == control) {
     // Phi already exists, add input.
-    value->set_op(common()->EffectPhi(inputs));
     value->InsertInput(graph_zone(), inputs - 1, other);
+    NodeProperties::ChangeOp(value, common()->EffectPhi(inputs));
   } else if (value != other) {
     // Phi does not exist yet, introduce one.
     value = NewEffectPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 
 Node* AstGraphBuilder::MergeValue(Node* value, Node* other, Node* control) {
   int inputs = control->op()->ControlInputCount();
   if (value->opcode() == IrOpcode::kPhi &&
       NodeProperties::GetControlInput(value) == control) {
     // Phi already exists, add input.
-    value->set_op(common()->Phi(kMachAnyTagged, inputs));
     value->InsertInput(graph_zone(), inputs - 1, other);
+    NodeProperties::ChangeOp(value, common()->Phi(kMachAnyTagged, inputs));
   } else if (value != other) {
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8