[turbofan] Turn JSTypedLowering into an AdvancedReducer.

src/compiler/graph-reducer.h

 // 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.
 
 #ifndef V8_COMPILER_GRAPH_REDUCER_H_
 #define V8_COMPILER_GRAPH_REDUCER_H_
 
 #include "src/compiler/node-marker.h"
 #include "src/zone-containers.h"
 
@@ skipping 85 matching lines @@
   void Revisit(Node* node) {
     DCHECK_NOT_NULL(editor_);
     editor_->Revisit(node);
   }
   void ReplaceWithValue(Node* node, Node* value, Node* effect = nullptr,
                         Node* control = nullptr) {
     DCHECK_NOT_NULL(editor_);
     editor_->ReplaceWithValue(node, value, effect, control);
   }
 
+  // Relax the effects of {node} by immediately replacing effect and control
+  // uses of {node} with the effect and control input to {node}.
+  // TODO(turbofan): replace the effect input to {node} with {graph->start()}.
+  void RelaxEffectsAndControls(Node* node) {
+    DCHECK_NOT_NULL(editor_);
+    editor_->ReplaceWithValue(node, node, nullptr, nullptr);
+  }
+
+  // Relax the control uses of {node} by immediately replacing them with the
+  // control input to {node}.
+  void RelaxControls(Node* node) {
+    DCHECK_NOT_NULL(editor_);
+    editor_->ReplaceWithValue(node, node, node, nullptr);
+  }
+
  private:
   Editor* const editor_;
 };
 
 
 // Performs an iterative reduction of a node graph.
 class GraphReducer final : public AdvancedReducer::Editor {
  public:
   GraphReducer(Graph* graph, Zone* zone);
   ~GraphReducer() final;
@@ skipping 48 matching lines @@
   ZoneStack<NodeState> stack_;
 
   DISALLOW_COPY_AND_ASSIGN(GraphReducer);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_GRAPH_REDUCER_H_