[turbofan] Renamed tracing flags for TurboFan reducers and graph trimmer

src/compiler/graph-reducer.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 <functional>
 #include <limits>
 
 #include "src/compiler/graph.h"
 #include "src/compiler/graph-reducer.h"
 #include "src/compiler/node.h"
@@ skipping 150 matching lines @@
   }
 }
 
 
 void GraphReducer::Replace(Node* node, Node* replacement) {
   Replace(node, replacement, std::numeric_limits<NodeId>::max());
 }
 
 
 void GraphReducer::Replace(Node* node, Node* replacement, NodeId max_id) {
+  if (FLAG_trace_turbo_reduction) {
+    OFStream os(stdout);
+    os << "- Replacing " << *node << " with " << *replacement << std::endl;
+  }
   if (node == graph()->start()) graph()->SetStart(replacement);
   if (node == graph()->end()) graph()->SetEnd(replacement);
   if (replacement->id() <= max_id) {
     // {replacement} is an old node, so unlink {node} and assume that
     // {replacement} was already reduced and finish.
     for (Edge edge : node->use_edges()) {
       Node* const user = edge.from();
       Verifier::VerifyEdgeInputReplacement(edge, replacement);
       edge.UpdateTo(replacement);
       // Don't revisit this node if it refers to itself.
@@ skipping 84 matching lines @@
 void GraphReducer::Revisit(Node* node) {
   if (state_.Get(node) == State::kVisited) {
     state_.Set(node, State::kRevisit);
     revisit_.push(node);
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8