[turbofan] Move graph trimming functionality to dedicated GraphTrimmer.

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"
 #include "src/compiler/node-properties.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-bool Reducer::Finish() { return true; }
-
-
 enum class GraphReducer::State : uint8_t {
   kUnvisited,
   kRevisit,
   kOnStack,
   kVisited
 };
 
 
 GraphReducer::GraphReducer(Zone* zone, Graph* graph, Node* dead_value,
                            Node* dead_control)
@@ skipping 33 matching lines @@
       }
     } else {
       break;
     }
   }
   DCHECK(revisit_.empty());
   DCHECK(stack_.empty());
 }
 
 
-void GraphReducer::ReduceGraph() {
-  for (;;) {
-    ReduceNode(graph()->end());
-    // TODO(turbofan): Remove this once the dead node trimming is in the
-    // GraphReducer.
-    bool done = true;
-    for (Reducer* const reducer : reducers_) {
-      if (!reducer->Finish()) {
-        done = false;
-        break;
-      }
-    }
-    if (done) break;
-    // Reset all marks on the graph in preparation to re-reduce the graph.
-    state_.Reset(graph());
-  }
-}
+void GraphReducer::ReduceGraph() { ReduceNode(graph()->end()); }
 
 
 Reduction GraphReducer::Reduce(Node* const node) {
   auto skip = reducers_.end();
   for (auto i = reducers_.begin(); i != reducers_.end();) {
     if (i != skip) {
       Reduction reduction = (*i)->Reduce(node);
       if (!reduction.Changed()) {
         // No change from this reducer.
       } else if (reduction.replacement() == node) {
@@ skipping 175 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