Move special RPO computation into separate class.

src/compiler/scheduler.h

 // Copyright 2013 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_SCHEDULER_H_
 #define V8_COMPILER_SCHEDULER_H_
 
 #include "src/v8.h"
 
 #include "src/compiler/opcodes.h"
@@ skipping 27 matching lines @@
     bool is_connected_control_;  // {true} if control-connected to the end node.
     bool is_floating_control_;   // {true} if control, but not control-connected
                                  // to the end node.
     Placement placement_;        // Whether the node is fixed, schedulable,
                                  // coupled to another node, or not yet known.
   };
 
   Zone* zone_;
   Graph* graph_;
   Schedule* schedule_;
-  NodeVectorVector scheduled_nodes_;
-  NodeVector schedule_root_nodes_;
-  ZoneQueue<Node*> schedule_queue_;
-  ZoneVector<SchedulerData> node_data_;
+  NodeVectorVector scheduled_nodes_;     // Per-block list of nodes in reverse.
+  NodeVector schedule_root_nodes_;       // Fixed root nodes seed the worklist.
+  ZoneQueue<Node*> schedule_queue_;      // Worklist of schedulable nodes.
+  ZoneVector<SchedulerData> node_data_;  // Per-node data for all nodes.
   bool has_floating_control_;
 
   Scheduler(Zone* zone, Graph* graph, Schedule* schedule);
 
   inline SchedulerData DefaultSchedulerData();
   inline SchedulerData* GetData(Node* node);
 
   Placement GetPlacement(Node* node);
 
   void IncrementUnscheduledUseCount(Node* node, Node* from);
   void DecrementUnscheduledUseCount(Node* node, Node* from);
 
   inline int GetRPONumber(BasicBlock* block);
   BasicBlock* GetCommonDominator(BasicBlock* b1, BasicBlock* b2);
 
-  // Phase 1: Build control-flow graph and dominator tree.
+  // Phase 1: Build control-flow graph.
   friend class CFGBuilder;
   void BuildCFG();
+
+  // Phase 2: Compute special RPO and dominator tree.
+  friend class SpecialRPONumberer;
+  void ComputeSpecialRPONumbering();
   void GenerateImmediateDominatorTree();
 
-  // Phase 2: Prepare use counts for nodes.
+  // Phase 3: Prepare use counts for nodes.
   friend class PrepareUsesVisitor;
   void PrepareUses();
 
-  // Phase 3: Schedule nodes early.
+  // Phase 4: Schedule nodes early.
   friend class ScheduleEarlyNodeVisitor;
   void ScheduleEarly();
 
-  // Phase 4: Schedule nodes late.
+  // Phase 5: Schedule nodes late.
   friend class ScheduleLateNodeVisitor;
   void ScheduleLate();
 
   bool ConnectFloatingControl();
   void ConnectFloatingControlSubgraph(BasicBlock* block, Node* node);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SCHEDULER_H_