[turbofan] Instruction scheduler: keep ready nodes list sorted by latency.

src/compiler/instruction-scheduler.h

 // Copyright 2015 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_INSTRUCTION_SCHEDULER_H_
 #define V8_COMPILER_INSTRUCTION_SCHEDULER_H_
 
 #include "src/compiler/instruction.h"
 #include "src/zone-containers.h"
 
@@ skipping 83 matching lines @@
   // have been scheduled. Note that this class is inteded to be extended by
   // concrete implementation of the scheduling queue which define the policy
   // to pop node from the queue.
   class SchedulingQueueBase {
    public:
     explicit SchedulingQueueBase(InstructionScheduler* scheduler)
       : scheduler_(scheduler),
         nodes_(scheduler->zone()) {
     }
 
-    void AddNode(ScheduleGraphNode* node) {
-      nodes_.push_back(node);
-    }
+    void AddNode(ScheduleGraphNode* node);
 
     bool IsEmpty() const {
       return nodes_.empty();
     }
 
    protected:
     InstructionScheduler* scheduler_;
     ZoneLinkedList<ScheduleGraphNode*> nodes_;
   };
 
   // A scheduling queue which prioritize nodes on the critical path (we look
   // for the instruction with the highest latency on the path to reach the end
   // of the graph).
   class CriticalPathFirstQueue : public SchedulingQueueBase  {
    public:
     explicit CriticalPathFirstQueue(InstructionScheduler* scheduler)
       : SchedulingQueueBase(scheduler) { }
 
     // Look for the best candidate to schedule, remove it from the queue and
     // return it.
     ScheduleGraphNode* PopBestCandidate(int cycle);
-
-   private:
-    // Compare the two nodes and return true if node1 is a better candidate than
-    // node2 (i.e. node1 should be scheduled before node2).
-    bool CompareNodes(ScheduleGraphNode *node1, ScheduleGraphNode *node2) const;
   };
 
   // A queue which pop a random node from the queue to perform stress tests on
   // the scheduler.
   class StressSchedulerQueue : public SchedulingQueueBase  {
    public:
     explicit StressSchedulerQueue(InstructionScheduler* scheduler)
       : SchedulingQueueBase(scheduler) { }
 
     ScheduleGraphNode* PopBestCandidate(int cycle);
@@ skipping 71 matching lines @@
   // Keep track of definition points for virtual registers. This is used to
   // record operand dependencies in the scheduling graph.
   ZoneMap<int32_t, ScheduleGraphNode*> operands_map_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SCHEDULER_H_