[turbofan] Split pure nodes in the scheduler if beneficial.

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/base/flags.h"
 #include "src/compiler/node.h"
 #include "src/compiler/opcodes.h"
 #include "src/compiler/schedule.h"
 #include "src/compiler/zone-pool.h"
 #include "src/zone-containers.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Forward declarations.
 class CFGBuilder;
 class ControlEquivalence;
 class Graph;
 class SpecialRPONumberer;
 
 
 // Computes a schedule from a graph, placing nodes into basic blocks and
 // ordering the basic blocks in the special RPO order.
 class Scheduler {
  public:
+  // Flags that control the mode of operation.
+  enum Flag { kNoFlags = 0u, kSplitNodes = 1u << 1 };
+  typedef base::Flags<Flag> Flags;
+
   // The complete scheduling algorithm. Creates a new schedule and places all
   // nodes from the graph into it.
-  static Schedule* ComputeSchedule(Zone* zone, Graph* graph);
+  static Schedule* ComputeSchedule(Zone* zone, Graph* graph, Flags flags);
 
   // Compute the RPO of blocks in an existing schedule.
   static BasicBlockVector* ComputeSpecialRPO(Zone* zone, Schedule* schedule);
 
  private:
   // Placement of a node changes during scheduling. The placement state
   // transitions over time while the scheduler is choosing a position:
   //
   //                   +---------------------+-----+----> kFixed
   //                  /                     /     /
   //    kUnknown ----+------> kCoupled ----+     /
   //                  \                         /
   //                   +----> kSchedulable ----+--------> kScheduled
   //
   // 1) GetPlacement(): kUnknown -> kCoupled|kSchedulable|kFixed
   // 2) UpdatePlacement(): kCoupled|kSchedulable -> kFixed|kScheduled
   enum Placement { kUnknown, kSchedulable, kFixed, kCoupled, kScheduled };
 
   // Per-node data tracked during scheduling.
   struct SchedulerData {
     BasicBlock* minimum_block_;  // Minimum legal RPO placement.
     int unscheduled_count_;      // Number of unscheduled uses of this node.
     Placement placement_;        // Whether the node is fixed, schedulable,
                                  // coupled to another node, or not yet known.
   };
 
   Zone* zone_;
   Graph* graph_;
   Schedule* schedule_;
+  Flags flags_;
   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.
   CFGBuilder* control_flow_builder_;     // Builds basic blocks for controls.
   SpecialRPONumberer* special_rpo_;      // Special RPO numbering of blocks.
   ControlEquivalence* equivalence_;      // Control dependence equivalence.
 
-  Scheduler(Zone* zone, Graph* graph, Schedule* schedule);
+  Scheduler(Zone* zone, Graph* graph, Schedule* schedule, Flags flags);
 
   inline SchedulerData DefaultSchedulerData();
   inline SchedulerData* GetData(Node* node);
 
   Placement GetPlacement(Node* node);
   void UpdatePlacement(Node* node, Placement placement);
 
   inline bool IsCoupledControlEdge(Node* node, int index);
   void IncrementUnscheduledUseCount(Node* node, int index, Node* from);
   void DecrementUnscheduledUseCount(Node* node, int index, Node* from);
@@ skipping 21 matching lines @@
   friend class ScheduleLateNodeVisitor;
   void ScheduleLate();
 
   // Phase 6: Seal the final schedule.
   void SealFinalSchedule();
 
   void FuseFloatingControl(BasicBlock* block, Node* node);
   void MovePlannedNodes(BasicBlock* from, BasicBlock* to);
 };
 
+
+DEFINE_OPERATORS_FOR_FLAGS(Scheduler::Flags)
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SCHEDULER_H_