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

src/compiler/scheduler.h

Index: src/compiler/scheduler.h
diff --git a/src/compiler/scheduler.h b/src/compiler/scheduler.h
index b4cea23328618cc8d339dc08adab6c6c3d509f11..882c761f2d524bf2ea4600263fa9731e09210998 100644
--- a/src/compiler/scheduler.h
+++ b/src/compiler/scheduler.h
@@ -7,6 +7,7 @@
 
 #include "src/v8.h"
 
+#include "src/base/flags.h"
 #include "src/compiler/node.h"
 #include "src/compiler/opcodes.h"
 #include "src/compiler/schedule.h"
@@ -28,9 +29,13 @@ class SpecialRPONumberer;
 // 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);
@@ -60,6 +65,7 @@ class Scheduler {
   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.
@@ -68,7 +74,7 @@ class Scheduler {
   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);
@@ -110,6 +116,9 @@ class Scheduler {
   void MovePlannedNodes(BasicBlock* from, BasicBlock* to);
 };
 
+
+DEFINE_OPERATORS_FOR_FLAGS(Scheduler::Flags)
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8