Make special RPO computation iterative during scheduling.

src/compiler/scheduler.h

Index: src/compiler/scheduler.h
diff --git a/src/compiler/scheduler.h b/src/compiler/scheduler.h
index b73d1bb19cfbf29a5ffa7197262175f07ba06faa..2839a0cb7a0585eba86bd338bbed5ec7f5e0bc8a 100644
--- a/src/compiler/scheduler.h
+++ b/src/compiler/scheduler.h
@@ -16,6 +16,8 @@ namespace v8 {
 namespace internal {
 namespace compiler {
 
+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 {
@@ -60,6 +62,7 @@ class Scheduler {
   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.
+  SpecialRPONumberer* special_rpo_;      // Special RPO numbering of blocks.
 
   Scheduler(Zone* zone, Graph* graph, Schedule* schedule);
 
@@ -73,7 +76,6 @@ class Scheduler {
   void IncrementUnscheduledUseCount(Node* node, int index, Node* from);
   void DecrementUnscheduledUseCount(Node* node, int index, Node* from);
 
-  inline int GetRPONumber(BasicBlock* block);
   BasicBlock* GetCommonDominator(BasicBlock* b1, BasicBlock* b2);
 
   // Phase 1: Build control-flow graph.
@@ -97,6 +99,9 @@ class Scheduler {
   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);
 };