[turbofan] Single entry into deferred regions

src/compiler/schedule.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_SCHEDULE_H_
 #define V8_COMPILER_SCHEDULE_H_
 
 #include <iosfwd>
 
 #include "src/zone-containers.h"
@@ skipping 239 matching lines @@
   BasicBlock* start() { return start_; }
   BasicBlock* end() { return end_; }
 
   Zone* zone() const { return zone_; }
 
  private:
   friend class Scheduler;
   friend class BasicBlockInstrumentor;
   friend class RawMachineAssembler;
 
+  // Ensure properties of the CFG assumed by further stages.
+  void EnsureCFGWellFormedness();
   // Ensure split-edge form for a hand-assembled schedule.
-  void EnsureSplitEdgeForm();
+  void EnsureSplitEdgeForm(BasicBlock* block);
+  // Ensure entry into a deferred block happens from a single hot block.
+  void EnsureDeferredCodeSingleEntryPoint(BasicBlock* block);
   // Copy deferred block markers down as far as possible
   void PropagateDeferredMark();
 
   void AddSuccessor(BasicBlock* block, BasicBlock* succ);
   void MoveSuccessors(BasicBlock* from, BasicBlock* to);
 
   void SetControlInput(BasicBlock* block, Node* node);
   void SetBlockForNode(BasicBlock* block, Node* node);
 
   Zone* zone_;
   BasicBlockVector all_blocks_;           // All basic blocks in the schedule.
   BasicBlockVector nodeid_to_block_;      // Map from node to containing block.
   BasicBlockVector rpo_order_;            // Reverse-post-order block list.
   BasicBlock* start_;
   BasicBlock* end_;
 
   DISALLOW_COPY_AND_ASSIGN(Schedule);
 };
 
 std::ostream& operator<<(std::ostream&, const Schedule&);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SCHEDULE_H_