[turbofan] Single entry into deferred regions

src/compiler/schedule.h

Index: src/compiler/schedule.h
diff --git a/src/compiler/schedule.h b/src/compiler/schedule.h
index c99a0fc525173841d75d70ad739ad35c91e365db..74ba8355184eb53ce7e8ae834b6e57b5e6e04ce3 100644
--- a/src/compiler/schedule.h
+++ b/src/compiler/schedule.h
@@ -257,8 +257,12 @@ class Schedule final : public ZoneObject {
   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();