[WIP][turbofan] Instruction scheduler for Turbofan.

src/compiler/instruction-selector.h

Index: src/compiler/instruction-selector.h
diff --git a/src/compiler/instruction-selector.h b/src/compiler/instruction-selector.h
index 8d62b9676d76ea657b165a84d4c65b0ffceb171c..7b59de5de5f40480c8d7281e7bddbf963f284af5 100644
--- a/src/compiler/instruction-selector.h
+++ b/src/compiler/instruction-selector.h
@@ -9,6 +9,7 @@
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/instruction.h"
+#include "src/compiler/instruction-scheduler.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node.h"
 #include "src/zone-containers.h"
@@ -46,6 +47,10 @@ class InstructionSelector final {
   // Visit code for the entire graph with the included schedule.
   void SelectInstructions();
 
+  void StartBlock(RpoNumber rpo);
+  void EndBlock(RpoNumber rpo);
+  void AddInstruction(Instruction* instr);
+
   // ===========================================================================
   // ============= Architecture-independent code emission methods. =============
   // ===========================================================================
@@ -242,6 +247,7 @@ class InstructionSelector final {
   BoolVector defined_;
   BoolVector used_;
   IntVector virtual_registers_;
+  InstructionScheduler* scheduler_;
 };
 
 }  // namespace compiler