[Turbofan] Reduce register allocation work when we can.

src/compiler/instruction.h

Index: src/compiler/instruction.h
diff --git a/src/compiler/instruction.h b/src/compiler/instruction.h
index 5d8864eea7d006197a54c19d6e44b6f7cbf2dd62..e68e823e952e738341faa657174d59362d68218f 100644
--- a/src/compiler/instruction.h
+++ b/src/compiler/instruction.h
@@ -1389,6 +1389,7 @@ class V8_EXPORT_PRIVATE InstructionSequence final
   }
   MachineRepresentation GetRepresentation(int virtual_register) const;
   void MarkAsRepresentation(MachineRepresentation rep, int virtual_register);
+  int representation_mask() const { return representation_mask_; }
 
   bool IsReference(int virtual_register) const {
     return CanBeTaggedPointer(GetRepresentation(virtual_register));
@@ -1396,14 +1397,6 @@ class V8_EXPORT_PRIVATE InstructionSequence final
   bool IsFP(int virtual_register) const {
     return IsFloatingPoint(GetRepresentation(virtual_register));
   }
-  bool IsFloat(int virtual_register) const {
-    return GetRepresentation(virtual_register) ==
-           MachineRepresentation::kFloat32;
-  }
-  bool IsDouble(int virtual_register) const {
-    return GetRepresentation(virtual_register) ==
-           MachineRepresentation::kFloat64;
-  }
 
   Instruction* GetBlockStart(RpoNumber rpo) const;
 
@@ -1521,6 +1514,7 @@ class V8_EXPORT_PRIVATE InstructionSequence final
   int next_virtual_register_;
   ReferenceMapDeque reference_maps_;
   ZoneVector<MachineRepresentation> representations_;
+  int representation_mask_;
   DeoptimizationVector deoptimization_entries_;
 
   // Used at construction time