[turbofan] Check instruction input/output count limits in instruction selector.

src/compiler/instruction.h

Index: src/compiler/instruction.h
diff --git a/src/compiler/instruction.h b/src/compiler/instruction.h
index 15d6d4c17b508ebdc6af25e1e911967a4f474a9d..b5c591416618eb65f99b920511d0a934a3e8023a 100644
--- a/src/compiler/instruction.h
+++ b/src/compiler/instruction.h
@@ -947,6 +947,14 @@ class Instruction final {
   void Print(const RegisterConfiguration* config) const;
   void Print() const;
 
+  typedef BitField<size_t, 0, 8> OutputCountField;
+  typedef BitField<size_t, 8, 16> InputCountField;
+  typedef BitField<size_t, 24, 6> TempCountField;
+
+  static const size_t kMaxOutputCount = OutputCountField::kMax;
+  static const size_t kMaxInputCount = InputCountField::kMax;
+  static const size_t kMaxTempCount = TempCountField::kMax;
+
  private:
   explicit Instruction(InstructionCode opcode);
 
@@ -955,9 +963,6 @@ class Instruction final {
               InstructionOperand* inputs, size_t temp_count,
               InstructionOperand* temps);
 
-  typedef BitField<size_t, 0, 8> OutputCountField;
-  typedef BitField<size_t, 8, 16> InputCountField;
-  typedef BitField<size_t, 24, 6> TempCountField;
   typedef BitField<bool, 30, 1> IsCallField;
 
   InstructionCode opcode_;