Introduce FeedbackVectorSlot type - better than int.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index af95c71310d9a2a46e4add2b4e40531054793844..c9d6d7bacfb971085cf0596a69907aeb3c311948 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -5474,12 +5474,12 @@ class HLoadGlobalGeneric FINAL : public HTemplateInstruction<2> {
   HValue* global_object() { return OperandAt(1); }
   Handle<String> name() const { return name_; }
   bool for_typeof() const { return for_typeof_; }
-  int slot() const {
-    DCHECK(FLAG_vector_ics && slot_ != AstNode::kInvalidFeedbackSlot);
+  FeedbackVectorSlot slot() const {
+    DCHECK(FLAG_vector_ics && !slot_.IsInvalid());
     return slot_;
   }
   Handle<FixedArray> feedback_vector() const { return feedback_vector_; }
-  void SetVectorAndSlot(Handle<FixedArray> vector, int slot) {
+  void SetVectorAndSlot(Handle<FixedArray> vector, FeedbackVectorSlot slot) {
     DCHECK(FLAG_vector_ics);
     feedback_vector_ = vector;
     slot_ = slot;
@@ -5498,7 +5498,7 @@ class HLoadGlobalGeneric FINAL : public HTemplateInstruction<2> {
                      Handle<String> name, bool for_typeof)
       : name_(name),
         for_typeof_(for_typeof),
-        slot_(AstNode::kInvalidFeedbackSlot) {
+        slot_(FeedbackVectorSlot::Invalid()) {
     SetOperandAt(0, context);
     SetOperandAt(1, global_object);
     set_representation(Representation::Tagged());
@@ -5508,7 +5508,7 @@ class HLoadGlobalGeneric FINAL : public HTemplateInstruction<2> {
   Handle<String> name_;
   bool for_typeof_;
   Handle<FixedArray> feedback_vector_;
-  int slot_;
+  FeedbackVectorSlot slot_;
 };
 
 
@@ -6479,12 +6479,12 @@ class HLoadNamedGeneric FINAL : public HTemplateInstruction<2> {
   HValue* object() const { return OperandAt(1); }
   Handle<Object> name() const { return name_; }
 
-  int slot() const {
-    DCHECK(FLAG_vector_ics && slot_ != AstNode::kInvalidFeedbackSlot);
+  FeedbackVectorSlot slot() const {
+    DCHECK(FLAG_vector_ics && !slot_.IsInvalid());
     return slot_;
   }
   Handle<FixedArray> feedback_vector() const { return feedback_vector_; }
-  void SetVectorAndSlot(Handle<FixedArray> vector, int slot) {
+  void SetVectorAndSlot(Handle<FixedArray> vector, FeedbackVectorSlot slot) {
     DCHECK(FLAG_vector_ics);
     feedback_vector_ = vector;
     slot_ = slot;
@@ -6500,7 +6500,7 @@ class HLoadNamedGeneric FINAL : public HTemplateInstruction<2> {
 
  private:
   HLoadNamedGeneric(HValue* context, HValue* object, Handle<Object> name)
-      : name_(name), slot_(AstNode::kInvalidFeedbackSlot) {
+      : name_(name), slot_(FeedbackVectorSlot::Invalid()) {
     SetOperandAt(0, context);
     SetOperandAt(1, object);
     set_representation(Representation::Tagged());
@@ -6509,7 +6509,7 @@ class HLoadNamedGeneric FINAL : public HTemplateInstruction<2> {
 
   Handle<Object> name_;
   Handle<FixedArray> feedback_vector_;
-  int slot_;
+  FeedbackVectorSlot slot_;
 };
 
 
@@ -6755,12 +6755,12 @@ class HLoadKeyedGeneric FINAL : public HTemplateInstruction<3> {
   HValue* object() const { return OperandAt(0); }
   HValue* key() const { return OperandAt(1); }
   HValue* context() const { return OperandAt(2); }
-  int slot() const {
-    DCHECK(FLAG_vector_ics && slot_ != AstNode::kInvalidFeedbackSlot);
+  FeedbackVectorSlot slot() const {
+    DCHECK(FLAG_vector_ics && !slot_.IsInvalid());
     return slot_;
   }
   Handle<FixedArray> feedback_vector() const { return feedback_vector_; }
-  void SetVectorAndSlot(Handle<FixedArray> vector, int slot) {
+  void SetVectorAndSlot(Handle<FixedArray> vector, FeedbackVectorSlot slot) {
     DCHECK(FLAG_vector_ics);
     feedback_vector_ = vector;
     slot_ = slot;
@@ -6779,7 +6779,7 @@ class HLoadKeyedGeneric FINAL : public HTemplateInstruction<3> {
 
  private:
   HLoadKeyedGeneric(HValue* context, HValue* obj, HValue* key)
-      : slot_(AstNode::kInvalidFeedbackSlot) {
+      : slot_(FeedbackVectorSlot::Invalid()) {
     set_representation(Representation::Tagged());
     SetOperandAt(0, obj);
     SetOperandAt(1, key);
@@ -6788,7 +6788,7 @@ class HLoadKeyedGeneric FINAL : public HTemplateInstruction<3> {
   }
 
   Handle<FixedArray> feedback_vector_;
-  int slot_;
+  FeedbackVectorSlot slot_;
 };