1 files changed, 10 insertions, 9 deletions
diff --git a/llvm/tools/llvm-exegesis/lib/Clustering.h b/llvm/tools/llvm-exegesis/lib/Clustering.h
index 6b8f5a654d9..3d6413d2256 100644
--- a/llvm/tools/llvm-exegesis/lib/Clustering.h
+++ b/llvm/tools/llvm-exegesis/lib/Clustering.h
@@ -33,14 +33,14 @@ public:
   public:
     static ClusterId noise() { return ClusterId(kNoise); }
     static ClusterId error() { return ClusterId(kError); }
-    static ClusterId makeValid(int Id) {
-      assert(Id >= 0);
+    static ClusterId makeValid(size_t Id) {
       return ClusterId(Id);
     }
     ClusterId() : Id_(kUndef) {}
     bool operator==(const ClusterId &O) const { return Id_ == O.Id_; }
+    bool operator<(const ClusterId &O) const {return Id_ < O.Id_; }
 
-    bool isValid() const { return Id_ >= 0; }
+    bool isValid() const { return Id_ <= kMaxValid; }
     bool isUndef() const { return Id_ == kUndef; }
     bool isNoise() const { return Id_ == kNoise; }
     bool isError() const { return Id_ == kError; }
@@ -48,15 +48,16 @@ public:
     // Precondition: isValid().
     size_t getId() const {
       assert(isValid());
-      return static_cast<size_t>(Id_);
+      return Id_;
     }
 
   private:
-    explicit ClusterId(int Id) : Id_(Id) {}
-    static constexpr const int kUndef = -1;
-    static constexpr const int kNoise = -2;
-    static constexpr const int kError = -3;
-    int Id_;
+    explicit ClusterId(size_t Id) : Id_(Id) {}
+    static constexpr const size_t kMaxValid = std::numeric_limits<size_t>::max() - 4;
+    static constexpr const size_t kNoise = kMaxValid + 1;
+    static constexpr const size_t kError = kMaxValid + 2;
+    static constexpr const size_t kUndef = kMaxValid + 3;
+    size_t Id_;
   };
 
   struct Cluster {