Index: include/llvm/CodeGen/LiveInterval.h
===================================================================
--- include/llvm/CodeGen/LiveInterval.h
+++ include/llvm/CodeGen/LiveInterval.h
@@ -605,6 +605,26 @@
     /// activated in the constructor of the live range.
     void flushSegmentSet();
 
+    /// Returns an array of indexes this LiveRange is live at.
+    /// R is a range of _ascending sorted_ _random_ access iterators
+    /// to the input indexes
+    template <typename Range>
+    std::vector<SlotIndex> findIndexesLiveAt(Range &&R) const {
+      std::vector<SlotIndex> IndexesLiveAt;
+      auto I = R.begin(), E = R.end();
+      for (auto &S : segments) {
+        auto Lower = std::lower_bound(I, E, S.start);
+        if (Lower == E)
+          break;
+        auto Upper = std::upper_bound(Lower, E, S.end);
+        IndexesLiveAt.insert(IndexesLiveAt.end(), Lower, Upper);
+        if (Upper == E)
+          break;
+        I = Upper;
+      }
+      return IndexesLiveAt;
+    }
+
     void print(raw_ostream &OS) const;
     void dump() const;