1 files changed, 8 insertions, 4 deletions
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 6b8cc88704..153d1c37df 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1196,11 +1196,15 @@ private:
       if (TargetRegisterInfo::isPhysicalRegister(Reg) && LIS.isReserved(Reg))
         continue;
 
+      // Collect ranges for register units. These live ranges are computed on
+      // demand, so just skip any that haven't been computed yet.
       if (TargetRegisterInfo::isPhysicalRegister(Reg) && LIS.trackingRegUnits())
-          for (MCRegUnitIterator Units(Reg, &TRI); Units.isValid(); ++Units)
-            collectRanges(MO, &LIS.getRegUnit(*Units),
-                          Entering, Internal, Exiting, OldIdx);
-      else if (LIS.hasInterval(Reg))
+        for (MCRegUnitIterator Units(Reg, &TRI); Units.isValid(); ++Units)
+          if (LiveInterval *LI = LIS.getCachedRegUnit(*Units))
+            collectRanges(MO, LI, Entering, Internal, Exiting, OldIdx);
+
+      // Collect ranges for individual registers.
+      if (LIS.hasInterval(Reg))
         collectRanges(MO, &LIS.getInterval(Reg),
                       Entering, Internal, Exiting, OldIdx);
     }