Index: llvm/include/llvm/CodeGen/LiveIntervals.h
===================================================================
--- llvm/include/llvm/CodeGen/LiveIntervals.h
+++ llvm/include/llvm/CodeGen/LiveIntervals.h
@@ -93,12 +93,27 @@
     /// interference.
     SmallVector<LiveRange*, 0> RegUnitRanges;
 
+
   public:
     static char ID;
 
     LiveIntervals();
+    LiveIntervals(MachineFunction &MF, SlotIndexes *Indexes,
+                  MachineDominatorTree *DT);
     ~LiveIntervals() override;
 
+    void init(MachineFunction &MF, SlotIndexes *Indexes,
+              MachineDominatorTree *DT);
+
+
+    MachineDominatorTree *getDomTree() {
+      return DomTree;
+    }
+
+    const MachineDominatorTree *getDomTree() const {
+      return DomTree;
+    }
+
     /// Calculate the spill weight to assign to a single instruction.
     static float getSpillWeight(bool isDef, bool isUse,
                                 const MachineBlockFrequencyInfo *MBFI,
Index: llvm/include/llvm/CodeGen/SlotIndexes.h
===================================================================
--- llvm/include/llvm/CodeGen/SlotIndexes.h
+++ llvm/include/llvm/CodeGen/SlotIndexes.h
@@ -357,6 +357,7 @@
     void getAnalysisUsage(AnalysisUsage &au) const override;
     void releaseMemory() override;
 
+    void calculate(MachineFunction &fn);
     bool runOnMachineFunction(MachineFunction &fn) override;
 
     /// Dump the indexes.
Index: llvm/lib/CodeGen/LiveIntervals.cpp
===================================================================
--- llvm/lib/CodeGen/LiveIntervals.cpp
+++ llvm/lib/CodeGen/LiveIntervals.cpp
@@ -117,13 +117,14 @@
   VNInfoAllocator.Reset();
 }
 
-bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
-  MF = &fn;
+void LiveIntervals::init(MachineFunction &MF_, SlotIndexes *Indexes_,
+                         MachineDominatorTree *DT_) {
+  MF = &MF_;
+  Indexes = Indexes_;
+  DomTree = DT_;
   MRI = &MF->getRegInfo();
   TRI = MF->getSubtarget().getRegisterInfo();
   TII = MF->getSubtarget().getInstrInfo();
-  Indexes = &getAnalysis<SlotIndexes>();
-  DomTree = &getAnalysis<MachineDominatorTree>();
 
   if (!LICalc)
     LICalc = new LiveIntervalCalc();
@@ -141,6 +142,10 @@
     for (unsigned i = 0, e = TRI->getNumRegUnits(); i != e; ++i)
       getRegUnit(i);
   }
+}
+
+bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
+  init(fn, &getAnalysis<SlotIndexes>(), &getAnalysis<MachineDominatorTree>());
   LLVM_DEBUG(dump());
   return false;
 }
Index: llvm/lib/CodeGen/SlotIndexes.cpp
===================================================================
--- llvm/lib/CodeGen/SlotIndexes.cpp
+++ llvm/lib/CodeGen/SlotIndexes.cpp
@@ -47,8 +47,7 @@
   ileAllocator.Reset();
 }
 
-bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
-
+void SlotIndexes::calculate(MachineFunction &fn) {
   // Compute numbering as follows:
   // Grab an iterator to the start of the index list.
   // Iterate over all MBBs, and within each MBB all MIs, keeping the MI
@@ -105,7 +104,10 @@
 
   // Sort the Idx2MBBMap
   llvm::sort(idx2MBBMap, less_first());
+}
 
+bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
+  calculate(fn);
   LLVM_DEBUG(mf->print(dbgs(), this));
 
   // And we're done!