diff --git a/llvm/include/llvm/CodeGen/LiveInterval.h b/llvm/include/llvm/CodeGen/LiveInterval.h
--- a/llvm/include/llvm/CodeGen/LiveInterval.h
+++ b/llvm/include/llvm/CodeGen/LiveInterval.h
@@ -704,12 +704,16 @@
   private:
     SubRange *SubRanges = nullptr; ///< Single linked list of subregister live
                                    /// ranges.
+    const unsigned Reg; // the register or stack slot of this interval.
+    float Weight = 0.0; // weight of this interval
 
   public:
-    const unsigned reg;  // the register or stack slot of this interval.
-    float weight;        // weight of this interval
+    unsigned reg() const { return Reg; }
+    float weight() const { return Weight; }
+    void incrementWeight(float Inc) { Weight += Inc; }
+    void setWeight(float Value) { Weight = Value; }
 
-    LiveInterval(unsigned Reg, float Weight) : reg(Reg), weight(Weight) {}
+    LiveInterval(unsigned Reg, float Weight) : Reg(Reg), Weight(Weight) {}
 
     ~LiveInterval() {
       clearSubRanges();
@@ -806,14 +810,10 @@
     unsigned getSize() const;
 
     /// isSpillable - Can this interval be spilled?
-    bool isSpillable() const {
-      return weight != huge_valf;
-    }
+    bool isSpillable() const { return Weight != huge_valf; }
 
     /// markNotSpillable - Mark interval as not spillable
-    void markNotSpillable() {
-      weight = huge_valf;
-    }
+    void markNotSpillable() { Weight = huge_valf; }
 
     /// For a given lane mask @p LaneMask, compute indexes at which the
     /// lane is marked undefined by subregister <def,read-undef> definitions.
@@ -870,7 +870,7 @@
     bool operator<(const LiveInterval& other) const {
       const SlotIndex &thisIndex = beginIndex();
       const SlotIndex &otherIndex = other.beginIndex();
-      return std::tie(thisIndex, reg) < std::tie(otherIndex, other.reg);
+      return std::tie(thisIndex, Reg) < std::tie(otherIndex, other.Reg);
     }
 
     void print(raw_ostream &OS) const;
diff --git a/llvm/include/llvm/CodeGen/LiveRangeEdit.h b/llvm/include/llvm/CodeGen/LiveRangeEdit.h
--- a/llvm/include/llvm/CodeGen/LiveRangeEdit.h
+++ b/llvm/include/llvm/CodeGen/LiveRangeEdit.h
@@ -152,7 +152,7 @@
     return *Parent;
   }
 
-  Register getReg() const { return getParent().reg; }
+  Register getReg() const { return getParent().reg(); }
 
   /// Iterator for accessing the new registers added by this edit.
   using iterator = SmallVectorImpl<Register>::const_iterator;
diff --git a/llvm/lib/CodeGen/CalcSpillWeights.cpp b/llvm/lib/CodeGen/CalcSpillWeights.cpp
--- a/llvm/lib/CodeGen/CalcSpillWeights.cpp
+++ b/llvm/lib/CodeGen/CalcSpillWeights.cpp
@@ -86,7 +86,7 @@
                                const LiveIntervals &LIS,
                                VirtRegMap *VRM,
                                const TargetInstrInfo &TII) {
-  unsigned Reg = LI.reg;
+  unsigned Reg = LI.reg();
   unsigned Original = VRM ? VRM->getOriginal(Reg) : 0;
   for (LiveInterval::const_vni_iterator I = LI.vni_begin(), E = LI.vni_end();
        I != E; ++I) {
@@ -140,7 +140,7 @@
   // Check if unspillable.
   if (weight < 0)
     return;
-  li.weight = weight;
+  li.setWeight(weight);
 }
 
 float VirtRegAuxInfo::futureWeight(LiveInterval &li, SlotIndex start,
@@ -159,10 +159,10 @@
   unsigned numInstr = 0; // Number of instructions using li
   SmallPtrSet<MachineInstr*, 8> visited;
 
-  std::pair<unsigned, unsigned> TargetHint = mri.getRegAllocationHint(li.reg);
+  std::pair<unsigned, unsigned> TargetHint = mri.getRegAllocationHint(li.reg());
 
   if (li.isSpillable() && VRM) {
-    Register Reg = li.reg;
+    Register Reg = li.reg();
     Register Original = VRM->getOriginal(Reg);
     const LiveInterval &OrigInt = LIS.getInterval(Original);
     // li comes from a split of OrigInt. If OrigInt was marked
@@ -215,7 +215,7 @@
   std::set<CopyHint> CopyHints;
 
   for (MachineRegisterInfo::reg_instr_nodbg_iterator
-           I = mri.reg_instr_nodbg_begin(li.reg),
+           I = mri.reg_instr_nodbg_begin(li.reg()),
            E = mri.reg_instr_nodbg_end();
        I != E;) {
     MachineInstr *mi = &*(I++);
@@ -243,7 +243,7 @@
 
       // Calculate instr weight.
       bool reads, writes;
-      std::tie(reads, writes) = mi->readsWritesVirtualRegister(li.reg);
+      std::tie(reads, writes) = mi->readsWritesVirtualRegister(li.reg());
       weight = LiveIntervals::getSpillWeight(writes, reads, &MBFI, *mi);
 
       // Give extra weight to what looks like a loop induction variable update.
@@ -256,7 +256,7 @@
     // Get allocation hints from copies.
     if (!mi->isCopy())
       continue;
-    Register hint = copyHint(mi, li.reg, tri, mri);
+    Register hint = copyHint(mi, li.reg(), tri, mri);
     if (!hint)
       continue;
     // Force hweight onto the stack so that x86 doesn't add hidden precision,
@@ -275,7 +275,7 @@
   if (updateLI && CopyHints.size()) {
     // Remove a generic hint if previously added by target.
     if (TargetHint.first == 0 && TargetHint.second)
-      mri.clearSimpleHint(li.reg);
+      mri.clearSimpleHint(li.reg());
 
     std::set<unsigned> HintedRegs;
     for (auto &Hint : CopyHints) {
@@ -283,7 +283,7 @@
           (TargetHint.first != 0 && Hint.Reg == TargetHint.second))
         // Don't add the same reg twice or the target-type hint again.
         continue;
-      mri.addRegAllocationHint(li.reg, Hint.Reg);
+      mri.addRegAllocationHint(li.reg(), Hint.Reg);
     }
 
     // Weakly boost the spill weight of hinted registers.
diff --git a/llvm/lib/CodeGen/InlineSpiller.cpp b/llvm/lib/CodeGen/InlineSpiller.cpp
--- a/llvm/lib/CodeGen/InlineSpiller.cpp
+++ b/llvm/lib/CodeGen/InlineSpiller.cpp
@@ -289,8 +289,9 @@
 
   // Check that all uses satisfy our criteria.
   for (MachineRegisterInfo::reg_instr_nodbg_iterator
-       RI = MRI.reg_instr_nodbg_begin(SnipLI.reg),
-       E = MRI.reg_instr_nodbg_end(); RI != E; ) {
+           RI = MRI.reg_instr_nodbg_begin(SnipLI.reg()),
+           E = MRI.reg_instr_nodbg_end();
+       RI != E;) {
     MachineInstr &MI = *RI++;
 
     // Allow copies to/from Reg.
@@ -299,11 +300,11 @@
 
     // Allow stack slot loads.
     int FI;
-    if (SnipLI.reg == TII.isLoadFromStackSlot(MI, FI) && FI == StackSlot)
+    if (SnipLI.reg() == TII.isLoadFromStackSlot(MI, FI) && FI == StackSlot)
       continue;
 
     // Allow stack slot stores.
-    if (SnipLI.reg == TII.isStoreToStackSlot(MI, FI) && FI == StackSlot)
+    if (SnipLI.reg() == TII.isStoreToStackSlot(MI, FI) && FI == StackSlot)
       continue;
 
     // Allow a single additional instruction.
@@ -432,7 +433,7 @@
   do {
     LiveInterval *LI;
     std::tie(LI, VNI) = WorkList.pop_back_val();
-    Register Reg = LI->reg;
+    Register Reg = LI->reg();
     LLVM_DEBUG(dbgs() << "Checking redundant spills for " << VNI->id << '@'
                       << VNI->def << " in " << *LI << '\n');
 
@@ -511,7 +512,7 @@
     if (!SnippetCopies.count(MI))
       continue;
     LiveInterval &SnipLI = LIS.getInterval(MI->getOperand(1).getReg());
-    assert(isRegToSpill(SnipLI.reg) && "Unexpected register in copy");
+    assert(isRegToSpill(SnipLI.reg()) && "Unexpected register in copy");
     VNInfo *SnipVNI = SnipLI.getVNInfoAt(VNI->def.getRegSlot(true));
     assert(SnipVNI && "Snippet undefined before copy");
     WorkList.push_back(std::make_pair(&SnipLI, SnipVNI));
@@ -556,7 +557,7 @@
 bool InlineSpiller::reMaterializeFor(LiveInterval &VirtReg, MachineInstr &MI) {
   // Analyze instruction
   SmallVector<std::pair<MachineInstr *, unsigned>, 8> Ops;
-  VirtRegInfo RI = AnalyzeVirtRegInBundle(MI, VirtReg.reg, &Ops);
+  VirtRegInfo RI = AnalyzeVirtRegInBundle(MI, VirtReg.reg(), &Ops);
 
   if (!RI.Reads)
     return false;
@@ -568,7 +569,7 @@
     LLVM_DEBUG(dbgs() << "\tadding <undef> flags: ");
     for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
       MachineOperand &MO = MI.getOperand(i);
-      if (MO.isReg() && MO.isUse() && MO.getReg() == VirtReg.reg)
+      if (MO.isReg() && MO.isUse() && MO.getReg() == VirtReg.reg())
         MO.setIsUndef();
     }
     LLVM_DEBUG(dbgs() << UseIdx << '\t' << MI);
@@ -608,7 +609,7 @@
 
   // If we can't guarantee that we'll be able to actually assign the new vreg,
   // we can't remat.
-  if (!canGuaranteeAssignmentAfterRemat(VirtReg.reg, MI)) {
+  if (!canGuaranteeAssignmentAfterRemat(VirtReg.reg(), MI)) {
     markValueUsed(&VirtReg, ParentVNI);
     LLVM_DEBUG(dbgs() << "\tcannot remat for " << UseIdx << '\t' << MI);
     return false;
@@ -633,7 +634,7 @@
   // Replace operands
   for (const auto &OpPair : Ops) {
     MachineOperand &MO = OpPair.first->getOperand(OpPair.second);
-    if (MO.isReg() && MO.isUse() && MO.getReg() == VirtReg.reg) {
+    if (MO.isReg() && MO.isUse() && MO.getReg() == VirtReg.reg()) {
       MO.setReg(NewVReg);
       MO.setIsKill();
     }
@@ -1171,7 +1172,7 @@
   // save a copy of LiveInterval in StackSlotToOrigLI because the original
   // LiveInterval may be cleared after all its references are spilled.
   if (StackSlotToOrigLI.find(StackSlot) == StackSlotToOrigLI.end()) {
-    auto LI = std::make_unique<LiveInterval>(OrigLI.reg, OrigLI.weight);
+    auto LI = std::make_unique<LiveInterval>(OrigLI.reg(), OrigLI.weight());
     LI->assign(OrigLI, Allocator);
     StackSlotToOrigLI[StackSlot] = std::move(LI);
   }
@@ -1199,7 +1200,7 @@
 bool HoistSpillHelper::isSpillCandBB(LiveInterval &OrigLI, VNInfo &OrigVNI,
                                      MachineBasicBlock &BB, Register &LiveReg) {
   SlotIndex Idx;
-  Register OrigReg = OrigLI.reg;
+  Register OrigReg = OrigLI.reg();
   MachineBasicBlock::iterator MI = IPA.getLastInsertPointIter(OrigLI, BB);
   if (MI != BB.end())
     Idx = LIS.getInstructionIndex(*MI);
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -777,12 +777,12 @@
   if (Kills.empty())
     return;
   // Don't track copies from physregs, there are too many uses.
-  if (!Register::isVirtualRegister(LI->reg))
+  if (!Register::isVirtualRegister(LI->reg()))
     return;
 
   // Collect all the (vreg, valno) pairs that are copies of LI.
   SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
-  for (MachineOperand &MO : MRI.use_nodbg_operands(LI->reg)) {
+  for (MachineOperand &MO : MRI.use_nodbg_operands(LI->reg())) {
     MachineInstr *MI = MO.getParent();
     // Copies of the full value.
     if (MO.getSubReg() || !MI->isCopy())
@@ -1066,7 +1066,7 @@
           LII->start < LocMapI.stop()) {
         // Overlapping correct location. Allocate NewLocNo now.
         if (NewLocNo == UndefLocNo) {
-          MachineOperand MO = MachineOperand::CreateReg(LI->reg, false);
+          MachineOperand MO = MachineOperand::CreateReg(LI->reg(), false);
           MO.setSubReg(locations[OldLocNo].getSubReg());
           NewLocNo = getLocationNo(MO);
           DidChange = true;
diff --git a/llvm/lib/CodeGen/LiveInterval.cpp b/llvm/lib/CodeGen/LiveInterval.cpp
--- a/llvm/lib/CodeGen/LiveInterval.cpp
+++ b/llvm/lib/CodeGen/LiveInterval.cpp
@@ -951,9 +951,9 @@
       MatchingRange = createSubRangeFrom(Allocator, Matching, SR);
       // Now that the subrange is split in half, make sure we
       // only keep in the subranges the VNIs that touch the related half.
-      stripValuesNotDefiningMask(reg, *MatchingRange, Matching, Indexes, TRI,
+      stripValuesNotDefiningMask(reg(), *MatchingRange, Matching, Indexes, TRI,
                                  ComposeSubRegIdx);
-      stripValuesNotDefiningMask(reg, SR, SR.LaneMask, Indexes, TRI,
+      stripValuesNotDefiningMask(reg(), SR, SR.LaneMask, Indexes, TRI,
                                  ComposeSubRegIdx);
     }
     Apply(*MatchingRange);
@@ -977,11 +977,11 @@
                                          LaneBitmask LaneMask,
                                          const MachineRegisterInfo &MRI,
                                          const SlotIndexes &Indexes) const {
-  assert(Register::isVirtualRegister(reg));
-  LaneBitmask VRegMask = MRI.getMaxLaneMaskForVReg(reg);
+  assert(Register::isVirtualRegister(reg()));
+  LaneBitmask VRegMask = MRI.getMaxLaneMaskForVReg(reg());
   assert((VRegMask & LaneMask).any());
   const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
-  for (const MachineOperand &MO : MRI.def_operands(reg)) {
+  for (const MachineOperand &MO : MRI.def_operands(reg())) {
     if (!MO.isUndef())
       continue;
     unsigned SubReg = MO.getSubReg();
@@ -1043,12 +1043,12 @@
 }
 
 void LiveInterval::print(raw_ostream &OS) const {
-  OS << printReg(reg) << ' ';
+  OS << printReg(reg()) << ' ';
   super::print(OS);
   // Print subranges
   for (const SubRange &SR : subranges())
     OS << SR;
-  OS << " weight:" << weight;
+  OS << " weight:" << Weight;
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
@@ -1087,7 +1087,7 @@
 
   // Make sure SubRanges are fine and LaneMasks are disjunct.
   LaneBitmask Mask;
-  LaneBitmask MaxMask = MRI != nullptr ? MRI->getMaxLaneMaskForVReg(reg)
+  LaneBitmask MaxMask = MRI != nullptr ? MRI->getMaxLaneMaskForVReg(reg())
                                        : LaneBitmask::getAll();
   for (const SubRange &SR : subranges()) {
     // Subrange lanemask should be disjunct to any previous subrange masks.
@@ -1361,8 +1361,9 @@
 void ConnectedVNInfoEqClasses::Distribute(LiveInterval &LI, LiveInterval *LIV[],
                                           MachineRegisterInfo &MRI) {
   // Rewrite instructions.
-  for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(LI.reg),
-       RE = MRI.reg_end(); RI != RE;) {
+  for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(LI.reg()),
+                                         RE = MRI.reg_end();
+       RI != RE;) {
     MachineOperand &MO = *RI;
     MachineInstr *MI = RI->getParent();
     ++RI;
@@ -1382,7 +1383,7 @@
     if (!VNI)
       continue;
     if (unsigned EqClass = getEqClass(VNI))
-      MO.setReg(LIV[EqClass-1]->reg);
+      MO.setReg(LIV[EqClass - 1]->reg());
   }
 
   // Distribute subregister liveranges.
diff --git a/llvm/lib/CodeGen/LiveIntervalCalc.cpp b/llvm/lib/CodeGen/LiveIntervalCalc.cpp
--- a/llvm/lib/CodeGen/LiveIntervalCalc.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalCalc.cpp
@@ -60,7 +60,7 @@
   // Visit all def operands. If the same instruction has multiple defs of Reg,
   // createDeadDef() will deduplicate.
   const TargetRegisterInfo &TRI = *MRI->getTargetRegisterInfo();
-  unsigned Reg = LI.reg;
+  unsigned Reg = LI.reg();
   for (const MachineOperand &MO : MRI->reg_nodbg_operands(Reg)) {
     if (!MO.isDef() && !MO.readsReg())
       continue;
@@ -127,7 +127,7 @@
     }
   }
   resetLiveOutMap();
-  extendToUses(MainRange, LI.reg, LaneBitmask::getAll(), &LI);
+  extendToUses(MainRange, LI.reg(), LaneBitmask::getAll(), &LI);
 }
 
 void LiveIntervalCalc::createDeadDefs(LiveRange &LR, Register Reg) {
diff --git a/llvm/lib/CodeGen/LiveIntervalUnion.cpp b/llvm/lib/CodeGen/LiveIntervalUnion.cpp
--- a/llvm/lib/CodeGen/LiveIntervalUnion.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalUnion.cpp
@@ -85,8 +85,8 @@
     return;
   }
   for (LiveSegments::const_iterator SI = Segments.begin(); SI.valid(); ++SI) {
-    OS << " [" << SI.start() << ' ' << SI.stop() << "):"
-       << printReg(SI.value()->reg, TRI);
+    OS << " [" << SI.start() << ' ' << SI.stop()
+       << "):" << printReg(SI.value()->reg(), TRI);
   }
   OS << '\n';
 }
@@ -95,7 +95,7 @@
 // Verify the live intervals in this union and add them to the visited set.
 void LiveIntervalUnion::verify(LiveVirtRegBitSet& VisitedVRegs) {
   for (SegmentIter SI = Segments.begin(); SI.valid(); ++SI)
-    VisitedVRegs.set(SI.value()->reg);
+    VisitedVRegs.set(SI.value()->reg());
 }
 #endif //!NDEBUG
 
diff --git a/llvm/lib/CodeGen/LiveIntervals.cpp b/llvm/lib/CodeGen/LiveIntervals.cpp
--- a/llvm/lib/CodeGen/LiveIntervals.cpp
+++ b/llvm/lib/CodeGen/LiveIntervals.cpp
@@ -193,7 +193,7 @@
   assert(LICalc && "LICalc not initialized.");
   assert(LI.empty() && "Should only compute empty intervals.");
   LICalc->reset(MF, getSlotIndexes(), DomTree, &getVNInfoAllocator());
-  LICalc->calculate(LI, MRI->shouldTrackSubRegLiveness(LI.reg));
+  LICalc->calculate(LI, MRI->shouldTrackSubRegLiveness(LI.reg()));
   return computeDeadValues(LI, nullptr);
 }
 
@@ -453,13 +453,13 @@
 bool LiveIntervals::shrinkToUses(LiveInterval *li,
                                  SmallVectorImpl<MachineInstr*> *dead) {
   LLVM_DEBUG(dbgs() << "Shrink: " << *li << '\n');
-  assert(Register::isVirtualRegister(li->reg) &&
+  assert(Register::isVirtualRegister(li->reg()) &&
          "Can only shrink virtual registers");
 
   // Shrink subregister live ranges.
   bool NeedsCleanup = false;
   for (LiveInterval::SubRange &S : li->subranges()) {
-    shrinkToUses(S, li->reg);
+    shrinkToUses(S, li->reg());
     if (S.empty())
       NeedsCleanup = true;
   }
@@ -469,8 +469,8 @@
   // Find all the values used, including PHI kills.
   ShrinkToUsesWorkList WorkList;
 
-  // Visit all instructions reading li->reg.
-  unsigned Reg = li->reg;
+  // Visit all instructions reading li->reg().
+  unsigned Reg = li->reg();
   for (MachineInstr &UseMI : MRI->reg_instructions(Reg)) {
     if (UseMI.isDebugValue() || !UseMI.readsVirtualRegister(Reg))
       continue;
@@ -523,7 +523,7 @@
 
     // Is the register live before? Otherwise we may have to add a read-undef
     // flag for subregister defs.
-    unsigned VReg = LI.reg;
+    unsigned VReg = LI.reg();
     if (MRI->shouldTrackSubRegLiveness(VReg)) {
       if ((I == LI.begin() || std::prev(I)->end < Def) && !VNI->isPHIDef()) {
         MachineInstr *MI = getInstructionFromIndex(Def);
@@ -543,7 +543,7 @@
       // This is a dead def. Make sure the instruction knows.
       MachineInstr *MI = getInstructionFromIndex(Def);
       assert(MI && "No instruction defining live value");
-      MI->addRegisterDead(LI.reg, TRI);
+      MI->addRegisterDead(LI.reg(), TRI);
       if (HaveDeadDef)
         MayHaveSplitComponents = true;
       HaveDeadDef = true;
@@ -1716,7 +1716,7 @@
   if (NumComp <= 1)
     return;
   LLVM_DEBUG(dbgs() << "  Split " << NumComp << " components: " << LI << '\n');
-  unsigned Reg = LI.reg;
+  unsigned Reg = LI.reg();
   const TargetRegisterClass *RegClass = MRI->getRegClass(Reg);
   for (unsigned I = 1; I < NumComp; ++I) {
     Register NewVReg = MRI->createVirtualRegister(RegClass);
diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
--- a/llvm/lib/CodeGen/LiveRangeEdit.cpp
+++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -188,7 +188,7 @@
   MachineInstr *DefMI = nullptr, *UseMI = nullptr;
 
   // Check that there is a single def and a single use.
-  for (MachineOperand &MO : MRI.reg_nodbg_operands(LI->reg)) {
+  for (MachineOperand &MO : MRI.reg_nodbg_operands(LI->reg())) {
     MachineInstr *MI = MO.getParent();
     if (MO.isDef()) {
       if (DefMI && DefMI != MI)
@@ -224,7 +224,7 @@
                     << "       into single use: " << *UseMI);
 
   SmallVector<unsigned, 8> Ops;
-  if (UseMI->readsWritesVirtualRegister(LI->reg, &Ops).second)
+  if (UseMI->readsWritesVirtualRegister(LI->reg(), &Ops).second)
     return false;
 
   MachineInstr *FoldMI = TII.foldMemoryOperand(*UseMI, Ops, *DefMI, &LIS);
@@ -236,7 +236,7 @@
   if (UseMI->shouldUpdateCallSiteInfo())
     UseMI->getMF()->moveCallSiteInfo(UseMI, FoldMI);
   UseMI->eraseFromParent();
-  DefMI->addRegisterDead(LI->reg, nullptr);
+  DefMI->addRegisterDead(LI->reg(), nullptr);
   Dead.push_back(DefMI);
   ++NumDCEFoldedLoads;
   return true;
@@ -332,7 +332,7 @@
     // Remove defined value.
     if (MOI->isDef()) {
       if (TheDelegate && LI.getVNInfoAt(Idx) != nullptr)
-        TheDelegate->LRE_WillShrinkVirtReg(LI.reg);
+        TheDelegate->LRE_WillShrinkVirtReg(LI.reg());
       LIS.removeVRegDefAt(LI, Idx);
       if (LI.empty())
         RegsToErase.push_back(Reg);
@@ -369,7 +369,7 @@
       pop_back();
       DeadRemats->insert(MI);
       const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
-      MI->substituteRegister(Dest, NewLI.reg, 0, TRI);
+      MI->substituteRegister(Dest, NewLI.reg(), 0, TRI);
       MI->getOperand(0).setIsDead(true);
     } else {
       if (TheDelegate)
@@ -409,7 +409,7 @@
     ToShrink.pop_back();
     if (foldAsLoad(LI, Dead))
       continue;
-    unsigned VReg = LI->reg;
+    unsigned VReg = LI->reg();
     if (TheDelegate)
       TheDelegate->LRE_WillShrinkVirtReg(VReg);
     if (!LIS.shrinkToUses(LI, &Dead))
@@ -442,9 +442,9 @@
       // intervals their own originals instead of referring to LI. The original
       // interval must contain all the split products, and LI doesn't.
       if (Original != VReg && Original != 0)
-        VRM->setIsSplitFromReg(SplitLI->reg, Original);
+        VRM->setIsSplitFromReg(SplitLI->reg(), Original);
       if (TheDelegate)
-        TheDelegate->LRE_DidCloneVirtReg(SplitLI->reg, VReg);
+        TheDelegate->LRE_DidCloneVirtReg(SplitLI->reg(), VReg);
     }
   }
 }
@@ -466,11 +466,11 @@
   VirtRegAuxInfo VRAI(MF, LIS, VRM, Loops, MBFI);
   for (unsigned I = 0, Size = size(); I < Size; ++I) {
     LiveInterval &LI = LIS.getInterval(get(I));
-    if (MRI.recomputeRegClass(LI.reg))
+    if (MRI.recomputeRegClass(LI.reg()))
       LLVM_DEBUG({
         const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
-        dbgs() << "Inflated " << printReg(LI.reg) << " to "
-               << TRI->getRegClassName(MRI.getRegClass(LI.reg)) << '\n';
+        dbgs() << "Inflated " << printReg(LI.reg()) << " to "
+               << TRI->getRegClassName(MRI.getRegClass(LI.reg())) << '\n';
       });
     VRAI.calculateSpillWeightAndHint(LI);
   }
diff --git a/llvm/lib/CodeGen/LiveRegMatrix.cpp b/llvm/lib/CodeGen/LiveRegMatrix.cpp
--- a/llvm/lib/CodeGen/LiveRegMatrix.cpp
+++ b/llvm/lib/CodeGen/LiveRegMatrix.cpp
@@ -102,10 +102,10 @@
 }
 
 void LiveRegMatrix::assign(LiveInterval &VirtReg, unsigned PhysReg) {
-  LLVM_DEBUG(dbgs() << "assigning " << printReg(VirtReg.reg, TRI) << " to "
+  LLVM_DEBUG(dbgs() << "assigning " << printReg(VirtReg.reg(), TRI) << " to "
                     << printReg(PhysReg, TRI) << ':');
-  assert(!VRM->hasPhys(VirtReg.reg) && "Duplicate VirtReg assignment");
-  VRM->assignVirt2Phys(VirtReg.reg, PhysReg);
+  assert(!VRM->hasPhys(VirtReg.reg()) && "Duplicate VirtReg assignment");
+  VRM->assignVirt2Phys(VirtReg.reg(), PhysReg);
 
   foreachUnit(
       TRI, VirtReg, PhysReg, [&](unsigned Unit, const LiveRange &Range) {
@@ -119,10 +119,10 @@
 }
 
 void LiveRegMatrix::unassign(LiveInterval &VirtReg) {
-  Register PhysReg = VRM->getPhys(VirtReg.reg);
-  LLVM_DEBUG(dbgs() << "unassigning " << printReg(VirtReg.reg, TRI) << " from "
-                    << printReg(PhysReg, TRI) << ':');
-  VRM->clearVirt(VirtReg.reg);
+  Register PhysReg = VRM->getPhys(VirtReg.reg());
+  LLVM_DEBUG(dbgs() << "unassigning " << printReg(VirtReg.reg(), TRI)
+                    << " from " << printReg(PhysReg, TRI) << ':');
+  VRM->clearVirt(VirtReg.reg());
 
   foreachUnit(TRI, VirtReg, PhysReg,
               [&](unsigned Unit, const LiveRange &Range) {
@@ -148,8 +148,8 @@
   // Check if the cached information is valid.
   // The same BitVector can be reused for all PhysRegs.
   // We could cache multiple VirtRegs if it becomes necessary.
-  if (RegMaskVirtReg != VirtReg.reg || RegMaskTag != UserTag) {
-    RegMaskVirtReg = VirtReg.reg;
+  if (RegMaskVirtReg != VirtReg.reg() || RegMaskTag != UserTag) {
+    RegMaskVirtReg = VirtReg.reg();
     RegMaskTag = UserTag;
     RegMaskUsable.clear();
     LIS->checkRegMaskInterference(VirtReg, RegMaskUsable);
@@ -165,7 +165,7 @@
                                              unsigned PhysReg) {
   if (VirtReg.empty())
     return false;
-  CoalescerPair CP(VirtReg.reg, PhysReg, *TRI);
+  CoalescerPair CP(VirtReg.reg(), PhysReg, *TRI);
 
   bool Result = foreachUnit(TRI, VirtReg, PhysReg, [&](unsigned Unit,
                                                        const LiveRange &Range) {
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -2529,7 +2529,7 @@
     }
 
     const LiveInterval &LI = LiveInts->getInterval(Reg);
-    assert(Reg == LI.reg && "Invalid reg to interval mapping");
+    assert(Reg == LI.reg() && "Invalid reg to interval mapping");
     verifyLiveInterval(LI);
   }
 
@@ -2855,7 +2855,7 @@
 }
 
 void MachineVerifier::verifyLiveInterval(const LiveInterval &LI) {
-  unsigned Reg = LI.reg;
+  unsigned Reg = LI.reg();
   assert(Register::isVirtualRegister(Reg));
   verifyLiveRange(LI, Reg);
 
@@ -2872,10 +2872,10 @@
     }
     if (SR.empty()) {
       report("Subrange must not be empty", MF);
-      report_context(SR, LI.reg, SR.LaneMask);
+      report_context(SR, LI.reg(), SR.LaneMask);
     }
     Mask |= SR.LaneMask;
-    verifyLiveRange(SR, LI.reg, SR.LaneMask);
+    verifyLiveRange(SR, LI.reg(), SR.LaneMask);
     if (!LI.covers(SR)) {
       report("A Subrange is not covered by the main range", MF);
       report_context(LI);
diff --git a/llvm/lib/CodeGen/RegAllocBase.cpp b/llvm/lib/CodeGen/RegAllocBase.cpp
--- a/llvm/lib/CodeGen/RegAllocBase.cpp
+++ b/llvm/lib/CodeGen/RegAllocBase.cpp
@@ -87,13 +87,13 @@
 
   // Continue assigning vregs one at a time to available physical registers.
   while (LiveInterval *VirtReg = dequeue()) {
-    assert(!VRM->hasPhys(VirtReg->reg) && "Register already assigned");
+    assert(!VRM->hasPhys(VirtReg->reg()) && "Register already assigned");
 
     // Unused registers can appear when the spiller coalesces snippets.
-    if (MRI->reg_nodbg_empty(VirtReg->reg)) {
+    if (MRI->reg_nodbg_empty(VirtReg->reg())) {
       LLVM_DEBUG(dbgs() << "Dropping unused " << *VirtReg << '\n');
       aboutToRemoveInterval(*VirtReg);
-      LIS->removeInterval(VirtReg->reg);
+      LIS->removeInterval(VirtReg->reg());
       continue;
     }
 
@@ -104,8 +104,8 @@
     // register if possible and populate a list of new live intervals that
     // result from splitting.
     LLVM_DEBUG(dbgs() << "\nselectOrSplit "
-                      << TRI->getRegClassName(MRI->getRegClass(VirtReg->reg))
-                      << ':' << *VirtReg << " w=" << VirtReg->weight << '\n');
+                      << TRI->getRegClassName(MRI->getRegClass(VirtReg->reg()))
+                      << ':' << *VirtReg << " w=" << VirtReg->weight() << '\n');
 
     using VirtRegVec = SmallVector<Register, 4>;
 
@@ -117,8 +117,9 @@
       // Probably caused by an inline asm.
       MachineInstr *MI = nullptr;
       for (MachineRegisterInfo::reg_instr_iterator
-           I = MRI->reg_instr_begin(VirtReg->reg), E = MRI->reg_instr_end();
-           I != E; ) {
+               I = MRI->reg_instr_begin(VirtReg->reg()),
+               E = MRI->reg_instr_end();
+           I != E;) {
         MI = &*(I++);
         if (MI->isInlineAsm())
           break;
@@ -133,8 +134,9 @@
         report_fatal_error("ran out of registers during register allocation");
       }
       // Keep going after reporting the error.
-      VRM->assignVirt2Phys(VirtReg->reg,
-                 RegClassInfo.getOrder(MRI->getRegClass(VirtReg->reg)).front());
+      VRM->assignVirt2Phys(
+          VirtReg->reg(),
+          RegClassInfo.getOrder(MRI->getRegClass(VirtReg->reg())).front());
       continue;
     }
 
@@ -145,16 +147,16 @@
       assert(LIS->hasInterval(Reg));
 
       LiveInterval *SplitVirtReg = &LIS->getInterval(Reg);
-      assert(!VRM->hasPhys(SplitVirtReg->reg) && "Register already assigned");
-      if (MRI->reg_nodbg_empty(SplitVirtReg->reg)) {
+      assert(!VRM->hasPhys(SplitVirtReg->reg()) && "Register already assigned");
+      if (MRI->reg_nodbg_empty(SplitVirtReg->reg())) {
         assert(SplitVirtReg->empty() && "Non-empty but used interval");
         LLVM_DEBUG(dbgs() << "not queueing unused  " << *SplitVirtReg << '\n');
         aboutToRemoveInterval(*SplitVirtReg);
-        LIS->removeInterval(SplitVirtReg->reg);
+        LIS->removeInterval(SplitVirtReg->reg());
         continue;
       }
       LLVM_DEBUG(dbgs() << "queuing new interval: " << *SplitVirtReg << "\n");
-      assert(Register::isVirtualRegister(SplitVirtReg->reg) &&
+      assert(Register::isVirtualRegister(SplitVirtReg->reg()) &&
              "expect split value in virtual register");
       enqueue(SplitVirtReg);
       ++NumNewQueued;
diff --git a/llvm/lib/CodeGen/RegAllocBasic.cpp b/llvm/lib/CodeGen/RegAllocBasic.cpp
--- a/llvm/lib/CodeGen/RegAllocBasic.cpp
+++ b/llvm/lib/CodeGen/RegAllocBasic.cpp
@@ -46,7 +46,7 @@
 namespace {
   struct CompSpillWeight {
     bool operator()(LiveInterval *A, LiveInterval *B) const {
-      return A->weight < B->weight;
+      return A->weight() < B->weight();
     }
   };
 }
@@ -213,7 +213,7 @@
     Q.collectInterferingVRegs();
     for (unsigned i = Q.interferingVRegs().size(); i; --i) {
       LiveInterval *Intf = Q.interferingVRegs()[i - 1];
-      if (!Intf->isSpillable() || Intf->weight > VirtReg.weight)
+      if (!Intf->isSpillable() || Intf->weight() > VirtReg.weight())
         return false;
       Intfs.push_back(Intf);
     }
@@ -227,7 +227,7 @@
     LiveInterval &Spill = *Intfs[i];
 
     // Skip duplicates.
-    if (!VRM->hasPhys(Spill.reg))
+    if (!VRM->hasPhys(Spill.reg()))
       continue;
 
     // Deallocate the interfering vreg by removing it from the union.
@@ -259,7 +259,7 @@
   SmallVector<Register, 8> PhysRegSpillCands;
 
   // Check for an available register in this class.
-  AllocationOrder Order(VirtReg.reg, *VRM, RegClassInfo, Matrix);
+  AllocationOrder Order(VirtReg.reg(), *VRM, RegClassInfo, Matrix);
   while (Register PhysReg = Order.next()) {
     // Check for interference in PhysReg
     switch (Matrix->checkInterference(VirtReg, PhysReg)) {
diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -247,12 +247,12 @@
   IndexedMap<RegInfo, VirtReg2IndexFunctor> ExtraRegInfo;
 
   LiveRangeStage getStage(const LiveInterval &VirtReg) const {
-    return ExtraRegInfo[VirtReg.reg].Stage;
+    return ExtraRegInfo[VirtReg.reg()].Stage;
   }
 
   void setStage(const LiveInterval &VirtReg, LiveRangeStage Stage) {
     ExtraRegInfo.resize(MRI->getNumVirtRegs());
-    ExtraRegInfo[VirtReg.reg].Stage = Stage;
+    ExtraRegInfo[VirtReg.reg()].Stage = Stage;
   }
 
   template<typename Iterator>
@@ -677,7 +677,7 @@
   // Prioritize live ranges by size, assigning larger ranges first.
   // The queue holds (size, reg) pairs.
   const unsigned Size = LI->getSize();
-  const unsigned Reg = LI->reg;
+  const unsigned Reg = LI->reg();
   assert(Register::isVirtualRegister(Reg) &&
          "Can only enqueue virtual registers");
   unsigned Prio;
@@ -768,7 +768,7 @@
 
   // If we missed a simple hint, try to cheaply evict interference from the
   // preferred register.
-  if (Register Hint = MRI->getSimpleHint(VirtReg.reg))
+  if (Register Hint = MRI->getSimpleHint(VirtReg.reg()))
     if (Order.isHint(Hint)) {
       LLVM_DEBUG(dbgs() << "missed hint " << printReg(Hint, TRI) << '\n');
       EvictionCost MaxCost;
@@ -800,7 +800,7 @@
 //===----------------------------------------------------------------------===//
 
 Register RAGreedy::canReassign(LiveInterval &VirtReg, Register PrevReg) {
-  AllocationOrder Order(VirtReg.reg, *VRM, RegClassInfo, Matrix);
+  AllocationOrder Order(VirtReg.reg(), *VRM, RegClassInfo, Matrix);
   Register PhysReg;
   while ((PhysReg = Order.next())) {
     if (PhysReg == PrevReg)
@@ -846,8 +846,8 @@
   if (CanSplit && IsHint && !BreaksHint)
     return true;
 
-  if (A.weight > B.weight) {
-    LLVM_DEBUG(dbgs() << "should evict: " << B << " w= " << B.weight << '\n');
+  if (A.weight() > B.weight()) {
+    LLVM_DEBUG(dbgs() << "should evict: " << B << " w= " << B.weight() << '\n');
     return true;
   }
   return false;
@@ -878,7 +878,7 @@
   //
   // This works out so a register without a cascade number is allowed to evict
   // anything, and it can be evicted by anything.
-  unsigned Cascade = ExtraRegInfo[VirtReg.reg].Cascade;
+  unsigned Cascade = ExtraRegInfo[VirtReg.reg()].Cascade;
   if (!Cascade)
     Cascade = NextCascade;
 
@@ -892,13 +892,13 @@
     // Check if any interfering live range is heavier than MaxWeight.
     for (unsigned i = Q.interferingVRegs().size(); i; --i) {
       LiveInterval *Intf = Q.interferingVRegs()[i - 1];
-      assert(Register::isVirtualRegister(Intf->reg) &&
+      assert(Register::isVirtualRegister(Intf->reg()) &&
              "Only expecting virtual register interference from query");
 
       // Do not allow eviction of a virtual register if we are in the middle
       // of last-chance recoloring and this virtual register is one that we
       // have scavenged a physical register for.
-      if (FixedRegisters.count(Intf->reg))
+      if (FixedRegisters.count(Intf->reg()))
         return false;
 
       // Never evict spill products. They cannot split or spill.
@@ -910,12 +910,14 @@
       //
       // Also allow urgent evictions of unspillable ranges from a strictly
       // larger allocation order.
-      bool Urgent = !VirtReg.isSpillable() &&
-        (Intf->isSpillable() ||
-         RegClassInfo.getNumAllocatableRegs(MRI->getRegClass(VirtReg.reg)) <
-         RegClassInfo.getNumAllocatableRegs(MRI->getRegClass(Intf->reg)));
+      bool Urgent =
+          !VirtReg.isSpillable() &&
+          (Intf->isSpillable() ||
+           RegClassInfo.getNumAllocatableRegs(MRI->getRegClass(VirtReg.reg())) <
+               RegClassInfo.getNumAllocatableRegs(
+                   MRI->getRegClass(Intf->reg())));
       // Only evict older cascades or live ranges without a cascade.
-      unsigned IntfCascade = ExtraRegInfo[Intf->reg].Cascade;
+      unsigned IntfCascade = ExtraRegInfo[Intf->reg()].Cascade;
       if (Cascade <= IntfCascade) {
         if (!Urgent)
           return false;
@@ -924,10 +926,10 @@
         Cost.BrokenHints += 10;
       }
       // Would this break a satisfied hint?
-      bool BreaksHint = VRM->hasPreferredPhys(Intf->reg);
+      bool BreaksHint = VRM->hasPreferredPhys(Intf->reg());
       // Update eviction cost.
       Cost.BrokenHints += BreaksHint;
-      Cost.MaxWeight = std::max(Cost.MaxWeight, Intf->weight);
+      Cost.MaxWeight = std::max(Cost.MaxWeight, Intf->weight());
       // Abort if this would be too expensive.
       if (!(Cost < MaxCost))
         return false;
@@ -977,17 +979,17 @@
         continue;
 
       // Cannot evict non virtual reg interference.
-      if (!Register::isVirtualRegister(Intf->reg))
+      if (!Register::isVirtualRegister(Intf->reg()))
         return false;
       // Never evict spill products. They cannot split or spill.
       if (getStage(*Intf) == RS_Done)
         return false;
 
       // Would this break a satisfied hint?
-      bool BreaksHint = VRM->hasPreferredPhys(Intf->reg);
+      bool BreaksHint = VRM->hasPreferredPhys(Intf->reg());
       // Update eviction cost.
       Cost.BrokenHints += BreaksHint;
-      Cost.MaxWeight = std::max(Cost.MaxWeight, Intf->weight);
+      Cost.MaxWeight = std::max(Cost.MaxWeight, Intf->weight());
       // Abort if this would be too expensive.
       if (!(Cost < MaxCost))
         return false;
@@ -1018,7 +1020,7 @@
                                             float *BestEvictweight) {
   EvictionCost BestEvictCost;
   BestEvictCost.setMax();
-  BestEvictCost.MaxWeight = VirtReg.weight;
+  BestEvictCost.MaxWeight = VirtReg.weight();
   unsigned BestEvicteePhys = 0;
 
   // Go over all physical registers and find the best candidate for eviction
@@ -1043,9 +1045,9 @@
   // Make sure that VirtReg has a cascade number, and assign that cascade
   // number to every evicted register. These live ranges than then only be
   // evicted by a newer cascade, preventing infinite loops.
-  unsigned Cascade = ExtraRegInfo[VirtReg.reg].Cascade;
+  unsigned Cascade = ExtraRegInfo[VirtReg.reg()].Cascade;
   if (!Cascade)
-    Cascade = ExtraRegInfo[VirtReg.reg].Cascade = NextCascade++;
+    Cascade = ExtraRegInfo[VirtReg.reg()].Cascade = NextCascade++;
 
   LLVM_DEBUG(dbgs() << "evicting " << printReg(PhysReg, TRI)
                     << " interference: Cascade " << Cascade << '\n');
@@ -1067,18 +1069,18 @@
   for (unsigned i = 0, e = Intfs.size(); i != e; ++i) {
     LiveInterval *Intf = Intfs[i];
     // The same VirtReg may be present in multiple RegUnits. Skip duplicates.
-    if (!VRM->hasPhys(Intf->reg))
+    if (!VRM->hasPhys(Intf->reg()))
       continue;
 
-    LastEvicted.addEviction(PhysReg, VirtReg.reg, Intf->reg);
+    LastEvicted.addEviction(PhysReg, VirtReg.reg(), Intf->reg());
 
     Matrix->unassign(*Intf);
-    assert((ExtraRegInfo[Intf->reg].Cascade < Cascade ||
+    assert((ExtraRegInfo[Intf->reg()].Cascade < Cascade ||
             VirtReg.isSpillable() < Intf->isSpillable()) &&
            "Cannot decrease cascade number, illegal eviction");
-    ExtraRegInfo[Intf->reg].Cascade = Cascade;
+    ExtraRegInfo[Intf->reg()].Cascade = Cascade;
     ++NumEvicted;
-    NewVRegs.push_back(Intf->reg);
+    NewVRegs.push_back(Intf->reg());
   }
 }
 
@@ -1114,10 +1116,10 @@
   // hints, and only evict smaller spill weights.
   if (CostPerUseLimit < ~0u) {
     BestCost.BrokenHints = 0;
-    BestCost.MaxWeight = VirtReg.weight;
+    BestCost.MaxWeight = VirtReg.weight();
 
     // Check of any registers in RC are below CostPerUseLimit.
-    const TargetRegisterClass *RC = MRI->getRegClass(VirtReg.reg);
+    const TargetRegisterClass *RC = MRI->getRegClass(VirtReg.reg());
     unsigned MinCost = RegClassInfo.getMinCost(RC);
     if (MinCost >= CostPerUseLimit) {
       LLVM_DEBUG(dbgs() << TRI->getRegClassName(RC) << " minimum cost = "
@@ -1578,7 +1580,7 @@
                                              bool *CanCauseEvictionChain) {
   BlockFrequency GlobalCost = 0;
   const BitVector &LiveBundles = Cand.LiveBundles;
-  unsigned VirtRegToSplit = SA->getParent().reg;
+  unsigned VirtRegToSplit = SA->getParent().reg();
   ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA->getUseBlocks();
   for (unsigned i = 0; i != UseBlocks.size(); ++i) {
     const SplitAnalysis::BlockInfo &BI = UseBlocks[i];
@@ -1679,7 +1681,7 @@
   // Isolate even single instructions when dealing with a proper sub-class.
   // That guarantees register class inflation for the stack interval because it
   // is all copies.
-  unsigned Reg = SA->getParent().reg;
+  unsigned Reg = SA->getParent().reg();
   bool SingleInstrs = RegClassInfo.isProperSubClass(MRI->getRegClass(Reg));
 
   // First handle all the blocks with uses.
@@ -1942,7 +1944,7 @@
     // See splitCanCauseEvictionChain for detailed description of bad
     // eviction chain scenarios.
     LLVM_DEBUG(dbgs() << "Best split candidate of vreg "
-                      << printReg(VirtReg.reg, TRI) << "  may ");
+                      << printReg(VirtReg.reg(), TRI) << "  may ");
     if (!(*CanCauseEvictionChain))
       LLVM_DEBUG(dbgs() << "not ");
     LLVM_DEBUG(dbgs() << "cause bad eviction chain\n");
@@ -2001,7 +2003,7 @@
 unsigned RAGreedy::tryBlockSplit(LiveInterval &VirtReg, AllocationOrder &Order,
                                  SmallVectorImpl<Register> &NewVRegs) {
   assert(&SA->getParent() == &VirtReg && "Live range wasn't analyzed");
-  Register Reg = VirtReg.reg;
+  Register Reg = VirtReg.reg();
   bool SingleInstrs = RegClassInfo.isProperSubClass(MRI->getRegClass(Reg));
   LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this, &DeadRemats);
   SE->reset(LREdit, SplitSpillMode);
@@ -2067,7 +2069,7 @@
 unsigned
 RAGreedy::tryInstructionSplit(LiveInterval &VirtReg, AllocationOrder &Order,
                               SmallVectorImpl<Register> &NewVRegs) {
-  const TargetRegisterClass *CurRC = MRI->getRegClass(VirtReg.reg);
+  const TargetRegisterClass *CurRC = MRI->getRegClass(VirtReg.reg());
   // There is no point to this if there are no larger sub-classes.
   if (!RegClassInfo.isProperSubClass(CurRC))
     return 0;
@@ -2095,8 +2097,8 @@
     if (const MachineInstr *MI = Indexes->getInstructionFromIndex(Uses[i]))
       if (MI->isFullCopy() ||
           SuperRCNumAllocatableRegs ==
-              getNumAllocatableRegsForConstraints(MI, VirtReg.reg, SuperRC, TII,
-                                                  TRI, RCI)) {
+              getNumAllocatableRegsForConstraints(MI, VirtReg.reg(), SuperRC,
+                                                  TII, TRI, RCI)) {
         LLVM_DEBUG(dbgs() << "    skip:\t" << Uses[i] << '\t' << *MI);
         continue;
       }
@@ -2113,7 +2115,7 @@
 
   SmallVector<unsigned, 8> IntvMap;
   SE->finish(&IntvMap);
-  DebugVars->splitRegister(VirtReg.reg, LREdit.regs(), *LIS);
+  DebugVars->splitRegister(VirtReg.reg(), LREdit.regs(), *LIS);
   ExtraRegInfo.resize(MRI->getNumVirtRegs());
 
   // Assign all new registers to RS_Spill. This was the last chance.
@@ -2169,7 +2171,7 @@
         break;
 
       // Update the gaps covered by IntI.
-      const float weight = IntI.value()->weight;
+      const float weight = IntI.value()->weight();
       for (; Gap != NumGaps; ++Gap) {
         GapWeight[Gap] = std::max(GapWeight[Gap], weight);
         if (Uses[Gap+1].getBaseIndex() >= IntI.stop())
@@ -2409,7 +2411,7 @@
   SE->useIntv(SegStart, SegStop);
   SmallVector<unsigned, 8> IntvMap;
   SE->finish(&IntvMap);
-  DebugVars->splitRegister(VirtReg.reg, LREdit.regs(), *LIS);
+  DebugVars->splitRegister(VirtReg.reg(), LREdit.regs(), *LIS);
 
   // If the new range has the same number of instructions as before, mark it as
   // RS_Split2 so the next split will be forced to make progress. Otherwise,
@@ -2511,7 +2513,7 @@
 RAGreedy::mayRecolorAllInterferences(unsigned PhysReg, LiveInterval &VirtReg,
                                      SmallLISet &RecoloringCandidates,
                                      const SmallVirtRegSet &FixedRegisters) {
-  const TargetRegisterClass *CurRC = MRI->getRegClass(VirtReg.reg);
+  const TargetRegisterClass *CurRC = MRI->getRegClass(VirtReg.reg());
 
   for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units) {
     LiveIntervalUnion::Query &Q = Matrix->query(VirtReg, *Units);
@@ -2530,9 +2532,10 @@
       // However, if VirtReg has tied defs and Intf doesn't, then
       // there is still a point in examining if it can be recolorable.
       if (((getStage(*Intf) == RS_Done &&
-            MRI->getRegClass(Intf->reg) == CurRC) &&
-           !(hasTiedDef(MRI, VirtReg.reg) && !hasTiedDef(MRI, Intf->reg))) ||
-          FixedRegisters.count(Intf->reg)) {
+            MRI->getRegClass(Intf->reg()) == CurRC) &&
+           !(hasTiedDef(MRI, VirtReg.reg()) &&
+             !hasTiedDef(MRI, Intf->reg()))) ||
+          FixedRegisters.count(Intf->reg())) {
         LLVM_DEBUG(
             dbgs() << "Early abort: the interference is not recolorable.\n");
         return false;
@@ -2608,8 +2611,8 @@
   DenseMap<Register, Register> VirtRegToPhysReg;
   // Mark VirtReg as fixed, i.e., it will not be recolored pass this point in
   // this recoloring "session".
-  assert(!FixedRegisters.count(VirtReg.reg));
-  FixedRegisters.insert(VirtReg.reg);
+  assert(!FixedRegisters.count(VirtReg.reg()));
+  FixedRegisters.insert(VirtReg.reg());
   SmallVector<Register, 4> CurrentNewVRegs;
 
   Order.rewind();
@@ -2644,7 +2647,7 @@
     for (SmallLISet::iterator It = RecoloringCandidates.begin(),
                               EndIt = RecoloringCandidates.end();
          It != EndIt; ++It) {
-      Register ItVirtReg = (*It)->reg;
+      Register ItVirtReg = (*It)->reg();
       enqueue(RecoloringQueue, *It);
       assert(VRM->hasPhys(ItVirtReg) &&
              "Interferences are supposed to be with allocated variables");
@@ -2697,7 +2700,7 @@
     for (SmallLISet::iterator It = RecoloringCandidates.begin(),
                               EndIt = RecoloringCandidates.end();
          It != EndIt; ++It) {
-      Register ItVirtReg = (*It)->reg;
+      Register ItVirtReg = (*It)->reg();
       if (VRM->hasPhys(ItVirtReg))
         Matrix->unassign(**It);
       Register ItPhysReg = VirtRegToPhysReg[ItVirtReg];
@@ -2743,7 +2746,7 @@
                       << " succeeded with: " << printReg(PhysReg, TRI) << '\n');
 
     Matrix->assign(*LI, PhysReg);
-    FixedRegisters.insert(LI->reg);
+    FixedRegisters.insert(LI->reg());
   }
   return true;
 }
@@ -2900,7 +2903,7 @@
   SmallSet<unsigned, 4> Visited;
   SmallVector<unsigned, 2> RecoloringCandidates;
   HintsInfo Info;
-  unsigned Reg = VirtReg.reg;
+  unsigned Reg = VirtReg.reg();
   Register PhysReg = VRM->getPhys(Reg);
   // Start the recoloring algorithm from the input live-interval, then
   // it will propagate to the ones that are copy-related with it.
@@ -3003,11 +3006,11 @@
 /// getting rid of 2 copies.
 void RAGreedy::tryHintsRecoloring() {
   for (LiveInterval *LI : SetOfBrokenHints) {
-    assert(Register::isVirtualRegister(LI->reg) &&
+    assert(Register::isVirtualRegister(LI->reg()) &&
            "Recoloring is possible only for virtual registers");
     // Some dead defs may be around (e.g., because of debug uses).
     // Ignore those.
-    if (!VRM->hasPhys(LI->reg))
+    if (!VRM->hasPhys(LI->reg()))
       continue;
     tryHintRecoloring(*LI);
   }
@@ -3019,10 +3022,10 @@
                                      unsigned Depth) {
   unsigned CostPerUseLimit = ~0u;
   // First try assigning a free register.
-  AllocationOrder Order(VirtReg.reg, *VRM, RegClassInfo, Matrix);
+  AllocationOrder Order(VirtReg.reg(), *VRM, RegClassInfo, Matrix);
   if (unsigned PhysReg = tryAssign(VirtReg, Order, NewVRegs, FixedRegisters)) {
     // If VirtReg got an assignment, the eviction info is no longre relevant.
-    LastEvicted.clearEvicteeInfo(VirtReg.reg);
+    LastEvicted.clearEvicteeInfo(VirtReg.reg());
     // When NewVRegs is not empty, we may have made decisions such as evicting
     // a virtual register, go with the earlier decisions and use the physical
     // register.
@@ -3040,7 +3043,7 @@
 
   LiveRangeStage Stage = getStage(VirtReg);
   LLVM_DEBUG(dbgs() << StageName[Stage] << " Cascade "
-                    << ExtraRegInfo[VirtReg.reg].Cascade << '\n');
+                    << ExtraRegInfo[VirtReg.reg()].Cascade << '\n');
 
   // Try to evict a less worthy live range, but only for ranges from the primary
   // queue. The RS_Split ranges already failed to do this, and they should not
@@ -3049,7 +3052,7 @@
     if (Register PhysReg =
             tryEvict(VirtReg, Order, NewVRegs, CostPerUseLimit,
                      FixedRegisters)) {
-      Register Hint = MRI->getSimpleHint(VirtReg.reg);
+      Register Hint = MRI->getSimpleHint(VirtReg.reg());
       // If VirtReg has a hint and that hint is broken record this
       // virtual register as a recoloring candidate for broken hint.
       // Indeed, since we evicted a variable in its neighborhood it is
@@ -3059,7 +3062,7 @@
         SetOfBrokenHints.insert(&VirtReg);
       // If VirtReg eviction someone, the eviction info for it as an evictee is
       // no longre relevant.
-      LastEvicted.clearEvicteeInfo(VirtReg.reg);
+      LastEvicted.clearEvicteeInfo(VirtReg.reg());
       return PhysReg;
     }
 
@@ -3071,7 +3074,7 @@
   if (Stage < RS_Split) {
     setStage(VirtReg, RS_Split);
     LLVM_DEBUG(dbgs() << "wait for second round\n");
-    NewVRegs.push_back(VirtReg.reg);
+    NewVRegs.push_back(VirtReg.reg());
     return 0;
   }
 
@@ -3081,7 +3084,7 @@
     Register PhysReg = trySplit(VirtReg, Order, NewVRegs, FixedRegisters);
     if (PhysReg || (NewVRegs.size() - NewVRegSizeBefore)) {
       // If VirtReg got split, the eviction info is no longer relevant.
-      LastEvicted.clearEvicteeInfo(VirtReg.reg);
+      LastEvicted.clearEvicteeInfo(VirtReg.reg());
       return PhysReg;
     }
   }
@@ -3100,7 +3103,7 @@
     // right thing here. Anyway, that is still good for early testing.
     setStage(VirtReg, RS_Memory);
     LLVM_DEBUG(dbgs() << "Do as if this register is in memory\n");
-    NewVRegs.push_back(VirtReg.reg);
+    NewVRegs.push_back(VirtReg.reg());
   } else {
     NamedRegionTimer T("spill", "Spiller", TimerGroupName,
                        TimerGroupDescription, TimePassesIsEnabled);
@@ -3111,7 +3114,7 @@
     // Tell LiveDebugVariables about the new ranges. Ranges not being covered by
     // the new regs are kept in LDV (still mapping to the old register), until
     // we rewrite spilled locations in LDV at a later stage.
-    DebugVars->splitRegister(VirtReg.reg, LRE.regs(), *LIS);
+    DebugVars->splitRegister(VirtReg.reg(), LRE.regs(), *LIS);
 
     if (VerifyEnabled)
       MF->verify(this, "After spilling");
diff --git a/llvm/lib/CodeGen/RegAllocPBQP.cpp b/llvm/lib/CodeGen/RegAllocPBQP.cpp
--- a/llvm/lib/CodeGen/RegAllocPBQP.cpp
+++ b/llvm/lib/CodeGen/RegAllocPBQP.cpp
@@ -199,7 +199,7 @@
 
     for (auto NId : G.nodeIds()) {
       PBQP::PBQPNum SpillCost =
-        LIS.getInterval(G.getNodeMetadata(NId).getVReg()).weight;
+          LIS.getInterval(G.getNodeMetadata(NId).getVReg()).weight();
       if (SpillCost == 0.0)
         SpillCost = std::numeric_limits<PBQP::PBQPNum>::min();
       else
@@ -290,7 +290,7 @@
     // If two intervals end at the same point, we need a way to break the tie or
     // the set will assume they're actually equal and refuse to insert a
     // "duplicate". Just compare the vregs - fast and guaranteed unique.
-    return std::get<0>(I1)->reg < std::get<0>(I2)->reg;
+    return std::get<0>(I1)->reg() < std::get<0>(I2)->reg();
   }
 
   static bool isAtLastSegment(const IntervalInfo &I) {
@@ -595,8 +595,8 @@
     // If this is an empty interval move it to the EmptyIntervalVRegs set then
     // continue.
     if (VRegLI.empty()) {
-      EmptyIntervalVRegs.insert(VRegLI.reg);
-      VRegsToAlloc.erase(VRegLI.reg);
+      EmptyIntervalVRegs.insert(VRegLI.reg());
+      VRegsToAlloc.erase(VRegLI.reg());
       continue;
     }
 
@@ -684,7 +684,7 @@
   const TargetRegisterInfo &TRI = *MF.getSubtarget().getRegisterInfo();
   (void)TRI;
   LLVM_DEBUG(dbgs() << "VREG " << printReg(VReg, &TRI) << " -> SPILLED (Cost: "
-                    << LRE.getParent().weight << ", New vregs: ");
+                    << LRE.getParent().weight() << ", New vregs: ");
 
   // Copy any newly inserted live intervals into the list of regs to
   // allocate.
@@ -692,8 +692,8 @@
        I != E; ++I) {
     const LiveInterval &LI = LIS.getInterval(*I);
     assert(!LI.empty() && "Empty spill range.");
-    LLVM_DEBUG(dbgs() << printReg(LI.reg, &TRI) << " ");
-    VRegsToAlloc.insert(LI.reg);
+    LLVM_DEBUG(dbgs() << printReg(LI.reg(), &TRI) << " ");
+    VRegsToAlloc.insert(LI.reg());
   }
 
   LLVM_DEBUG(dbgs() << ")\n");
@@ -749,10 +749,10 @@
          I != E; ++I) {
     LiveInterval &LI = LIS.getInterval(*I);
 
-    unsigned PReg = MRI.getSimpleHint(LI.reg);
+    unsigned PReg = MRI.getSimpleHint(LI.reg());
 
     if (PReg == 0) {
-      const TargetRegisterClass &RC = *MRI.getRegClass(LI.reg);
+      const TargetRegisterClass &RC = *MRI.getRegClass(LI.reg());
       const ArrayRef<MCPhysReg> RawPRegOrder = RC.getRawAllocationOrder(MF);
       for (unsigned CandidateReg : RawPRegOrder) {
         if (!VRM.getRegInfo().isReserved(CandidateReg)) {
@@ -764,7 +764,7 @@
              "No un-reserved physical registers in this register class");
     }
 
-    VRM.assignVirt2Phys(LI.reg, PReg);
+    VRM.assignVirt2Phys(LI.reg(), PReg);
   }
 }
 
diff --git a/llvm/lib/CodeGen/RegisterCoalescer.cpp b/llvm/lib/CodeGen/RegisterCoalescer.cpp
--- a/llvm/lib/CodeGen/RegisterCoalescer.cpp
+++ b/llvm/lib/CodeGen/RegisterCoalescer.cpp
@@ -649,7 +649,7 @@
   // in IntB, we can merge them.
   if (ValS+1 != BS) return false;
 
-  LLVM_DEBUG(dbgs() << "Extending: " << printReg(IntB.reg, TRI));
+  LLVM_DEBUG(dbgs() << "Extending: " << printReg(IntB.reg(), TRI));
 
   SlotIndex FillerStart = ValS->end, FillerEnd = BS->start;
   // We are about to delete CopyMI, so need to remove it as the 'instruction
@@ -692,13 +692,13 @@
 
   // If the source instruction was killing the source register before the
   // merge, unset the isKill marker given the live range has been extended.
-  int UIdx = ValSEndInst->findRegisterUseOperandIdx(IntB.reg, true);
+  int UIdx = ValSEndInst->findRegisterUseOperandIdx(IntB.reg(), true);
   if (UIdx != -1) {
     ValSEndInst->getOperand(UIdx).setIsKill(false);
   }
 
   // Rewrite the copy.
-  CopyMI->substituteRegister(IntA.reg, IntB.reg, 0, *TRI);
+  CopyMI->substituteRegister(IntA.reg(), IntB.reg(), 0, *TRI);
   // If the copy instruction was killing the destination register or any
   // subrange before the merge trim the live range.
   bool RecomputeLiveRange = AS->end == CopyIdx;
@@ -817,7 +817,7 @@
     return { false, false };
   // If DefMI is a two-address instruction then commuting it will change the
   // destination register.
-  int DefIdx = DefMI->findRegisterDefOperandIdx(IntA.reg);
+  int DefIdx = DefMI->findRegisterDefOperandIdx(IntA.reg());
   assert(DefIdx != -1);
   unsigned UseOpIdx;
   if (!DefMI->isRegTiedToUseOperand(DefIdx, &UseOpIdx))
@@ -838,7 +838,7 @@
 
   MachineOperand &NewDstMO = DefMI->getOperand(NewDstIdx);
   Register NewReg = NewDstMO.getReg();
-  if (NewReg != IntB.reg || !IntB.Query(AValNo->def).isKill())
+  if (NewReg != IntB.reg() || !IntB.Query(AValNo->def).isKill())
     return { false, false };
 
   // Make sure there are no other definitions of IntB that would reach the
@@ -848,7 +848,7 @@
 
   // If some of the uses of IntA.reg is already coalesced away, return false.
   // It's not possible to determine whether it's safe to perform the coalescing.
-  for (MachineOperand &MO : MRI->use_nodbg_operands(IntA.reg)) {
+  for (MachineOperand &MO : MRI->use_nodbg_operands(IntA.reg())) {
     MachineInstr *UseMI = MO.getParent();
     unsigned OpNo = &MO - &UseMI->getOperand(0);
     SlotIndex UseIdx = LIS->getInstructionIndex(*UseMI);
@@ -870,9 +870,9 @@
       TII->commuteInstruction(*DefMI, false, UseOpIdx, NewDstIdx);
   if (!NewMI)
     return { false, false };
-  if (Register::isVirtualRegister(IntA.reg) &&
-      Register::isVirtualRegister(IntB.reg) &&
-      !MRI->constrainRegClass(IntB.reg, MRI->getRegClass(IntA.reg)))
+  if (Register::isVirtualRegister(IntA.reg()) &&
+      Register::isVirtualRegister(IntB.reg()) &&
+      !MRI->constrainRegClass(IntB.reg(), MRI->getRegClass(IntA.reg())))
     return { false, false };
   if (NewMI != DefMI) {
     LIS->ReplaceMachineInstrInMaps(*DefMI, *NewMI);
@@ -891,9 +891,10 @@
   //   = B
 
   // Update uses of IntA of the specific Val# with IntB.
-  for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(IntA.reg),
+  for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(IntA.reg()),
                                          UE = MRI->use_end();
-       UI != UE; /* ++UI is below because of possible MI removal */) {
+       UI != UE;
+       /* ++UI is below because of possible MI removal */) {
     MachineOperand &UseMO = *UI;
     ++UI;
     if (UseMO.isUndef())
@@ -920,7 +921,7 @@
       continue;
     if (!UseMI->isCopy())
       continue;
-    if (UseMI->getOperand(0).getReg() != IntB.reg ||
+    if (UseMI->getOperand(0).getReg() != IntB.reg() ||
         UseMI->getOperand(0).getSubReg())
       continue;
 
@@ -951,10 +952,10 @@
   BumpPtrAllocator &Allocator = LIS->getVNInfoAllocator();
   if (IntA.hasSubRanges() || IntB.hasSubRanges()) {
     if (!IntA.hasSubRanges()) {
-      LaneBitmask Mask = MRI->getMaxLaneMaskForVReg(IntA.reg);
+      LaneBitmask Mask = MRI->getMaxLaneMaskForVReg(IntA.reg());
       IntA.createSubRangeFrom(Allocator, Mask, IntA);
     } else if (!IntB.hasSubRanges()) {
-      LaneBitmask Mask = MRI->getMaxLaneMaskForVReg(IntB.reg);
+      LaneBitmask Mask = MRI->getMaxLaneMaskForVReg(IntB.reg());
       IntB.createSubRangeFrom(Allocator, Mask, IntB);
     }
     SlotIndex AIdx = CopyIdx.getRegSlot(true);
@@ -1100,8 +1101,8 @@
       continue;
     }
     // Check DefMI is a reverse copy and it is in BB Pred.
-    if (DefMI->getOperand(0).getReg() != IntA.reg ||
-        DefMI->getOperand(1).getReg() != IntB.reg ||
+    if (DefMI->getOperand(0).getReg() != IntA.reg() ||
+        DefMI->getOperand(1).getReg() != IntB.reg() ||
         DefMI->getParent() != Pred) {
       CopyLeftBB = Pred;
       continue;
@@ -1158,8 +1159,8 @@
 
     // Insert new copy to CopyLeftBB.
     MachineInstr *NewCopyMI = BuildMI(*CopyLeftBB, InsPos, CopyMI.getDebugLoc(),
-                                      TII->get(TargetOpcode::COPY), IntB.reg)
-                                  .addReg(IntA.reg);
+                                      TII->get(TargetOpcode::COPY), IntB.reg())
+                                  .addReg(IntA.reg());
     SlotIndex NewCopyIdx =
         LIS->InsertMachineInstrInMaps(*NewCopyMI).getRegSlot();
     IntB.createDeadDef(NewCopyIdx, LIS->getVNInfoAllocator());
@@ -1752,7 +1753,7 @@
       if (SubIdx != 0 && MO.isUse() && MRI->shouldTrackSubRegLiveness(DstReg)) {
         if (!DstInt->hasSubRanges()) {
           BumpPtrAllocator &Allocator = LIS->getVNInfoAllocator();
-          LaneBitmask FullMask = MRI->getMaxLaneMaskForVReg(DstInt->reg);
+          LaneBitmask FullMask = MRI->getMaxLaneMaskForVReg(DstInt->reg());
           LaneBitmask UsedLanes = TRI->getSubRegIndexLaneMask(SubIdx);
           LaneBitmask UnusedLanes = FullMask & ~UsedLanes;
           DstInt->createSubRangeFrom(Allocator, UsedLanes, *DstInt);
@@ -1991,7 +1992,7 @@
         continue;
       LLVM_DEBUG(dbgs() << "Shrink LaneUses (Lane " << PrintLaneMask(S.LaneMask)
                         << ")\n");
-      LIS->shrinkToUses(S, LI.reg);
+      LIS->shrinkToUses(S, LI.reg());
     }
     LI.removeEmptySubRanges();
   }
@@ -3353,7 +3354,7 @@
 bool RegisterCoalescer::isHighCostLiveInterval(LiveInterval &LI) {
   if (LI.valnos.size() < LargeIntervalSizeThreshold)
     return false;
-  auto &Counter = LargeLIVisitCounter[LI.reg];
+  auto &Counter = LargeLIVisitCounter[LI.reg()];
   if (Counter < LargeIntervalFreqThreshold) {
     Counter++;
     return false;
@@ -3456,8 +3457,8 @@
   // Kill flags are going to be wrong if the live ranges were overlapping.
   // Eventually, we should simply clear all kill flags when computing live
   // ranges. They are reinserted after register allocation.
-  MRI->clearKillFlags(LHS.reg);
-  MRI->clearKillFlags(RHS.reg);
+  MRI->clearKillFlags(LHS.reg());
+  MRI->clearKillFlags(RHS.reg());
 
   if (!EndPoints.empty()) {
     // Recompute the parts of the live range we had to remove because of
diff --git a/llvm/lib/CodeGen/RenameIndependentSubregs.cpp b/llvm/lib/CodeGen/RenameIndependentSubregs.cpp
--- a/llvm/lib/CodeGen/RenameIndependentSubregs.cpp
+++ b/llvm/lib/CodeGen/RenameIndependentSubregs.cpp
@@ -130,7 +130,7 @@
     return false;
 
   // Create a new VReg for each class.
-  unsigned Reg = LI.reg;
+  unsigned Reg = LI.reg();
   const TargetRegisterClass *RegClass = MRI->getRegClass(Reg);
   SmallVector<LiveInterval*, 4> Intervals;
   Intervals.push_back(&LI);
@@ -175,7 +175,7 @@
   // across subranges when they are affected by the same MachineOperand.
   const TargetRegisterInfo &TRI = *MRI->getTargetRegisterInfo();
   Classes.grow(NumComponents);
-  unsigned Reg = LI.reg;
+  unsigned Reg = LI.reg();
   for (const MachineOperand &MO : MRI->reg_nodbg_operands(Reg)) {
     if (!MO.isDef() && !MO.readsReg())
       continue;
@@ -212,7 +212,7 @@
     const SmallVectorImpl<SubRangeInfo> &SubRangeInfos,
     const SmallVectorImpl<LiveInterval*> &Intervals) const {
   const TargetRegisterInfo &TRI = *MRI->getTargetRegisterInfo();
-  unsigned Reg = Intervals[0]->reg;
+  unsigned Reg = Intervals[0]->reg();
   for (MachineRegisterInfo::reg_nodbg_iterator I = MRI->reg_nodbg_begin(Reg),
        E = MRI->reg_nodbg_end(); I != E; ) {
     MachineOperand &MO = *I++;
@@ -242,7 +242,7 @@
       break;
     }
 
-    unsigned VReg = Intervals[ID]->reg;
+    unsigned VReg = Intervals[ID]->reg();
     MO.setReg(VReg);
 
     if (MO.isTied() && Reg != VReg) {
@@ -304,7 +304,7 @@
   const SlotIndexes &Indexes = *LIS->getSlotIndexes();
   for (size_t I = 0, E = Intervals.size(); I < E; ++I) {
     LiveInterval &LI = *Intervals[I];
-    unsigned Reg = LI.reg;
+    unsigned Reg = LI.reg();
 
     LI.removeEmptySubRanges();
 
diff --git a/llvm/lib/CodeGen/SplitKit.cpp b/llvm/lib/CodeGen/SplitKit.cpp
--- a/llvm/lib/CodeGen/SplitKit.cpp
+++ b/llvm/lib/CodeGen/SplitKit.cpp
@@ -168,7 +168,7 @@
 
   // Get use slots form the use-def chain.
   const MachineRegisterInfo &MRI = MF.getRegInfo();
-  for (MachineOperand &MO : MRI.use_nodbg_operands(CurLI->reg))
+  for (MachineOperand &MO : MRI.use_nodbg_operands(CurLI->reg()))
     if (!MO.isUndef())
       UseSlots.push_back(LIS.getInstructionIndex(*MO.getParent()).getRegSlot());
 
@@ -333,7 +333,7 @@
 }
 
 bool SplitAnalysis::isOriginalEndpoint(SlotIndex Idx) const {
-  unsigned OrigReg = VRM.getOriginal(CurLI->reg);
+  unsigned OrigReg = VRM.getOriginal(CurLI->reg());
   const LiveInterval &Orig = LIS.getInterval(OrigReg);
   assert(!Orig.empty() && "Splitting empty interval?");
   LiveInterval::const_iterator I = Orig.find(Idx);
@@ -433,7 +433,7 @@
     LaneBitmask LM;
     for (const MachineOperand &DefOp : DefMI->defs()) {
       Register R = DefOp.getReg();
-      if (R != LI.reg)
+      if (R != LI.reg())
         continue;
       if (unsigned SR = DefOp.getSubReg())
         LM |= TRI.getSubRegIndexLaneMask(SR);
@@ -636,7 +636,7 @@
   LiveInterval &OrigLI = LIS.getInterval(Original);
   VNInfo *OrigVNI = OrigLI.getVNInfoAt(UseIdx);
 
-  unsigned Reg = LI->reg;
+  unsigned Reg = LI->reg();
   bool DidRemat = false;
   if (OrigVNI) {
     LiveRangeEdit::Remat RM(ParentVNI);
@@ -1329,7 +1329,7 @@
     // Rewrite to the mapped register at Idx.
     unsigned RegIdx = RegAssign.lookup(Idx);
     LiveInterval &LI = LIS.getInterval(Edit->get(RegIdx));
-    MO.setReg(LI.reg);
+    MO.setReg(LI.reg());
     LLVM_DEBUG(dbgs() << "  rewr " << printMBBReference(*MI->getParent())
                       << '\t' << Idx << ':' << RegIdx << '\t' << *MI);
 
@@ -1411,7 +1411,7 @@
         continue;
       MachineInstr *MI = LIS.getInstructionFromIndex(S.valno->def);
       assert(MI && "Missing instruction for dead def");
-      MI->addRegisterDead(LI->reg, &TRI);
+      MI->addRegisterDead(LI->reg(), &TRI);
 
       if (!MI->allDefsAreDead())
         continue;
@@ -1531,7 +1531,7 @@
     LIS.splitSeparateComponents(LI, SplitLIs);
     unsigned Original = VRM.getOriginal(VReg);
     for (LiveInterval *SplitLI : SplitLIs)
-      VRM.setIsSplitFromReg(SplitLI->reg, Original);
+      VRM.setIsSplitFromReg(SplitLI->reg(), Original);
 
     // The new intervals all map back to i.
     if (LRMap)
diff --git a/llvm/lib/CodeGen/StackSlotColoring.cpp b/llvm/lib/CodeGen/StackSlotColoring.cpp
--- a/llvm/lib/CodeGen/StackSlotColoring.cpp
+++ b/llvm/lib/CodeGen/StackSlotColoring.cpp
@@ -145,7 +145,7 @@
 // their weight.
 struct IntervalSorter {
   bool operator()(LiveInterval* LHS, LiveInterval* RHS) const {
-    return LHS->weight > RHS->weight;
+    return LHS->weight() > RHS->weight();
   }
 };
 
@@ -174,7 +174,8 @@
           continue;
         LiveInterval &li = LS->getInterval(FI);
         if (!MI.isDebugValue())
-          li.weight += LiveIntervals::getSpillWeight(false, true, MBFI, MI);
+          li.incrementWeight(
+              LiveIntervals::getSpillWeight(false, true, MBFI, MI));
       }
       for (MachineInstr::mmo_iterator MMOI = MI.memoperands_begin(),
                                       EE = MI.memoperands_end();
@@ -222,7 +223,7 @@
   for (auto *I : Intervals) {
     LiveInterval &li = I->second;
     LLVM_DEBUG(li.dump());
-    int FI = Register::stackSlot2Index(li.reg);
+    int FI = Register::stackSlot2Index(li.reg());
     if (MFI->isDeadObjectIndex(FI))
       continue;
 
@@ -269,7 +270,7 @@
 int StackSlotColoring::ColorSlot(LiveInterval *li) {
   int Color = -1;
   bool Share = false;
-  int FI = Register::stackSlot2Index(li->reg);
+  int FI = Register::stackSlot2Index(li->reg());
   uint8_t StackID = MFI->getStackID(FI);
 
   if (!DisableSharing) {
@@ -331,12 +332,12 @@
   bool Changed = false;
   for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {
     LiveInterval *li = SSIntervals[i];
-    int SS = Register::stackSlot2Index(li->reg);
+    int SS = Register::stackSlot2Index(li->reg());
     int NewSS = ColorSlot(li);
     assert(NewSS >= 0 && "Stack coloring failed?");
     SlotMapping[SS] = NewSS;
     RevMap[NewSS].push_back(SS);
-    SlotWeights[NewSS] += li->weight;
+    SlotWeights[NewSS] += li->weight();
     UsedColors.set(NewSS);
     Changed |= (SS != NewSS);
   }
@@ -344,8 +345,8 @@
   LLVM_DEBUG(dbgs() << "\nSpill slots after coloring:\n");
   for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {
     LiveInterval *li = SSIntervals[i];
-    int SS = Register::stackSlot2Index(li->reg);
-    li->weight = SlotWeights[SS];
+    int SS = Register::stackSlot2Index(li->reg());
+    li->setWeight(SlotWeights[SS]);
   }
   // Sort them by new weight.
   llvm::stable_sort(SSIntervals, IntervalSorter());
diff --git a/llvm/lib/CodeGen/TargetRegisterInfo.cpp b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
--- a/llvm/lib/CodeGen/TargetRegisterInfo.cpp
+++ b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
@@ -68,7 +68,7 @@
     const MachineFunction &MF, const LiveInterval &VirtReg) const {
   const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
   const MachineRegisterInfo &MRI = MF.getRegInfo();
-  MachineInstr *MI = MRI.getUniqueVRegDef(VirtReg.reg);
+  MachineInstr *MI = MRI.getUniqueVRegDef(VirtReg.reg());
   if (MI && TII->isTriviallyReMaterializable(*MI) &&
       VirtReg.size() > HugeSizeForSplit)
     return false;
diff --git a/llvm/lib/Target/AMDGPU/GCNNSAReassign.cpp b/llvm/lib/Target/AMDGPU/GCNNSAReassign.cpp
--- a/llvm/lib/Target/AMDGPU/GCNNSAReassign.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNNSAReassign.cpp
@@ -114,7 +114,7 @@
   unsigned NumRegs = Intervals.size();
 
   for (unsigned N = 0; N < NumRegs; ++N)
-    if (VRM->hasPhys(Intervals[N]->reg))
+    if (VRM->hasPhys(Intervals[N]->reg()))
       LRM->unassign(*Intervals[N]);
 
   for (unsigned N = 0; N < NumRegs; ++N)
@@ -302,14 +302,15 @@
 
     LLVM_DEBUG(dbgs() << "Attempting to reassign NSA: " << *MI
                       << "\tOriginal allocation:\t";
-               for(auto *LI : Intervals)
-                 dbgs() << " " << llvm::printReg((VRM->getPhys(LI->reg)), TRI);
+               for (auto *LI
+                    : Intervals) dbgs()
+               << " " << llvm::printReg((VRM->getPhys(LI->reg())), TRI);
                dbgs() << '\n');
 
     bool Success = scavengeRegs(Intervals);
     if (!Success) {
       LLVM_DEBUG(dbgs() << "\tCannot reallocate.\n");
-      if (VRM->hasPhys(Intervals.back()->reg)) // Did not change allocation.
+      if (VRM->hasPhys(Intervals.back()->reg())) // Did not change allocation.
         continue;
     } else {
       // Check we did not make it worse for other instructions.
@@ -328,7 +329,7 @@
 
     if (!Success) {
       for (unsigned I = 0; I < Info->VAddrDwords; ++I)
-        if (VRM->hasPhys(Intervals[I]->reg))
+        if (VRM->hasPhys(Intervals[I]->reg()))
           LRM->unassign(*Intervals[I]);
 
       for (unsigned I = 0; I < Info->VAddrDwords; ++I)
@@ -339,11 +340,12 @@
 
     C.second = true;
     ++NumNSAConverted;
-    LLVM_DEBUG(dbgs() << "\tNew allocation:\t\t ["
-                 << llvm::printReg((VRM->getPhys(Intervals.front()->reg)), TRI)
-                 << " : "
-                 << llvm::printReg((VRM->getPhys(Intervals.back()->reg)), TRI)
-                 << "]\n");
+    LLVM_DEBUG(
+        dbgs() << "\tNew allocation:\t\t ["
+               << llvm::printReg((VRM->getPhys(Intervals.front()->reg())), TRI)
+               << " : "
+               << llvm::printReg((VRM->getPhys(Intervals.back()->reg())), TRI)
+               << "]\n");
     Changed = true;
   }
 
diff --git a/llvm/lib/Target/AMDGPU/GCNRegBankReassign.cpp b/llvm/lib/Target/AMDGPU/GCNRegBankReassign.cpp
--- a/llvm/lib/Target/AMDGPU/GCNRegBankReassign.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNRegBankReassign.cpp
@@ -650,7 +650,7 @@
 
 unsigned GCNRegBankReassign::scavengeReg(LiveInterval &LI, unsigned Bank,
                                          unsigned SubReg) const {
-  const TargetRegisterClass *RC = MRI->getRegClass(LI.reg);
+  const TargetRegisterClass *RC = MRI->getRegClass(LI.reg());
   unsigned MaxNumRegs = (Bank < NUM_VGPR_BANKS) ? MaxNumVGPRs
                                                 : MaxNumSGPRs;
   unsigned MaxReg = MaxNumRegs + (Bank < NUM_VGPR_BANKS ? AMDGPU::VGPR0
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyOptimizeLiveIntervals.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyOptimizeLiveIntervals.cpp
--- a/llvm/lib/Target/WebAssembly/WebAssemblyOptimizeLiveIntervals.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyOptimizeLiveIntervals.cpp
@@ -97,7 +97,7 @@
       // values through live-range splitting and stackification, it will have to
       // do.
       MF.getInfo<WebAssemblyFunctionInfo>()->setFrameBaseVreg(
-          SplitLIs.back()->reg);
+          SplitLIs.back()->reg());
     }
     SplitLIs.clear();
   }
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegColoring.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
@@ -106,8 +106,8 @@
       continue;
 
     LiveInterval *LI = &Liveness->getInterval(VReg);
-    assert(LI->weight == 0.0f);
-    LI->weight = computeWeight(MRI, MBFI, VReg);
+    assert(LI->weight() == 0.0f);
+    LI->setWeight(computeWeight(MRI, MBFI, VReg));
     LLVM_DEBUG(LI->dump());
     SortedIntervals.push_back(LI);
   }
@@ -118,10 +118,10 @@
   // TODO: Investigate more intelligent sorting heuristics. For starters, we
   // should try to coalesce adjacent live intervals before non-adjacent ones.
   llvm::sort(SortedIntervals, [MRI](LiveInterval *LHS, LiveInterval *RHS) {
-    if (MRI->isLiveIn(LHS->reg) != MRI->isLiveIn(RHS->reg))
-      return MRI->isLiveIn(LHS->reg);
-    if (LHS->weight != RHS->weight)
-      return LHS->weight > RHS->weight;
+    if (MRI->isLiveIn(LHS->reg()) != MRI->isLiveIn(RHS->reg()))
+      return MRI->isLiveIn(LHS->reg());
+    if (LHS->weight() != RHS->weight())
+      return LHS->weight() > RHS->weight();
     if (LHS->empty() || RHS->empty())
       return !LHS->empty() && RHS->empty();
     return *LHS < *RHS;
@@ -135,14 +135,14 @@
   bool Changed = false;
   for (size_t I = 0, E = SortedIntervals.size(); I < E; ++I) {
     LiveInterval *LI = SortedIntervals[I];
-    unsigned Old = LI->reg;
+    unsigned Old = LI->reg();
     size_t Color = I;
     const TargetRegisterClass *RC = MRI->getRegClass(Old);
 
     // Check if it's possible to reuse any of the used colors.
     if (!MRI->isLiveIn(Old))
       for (unsigned C : UsedColors.set_bits()) {
-        if (MRI->getRegClass(SortedIntervals[C]->reg) != RC)
+        if (MRI->getRegClass(SortedIntervals[C]->reg()) != RC)
           continue;
         for (LiveInterval *OtherLI : Assignments[C])
           if (!OtherLI->empty() && OtherLI->overlaps(*LI))
@@ -152,7 +152,7 @@
       continue_outer:;
       }
 
-    unsigned New = SortedIntervals[Color]->reg;
+    unsigned New = SortedIntervals[Color]->reg();
     SlotMapping[I] = New;
     Changed |= Old != New;
     UsedColors.set(Color);
@@ -160,7 +160,7 @@
     // If we reassigned the stack pointer, update the debug frame base info.
     if (Old != New && MFI.isFrameBaseVirtual() && MFI.getFrameBaseVreg() == Old)
       MFI.setFrameBaseVreg(New);
-    LLVM_DEBUG(dbgs() << "Assigning vreg" << Register::virtReg2Index(LI->reg)
+    LLVM_DEBUG(dbgs() << "Assigning vreg" << Register::virtReg2Index(LI->reg())
                       << " to vreg" << Register::virtReg2Index(New) << "\n");
   }
   if (!Changed)
@@ -168,7 +168,7 @@
 
   // Rewrite register operands.
   for (size_t I = 0, E = SortedIntervals.size(); I < E; ++I) {
-    unsigned Old = SortedIntervals[I]->reg;
+    unsigned Old = SortedIntervals[I]->reg();
     unsigned New = SlotMapping[I];
     if (Old != New)
       MRI->replaceRegWith(Old, New);