[NFC] Use [MC]Register in register allocation

[mtrofin]

lgtm

llvm/lib/CodeGen/RegAllocGreedy.cpp

474

I can't tell what the notation is here on line 474 - is it a blank space, or?

(if you ran clang-format, it's probably fine)

689

nit: can you also change the assert to Reg.isVirtual()? so we can eventually get rid of the statics

[gjain]

Address comments

[gjain]

llvm/lib/CodeGen/RegAllocGreedy.cpp

474

Not sure what's happening here. I think it's just phabricator noting that 2 spaces were added for indentation. Note I run arc lint before putting up changes which I believe would do clang format etc.

llvm/include/llvm/CodeGen/LiveRangeEdit.h

public:
   public:
     virtual ~Delegate() = default;
 
     /// Called immediately before erasing a dead machine instruction.
     virtual void LRE_WillEraseInstruction(MachineInstr *MI) {}
 
     /// Called when a virtual register is no longer used. Return false to defer
     /// its deletion from LiveIntervals.
-    virtual bool LRE_CanEraseVirtReg(unsigned) { return true; }
+    virtual bool LRE_CanEraseVirtReg(Register) { return true; }
 
     /// Called before shrinking the live range of a virtual register.
-    virtual void LRE_WillShrinkVirtReg(unsigned) {}
+    virtual void LRE_WillShrinkVirtReg(Register) {}
 
     /// Called after cloning a virtual register.
     /// This is used for new registers representing connected components of Old.
-    virtual void LRE_DidCloneVirtReg(unsigned New, unsigned Old) {}
+    virtual void LRE_DidCloneVirtReg(Register New, Register Old) {}
   };
 
 private:
   LiveInterval *Parent;
   SmallVectorImpl<Register> &NewRegs;
   MachineRegisterInfo &MRI;
   LiveIntervals &LIS;
   VirtRegMap *VRM;

llvm/lib/CodeGen/InlineSpiller.cpp

HoistSpillHelper(MachineFunctionPass &pass, MachineFunction &mf,
         TRI(*mf.getSubtarget().getRegisterInfo()),
         MBFI(pass.getAnalysis<MachineBlockFrequencyInfo>()),
         IPA(LIS, mf.getNumBlockIDs()) {}
 
   void addToMergeableSpills(MachineInstr &Spill, int StackSlot,
                             unsigned Original);
   bool rmFromMergeableSpills(MachineInstr &Spill, int StackSlot);
   void hoistAllSpills();
-  void LRE_DidCloneVirtReg(unsigned, unsigned) override;
+  void LRE_DidCloneVirtReg(Register, Register) override;
 };
 
 class InlineSpiller : public Spiller {
   MachineFunction &MF;
   LiveIntervals &LIS;
   LiveStacks &LSS;
   AliasAnalysis *AA;
   MachineDominatorTree &MDT;
for (auto const RMEnt : SpillsToRm) {
       }
     }
     Edit.eliminateDeadDefs(SpillsToRm, None, AA);
   }
 }
 
 /// For VirtReg clone, the \p New register should have the same physreg or
 /// stackslot as the \p old register.
-void HoistSpillHelper::LRE_DidCloneVirtReg(unsigned New, unsigned Old) {
+void HoistSpillHelper::LRE_DidCloneVirtReg(Register New, Register Old) {
   if (VRM.hasPhys(Old))
     VRM.assignVirt2Phys(New, VRM.getPhys(Old));
   else if (VRM.getStackSlot(Old) != VirtRegMap::NO_STACK_SLOT)
     VRM.assignVirt2StackSlot(New, VRM.getStackSlot(Old));
   else
     llvm_unreachable("VReg should be assigned either physreg or stackslot");
 }

llvm/lib/CodeGen/RegAllocBase.cpp

 
 // Visit all the live registers. If they are already assigned to a physical
 // register, unify them with the corresponding LiveIntervalUnion, otherwise push
 // them on the priority queue for later assignment.
 void RegAllocBase::seedLiveRegs() {
   NamedRegionTimer T("seed", "Seed Live Regs", TimerGroupName,
                      TimerGroupDescription, TimePassesIsEnabled);
   for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
-    unsigned Reg = Register::index2VirtReg(i);
+    Register Reg = Register::index2VirtReg(i);
     if (MRI->reg_nodbg_empty(Reg))
       continue;
     enqueue(&LIS->getInterval(Reg));
   }
 }
 
 // Top-level driver to manage the queue of unassigned VirtRegs and call the
 // selectOrSplit implementation.
if (AvailablePhysReg == ~0u) {
           VirtReg->reg(),
           RegClassInfo.getOrder(MRI->getRegClass(VirtReg->reg())).front());
       continue;
     }
 
     if (AvailablePhysReg)
       Matrix->assign(*VirtReg, AvailablePhysReg);
 
-    for (unsigned Reg : SplitVRegs) {
+    for (Register Reg : SplitVRegs) {
       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(SplitVirtReg->empty() && "Non-empty but used interval");
         LLVM_DEBUG(dbgs() << "not queueing unused  " << *SplitVirtReg << '\n');
         aboutToRemoveInterval(*SplitVirtReg);

llvm/lib/CodeGen/RegAllocBasic.cpp

class RABasic : public MachineFunctionPass,
   std::unique_ptr<Spiller> SpillerInstance;
   std::priority_queue<LiveInterval*, std::vector<LiveInterval*>,
                       CompSpillWeight> Queue;
 
   // Scratch space.  Allocated here to avoid repeated malloc calls in
   // selectOrSplit().
   BitVector UsableRegs;
 
-  bool LRE_CanEraseVirtReg(unsigned) override;
-  void LRE_WillShrinkVirtReg(unsigned) override;
+  bool LRE_CanEraseVirtReg(Register) override;
+  void LRE_WillShrinkVirtReg(Register) override;
 
 public:
   RABasic();
 
   /// Return the pass name.
   StringRef getPassName() const override { return "Basic Register Allocator"; }
 
   /// RABasic analysis usage.

 INITIALIZE_PASS_DEPENDENCY(LiveStacks)
 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
 INITIALIZE_PASS_DEPENDENCY(VirtRegMap)
 INITIALIZE_PASS_DEPENDENCY(LiveRegMatrix)
 INITIALIZE_PASS_END(RABasic, "regallocbasic", "Basic Register Allocator", false,
                     false)
 
-bool RABasic::LRE_CanEraseVirtReg(unsigned VirtReg) {
+bool RABasic::LRE_CanEraseVirtReg(Register VirtReg) {
   LiveInterval &LI = LIS->getInterval(VirtReg);
   if (VRM->hasPhys(VirtReg)) {
     Matrix->unassign(LI);
     aboutToRemoveInterval(LI);
     return true;
   }
   // Unassigned virtreg is probably in the priority queue.
   // RegAllocBase will erase it after dequeueing.
   // Nonetheless, clear the live-range so that the debug
   // dump will show the right state for that VirtReg.
   LI.clear();
   return false;
 }
 
-void RABasic::LRE_WillShrinkVirtReg(unsigned VirtReg) {
+void RABasic::LRE_WillShrinkVirtReg(Register VirtReg) {
   if (!VRM->hasPhys(VirtReg))
     return;
 
   // Register is assigned, put it back on the queue for reassignment.
   LiveInterval &LI = LIS->getInterval(VirtReg);
   Matrix->unassign(LI);
   enqueue(&LI);
 }

llvm/lib/CodeGen/RegAllocGreedy.cpp

public:
   }
 
   static char ID;
 
 private:
   MCRegister selectOrSplitImpl(LiveInterval &, SmallVectorImpl<Register> &,
                                SmallVirtRegSet &, unsigned = 0);
 
-  bool LRE_CanEraseVirtReg(unsigned) override;
-  void LRE_WillShrinkVirtReg(unsigned) override;
-  void LRE_DidCloneVirtReg(unsigned, unsigned) override;
+  bool LRE_CanEraseVirtReg(Register) override;
+  void LRE_WillShrinkVirtReg(Register) override;
+  void LRE_DidCloneVirtReg(Register, Register) override;
   void enqueue(PQueue &CurQueue, LiveInterval *LI);
   LiveInterval *dequeue(PQueue &CurQueue);
 
   BlockFrequency calcSpillCost();
   bool addSplitConstraints(InterferenceCache::Cursor, BlockFrequency&);
   bool addThroughConstraints(InterferenceCache::Cursor, ArrayRef<unsigned>);
   bool growRegion(GlobalSplitCandidate &Cand);
   bool splitCanCauseEvictionChain(Register Evictee, GlobalSplitCandidate &Cand,
private:
   void calcGapWeights(MCRegister, SmallVectorImpl<float> &);
   Register canReassign(LiveInterval &VirtReg, Register PrevReg);
   bool shouldEvict(LiveInterval &A, bool, LiveInterval &B, bool);
   bool canEvictInterference(LiveInterval &, MCRegister, bool, EvictionCost &,
                             const SmallVirtRegSet &);
   bool canEvictInterferenceInRange(LiveInterval &VirtReg, MCRegister PhysReg,
                                    SlotIndex Start, SlotIndex End,
                                    EvictionCost &MaxCost);
-  unsigned getCheapestEvicteeWeight(const AllocationOrder &Order,
+  MCRegister getCheapestEvicteeWeight(const AllocationOrder &Order,
                                       LiveInterval &VirtReg, SlotIndex Start,
                                       SlotIndex End, float *BestEvictWeight);
   void evictInterference(LiveInterval &, MCRegister,
                          SmallVectorImpl<Register> &);
   bool mayRecolorAllInterferences(MCRegister PhysReg, LiveInterval &VirtReg,
                                   SmallLISet &RecoloringCandidates,
                                   const SmallVirtRegSet &FixedRegisters);
 
   Register tryAssign(LiveInterval&, AllocationOrder&,
                      SmallVectorImpl<Register>&,
unsigned calculateRegionSplitCost(LiveInterval &VirtReg,
                                     unsigned &NumCands, bool IgnoreCSR,
                                     bool *CanCauseEvictionChain = nullptr);
   /// Perform region splitting.
   unsigned doRegionSplit(LiveInterval &VirtReg, unsigned BestCand,
                          bool HasCompact,
                          SmallVectorImpl<Register> &NewVRegs);
   /// Check other options before using a callee-saved register for the first
   /// time.
-  unsigned tryAssignCSRFirstTime(LiveInterval &VirtReg, AllocationOrder &Order,
-                                 Register PhysReg, unsigned &CostPerUseLimit,
+  MCRegister tryAssignCSRFirstTime(LiveInterval &VirtReg,
+                                   AllocationOrder &Order, MCRegister PhysReg,
+                                   unsigned &CostPerUseLimit,
                                    SmallVectorImpl<Register> &NewVRegs);
   void initializeCSRCost();
   unsigned tryBlockSplit(LiveInterval&, AllocationOrder&,
                          SmallVectorImpl<Register>&);
   unsigned tryInstructionSplit(LiveInterval&, AllocationOrder&,
                                SmallVectorImpl<Register>&);
   unsigned tryLocalSplit(LiveInterval&, AllocationOrder&,
     SmallVectorImpl<Register>&);
   unsigned trySplit(LiveInterval&, AllocationOrder&,
struct HintInfo {
     MCRegister PhysReg;
 
     HintInfo(BlockFrequency Freq, Register Reg, MCRegister PhysReg)
         : Freq(Freq), Reg(Reg), PhysReg(PhysReg) {}
   };
   using HintsInfo = SmallVector<HintInfo, 4>;
 
   BlockFrequency getBrokenHintFreq(const HintsInfo &, MCRegister);
-  void collectHintInfo(unsigned, HintsInfo &);
+  void collectHintInfo(Register, HintsInfo &);
 
   bool isUnusedCalleeSavedReg(MCRegister PhysReg) const;
 
   /// Compute and report the number of spills and reloads for a loop.
   void reportNumberOfSplillsReloads(MachineLoop *L, unsigned &Reloads,
                                     unsigned &FoldedReloads, unsigned &Spills,
                                     unsigned &FoldedSpills);
 
void RAGreedy::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<MachineOptimizationRemarkEmitterPass>();
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
 //===----------------------------------------------------------------------===//
 //                     LiveRangeEdit delegate methods
 //===----------------------------------------------------------------------===//
 
-bool RAGreedy::LRE_CanEraseVirtReg(unsigned VirtReg) {
+bool RAGreedy::LRE_CanEraseVirtReg(Register VirtReg) {
   LiveInterval &LI = LIS->getInterval(VirtReg);
   if (VRM->hasPhys(VirtReg)) {
     Matrix->unassign(LI);
     aboutToRemoveInterval(LI);
     return true;
   }
   // Unassigned virtreg is probably in the priority queue.
   // RegAllocBase will erase it after dequeueing.
   // Nonetheless, clear the live-range so that the debug
   // dump will show the right state for that VirtReg.
   LI.clear();
   return false;
 }
 
-void RAGreedy::LRE_WillShrinkVirtReg(unsigned VirtReg) {
+void RAGreedy::LRE_WillShrinkVirtReg(Register VirtReg) {
   if (!VRM->hasPhys(VirtReg))
     return;
 
   // Register is assigned, put it back on the queue for reassignment.
   LiveInterval &LI = LIS->getInterval(VirtReg);
   Matrix->unassign(LI);
   enqueue(&LI);
 }
 
-void RAGreedy::LRE_DidCloneVirtReg(unsigned New, unsigned Old) {
+void RAGreedy::LRE_DidCloneVirtReg(Register New, Register Old) {
   // Cloning a register we haven't even heard about yet?  Just ignore it.
   if (!ExtraRegInfo.inBounds(Old))
     return;
 
   // LRE may clone a virtual register because dead code elimination causes it to
   // be split into connected components. The new components are much smaller
   // than the original, so they should get a new chance at being assigned.
   // same stage as the parent.

 }
 
 void RAGreedy::enqueue(LiveInterval *LI) { enqueue(Queue, LI); }
 
 void RAGreedy::enqueue(PQueue &CurQueue, LiveInterval *LI) {
   // 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 Register Reg = LI->reg();
   assert(Register::isVirtualRegister(Reg) &&
          "Can only enqueue virtual registers");
   unsigned Prio;
 
   ExtraRegInfo.grow(Reg);
   if (ExtraRegInfo[Reg].Stage == RS_New)
     ExtraRegInfo[Reg].Stage = RS_Assign;
 
   if (ExtraRegInfo[Reg].Stage == RS_Split) {

 ///
 /// \param Order            The allocation order
 /// \param VirtReg          Live range that is about to be assigned.
 /// \param Start            Start of range to look for interferences
 /// \param End              End of range to look for interferences
 /// \param BestEvictweight  The eviction cost of that eviction
 /// \return The PhysReg which is the best candidate for eviction and the
 /// eviction cost in BestEvictweight
-unsigned RAGreedy::getCheapestEvicteeWeight(const AllocationOrder &Order,
+MCRegister RAGreedy::getCheapestEvicteeWeight(const AllocationOrder &Order,
                                               LiveInterval &VirtReg,
                                               SlotIndex Start, SlotIndex End,
                                               float *BestEvictweight) {
   EvictionCost BestEvictCost;
   BestEvictCost.setMax();
   BestEvictCost.MaxWeight = VirtReg.weight();
-  unsigned BestEvicteePhys = 0;
+  MCRegister BestEvicteePhys;
 
   // Go over all physical registers and find the best candidate for eviction
-  for (auto PhysReg : Order.getOrder()) {
+  for (MCRegister PhysReg : Order.getOrder()) {
 
     if (!canEvictInterferenceInRange(VirtReg, PhysReg, Start, End,
                                      BestEvictCost))
       continue;
 
     // Best so far.
     BestEvicteePhys = PhysReg;
   }
bool RAGreedy::splitCanCauseEvictionChain(Register Evictee,
   unsigned Evictor = VregEvictorInfo.first;
   MCRegister PhysReg = VregEvictorInfo.second;
 
   // No actual evictor.
   if (!Evictor || !PhysReg)
     return false;
 
   float MaxWeight = 0;
-  unsigned FutureEvictedPhysReg =
+  MCRegister FutureEvictedPhysReg =
       getCheapestEvicteeWeight(Order, LIS->getInterval(Evictee),
                                Cand.Intf.first(), Cand.Intf.last(), &MaxWeight);
 
   // The bad eviction chain occurs when either the split candidate is the
   // evicting reg or one of the split artifact will evict the evicting reg.
   if ((PhysReg != Cand.PhysReg) && (PhysReg != FutureEvictedPhysReg))
     return false;
 
bool RAGreedy::splitCanCauseLocalSpill(unsigned VirtRegToSplit,
   for (auto PhysReg : Order.getOrder()) {
     if (!Matrix->checkInterference(Cand.Intf.first().getPrevIndex(),
                                    Cand.Intf.last(), PhysReg))
       return false;
   }
 
   // Check if the local interval will evict a cheaper interval.
   float CheapestEvictWeight = 0;
-  unsigned FutureEvictedPhysReg = getCheapestEvicteeWeight(
+  MCRegister FutureEvictedPhysReg = getCheapestEvicteeWeight(
       Order, LIS->getInterval(VirtRegToSplit), Cand.Intf.first(),
       Cand.Intf.last(), &CheapestEvictWeight);
 
   // Have we found an interval that can be evicted?
   if (FutureEvictedPhysReg) {
     float splitArtifactWeight =
         VRAI->futureWeight(LIS->getInterval(VirtRegToSplit),
                            Cand.Intf.first().getPrevIndex(), Cand.Intf.last());
void RAGreedy::splitAroundRegion(LiveRangeEdit &LREdit,
   const unsigned NumGlobalIntvs = LREdit.size();
   LLVM_DEBUG(dbgs() << "splitAroundRegion with " << NumGlobalIntvs
                     << " globals.\n");
   assert(NumGlobalIntvs && "No global intervals configured");
 
   // 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();
+  Register Reg = SA->getParent().reg();
   bool SingleInstrs = RegClassInfo.isProperSubClass(MRI->getRegClass(Reg));
 
   // First handle all the blocks with uses.
   ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA->getUseBlocks();
   for (const SplitAnalysis::BlockInfo &BI : UseBlocks) {
     unsigned Number = BI.MBB->getNumber();
     unsigned IntvIn = 0, IntvOut = 0;
     SlotIndex IntfIn, IntfOut;

 
 //===----------------------------------------------------------------------===//
 //                         Per-Instruction Splitting
 //===----------------------------------------------------------------------===//
 
 /// Get the number of allocatable registers that match the constraints of \p Reg
 /// on \p MI and that are also in \p SuperRC.
 static unsigned getNumAllocatableRegsForConstraints(
-    const MachineInstr *MI, unsigned Reg, const TargetRegisterClass *SuperRC,
+    const MachineInstr *MI, Register Reg, const TargetRegisterClass *SuperRC,
     const TargetInstrInfo *TII, const TargetRegisterInfo *TRI,
     const RegisterClassInfo &RCI) {
   assert(SuperRC && "Invalid register class");
 
   const TargetRegisterClass *ConstrainedRC =
       MI->getRegClassConstraintEffectForVReg(Reg, SuperRC, TII, TRI,
                                              /* ExploreBundle */ true);
   if (!ConstrainedRC)

 }
 
 /// Using a CSR for the first time has a cost because it causes push|pop
 /// to be added to prologue|epilogue. Splitting a cold section of the live
 /// range can have lower cost than using the CSR for the first time;
 /// Spilling a live range in the cold path can have lower cost than using
 /// the CSR for the first time. Returns the physical register if we decide
 /// to use the CSR; otherwise return 0.
-unsigned RAGreedy::tryAssignCSRFirstTime(LiveInterval &VirtReg,
-                                         AllocationOrder &Order,
-                                         Register PhysReg,
-                                         unsigned &CostPerUseLimit,
-                                         SmallVectorImpl<Register> &NewVRegs) {
+MCRegister
+RAGreedy::tryAssignCSRFirstTime(LiveInterval &VirtReg, AllocationOrder &Order,
+                                MCRegister PhysReg, unsigned &CostPerUseLimit,
   if (getStage(VirtReg) == RS_Spill && VirtReg.isSpillable()) {
     // We choose spill over using the CSR for the first time if the spill cost
     // is lower than CSRCost.
     SA->analyze(&VirtReg);
     if (calcSpillCost() >= CSRCost)
       return PhysReg;
 
     // We are going to spill, set CostPerUseLimit to 1 to make sure that
void RAGreedy::initializeCSRCost() {
   else
     // Can't use BranchProbability in general, since it takes 32-bit numbers.
     CSRCost = CSRCost.getFrequency() * (ActualEntry / FixedEntry);
 }
 
 /// Collect the hint info for \p Reg.
 /// The results are stored into \p Out.
 /// \p Out is not cleared before being populated.
-void RAGreedy::collectHintInfo(unsigned Reg, HintsInfo &Out) {
+void RAGreedy::collectHintInfo(Register Reg, HintsInfo &Out) {
   for (const MachineInstr &Instr : MRI->reg_nodbg_instructions(Reg)) {
     if (!Instr.isFullCopy())
       continue;
     // Look for the other end of the copy.
     Register OtherReg = Instr.getOperand(0).getReg();
     if (OtherReg == Reg) {
       OtherReg = Instr.getOperand(1).getReg();
       if (OtherReg == Reg)
         continue;
     }
     // Get the current assignment.
-    Register OtherPhysReg = Register::isPhysicalRegister(OtherReg)
-                                ? OtherReg
-                                : Register(VRM->getPhys(OtherReg));
+    MCRegister OtherPhysReg =
+        OtherReg.isPhysical() ? OtherReg.asMCReg() : VRM->getPhys(OtherReg);
     // Push the collected information.
     Out.push_back(HintInfo(MBFI->getBlockFreq(Instr.getParent()), OtherReg,
                            OtherPhysReg));
   }
 }
 
 /// Using the given \p List, compute the cost of the broken hints if
 /// \p PhysReg was used.

 /// it is not profitable.
 /// For a given live range, profitability is determined by the sum of the
 /// frequencies of the non-identity copies it would introduce with the old
 /// and new register.
 void RAGreedy::tryHintRecoloring(LiveInterval &VirtReg) {
   // We have a broken hint, check if it is possible to fix it by
   // reusing PhysReg for the copy-related live-ranges. Indeed, we evicted
   // some register and PhysReg may be available for the other live-ranges.
-  SmallSet<unsigned, 4> Visited;
+  SmallSet<Register, 4> Visited;
   SmallVector<unsigned, 2> RecoloringCandidates;
   HintsInfo Info;
-  unsigned Reg = VirtReg.reg();
+  Register Reg = VirtReg.reg();
   MCRegister 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.
   Visited.insert(Reg);
   RecoloringCandidates.push_back(Reg);
 
   LLVM_DEBUG(dbgs() << "Trying to reconcile hints for: " << printReg(Reg, TRI)
                     << '(' << printReg(PhysReg, TRI) << ")\n");

 MCRegister RAGreedy::selectOrSplitImpl(LiveInterval &VirtReg,
                                        SmallVectorImpl<Register> &NewVRegs,
                                        SmallVirtRegSet &FixedRegisters,
                                        unsigned Depth) {
   unsigned CostPerUseLimit = ~0u;
   // First try assigning a free register.
   auto Order =
       AllocationOrder::create(VirtReg.reg(), *VRM, RegClassInfo, Matrix);
-  if (unsigned PhysReg = tryAssign(VirtReg, Order, NewVRegs, FixedRegisters)) {
+  if (MCRegister PhysReg =
+          tryAssign(VirtReg, Order, NewVRegs, FixedRegisters)) {
     // If VirtReg got an assignment, the eviction info is no longre relevant.
     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.
     if (CSRCost.getFrequency() && isUnusedCalleeSavedReg(PhysReg) &&
         NewVRegs.empty()) {
       MCRegister CSRReg = tryAssignCSRFirstTime(VirtReg, Order, PhysReg,

llvm/lib/CodeGen/RegAllocPBQP.cpp

public:
   }
 
   MachineFunctionProperties getClearedProperties() const override {
     return MachineFunctionProperties().set(
       MachineFunctionProperties::Property::IsSSA);
   }
 
 private:
-  using LI2NodeMap = std::map<const LiveInterval *, unsigned>;
-  using Node2LIMap = std::vector<const LiveInterval *>;
-  using AllowedSet = std::vector<unsigned>;
-  using AllowedSetMap = std::vector<AllowedSet>;
-  using RegPair = std::pair<unsigned, unsigned>;
-  using CoalesceMap = std::map<RegPair, PBQP::PBQPNum>;
   using RegSet = std::set<Register>;
 
   char *customPassID;
 
   RegSet VRegsToAlloc, EmptyIntervalVRegs;
 
   /// Inst which is a def of an original reg and whose defs are already all
   /// dead after remat is saved in DeadRemats. The deletion of such inst is
while (!Worklist.empty()) {
 
     // Check for vregs that have no allowed registers. These should be
     // pre-spilled and the new vregs added to the worklist.
     if (VRegAllowed.empty()) {
       SmallVector<Register, 8> NewVRegs;
       spillVReg(VReg, NewVRegs, MF, LIS, VRM, VRegSpiller);
       Worklist.insert(Worklist.end(), NewVRegs.begin(), NewVRegs.end());
       continue;
-    } else
-      VRegAllowedMap[VReg] = std::move(VRegAllowed);
+    }
+
+    VRegAllowedMap[VReg.id()] = std::move(VRegAllowed);
   }
 
   for (auto &KV : VRegAllowedMap) {
     auto VReg = KV.first;
 
     // Move empty intervals to the EmptyIntervalVReg set.
     if (LIS.getInterval(VReg).empty()) {
       EmptyIntervalVRegs.insert(VReg);
for (RegSet::const_iterator
          I != E; ++I) {
     LiveInterval &LI = LIS.getInterval(*I);
 
     Register PReg = MRI.getSimpleHint(LI.reg());
 
     if (PReg == 0) {
       const TargetRegisterClass &RC = *MRI.getRegClass(LI.reg());
       const ArrayRef<MCPhysReg> RawPRegOrder = RC.getRawAllocationOrder(MF);
-      for (unsigned CandidateReg : RawPRegOrder) {
+      for (MCRegister CandidateReg : RawPRegOrder) {
         if (!VRM.getRegInfo().isReserved(CandidateReg)) {
           PReg = CandidateReg;
           break;
         }
       }
       assert(PReg &&
              "No un-reserved physical registers in this register class");
     }