diff --git a/llvm/include/llvm/CodeGen/TargetInstrInfo.h b/llvm/include/llvm/CodeGen/TargetInstrInfo.h
index 9e7893d5c4142..dd1a1d8a792d6 100644
--- a/llvm/include/llvm/CodeGen/TargetInstrInfo.h
+++ b/llvm/include/llvm/CodeGen/TargetInstrInfo.h
@@ -1306,7 +1306,7 @@ class TargetInstrInfo : public MCInstrInfo {
       MachineInstr &Root, unsigned Pattern,
       SmallVectorImpl<MachineInstr *> &InsInstrs,
       SmallVectorImpl<MachineInstr *> &DelInstrs,
-      DenseMap<unsigned, unsigned> &InstIdxForVirtReg) const;
+      DenseMap<Register, unsigned> &InstIdxForVirtReg) const;
 
   /// When calculate the latency of the root instruction, accumulate the
   /// latency of the sequence to the root latency.
@@ -1329,7 +1329,7 @@ class TargetInstrInfo : public MCInstrInfo {
                       SmallVectorImpl<MachineInstr *> &InsInstrs,
                       SmallVectorImpl<MachineInstr *> &DelInstrs,
                       ArrayRef<unsigned> OperandIndices,
-                      DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const;
+                      DenseMap<Register, unsigned> &InstrIdxForVirtReg) const;
 
   /// Reassociation of some instructions requires inverse operations (e.g.
   /// (X + A) - Y => (X - Y) + A). This method returns a pair of new opcodes
diff --git a/llvm/lib/CodeGen/MachineCombiner.cpp b/llvm/lib/CodeGen/MachineCombiner.cpp
index b8d59214a6ec3..54e2a009b464d 100644
--- a/llvm/lib/CodeGen/MachineCombiner.cpp
+++ b/llvm/lib/CodeGen/MachineCombiner.cpp
@@ -91,7 +91,7 @@ class MachineCombiner : public MachineFunctionPass {
   MachineInstr *getOperandDef(const MachineOperand &MO);
   bool isTransientMI(const MachineInstr *MI);
   unsigned getDepth(SmallVectorImpl<MachineInstr *> &InsInstrs,
-                    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg,
+                    DenseMap<Register, unsigned> &InstrIdxForVirtReg,
                     MachineTraceMetrics::Trace BlockTrace,
                     const MachineBasicBlock &MBB);
   unsigned getLatency(MachineInstr *Root, MachineInstr *NewRoot,
@@ -100,7 +100,7 @@ class MachineCombiner : public MachineFunctionPass {
                                MachineTraceMetrics::Trace BlockTrace,
                                SmallVectorImpl<MachineInstr *> &InsInstrs,
                                SmallVectorImpl<MachineInstr *> &DelInstrs,
-                               DenseMap<unsigned, unsigned> &InstrIdxForVirtReg,
+                               DenseMap<Register, unsigned> &InstrIdxForVirtReg,
                                unsigned Pattern, bool SlackIsAccurate);
   bool reduceRegisterPressure(MachineInstr &Root, MachineBasicBlock *MBB,
                               SmallVectorImpl<MachineInstr *> &InsInstrs,
@@ -202,7 +202,7 @@ bool MachineCombiner::isTransientMI(const MachineInstr *MI) {
 /// \returns Depth of last instruction in \InsInstrs ("NewRoot")
 unsigned
 MachineCombiner::getDepth(SmallVectorImpl<MachineInstr *> &InsInstrs,
-                          DenseMap<unsigned, unsigned> &InstrIdxForVirtReg,
+                          DenseMap<Register, unsigned> &InstrIdxForVirtReg,
                           MachineTraceMetrics::Trace BlockTrace,
                           const MachineBasicBlock &MBB) {
   SmallVector<unsigned, 16> InstrDepth;
@@ -217,7 +217,7 @@ MachineCombiner::getDepth(SmallVectorImpl<MachineInstr *> &InsInstrs,
         continue;
       unsigned DepthOp = 0;
       unsigned LatencyOp = 0;
-      DenseMap<unsigned, unsigned>::iterator II =
+      DenseMap<Register, unsigned>::iterator II =
           InstrIdxForVirtReg.find(MO.getReg());
       if (II != InstrIdxForVirtReg.end()) {
         // Operand is new virtual register not in trace
@@ -353,7 +353,7 @@ bool MachineCombiner::improvesCriticalPathLen(
     MachineTraceMetrics::Trace BlockTrace,
     SmallVectorImpl<MachineInstr *> &InsInstrs,
     SmallVectorImpl<MachineInstr *> &DelInstrs,
-    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg, unsigned Pattern,
+    DenseMap<Register, unsigned> &InstrIdxForVirtReg, unsigned Pattern,
     bool SlackIsAccurate) {
   // Get depth and latency of NewRoot and Root.
   unsigned NewRootDepth =
@@ -527,7 +527,7 @@ void MachineCombiner::verifyPatternOrder(MachineBasicBlock *MBB,
   for (auto P : Patterns) {
     SmallVector<MachineInstr *, 16> InsInstrs;
     SmallVector<MachineInstr *, 16> DelInstrs;
-    DenseMap<unsigned, unsigned> InstrIdxForVirtReg;
+    DenseMap<Register, unsigned> InstrIdxForVirtReg;
     TII->genAlternativeCodeSequence(Root, P, InsInstrs, DelInstrs,
                                     InstrIdxForVirtReg);
     // Found pattern, but did not generate alternative sequence.
@@ -612,7 +612,7 @@ bool MachineCombiner::combineInstructions(MachineBasicBlock *MBB) {
     for (const auto P : Patterns) {
       SmallVector<MachineInstr *, 16> InsInstrs;
       SmallVector<MachineInstr *, 16> DelInstrs;
-      DenseMap<unsigned, unsigned> InstrIdxForVirtReg;
+      DenseMap<Register, unsigned> InstrIdxForVirtReg;
       TII->genAlternativeCodeSequence(MI, P, InsInstrs, DelInstrs,
                                       InstrIdxForVirtReg);
       // Found pattern, but did not generate alternative sequence.
diff --git a/llvm/lib/CodeGen/TargetInstrInfo.cpp b/llvm/lib/CodeGen/TargetInstrInfo.cpp
index 7a905b65f26e5..e517ae1a7c44c 100644
--- a/llvm/lib/CodeGen/TargetInstrInfo.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfo.cpp
@@ -1085,7 +1085,7 @@ void TargetInstrInfo::reassociateOps(
     SmallVectorImpl<MachineInstr *> &InsInstrs,
     SmallVectorImpl<MachineInstr *> &DelInstrs,
     ArrayRef<unsigned> OperandIndices,
-    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const {
+    DenseMap<Register, unsigned> &InstrIdxForVirtReg) const {
   MachineFunction *MF = Root.getMF();
   MachineRegisterInfo &MRI = MF->getRegInfo();
   const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
@@ -1250,7 +1250,7 @@ void TargetInstrInfo::genAlternativeCodeSequence(
     MachineInstr &Root, unsigned Pattern,
     SmallVectorImpl<MachineInstr *> &InsInstrs,
     SmallVectorImpl<MachineInstr *> &DelInstrs,
-    DenseMap<unsigned, unsigned> &InstIdxForVirtReg) const {
+    DenseMap<Register, unsigned> &InstIdxForVirtReg) const {
   MachineRegisterInfo &MRI = Root.getMF()->getRegInfo();
 
   // Select the previous instruction in the sequence based on the input pattern.
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 1d600e87230f3..c91590fa43601 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -7360,7 +7360,7 @@ static MachineInstr *genFusedMultiplyAcc(
 static Register genNeg(MachineFunction &MF, MachineRegisterInfo &MRI,
                        const TargetInstrInfo *TII, MachineInstr &Root,
                        SmallVectorImpl<MachineInstr *> &InsInstrs,
-                       DenseMap<unsigned, unsigned> &InstrIdxForVirtReg,
+                       DenseMap<Register, unsigned> &InstrIdxForVirtReg,
                        unsigned MnegOpc, const TargetRegisterClass *RC) {
   Register NewVR = MRI.createVirtualRegister(RC);
   MachineInstrBuilder MIB =
@@ -7379,7 +7379,7 @@ static Register genNeg(MachineFunction &MF, MachineRegisterInfo &MRI,
 static MachineInstr *genFusedMultiplyAccNeg(
     MachineFunction &MF, MachineRegisterInfo &MRI, const TargetInstrInfo *TII,
     MachineInstr &Root, SmallVectorImpl<MachineInstr *> &InsInstrs,
-    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg, unsigned IdxMulOpd,
+    DenseMap<Register, unsigned> &InstrIdxForVirtReg, unsigned IdxMulOpd,
     unsigned MaddOpc, unsigned MnegOpc, const TargetRegisterClass *RC) {
   assert(IdxMulOpd == 1);
 
@@ -7406,7 +7406,7 @@ static MachineInstr *genFusedMultiplyIdx(
 static MachineInstr *genFusedMultiplyIdxNeg(
     MachineFunction &MF, MachineRegisterInfo &MRI, const TargetInstrInfo *TII,
     MachineInstr &Root, SmallVectorImpl<MachineInstr *> &InsInstrs,
-    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg, unsigned IdxMulOpd,
+    DenseMap<Register, unsigned> &InstrIdxForVirtReg, unsigned IdxMulOpd,
     unsigned MaddOpc, unsigned MnegOpc, const TargetRegisterClass *RC) {
   assert(IdxMulOpd == 1);
 
@@ -7472,13 +7472,12 @@ static MachineInstr *genMaddR(MachineFunction &MF, MachineRegisterInfo &MRI,
 /// Do the following transformation
 /// A - (B + C)  ==>   (A - B) - C
 /// A - (B + C)  ==>   (A - C) - B
-static void
-genSubAdd2SubSub(MachineFunction &MF, MachineRegisterInfo &MRI,
-                 const TargetInstrInfo *TII, MachineInstr &Root,
-                 SmallVectorImpl<MachineInstr *> &InsInstrs,
-                 SmallVectorImpl<MachineInstr *> &DelInstrs,
-                 unsigned IdxOpd1,
-                 DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) {
+static void genSubAdd2SubSub(MachineFunction &MF, MachineRegisterInfo &MRI,
+                             const TargetInstrInfo *TII, MachineInstr &Root,
+                             SmallVectorImpl<MachineInstr *> &InsInstrs,
+                             SmallVectorImpl<MachineInstr *> &DelInstrs,
+                             unsigned IdxOpd1,
+                             DenseMap<Register, unsigned> &InstrIdxForVirtReg) {
   assert(IdxOpd1 == 1 || IdxOpd1 == 2);
   unsigned IdxOtherOpd = IdxOpd1 == 1 ? 2 : 1;
   MachineInstr *AddMI = MRI.getUniqueVRegDef(Root.getOperand(2).getReg());
@@ -7531,7 +7530,7 @@ void AArch64InstrInfo::genAlternativeCodeSequence(
     MachineInstr &Root, unsigned Pattern,
     SmallVectorImpl<MachineInstr *> &InsInstrs,
     SmallVectorImpl<MachineInstr *> &DelInstrs,
-    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const {
+    DenseMap<Register, unsigned> &InstrIdxForVirtReg) const {
   MachineBasicBlock &MBB = *Root.getParent();
   MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
   MachineFunction &MF = *MBB.getParent();
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.h b/llvm/lib/Target/AArch64/AArch64InstrInfo.h
index 3eab98139fa7c..6503d105c82cc 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.h
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.h
@@ -454,7 +454,7 @@ class AArch64InstrInfo final : public AArch64GenInstrInfo {
       MachineInstr &Root, unsigned Pattern,
       SmallVectorImpl<MachineInstr *> &InsInstrs,
       SmallVectorImpl<MachineInstr *> &DelInstrs,
-      DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const override;
+      DenseMap<Register, unsigned> &InstrIdxForVirtReg) const override;
   /// AArch64 supports MachineCombiner.
   bool useMachineCombiner() const override;
 
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
index f12400490832b..f017073911950 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -767,7 +767,7 @@ void PPCInstrInfo::genAlternativeCodeSequence(
     MachineInstr &Root, unsigned Pattern,
     SmallVectorImpl<MachineInstr *> &InsInstrs,
     SmallVectorImpl<MachineInstr *> &DelInstrs,
-    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const {
+    DenseMap<Register, unsigned> &InstrIdxForVirtReg) const {
   switch (Pattern) {
   case PPCMachineCombinerPattern::REASSOC_XY_AMM_BMM:
   case PPCMachineCombinerPattern::REASSOC_XMM_AMM_BMM:
@@ -787,7 +787,7 @@ void PPCInstrInfo::reassociateFMA(
     MachineInstr &Root, unsigned Pattern,
     SmallVectorImpl<MachineInstr *> &InsInstrs,
     SmallVectorImpl<MachineInstr *> &DelInstrs,
-    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const {
+    DenseMap<Register, unsigned> &InstrIdxForVirtReg) const {
   MachineFunction *MF = Root.getMF();
   MachineRegisterInfo &MRI = MF->getRegInfo();
   const TargetRegisterInfo *TRI = &getRegisterInfo();
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.h b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
index d4554379cdb1d..83bc39e0c06bd 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
@@ -241,7 +241,7 @@ class PPCInstrInfo : public PPCGenInstrInfo {
   void reassociateFMA(MachineInstr &Root, unsigned Pattern,
                       SmallVectorImpl<MachineInstr *> &InsInstrs,
                       SmallVectorImpl<MachineInstr *> &DelInstrs,
-                      DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const;
+                      DenseMap<Register, unsigned> &InstrIdxForVirtReg) const;
   Register
   generateLoadForNewConst(unsigned Idx, MachineInstr *MI, Type *Ty,
                           SmallVectorImpl<MachineInstr *> &InsInstrs) const;
@@ -370,7 +370,7 @@ class PPCInstrInfo : public PPCGenInstrInfo {
       MachineInstr &Root, unsigned Pattern,
       SmallVectorImpl<MachineInstr *> &InsInstrs,
       SmallVectorImpl<MachineInstr *> &DelInstrs,
-      DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const override;
+      DenseMap<Register, unsigned> &InstrIdxForVirtReg) const override;
 
   /// Return true when there is potentially a faster code sequence for a fma
   /// chain ending in \p Root. All potential patterns are output in the \p
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index 2fdf6bd36e88f..c197f06855b6e 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -2376,7 +2376,7 @@ static void
 genShXAddAddShift(MachineInstr &Root, unsigned AddOpIdx,
                   SmallVectorImpl<MachineInstr *> &InsInstrs,
                   SmallVectorImpl<MachineInstr *> &DelInstrs,
-                  DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) {
+                  DenseMap<Register, unsigned> &InstrIdxForVirtReg) {
   MachineFunction *MF = Root.getMF();
   MachineRegisterInfo &MRI = MF->getRegInfo();
   const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
@@ -2435,7 +2435,7 @@ void RISCVInstrInfo::genAlternativeCodeSequence(
     MachineInstr &Root, unsigned Pattern,
     SmallVectorImpl<MachineInstr *> &InsInstrs,
     SmallVectorImpl<MachineInstr *> &DelInstrs,
-    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const {
+    DenseMap<Register, unsigned> &InstrIdxForVirtReg) const {
   MachineRegisterInfo &MRI = Root.getMF()->getRegInfo();
   switch (Pattern) {
   default:
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.h b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
index 656cb38e11297..d68bd58885873 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
@@ -274,7 +274,7 @@ class RISCVInstrInfo : public RISCVGenInstrInfo {
       MachineInstr &Root, unsigned Pattern,
       SmallVectorImpl<MachineInstr *> &InsInstrs,
       SmallVectorImpl<MachineInstr *> &DelInstrs,
-      DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const override;
+      DenseMap<Register, unsigned> &InstrIdxForVirtReg) const override;
 
   bool hasReassociableOperands(const MachineInstr &Inst,
                                const MachineBasicBlock *MBB) const override;
diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 99a0259119d42..b13412df4b8b0 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -10857,7 +10857,7 @@ static void
 genAlternativeDpCodeSequence(MachineInstr &Root, const TargetInstrInfo &TII,
                              SmallVectorImpl<MachineInstr *> &InsInstrs,
                              SmallVectorImpl<MachineInstr *> &DelInstrs,
-                             DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) {
+                             DenseMap<Register, unsigned> &InstrIdxForVirtReg) {
   MachineFunction *MF = Root.getMF();
   MachineRegisterInfo &RegInfo = MF->getRegInfo();
 
@@ -10947,7 +10947,7 @@ void X86InstrInfo::genAlternativeCodeSequence(
     MachineInstr &Root, unsigned Pattern,
     SmallVectorImpl<MachineInstr *> &InsInstrs,
     SmallVectorImpl<MachineInstr *> &DelInstrs,
-    DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const {
+    DenseMap<Register, unsigned> &InstrIdxForVirtReg) const {
   switch (Pattern) {
   default:
     // Reassociate instructions.
diff --git a/llvm/lib/Target/X86/X86InstrInfo.h b/llvm/lib/Target/X86/X86InstrInfo.h
index f383eaddfd0b4..ee86da71d81a4 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.h
+++ b/llvm/lib/Target/X86/X86InstrInfo.h
@@ -641,7 +641,7 @@ class X86InstrInfo final : public X86GenInstrInfo {
       MachineInstr &Root, unsigned Pattern,
       SmallVectorImpl<MachineInstr *> &InsInstrs,
       SmallVectorImpl<MachineInstr *> &DelInstrs,
-      DenseMap<unsigned, unsigned> &InstrIdxForVirtReg) const override;
+      DenseMap<Register, unsigned> &InstrIdxForVirtReg) const override;
 
   /// When calculate the latency of the root instruction, accumulate the
   /// latency of the sequence to the root latency.