diff --git a/include/llvm/CodeGen/MachineRegisterInfo.h b/include/llvm/CodeGen/MachineRegisterInfo.h
index 0ae1065..74df8da 100644
--- a/include/llvm/CodeGen/MachineRegisterInfo.h
+++ b/include/llvm/CodeGen/MachineRegisterInfo.h
@@ -159,15 +159,15 @@
   /// getRegUseDefListHead - Return the head pointer for the register use/def
   /// list for the specified virtual or physical register.
   MachineOperand *&getRegUseDefListHead(unsigned RegNo) {
-    if (!RegNo || TargetRegisterInfo::isPhysicalRegister(RegNo))
-      return PhysRegUseDefLists[RegNo];
-    return VRegInfo[RegNo].second;
+    if (TargetRegisterInfo::isVirtualRegister(RegNo))
+      return VRegInfo[RegNo].second;
+    return PhysRegUseDefLists[RegNo];
   }
   
   MachineOperand *getRegUseDefListHead(unsigned RegNo) const {
-    if (!RegNo || TargetRegisterInfo::isPhysicalRegister(RegNo))
-      return PhysRegUseDefLists[RegNo];
-    return VRegInfo[RegNo].second;
+    if (TargetRegisterInfo::isVirtualRegister(RegNo))
+      return VRegInfo[RegNo].second;
+    return PhysRegUseDefLists[RegNo];
   }
 
   /// getVRegDef - Return the machine instr that defines the specified virtual
diff --git a/lib/CodeGen/AllocationOrder.cpp b/lib/CodeGen/AllocationOrder.cpp
index 26d4cd4..20c7625 100644
--- a/lib/CodeGen/AllocationOrder.cpp
+++ b/lib/CodeGen/AllocationOrder.cpp
@@ -33,7 +33,7 @@
   Hint = HintPair.second;
 
   // Translate to physreg, or 0 if not assigned yet.
-  if (Hint && TargetRegisterInfo::isVirtualRegister(Hint))
+  if (TargetRegisterInfo::isVirtualRegister(Hint))
     Hint = VRM.getPhys(Hint);
 
   // The remaining allocation order may depend on the hint.
diff --git a/lib/CodeGen/DeadMachineInstructionElim.cpp b/lib/CodeGen/DeadMachineInstructionElim.cpp
index 32040e5..fdc1d91 100644
--- a/lib/CodeGen/DeadMachineInstructionElim.cpp
+++ b/lib/CodeGen/DeadMachineInstructionElim.cpp
@@ -159,7 +159,7 @@
         const MachineOperand &MO = MI->getOperand(i);
         if (MO.isReg() && MO.isDef()) {
           unsigned Reg = MO.getReg();
-          if (Reg != 0 && TargetRegisterInfo::isPhysicalRegister(Reg)) {
+          if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
             LivePhysRegs.reset(Reg);
             // Check the subreg set, not the alias set, because a def
             // of a super-register may still be partially live after
@@ -176,7 +176,7 @@
         const MachineOperand &MO = MI->getOperand(i);
         if (MO.isReg() && MO.isUse()) {
           unsigned Reg = MO.getReg();
-          if (Reg != 0 && TargetRegisterInfo::isPhysicalRegister(Reg)) {
+          if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
             LivePhysRegs.set(Reg);
             for (const unsigned *AliasSet = TRI->getAliasSet(Reg);
                  *AliasSet; ++AliasSet)
diff --git a/lib/CodeGen/LiveDebugVariables.cpp b/lib/CodeGen/LiveDebugVariables.cpp
index ac95e73..da4b017 100644
--- a/lib/CodeGen/LiveDebugVariables.cpp
+++ b/lib/CodeGen/LiveDebugVariables.cpp
@@ -359,7 +359,7 @@
   // If the location is a virtual register, make sure it is mapped.
   if (MI->getOperand(0).isReg()) {
     unsigned Reg = MI->getOperand(0).getReg();
-    if (Reg && TargetRegisterInfo::isVirtualRegister(Reg))
+    if (TargetRegisterInfo::isVirtualRegister(Reg))
       mapVirtReg(Reg, UV);
   }
 
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 0b5c582..000fc40 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -988,7 +988,7 @@
     if (!MO.isReg())
       continue;
     unsigned Reg = MO.getReg();
-    if (Reg == 0 || TargetRegisterInfo::isPhysicalRegister(Reg))
+    if (!TargetRegisterInfo::isVirtualRegister(Reg))
       continue;
     if (!vrm.isReMaterialized(Reg))
       continue;
@@ -1022,7 +1022,7 @@
     if (!mop.isReg())
       continue;
     unsigned Reg = mop.getReg();
-    if (Reg == 0 || TargetRegisterInfo::isPhysicalRegister(Reg))
+    if (!TargetRegisterInfo::isVirtualRegister(Reg))
       continue;
     if (Reg != li.reg)
       continue;
diff --git a/lib/CodeGen/MachineCSE.cpp b/lib/CodeGen/MachineCSE.cpp
index 3e54784..60ad46a 100644
--- a/lib/CodeGen/MachineCSE.cpp
+++ b/lib/CodeGen/MachineCSE.cpp
@@ -116,7 +116,7 @@
     if (!MO.isReg() || !MO.isUse())
       continue;
     unsigned Reg = MO.getReg();
-    if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg))
+    if (!TargetRegisterInfo::isVirtualRegister(Reg))
       continue;
     if (!MRI->hasOneNonDBGUse(Reg))
       // Only coalesce single use copies. This ensure the copy will be
@@ -300,7 +300,7 @@
   bool HasVRegUse = false;
   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
     const MachineOperand &MO = MI->getOperand(i);
-    if (MO.isReg() && MO.isUse() && MO.getReg() &&
+    if (MO.isReg() && MO.isUse() &&
         TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
       HasVRegUse = true;
       break;
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index 385fbb5..aa9ea61 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -1326,7 +1326,7 @@
     if (StartOp != 0) OS << ", ";
     getOperand(StartOp).print(OS, TM);
     unsigned Reg = getOperand(StartOp).getReg();
-    if (Reg && TargetRegisterInfo::isVirtualRegister(Reg))
+    if (TargetRegisterInfo::isVirtualRegister(Reg))
       VirtRegs.push_back(Reg);
   }
 
@@ -1360,8 +1360,7 @@
   for (unsigned i = StartOp, e = getNumOperands(); i != e; ++i) {
     const MachineOperand &MO = getOperand(i);
 
-    if (MO.isReg() && MO.getReg() &&
-        TargetRegisterInfo::isVirtualRegister(MO.getReg()))
+    if (MO.isReg() && TargetRegisterInfo::isVirtualRegister(MO.getReg()))
       VirtRegs.push_back(MO.getReg());
 
     // Omit call-clobbered registers which aren't used anywhere. This makes
@@ -1371,7 +1370,7 @@
     if (MF && getDesc().isCall() &&
         MO.isReg() && MO.isImplicit() && MO.isDef()) {
       unsigned Reg = MO.getReg();
-      if (Reg != 0 && TargetRegisterInfo::isPhysicalRegister(Reg)) {
+      if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
         const MachineRegisterInfo &MRI = MF->getRegInfo();
         if (MRI.use_empty(Reg) && !MRI.isLiveOut(Reg)) {
           bool HasAliasLive = false;
@@ -1620,8 +1619,7 @@
     switch (MO.getType()) {
     default: break;
     case MachineOperand::MO_Register:
-      if (MO.isDef() && MO.getReg() &&
-          TargetRegisterInfo::isVirtualRegister(MO.getReg()))
+      if (MO.isDef() && TargetRegisterInfo::isVirtualRegister(MO.getReg()))
         continue;  // Skip virtual register defs.
       Key |= MO.getReg();
       break;
diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp
index e3b21c4..7766e11 100644
--- a/lib/CodeGen/MachineLICM.cpp
+++ b/lib/CodeGen/MachineLICM.cpp
@@ -622,7 +622,7 @@
       if (!MO.isReg() || MO.isImplicit())
         continue;
       unsigned Reg = MO.getReg();
-      if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg))
+      if (!TargetRegisterInfo::isVirtualRegister(Reg))
         continue;
 
       bool isNew = RegSeen.insert(Reg);
@@ -655,7 +655,7 @@
     if (!MO.isReg() || MO.isImplicit())
       continue;
     unsigned Reg = MO.getReg();
-    if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg))
+    if (!TargetRegisterInfo::isVirtualRegister(Reg))
       continue;
 
     bool isNew = RegSeen.insert(Reg);
@@ -889,7 +889,7 @@
     if (!MO.isReg() || MO.isImplicit())
       continue;
     unsigned Reg = MO.getReg();
-    if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg))
+    if (!TargetRegisterInfo::isVirtualRegister(Reg))
       continue;
 
     const TargetRegisterClass *RC = MRI->getRegClass(Reg);
@@ -952,7 +952,7 @@
       if (!MO.isReg() || MO.isImplicit())
         continue;
       unsigned Reg = MO.getReg();
-      if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg))
+      if (!TargetRegisterInfo::isVirtualRegister(Reg))
         continue;
       if (MO.isDef()) {
         if (HasHighOperandLatency(MI, i, Reg)) {
diff --git a/lib/CodeGen/PeepholeOptimizer.cpp b/lib/CodeGen/PeepholeOptimizer.cpp
index 54466ef..5f6ee30 100644
--- a/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/lib/CodeGen/PeepholeOptimizer.cpp
@@ -295,7 +295,7 @@
     if (!MO.isReg() || MO.isDef())
       continue;
     unsigned Reg = MO.getReg();
-    if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg))
+    if (!TargetRegisterInfo::isVirtualRegister(Reg))
       continue;
     if (ImmDefRegs.count(Reg) == 0)
       continue;
diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp
index 6666d9a..5793477 100644
--- a/lib/CodeGen/RegAllocFast.cpp
+++ b/lib/CodeGen/RegAllocFast.cpp
@@ -656,7 +656,8 @@
     MachineOperand &MO = MI->getOperand(i);
     if (!MO.isReg()) continue;
     unsigned Reg = MO.getReg();
-    if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
+    if (!TargetRegisterInfo::isVirtualRegister(Reg))
+      continue;
     if (MO.isEarlyClobber() || MI->isRegTiedToDefOperand(i) ||
         (MO.getSubReg() && MI->readsVirtualRegister(Reg))) {
       if (ThroughRegs.insert(Reg))
@@ -688,7 +689,7 @@
     MachineOperand &MO = MI->getOperand(i);
     if (!MO.isReg()) continue;
     unsigned Reg = MO.getReg();
-    if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
+    if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
     if (MO.isUse()) {
       unsigned DefIdx = 0;
       if (!MI->isRegTiedToDefOperand(i, &DefIdx)) continue;
@@ -794,7 +795,7 @@
           MachineOperand &MO = MI->getOperand(i);
           if (!MO.isReg()) continue;
           unsigned Reg = MO.getReg();
-          if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
+          if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
           LiveDbgValueMap[Reg] = MI;
           LiveRegMap::iterator LRI = LiveVirtRegs.find(Reg);
           if (LRI != LiveVirtRegs.end())
@@ -909,7 +910,7 @@
       MachineOperand &MO = MI->getOperand(i);
       if (!MO.isReg()) continue;
       unsigned Reg = MO.getReg();
-      if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
+      if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
       if (MO.isUse()) {
         LiveRegMap::iterator LRI = reloadVirtReg(MI, i, Reg, CopyDst);
         unsigned PhysReg = LRI->second.PhysReg;
diff --git a/lib/CodeGen/RegAllocLinearScan.cpp b/lib/CodeGen/RegAllocLinearScan.cpp
index bbff424..14f6726 100644
--- a/lib/CodeGen/RegAllocLinearScan.cpp
+++ b/lib/CodeGen/RegAllocLinearScan.cpp
@@ -1421,8 +1421,7 @@
   std::pair<unsigned, unsigned> Hint = mri_->getRegAllocationHint(cur->reg);
   // Resolve second part of the hint (if possible) given the current allocation.
   unsigned physReg = Hint.second;
-  if (physReg &&
-      TargetRegisterInfo::isVirtualRegister(physReg) && vrm_->hasPhys(physReg))
+  if (TargetRegisterInfo::isVirtualRegister(physReg) && vrm_->hasPhys(physReg))
     physReg = vrm_->getPhys(physReg);
 
   TargetRegisterClass::iterator I, E;
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index d7bf6c1..e309def 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -703,7 +703,7 @@
         for (unsigned i = 0, e = F->getNumOperands(); i != e; ++i)
           if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(F->getOperand(i))) {
             unsigned Reg = R->getReg();
-            if (Reg != 0 && TargetRegisterInfo::isPhysicalRegister(Reg))
+            if (TargetRegisterInfo::isPhysicalRegister(Reg))
               UsedRegs.push_back(Reg);
           }
       }
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 05acb03..4ea8e4d 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4070,7 +4070,7 @@
 
   if (N.getNode() && N.getOpcode() == ISD::CopyFromReg) {
     Reg = cast<RegisterSDNode>(N.getOperand(1))->getReg();
-    if (Reg && TargetRegisterInfo::isVirtualRegister(Reg)) {
+    if (TargetRegisterInfo::isVirtualRegister(Reg)) {
       MachineRegisterInfo &RegInfo = MF.getRegInfo();
       unsigned PR = RegInfo.getLiveInPhysReg(Reg);
       if (PR)
diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp
index a815b36..ce4b1be 100644
--- a/lib/CodeGen/TailDuplication.cpp
+++ b/lib/CodeGen/TailDuplication.cpp
@@ -350,7 +350,7 @@
     if (!MO.isReg())
       continue;
     unsigned Reg = MO.getReg();
-    if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg))
+    if (!TargetRegisterInfo::isVirtualRegister(Reg))
       continue;
     if (MO.isDef()) {
       const TargetRegisterClass *RC = MRI->getRegClass(Reg);
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 63e6ec3..a30279d 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -954,7 +954,7 @@
           if (LV) {
             for (unsigned i = 0, e = mi->getNumOperands(); i != e; ++i) {
               MachineOperand &MO = mi->getOperand(i);
-              if (MO.isReg() && MO.getReg() != 0 &&
+              if (MO.isReg() && 
                   TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
                 if (MO.isUse()) {
                   if (MO.isKill()) {
diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index df8a021..82c64f3 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -115,11 +115,10 @@
 unsigned VirtRegMap::getRegAllocPref(unsigned virtReg) {
   std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(virtReg);
   unsigned physReg = Hint.second;
-  if (physReg &&
-      TargetRegisterInfo::isVirtualRegister(physReg) && hasPhys(physReg))
+  if (TargetRegisterInfo::isVirtualRegister(physReg) && hasPhys(physReg))
     physReg = getPhys(physReg);
   if (Hint.first == 0)
-    return (physReg && TargetRegisterInfo::isPhysicalRegister(physReg))
+    return (TargetRegisterInfo::isPhysicalRegister(physReg))
       ? physReg : 0;
   return TRI->ResolveRegAllocHint(Hint.first, physReg, *MF);
 }
diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 046ba8e..a53d8cb 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -234,8 +234,7 @@
   if (LV) {
     for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
       MachineOperand &MO = MI->getOperand(i);
-      if (MO.isReg() && MO.getReg() &&
-          TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
+      if (MO.isReg() && TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
         unsigned Reg = MO.getReg();
 
         LiveVariables::VarInfo &VI = LV->getVarInfo(Reg);
diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index 9928105..e1f179e 100644
--- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -517,7 +517,7 @@
   std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(Reg);
   if ((Hint.first == (unsigned)ARMRI::RegPairOdd ||
        Hint.first == (unsigned)ARMRI::RegPairEven) &&
-      Hint.second && TargetRegisterInfo::isVirtualRegister(Hint.second)) {
+      TargetRegisterInfo::isVirtualRegister(Hint.second)) {
     // If 'Reg' is one of the even / odd register pair and it's now changed
     // (e.g. coalesced) into a different register. The other register of the
     // pair allocation hint must be updated to reflect the relationship
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 21f7b51..370dd7b 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -1458,7 +1458,7 @@
   int FI = INT_MAX;
   if (Arg.getOpcode() == ISD::CopyFromReg) {
     unsigned VR = cast<RegisterSDNode>(Arg.getOperand(1))->getReg();
-    if (!VR || TargetRegisterInfo::isPhysicalRegister(VR))
+    if (!TargetRegisterInfo::isVirtualRegister(VR))
       return false;
     MachineInstr *Def = MRI->getVRegDef(VR);
     if (!Def)
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 99ada98..0f8e9d5 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2323,7 +2323,7 @@
   int FI = INT_MAX;
   if (Arg.getOpcode() == ISD::CopyFromReg) {
     unsigned VR = cast<RegisterSDNode>(Arg.getOperand(1))->getReg();
-    if (!VR || TargetRegisterInfo::isPhysicalRegister(VR))
+    if (!TargetRegisterInfo::isVirtualRegister(VR))
       return false;
     MachineInstr *Def = MRI->getVRegDef(VR);
     if (!Def)