[CodeGen] Use range-based for loops (NFC)

llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp

@@ -3082,9 +3082,9 @@ void CombinerHelper::applyCombineInsertVecElts(
     UndefReg = Builder.buildUndef(DstTy.getScalarType()).getReg(0);
     return UndefReg;
   };
-  for (unsigned I = 0; I < MatchInfo.size(); ++I) {
-    if (!MatchInfo[I])
-      MatchInfo[I] = GetUndef();
+  for (Register &Reg : MatchInfo) {
+    if (!Reg)
+      Reg = GetUndef();
   }
   Builder.buildBuildVector(MI.getOperand(0).getReg(), MatchInfo);
   MI.eraseFromParent();

llvm/lib/CodeGen/MachineInstrBundle.cpp

@@ -177,26 +177,25 @@ void llvm::finalizeBundle(MachineBasicBlock &MBB,
       }
     }
 
-    for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
-      MachineOperand &MO = *Defs[i];
-      Register Reg = MO.getReg();
+    for (MachineOperand *MO : Defs) {
+      Register Reg = MO->getReg();
       if (!Reg)
         continue;
 
       if (LocalDefSet.insert(Reg).second) {
         LocalDefs.push_back(Reg);
-        if (MO.isDead()) {
+        if (MO->isDead()) {
           DeadDefSet.insert(Reg);
         }
       } else {
         // Re-defined inside the bundle, it's no longer killed.
         KilledDefSet.erase(Reg);
-        if (!MO.isDead())
+        if (!MO->isDead())
           // Previously defined but dead.
           DeadDefSet.erase(Reg);
       }
 
-      if (!MO.isDead() && Reg.isPhysical()) {
+      if (!MO->isDead() && Reg.isPhysical()) {
         for (MCPhysReg SubReg : TRI->subregs(Reg)) {
           if (LocalDefSet.insert(SubReg).second)
             LocalDefs.push_back(SubReg);

llvm/lib/CodeGen/MachineTraceMetrics.cpp

@@ -939,15 +939,15 @@ static unsigned updatePhysDepsUpwards(const MachineInstr &MI, unsigned Height,
   }
 
   // Now we know the height of MI. Update any regunits read.
-  for (size_t I = 0, E = ReadOps.size(); I != E; ++I) {
-    MCRegister Reg = MI.getOperand(ReadOps[I]).getReg().asMCReg();
+  for (unsigned Op : ReadOps) {
+    MCRegister Reg = MI.getOperand(Op).getReg().asMCReg();
     for (MCRegUnit Unit : TRI->regunits(Reg)) {
       LiveRegUnit &LRU = RegUnits[Unit];
       // Set the height to the highest reader of the unit.
       if (LRU.Cycle <= Height && LRU.MI != &MI) {
         LRU.Cycle = Height;
         LRU.MI = &MI;
-        LRU.Op = ReadOps[I];
+        LRU.Op = Op;
       }
     }
   }

llvm/lib/CodeGen/RegAllocBasic.cpp

@@ -226,19 +226,17 @@ bool RABasic::spillInterferences(const LiveInterval &VirtReg,
   assert(!Intfs.empty() && "expected interference");
 
   // Spill each interfering vreg allocated to PhysReg or an alias.
-  for (unsigned i = 0, e = Intfs.size(); i != e; ++i) {
-    const LiveInterval &Spill = *Intfs[i];
-
+  for (const LiveInterval *Spill : Intfs) {
     // Skip duplicates.
-    if (!VRM->hasPhys(Spill.reg()))
+    if (!VRM->hasPhys(Spill->reg()))
       continue;
 
     // Deallocate the interfering vreg by removing it from the union.
     // A LiveInterval instance may not be in a union during modification!
-    Matrix->unassign(Spill);
+    Matrix->unassign(*Spill);
 
     // Spill the extracted interval.
-    LiveRangeEdit LRE(&Spill, SplitVRegs, *MF, *LIS, VRM, this, &DeadRemats);
+    LiveRangeEdit LRE(Spill, SplitVRegs, *MF, *LIS, VRM, this, &DeadRemats);
     spiller().spill(LRE);
   }
   return true;

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -1455,13 +1455,12 @@ void SelectionDAGISel::reportIPToStateForBlocks(MachineFunction *MF) {
   llvm::WinEHFuncInfo *EHInfo = MF->getWinEHFuncInfo();
   if (!EHInfo)
     return;
-  for (auto MBBI = MF->begin(), E = MF->end(); MBBI != E; ++MBBI) {
-    MachineBasicBlock *MBB = &*MBBI;
-    const BasicBlock *BB = MBB->getBasicBlock();
+  for (MachineBasicBlock &MBB : *MF) {
+    const BasicBlock *BB = MBB.getBasicBlock();
     int State = EHInfo->BlockToStateMap[BB];
     if (BB->getFirstMayFaultInst()) {
       // Report IP range only for blocks with Faulty inst
-      auto MBBb = MBB->getFirstNonPHI();
+      auto MBBb = MBB.getFirstNonPHI();
       MachineInstr *MIb = &*MBBb;
       if (MIb->isTerminator())
         continue;
@@ -1470,16 +1469,16 @@ void SelectionDAGISel::reportIPToStateForBlocks(MachineFunction *MF) {
       MCSymbol *BeginLabel = MMI.getContext().createTempSymbol();
       MCSymbol *EndLabel = MMI.getContext().createTempSymbol();
       EHInfo->addIPToStateRange(State, BeginLabel, EndLabel);
-      BuildMI(*MBB, MBBb, SDB->getCurDebugLoc(),
+      BuildMI(MBB, MBBb, SDB->getCurDebugLoc(),
               TII->get(TargetOpcode::EH_LABEL))
           .addSym(BeginLabel);
-      auto MBBe = MBB->instr_end();
+      auto MBBe = MBB.instr_end();
       MachineInstr *MIe = &*(--MBBe);
       // insert before (possible multiple) terminators
       while (MIe->isTerminator())
         MIe = &*(--MBBe);
       ++MBBe;
-      BuildMI(*MBB, MBBe, SDB->getCurDebugLoc(),
+      BuildMI(MBB, MBBe, SDB->getCurDebugLoc(),
               TII->get(TargetOpcode::EH_LABEL))
           .addSym(EndLabel);
     }
@@ -2125,8 +2124,8 @@ SelectionDAGISel::FinishBasicBlock() {
     // from the original BB before switch expansion.  Note that PHI nodes can
     // occur multiple times in PHINodesToUpdate.  We have to be very careful to
     // handle them the right number of times.
-    for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
-      FuncInfo->MBB = Succs[i];
+    for (MachineBasicBlock *Succ : Succs) {
+      FuncInfo->MBB = Succ;
       FuncInfo->InsertPt = FuncInfo->MBB->end();
       // FuncInfo->MBB may have been removed from the CFG if a branch was
       // constant folded.

llvm/lib/CodeGen/TailDuplicator.cpp

@@ -201,8 +201,7 @@ bool TailDuplicator::tailDuplicateAndUpdate(
 
   // Update SSA form.
   if (!SSAUpdateVRs.empty()) {
-    for (unsigned i = 0, e = SSAUpdateVRs.size(); i != e; ++i) {
-      unsigned VReg = SSAUpdateVRs[i];
+    for (unsigned VReg : SSAUpdateVRs) {
       SSAUpdate.Initialize(VReg);
 
       // If the original definition is still around, add it as an available