MachineTraceMetrics: modernize loops (NFC)

[barannikov88]

LGTM

llvm/lib/CodeGen/MachineTraceMetrics.cpp

if (Succ) {
           if (pushDepHeight(Deps.front(), PHI, Height, Heights, MTM.SchedModel,
                             MTM.TII))
             addLiveIns(Deps.front().DefMI, Deps.front().DefOp, Stack);
         }
       }
     }
 
     // Go through the block backwards.
-    for (MachineBasicBlock::const_iterator BI = MBB->end(), BB = MBB->begin();
-         BI != BB;) {
-      const MachineInstr &MI = *--BI;
-
+    for (const MachineInstr &MI : reverse(*MBB)) {
       // Find the MI height as determined by virtual register uses in the
       // trace below.
       unsigned Cycle = 0;
       MIHeightMap::iterator HeightI = Heights.find(&MI);
       if (HeightI != Heights.end()) {
         Cycle = HeightI->second;
         // We won't be seeing any more MI uses.
         Heights.erase(HeightI);
for (;!Stack.empty(); Stack.pop_back()) {
     LLVM_DEBUG(dbgs() << printMBBReference(*MBB) << " Live-ins:");
     for (LiveInReg &LIR : TBI.LiveIns) {
       const MachineInstr *DefMI = MTM.MRI->getVRegDef(LIR.Reg);
       LIR.Height = Heights.lookup(DefMI);
       LLVM_DEBUG(dbgs() << ' ' << printReg(LIR.Reg) << '@' << LIR.Height);
     }
 
     // Transfer the live regunits to the live-in list.
-    for (SparseSet<LiveRegUnit>::const_iterator
-         RI = RegUnits.begin(), RE = RegUnits.end(); RI != RE; ++RI) {
-      TBI.LiveIns.push_back(LiveInReg(RI->RegUnit, RI->Cycle));
-      LLVM_DEBUG(dbgs() << ' ' << printRegUnit(RI->RegUnit, MTM.TRI) << '@'
-                        << RI->Cycle);
+    for (const LiveRegUnit &RU : RegUnits) {
+      TBI.LiveIns.push_back(LiveInReg(RU.RegUnit, RU.Cycle));
+      LLVM_DEBUG(dbgs() << ' ' << printRegUnit(RU.RegUnit, MTM.TRI) << '@'
+                        << RU.Cycle);
     }
     LLVM_DEBUG(dbgs() << '\n');
 
     if (!TBI.HasValidInstrDepths)
       continue;
     // Add live-ins to the critical path length.
     TBI.CriticalPath = std::max(TBI.CriticalPath,
                                 computeCrossBlockCriticalPath(TBI));