[CodeGen] Construct SmallVector with iterator ranges (NFC) (#105622)

Author: kazutakahirata

llvm/lib/CodeGen/MachineSink.cpp

@@ -766,8 +766,7 @@ bool MachineSinking::runOnMachineFunction(MachineFunction &MF) {
   }
 
   if (SinkInstsIntoCycle) {
-    SmallVector<MachineCycle *, 8> Cycles(CI->toplevel_begin(),
-                                          CI->toplevel_end());
+    SmallVector<MachineCycle *, 8> Cycles(CI->toplevel_cycles());
     for (auto *Cycle : Cycles) {
       MachineBasicBlock *Preheader = Cycle->getCyclePreheader();
       if (!Preheader) {

llvm/lib/CodeGen/ShrinkWrap.cpp

@@ -411,8 +411,7 @@ hasDirtyPred(const DenseSet<const MachineBasicBlock *> &ReachableByDirty,
 /// Derives the list of all the basic blocks reachable from MBB.
 static void markAllReachable(DenseSet<const MachineBasicBlock *> &Visited,
                              const MachineBasicBlock &MBB) {
-  SmallVector<MachineBasicBlock *, 4> Worklist(MBB.succ_begin(),
-                                               MBB.succ_end());
+  SmallVector<MachineBasicBlock *, 4> Worklist(MBB.successors());
   Visited.insert(&MBB);
   while (!Worklist.empty()) {
     MachineBasicBlock *SuccMBB = Worklist.pop_back_val();