[SelectionDAG] Use a range-based for loop (NFC) (#97154)

UI++ in the loop might appear to indicate that the loop modifies the
container in some way (deletion or insertion), but the loop just
examines the container.

Author: kazutakahirata

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -756,16 +756,16 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
       // that COPY instructions also need DBG_VALUE, if it is the only
       // user of LDI->second.
       MachineInstr *CopyUseMI = nullptr;
-      for (MachineRegisterInfo::use_instr_iterator
-           UI = RegInfo->use_instr_begin(LDI->second),
-           E = RegInfo->use_instr_end(); UI != E; ) {
-        MachineInstr *UseMI = &*(UI++);
-        if (UseMI->isDebugValue()) continue;
-        if (UseMI->isCopy() && !CopyUseMI && UseMI->getParent() == EntryMBB) {
-          CopyUseMI = UseMI; continue;
+      for (MachineInstr &UseMI : RegInfo->use_instructions(LDI->second)) {
+        if (UseMI.isDebugValue())
+          continue;
+        if (UseMI.isCopy() && !CopyUseMI && UseMI.getParent() == EntryMBB) {
+          CopyUseMI = &UseMI;
+          continue;
         }
         // Otherwise this is another use or second copy use.
-        CopyUseMI = nullptr; break;
+        CopyUseMI = nullptr;
+        break;
       }
       if (CopyUseMI &&
           TRI.getRegSizeInBits(LDI->second, MRI) ==