[CodeGen] Use a range-based for loop (NFC)

Author: kazutakahirata

llvm/lib/CodeGen/SelectionDAG/FastISel.cpp

@@ -2210,15 +2210,12 @@ Register FastISel::fastEmitZExtFromI1(MVT VT, unsigned Op0) {
 /// might result in multiple MBB's for one BB.  As such, the start of the
 /// BB might correspond to a different MBB than the end.
 bool FastISel::handlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB) {
-  const Instruction *TI = LLVMBB->getTerminator();
-
   SmallPtrSet<MachineBasicBlock *, 4> SuccsHandled;
   FuncInfo.OrigNumPHINodesToUpdate = FuncInfo.PHINodesToUpdate.size();
 
   // Check successor nodes' PHI nodes that expect a constant to be available
   // from this block.
-  for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) {
-    const BasicBlock *SuccBB = TI->getSuccessor(succ);
+  for (const BasicBlock *SuccBB : successors(LLVMBB)) {
     if (!isa<PHINode>(SuccBB->begin()))
       continue;
     MachineBasicBlock *SuccMBB = FuncInfo.MBBMap[SuccBB];