[splitkit] Add a minor wrapper function for readability [NFC]

GitOrigin-RevId: 5318d9e5165a6e7f10c602ab85cb24ed2dfceed4
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index ff993b4..5f97729 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -1531,7 +1531,7 @@
 
 void SplitEditor::splitSingleBlock(const SplitAnalysis::BlockInfo &BI) {
   openIntv();
-  SlotIndex LastSplitPoint = SA.getLastSplitPoint(BI.MBB->getNumber());
+  SlotIndex LastSplitPoint = SA.getLastSplitPoint(BI.MBB);
   SlotIndex SegStart = enterIntvBefore(std::min(BI.FirstInstr,
     LastSplitPoint));
   if (!BI.LiveOut || BI.LastInstr < LastSplitPoint) {
@@ -1685,7 +1685,7 @@
     return;
   }
 
-  SlotIndex LSP = SA.getLastSplitPoint(BI.MBB->getNumber());
+  SlotIndex LSP = SA.getLastSplitPoint(BI.MBB);
 
   if (!LeaveBefore || LeaveBefore > BI.LastInstr.getBoundaryIndex()) {
     //
@@ -1762,7 +1762,7 @@
                     << ", enter after " << EnterAfter
                     << (BI.LiveIn ? ", stack-in" : ", defined in block"));
 
-  SlotIndex LSP = SA.getLastSplitPoint(BI.MBB->getNumber());
+  SlotIndex LSP = SA.getLastSplitPoint(BI.MBB);
 
   assert(IntvOut && "Must have register out");
   assert(BI.LiveOut && "Must be live-out");
diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h
index ec51014..0963576 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -238,6 +238,10 @@
     return IPA.getLastInsertPoint(*CurLI, *MF.getBlockNumbered(Num));
   }
 
+  SlotIndex getLastSplitPoint(MachineBasicBlock *BB) {
+    return IPA.getLastInsertPoint(*CurLI, *BB);
+  }
+
   MachineBasicBlock::iterator getLastSplitPointIter(MachineBasicBlock *BB) {
     return IPA.getLastInsertPointIter(*CurLI, *BB);
   }