Replace SelectInst with auto

Comment from Alexey

Co-authored-by: Alexey Bataev <[email protected]>

Author: Mel-Chen

llvm/lib/Analysis/IVDescriptors.cpp

@@ -699,7 +699,7 @@ RecurrenceDescriptor::isFindLastIVPattern(Loop *Loop, PHINode *OrigPhi,
                          m_Value())))
     return InstDesc(false, I);
 
-  SelectInst *SI = cast<SelectInst>(I);
+  auto *SI = cast<SelectInst>(I);
   Value *NonRdxPhi = nullptr;
 
   if (OrigPhi == dyn_cast<PHINode>(SI->getTrueValue()))