LoopSimplifyCFG: Prefer `const auto &` to `auto &`, for clarity. NFC

llvm-svn: 273023
diff --git a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
index 3de5832..ec22793 100644
--- a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
@@ -65,7 +65,8 @@
 }
 
 PreservedAnalyses LoopSimplifyCFGPass::run(Loop &L, AnalysisManager<Loop> &AM) {
-  auto &FAM = AM.getResult<FunctionAnalysisManagerLoopProxy>(L).getManager();
+  const auto &FAM =
+      AM.getResult<FunctionAnalysisManagerLoopProxy>(L).getManager();
   Function *F = L.getHeader()->getParent();
 
   auto *LI = FAM.getCachedResult<LoopAnalysis>(*F);