Index: lib/Transforms/Scalar/GVN.cpp
===================================================================
--- lib/Transforms/Scalar/GVN.cpp
+++ lib/Transforms/Scalar/GVN.cpp
@@ -2195,7 +2195,9 @@
     // It is not safe to do PRE when P->CurrentBlock is a loop backedge, and
     // when CurInst has operand defined in CurrentBlock (so it may be defined
     // by phi in the loop header).
-    if (BlockRPONumber[P] >= BlockRPONumber[CurrentBlock] &&
+    const auto PNum = BlockRPONumber[P];
+    const auto CNum = BlockRPONumber[CurrentBlock];
+    if (PNum >= CNum &&
         llvm::any_of(CurInst->operands(), [&](const Use &U) {
           if (auto *Inst = dyn_cast<Instruction>(U.get()))
             return Inst->getParent() == CurrentBlock;