diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1269,6 +1269,7 @@
 
   const std::vector<MCCFIInstruction> &Instrs = MF->getFrameInstructions();
   unsigned CFIIndex = MI.getOperand(0).getCFIIndex();
+  assert(CFIIndex < Instrs.size() && "CFIIndex out of range");
   const MCCFIInstruction &CFI = Instrs[CFIIndex];
   emitCFIInstruction(CFI);
 }