Fix a bug which occurred with empty basic blocks

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5982 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
index 2f7f1f4ef30a8e49a595edf2f7d77333828912e0..4839c09751dbfeae95d6a15ee9409ac34c8cace0 100644 (file)
--- a/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/lib/CodeGen/PrologEpilogInserter.cpp
@@ -160,7 +160,7 @@ void PEI::saveCallerSavedRegisters(MachineFunction &Fn) {
   const TargetInstrInfo &TII = Fn.getTarget().getInstrInfo();
   for (MachineFunction::iterator FI = Fn.begin(), E = Fn.end(); FI != E; ++FI) {
     // If last instruction is a return instruction, add an epilogue
-    if (TII.isReturn(FI->back()->getOpcode())) {
+    if (!FI->empty() && TII.isReturn(FI->back()->getOpcode())) {
       MBB = FI; I = MBB->end()-1;
 
       for (unsigned i = 0, e = RegsToSave.size(); i != e; ++i) {