Convert assert(0) to llvm_unreachable

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149961 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 7f40ffd..2d7df09 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -156,9 +156,7 @@
   unsigned OffImm = MI->getOperand(NumOps-2).getImm();
   ARMCC::CondCodes Pred = (ARMCC::CondCodes)MI->getOperand(NumOps-1).getImm();
   switch (AddrMode) {
-  default:
-    assert(false && "Unknown indexed op!");
-    return NULL;
+  default: llvm_unreachable("Unknown indexed op!");
   case ARMII::AddrMode2: {
     bool isSub = ARM_AM::getAM2Op(OffImm) == ARM_AM::sub;
     unsigned Amt = ARM_AM::getAM2Offset(OffImm);