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/PowerPC/PPCMCInstLower.cpp b/lib/Target/PowerPC/PPCMCInstLower.cpp
index ff6ebba..276edcb 100644
--- a/lib/Target/PowerPC/PPCMCInstLower.cpp
+++ b/lib/Target/PowerPC/PPCMCInstLower.cpp
@@ -140,7 +140,7 @@
     switch (MO.getType()) {
     default:
       MI->dump();
-      assert(0 && "unknown operand type");
+      llvm_unreachable("unknown operand type");
     case MachineOperand::MO_Register:
       assert(!MO.getSubReg() && "Subregs should be eliminated!");
       MCOp = MCOperand::CreateReg(MO.getReg());