Index: lib/Target/PowerPC/PPCMCInstLower.cpp
===================================================================
--- lib/Target/PowerPC/PPCMCInstLower.cpp
+++ lib/Target/PowerPC/PPCMCInstLower.cpp
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "PPC.h"
+#include "InstPrinter/PPCInstPrinter.h"
 #include "MCTargetDesc/PPCMCExpr.h"
 #include "PPCSubtarget.h"
 #include "llvm/ADT/SmallString.h"
@@ -184,6 +185,8 @@
       llvm_unreachable("unknown operand type");
     case MachineOperand::MO_Register:
       assert(!MO.getSubReg() && "Subregs should be eliminated!");
+      assert(PPCInstPrinter::getRegisterName(MO.getReg()) &&
+             "A valid register must have a valid name!");
       MCOp = MCOperand::CreateReg(MO.getReg());
       break;
     case MachineOperand::MO_Immediate: