Fix malformed assert.

If anybody has strong feelings about 'default: assert(0 && "blah")' vs
'default: llvm_unreachable("blah")', feel free to regularize the instances of
each in this file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147459 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 7058254..7e5e770 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -6192,7 +6192,7 @@
     ARM_AM::ShiftOpc SOpc = ARM_AM::getSORegShOp(Inst.getOperand(3).getImm());
     if (SOpc == ARM_AM::rrx) return false;
     switch (Inst.getOpcode()) {
-    default: assert("unexpected opcode!");
+    default: assert(0 && "unexpected opcode!");
     case ARM::ANDrsi: newOpc = ARM::ANDrr; break;
     case ARM::ORRrsi: newOpc = ARM::ORRrr; break;
     case ARM::EORrsi: newOpc = ARM::EORrr; break;