Add 'llvm_unreachable' to passify GCC's understanding of the constraints
of several newly un-defaulted switches. This also helps optimizers
(including LLVM's) recognize that every case is covered, and we should
assume as much.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147861 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index 28c63a7..a11c55d 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -96,6 +96,7 @@
   case cl::BOU_TRUE:  return true;
   case cl::BOU_FALSE: return false;
   }
+  llvm_unreachable("Invalid verbose asm state");
 }
 
 // Enable or disable FastISel. Both options are needed, because