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/Target/TargetLoweringObjectFile.cpp b/lib/Target/TargetLoweringObjectFile.cpp
index 9f2b715..70abe5a 100644
--- a/lib/Target/TargetLoweringObjectFile.cpp
+++ b/lib/Target/TargetLoweringObjectFile.cpp
@@ -240,6 +240,7 @@
   case Constant::GlobalRelocations:
     return SectionKind::getDataRel();
   }
+  llvm_unreachable("Invalid relocation");
 }
 
 /// SectionForGlobal - This method computes the appropriate section to emit