Add a couple llvm_unreachables.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155332 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 783c752..119e49a 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -10291,6 +10291,7 @@
           Res = DAG.getNode(ISD::SUB, dl, VT, Res, Mask);
           return Res;
         }
+        llvm_unreachable("Unknown shift opcode.");
       }
 
       if (Subtarget->hasAVX2() && VT == MVT::v32i8) {
@@ -10334,6 +10335,7 @@
           Res = DAG.getNode(ISD::SUB, dl, VT, Res, Mask);
           return Res;
         }
+        llvm_unreachable("Unknown shift opcode.");
       }
     }
   }