Convert assert(0) to llvm_unreachable

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149967 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 81bad63..068be3d 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -2837,7 +2837,7 @@
     }
 
     switch (ParseInstruction(Inst, BB, PFS)) {
-    default: assert(0 && "Unknown ParseInstruction result!");
+    default: llvm_unreachable("Unknown ParseInstruction result!");
     case InstError: return true;
     case InstNormal:
       BB->getInstList().push_back(Inst);