Remove unreachable code. (replace with llvm_unreachable to help GCC where necessary)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148284 91177308-0d34-0410-b5e6-96231b3b80d8

utils/TableGen/CodeGenDAGPatterns.cpp

@@ -18,6 +18,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include <set>
 #include <algorithm>
 using namespace llvm;
@@ -912,7 +913,7 @@ bool SDTypeConstraint::ApplyTypeConstraint(TreePatternNode *N,
       EnforceVectorSubVectorTypeIs(NodeToApply->getExtType(ResNo), TP);
   }
   }
-  return false;
+  llvm_unreachable("Make GCC's unreachability happy");
 }
 
 //===----------------------------------------------------------------------===//

utils/TableGen/X86DisassemblerTables.cpp

@@ -102,7 +102,6 @@ static inline bool inheritsFrom(InstructionContext child,
     return false;
   default:
     llvm_unreachable("Unknown instruction class");
-    return false;
   }
 }