Change getX86SubSuperRegister to take an MVT::SimpleValueType rather than an EVT and add llvm_unreachable to the switches. Helps it compile to dramatically better code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164919 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86AsmPrinter.cpp b/lib/Target/X86/X86AsmPrinter.cpp
index 33ab567..2fc83a2 100644
--- a/lib/Target/X86/X86AsmPrinter.cpp
+++ b/lib/Target/X86/X86AsmPrinter.cpp
@@ -243,7 +243,7 @@
     if (AsmVariant == 0) O << '%';
     unsigned Reg = MO.getReg();
     if (Modifier && strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
-      EVT VT = (strcmp(Modifier+6,"64") == 0) ?
+      MVT::SimpleValueType VT = (strcmp(Modifier+6,"64") == 0) ?
         MVT::i64 : ((strcmp(Modifier+6, "32") == 0) ? MVT::i32 :
                     ((strcmp(Modifier+6,"16") == 0) ? MVT::i16 : MVT::i8));
       Reg = getX86SubSuperRegister(Reg, VT);