Subzero. X86. Refactors initRegisterSet.

src/IceRegistersX8664.h

Index: src/IceRegistersX8664.h
diff --git a/src/IceRegistersX8664.h b/src/IceRegistersX8664.h
index 7587995c5c5390f40d8a9276b53264f1d7755b84..7be93e24f47fd27f1909915a6c526bb60f27f32e 100644
--- a/src/IceRegistersX8664.h
+++ b/src/IceRegistersX8664.h
@@ -26,6 +26,7 @@ public:
   /// An enum of every register. The enum value may not match the encoding used
   /// to binary encode register operands in instructions.
   enum AllRegisters {
+    Reg_Invalid,
 #define X(val, encode, name, base, scratch, preserved, stackptr, frameptr,     \
           isGPR, is64, is32, is16, is8, isXmm, is64To8, is32To8, is16To8,      \
           isTrunc8Rcvr, isAhRcvr, aliases)                                     \