-// getX86SubSuperRegister - X86 utility function. It returns the sub or super
-// register of a specific X86 register.
-// e.g. getX86SubSuperRegister(X86::EAX, MVT::i16) return X86:AX
-unsigned getX86SubSuperRegister(unsigned, MVT::SimpleValueType, bool High=false);
+/// Returns the sub or super register of a specific X86 register.
+/// e.g. getX86SubSuperRegister(X86::EAX, 16) returns X86::AX.
+/// Aborts on error.
+unsigned getX86SubSuperRegister(unsigned, unsigned, bool High=false);
+
+/// Returns the sub or super register of a specific X86 register.
+/// Like getX86SubSuperRegister() but returns 0 on error.
+unsigned getX86SubSuperRegisterOrZero(unsigned, unsigned,
+ bool High = false);