- /// Return true if the two specified registers belong to different
- /// register classes. The registers may be either phys or virt regs.
- bool differingRegisterClasses(unsigned RegA, unsigned RegB) const;
+ /// Return true if the two specified registers belong to different register
+ /// classes. The registers may be either phys or virt regs. In the
+ /// case where both registers are virtual registers, it would also returns
+ /// true by reference the RegB register class in SubRC if it is a subset of
+ /// RegA's register class.
+ bool differingRegisterClasses(unsigned RegA, unsigned RegB,
+ const TargetRegisterClass *&SubRC) const;