+ // Either PhysReg is a subregister of Alias and we mark the
+ // whole register as free, or PhysReg is the superregister of
+ // Alias and we mark all the aliases as disabled before freeing
+ // PhysReg.
+ // In the latter case, since PhysReg was disabled, this means that
+ // its value is defined only by physical sub-registers. This check
+ // is performed by the assert of the default case in this loop.
+ // Note: The value of the superregister may only be partial
+ // defined, that is why regDisabled is a valid state for aliases.
+ assert((TRI->isSuperRegister(PhysReg, Alias) ||
+ TRI->isSuperRegister(Alias, PhysReg)) &&