Hans-Peter Nilsson <h...@bitrange.com> writes: > Index: tm.texi.in > =================================================================== > --- tm.texi.in (revision 174376) > +++ tm.texi.in (working copy) > @@ -2327,6 +2327,11 @@ constraints is through machine-dependent > You can define such letters to correspond to various classes, then use > them in operand constraints. > > +You must define the narrowest register class for a register so that > +class either has no subclasses, or that for some mode, the move cost > +between registers within the class are cheaper than moving a register > +in the class to or from memory (@pxref{Costs}). > +
I fear this isn't true for some MIPS classes. Richard