https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125780
--- Comment #1 from Stefan Schulze Frielinghaus <stefansf at gcc dot gnu.org> --- This is conceptually a dup of PR125518. If register pressure is low, simply reloading works. However, as soon as register pressure is high it is non-trivial to decide when to spill. That being said, the more freedom you take from the register allocator, the more corner cases you will hit. This is independent on whether you use hard register constraints or constraints associated a single register class. At some point it might be questionable whether it isn't better to utilize hard registers directly. Especially for targets like AVR when heavy use of register-quadruples is made but only a few exist.
