https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106895
--- Comment #11 from Nicholas Piggin <npiggin at gmail dot com> --- (In reply to Segher Boessenkool from comment #10) > (In reply to Nicholas Piggin from comment #9) > > I don't know why constraint is wrong and mode is right > > Simple: you would need O(2**T*N) constraints for our existing N register > constraints, together with T features like this. But only O(2**T) modes at > most. I guess that would be annoying if you couldn't have modifiers on constraints or a bad algorithm for working them out. Fair enough. > > > or why TI doesn't work but PTI apparently would, > > Because this is exactly what PTImode is *for*! Right I accept it is, I meant I just would not have been able to work it out (assuming if PTI was documented it would be "Partial Tetra Integer" and be no more useful than the other P?I type documentation. > > > but I'll take anything that works. Could we > > get PTI implemented? Does it need a new issue opened? > > It was implemented in 2013. The restriction to only even pairs was a bugfix, > also from 2013. > > If you have code like > > typedef __int128 __attribute__((mode(PTI))) even; > > you get an error like > > error: no data type for mode 'PTI' > > This needs fixing. You can keep it in this PR? Sure, that would be much appreciated.
