https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106895
--- Comment #12 from Segher Boessenkool <segher at gcc dot gnu.org> ---
> I guess that would be annoying if you couldn't have modifiers on constraints
There is no such thing as "operand modifiers". There are *output* modifiers:
they change how an operand is *printed*, they do not change the operand in any
way, shape, or form.
> or a bad algorithm for working them out. Fair enough.
No idea what you mean here?
> > > 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.
For the rs6000 port, multi-register operands are not restricted to aligned
register numbers ("even/odd pairs"). (Some other ports do have this). We use
the existing PTI mode for that (it also can be allocated in GPRs only, never in
VSRs, unlike TImode).
"Partial" does not have much meaning here. A minority of ports use partial
integer words for what they were introduced for originally: modes that are
smaller than a full register, say, a 24-bit mode when registers are 32 bits.
We use it as another integer mode that is the same size. It is unfortunate
that we still have to resort to such tricks.
