https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111334
--- Comment #12 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(In reply to chenglulu from comment #11)
> (In reply to Xi Ruoyao from comment #10)
> > (In reply to Xi Ruoyao from comment #9)
> >
> > > (define_insn "<optab>di3_fake"
> > > [(set (match_operand:DI 0 "register_operand" "=r,&r,&r")
> > > - (sign_extend:DI
> > > - (any_div:SI (match_operand:DI 1 "register_operand" "r,r,0")
> > > - (match_operand:DI 2 "register_operand" "r,r,r"))))]
> > > - ""
> > > + (if_then_else
> > > + (and (eq (match_operand:DI 1 "register_operand" "r,r,0")
> > > + (sign_extend:DI (subreg:SI (match_dup 1) 0)))
> > > + (eq (match_operand:DI 2 "register_operand" "r,r,r")
> > > + (sign_extend:DI (subreg:SI (match_dup 2) 0))))
> > > + (sign_extend:DI
> > > + (any_div:SI (subreg:SI (match_dup 1) 0)
> > > + (subreg:SI (match_dup 2) 0)))
> > > + (unspec:DI [(const_int 0)] UNSPEC_BAD_DIVW)))]
> >
> > With this the compiler will still believe all bad {div,mod}.w{,u}
>
> I think this is already defined as UNSPEC. Isn’t the simpler the logic, the
> better?
Yes, I think we should just use 4 different UNSPEC_ values and the simple
version. But I've not find a way to use 4 different UNSPEC_ values in the RTL
template except duplicating everything 4 times...
