https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111334
--- Comment #13 from chenglulu <chenglulu at loongson dot cn> ---
(In reply to Xi Ruoyao from comment #12)
> (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...
I still have a question that I don't quite understand, that is, why that the
four generated strings are equivalent when using an UNSPEC name? My template
names are different, and they will not be automatically matched during
optimization.???
