https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111334
--- Comment #7 from chenglulu <chenglulu at loongson dot cn> ---
(In reply to Xi Ruoyao from comment #6)
> (In reply to Xi Ruoyao from comment #5)
> > (In reply to chenglulu from comment #3)
> > > This involves the template <optab>di3_fake:
> > > (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"))))]
> > > ""
> > > {
> > > return loongarch_output_division ("<insn>.w<u>\t%0,%1,%2", operands);
> > > }
> > > [(set_attr "type" "idiv")
> > > (set_attr "mode" "SI")
> > > (set (attr "enabled")
> > > (if_then_else
> > > (match_test "!!which_alternative == loongarch_check_zero_div_p()")
> > > (const_string "yes")
> > > (const_string "no")))])
> > >
> > >
> > > I think there is a problem with the implementation of this template.
> > > First, the instructions generated in the template are [u]div.w[u], etc.
> > > The
> > > description of such instructions in the instruction manual is that if the
> > > upper 32 bits are not extended by the 31st bit sign then the result is
> > > uncertain.
> >
> > I think this reason alone makes the pattern looks very wrong.
> >
> > I'll take a look...
>
> Hmm, I guess we should just make di3_fake an UNSPEC because there is no way
> to use div.w and its friends out of <optab:any_div><mode>3.
I agree with your idea, so I tried changing it to something like this.Do you
think it's okay for me to change like this?
(define_insn "<optab>di3_fake"
[(set (match_operand:DI 0 "register_operand" "=r,&r,&r")
(sign_extend:DI
(unspec:SI [(any_div:SI (match_operand:DI 1 "register_operand"
"r,r,0")
(match_operand:DI 2 "register_operand" "r,r,r"))]
UNSPEC_ANY_DIV)))]
""
{
return loongarch_output_division ("<insn>.w<u>\t%0,%1,%2", operands);
}
[(set_attr "type" "idiv")
(set_attr "mode" "SI")
(set (attr "enabled")
(if_then_else
(match_test "!!which_alternative == loongarch_check_zero_div_p()")
(const_string "yes")
(const_string "no")))])
