https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111334
Xi Ruoyao <xry111 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Last reconfirmed| |2023-09-08
--- Comment #5 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(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...
