Re: [PATCH v3 4/5] target/s390x: Implement DIVIDE TO INTEGER

[Ilya Leoshkevich <iii@linux.ibm.com>]

On 2026-01-29 19:57, Ilya Leoshkevich wrote:
> DIVIDE TO INTEGER computes floating point remainder and is used by
> LuaJIT, so add it to QEMU.
> 
> Put the main logic into fpu/, because it is way more convenient to
> operate on FloatParts than to convert floats back-and-forth.
> 
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>  fpu/softfloat.c                  | 144 +++++++++++++++++++++++++++++++
>  include/fpu/softfloat.h          |  11 +++
>  target/s390x/helper.h            |   1 +
>  target/s390x/tcg/fpu_helper.c    |  56 ++++++++++++
>  target/s390x/tcg/insn-data.h.inc |   5 +-
>  target/s390x/tcg/translate.c     |  26 ++++++
>  6 files changed, 242 insertions(+), 1 deletion(-)

I've taken a fresh look and I think I can improve one small thing.
I will change this alongside other feedback (if any) in v4.

[...]

> +
> +        /*
> +         * Final quotient is rounded using final-quotient-rounding 
> method, and
> +         * partial quotient is rounded toward zero.
> +         *
> +         * Rounding of partial quotient may be inexact. This is the 
> whole point
> +         * of distinguishing partial quotients, so ignore the 
> exception.
> +         */
> +        *n = *q;
> +        saved_flags = status->float_exception_flags;
> +        parts_round_to_int(n,
> +                           is_q_smallish ? 
> final_quotient_rounding_mode :
> +                                           float_round_to_zero,
> +                           0, status, fmt);
> +        float_exception_flags = saved_flags;

saved_flags can probably be eliminated; I can assign directly to 
float_exception_flags.
I think I can also use parts_round_to_int_normal(), because all the 
other cases are taken care of above.

[...]