Re: [PATCH for-5.0, v1] target/mips: Fix loongson multimedia condition instructions

[Philippe Mathieu-Daudé]

On 3/30/20 6:18 PM, Jiaxun Yang wrote:
> 于 2020年3月30日 GMT+08:00 下午11:39:44, "Philippe Mathieu-Daudé" <address@hidden> 写到:
> > Hi Jiaxun Yang,
> >
> > On 3/24/20 1:22 PM, Jiaxun Yang wrote:
> > > Loongson multimedia condition instructions were previously
> > implemented as
> > > write 0 to rd due to lack of documentation. So I just confirmed with
> > Loongson
> > > about their encoding and implemented them correctly.
> >
> > If you have a binary using loongson multimedia instructions, can you
> > add
> > a test? So this code won't bitrot.
>
> I know ffmpeg uses it.
> But I think that's too fat.

Looks perfect to me!

It'll be simpler if you use a pre-build binary from a known distribution.

> > I'm in particular interested by a test covering the MAC2008
> > instructions. You can look at examples in the tests/tcg/mips/
> > directory,
> > Aleksandar added a lot of tests there.
>
> I'm going to try that.
>
> Thanks.
>
> > Thanks,
> >
> > Phil.
> >
> > > Signed-off-by: Jiaxun Yang <address@hidden>
> > > Acked-by: Huacai Chen <address@hidden>
> > > ---
> > > v1: Use deposit opreations according to Richard's suggestion.
> > > ---
> > >    target/mips/translate.c | 35 +++++++++++++++++++++++++++++++----
> > >    1 file changed, 31 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/target/mips/translate.c b/target/mips/translate.c
> > > index d745bd2803..25b595a17d 100644
> > > --- a/target/mips/translate.c
> > > +++ b/target/mips/translate.c
> > > @@ -5529,6 +5529,7 @@ static void
> > gen_loongson_multimedia(DisasContext *ctx, int rd, int rs, int rt)
> > >    {
> > >        uint32_t opc, shift_max;
> > >        TCGv_i64 t0, t1;
> > > +    TCGCond cond;
> > >    
> > >        opc = MASK_LMI(ctx->opcode);
> > >        switch (opc) {
> > > @@ -5862,14 +5863,39 @@ static void
> > gen_loongson_multimedia(DisasContext *ctx, int rd, int rs, int rt)
> > >    
> > >        case OPC_SEQU_CP2:
> > >        case OPC_SEQ_CP2:
> > > +        cond = TCG_COND_EQ;
> > > +        goto do_cc_cond;
> > > +        break;
> > >        case OPC_SLTU_CP2:
> > > +        cond = TCG_COND_LTU;
> > > +        goto do_cc_cond;
> > > +        break;
> > >        case OPC_SLT_CP2:
> > > +        cond = TCG_COND_LT;
> > > +        goto do_cc_cond;
> > > +        break;
> > >        case OPC_SLEU_CP2:
> > > +        cond = TCG_COND_LEU;
> > > +        goto do_cc_cond;
> > > +        break;
> > >        case OPC_SLE_CP2:
> > > -        /*
> > > -         * ??? Document is unclear: Set FCC[CC].  Does that mean the
> > > -         * FD field is the CC field?
> > > -         */
> > > +        cond = TCG_COND_LE;
> > > +    do_cc_cond:
> > > +        {
> > > +            int cc = (ctx->opcode >> 8) & 0x7;
> > > +            TCGv_i64 t64 = tcg_temp_new_i64();
> > > +            TCGv_i32 t32 = tcg_temp_new_i32();
> > > +
> > > +            tcg_gen_setcond_i64(cond, t64, t0, t1);
> > > +            tcg_gen_extrl_i64_i32(t32, t64);
> > > +            tcg_gen_deposit_i32(fpu_fcr31, fpu_fcr31, t32,
> > > +                                get_fp_bit(cc), 1);
> > > +
> > > +            tcg_temp_free_i32(t32);
> > > +            tcg_temp_free_i64(t64);
> > > +        }
> > > +        goto no_rd;
> > > +        break;
> > >        default:
> > >            MIPS_INVAL("loongson_cp2");
> > >            generate_exception_end(ctx, EXCP_RI);
> > > @@ -5878,6 +5904,7 @@ static void
> > gen_loongson_multimedia(DisasContext *ctx, int rd, int rs, int rt)
> > >    
> > >        gen_store_fpr64(ctx, t0, rd);
> > >    
> > > +no_rd:
> > >        tcg_temp_free_i64(t0);
> > >        tcg_temp_free_i64(t1);
> > >    }