Re: [Qemu-devel] [PATCH] target/arm: Fix sign-extension for SMLAL*

[Laurent Desnogues]

Hello,

On Thu, Sep 12, 2019 at 8:31 PM Richard Henderson
<address@hidden> wrote:
>
> The 32-bit product should be sign-extended, not zero-extended.
>
> Fixes: ea96b374641b
> Reported-by: Laurent Desnogues <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>

No more failures on my tests.

Tested-by: Laurent Desnogues <address@hidden>

Thanks,

Laurent

> ---
>  target/arm/translate.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/target/arm/translate.c b/target/arm/translate.c
> index 34bb280e3d..fd2f0e3048 100644
> --- a/target/arm/translate.c
> +++ b/target/arm/translate.c
> @@ -8045,7 +8045,9 @@ static bool op_smlaxxx(DisasContext *s, arg_rrrr *a,
>      case 2:
>          tl = load_reg(s, a->ra);
>          th = load_reg(s, a->rd);
> -        t1 = tcg_const_i32(0);
> +        /* Sign-extend the 32-bit product to 64 bits.  */
> +        t1 = tcg_temp_new_i32();
> +        tcg_gen_sari_i32(t1, t0, 31);
>          tcg_gen_add2_i32(tl, th, tl, th, t0, t1);
>          tcg_temp_free_i32(t0);
>          tcg_temp_free_i32(t1);
> --
> 2.17.1
>