Re: [Qemu-devel] [PATCH 11/20] target-i386: fix helper_flbd_ST0() wrt softfloat

[Peter Maydell]

On 18 April 2011 22:00, Aurelien Jarno <address@hidden> wrote:
> Signed-off-by: Aurelien Jarno <address@hidden>
> ---
>  target-i386/op_helper.c |    7 ++++---
>  1 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/target-i386/op_helper.c b/target-i386/op_helper.c
> index f614893..7dddd37 100644
> --- a/target-i386/op_helper.c
> +++ b/target-i386/op_helper.c
> @@ -3920,9 +3920,10 @@ void helper_fbld_ST0(target_ulong ptr)
>         v = ldub(ptr + i);
>         val = (val * 100) + ((v >> 4) * 10) + (v & 0xf);
>     }
> -    tmp = val;
> -    if (ldub(ptr + 9) & 0x80)
> -        tmp = -tmp;
> +    if (ldub(ptr + 9) & 0x80) {
> +        val = -val;
> +    }
> +    tmp = int64_to_floatx(val, &env->fp_status);
>     fpush();
>     ST0 = tmp;
>  }

This doesn't do the right thing for -0 (should generate -0,
not +0). I think:

 tmp = int64_to_floatx(val, &env->fp_status);
 if (ldub(ptr + 9) & 0x80) {
     floatx_chs(tmp);
 }

ought to do the right thing and work for both softfloat and
sf-native, but I haven't tested it.

-- PMM