From: Richard Henderson <rth@twiddle.net>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: qemu-devel@nongnu.org, Alexander Graf <agraf@suse.de>
Subject: Re: [Qemu-devel] [PATCH] target-ppc: fix nego and subf*o instructions
Date: Sun, 31 Mar 2013 16:19:45 -0700 [thread overview]
Message-ID: <5158C491.4010509@twiddle.net> (raw)
In-Reply-To: <1364687686-6006-1-git-send-email-aurelien@aurel32.net>
On 2013-03-30 16:54, Aurelien Jarno wrote:
> The overflow computation of nego and subf*o instructions has been broken
> in commit ffe30937. This patch fixes it.
>
> With this change the PPC emulation passes the Gwenole Beauchesne
> testsuite again.
>
> Cc: Alexander Graf <agraf@suse.de>
> Cc: Richard Henderson <rth@twiddle.net>
> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> ---
> target-ppc/translate.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target-ppc/translate.c b/target-ppc/translate.c
> index 5e741d1..062493a 100644
> --- a/target-ppc/translate.c
> +++ b/target-ppc/translate.c
> @@ -749,7 +749,7 @@ static inline void gen_op_arith_compute_ov(DisasContext *ctx, TCGv arg0,
> tcg_gen_xor_tl(cpu_ov, arg0, arg1);
> tcg_gen_xor_tl(t0, arg1, arg2);
> if (sub) {
> - tcg_gen_and_tl(cpu_ov, cpu_ov, t0);
> + tcg_gen_andc_tl(cpu_ov, t0, cpu_ov);
> } else {
> tcg_gen_andc_tl(cpu_ov, cpu_ov, t0);
> }
I'm a bit confused. This is the exact same algorithm that's used on ARM and
i386. And as far as I can determine, all three platforms have the same
definition of "overflow".
r~
next prev parent reply other threads:[~2013-03-31 23:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-30 23:54 [Qemu-devel] [PATCH] target-ppc: fix nego and subf*o instructions Aurelien Jarno
2013-03-31 23:19 ` Richard Henderson [this message]
2013-03-31 23:50 ` Peter Maydell
2013-04-01 0:31 ` Aurelien Jarno
2013-04-01 1:15 ` Richard Henderson
2013-04-01 0:22 ` Aurelien Jarno
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