From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:44062)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <alex.bennee@linaro.org>) id 1WUxY1-0000dq-5I
	for qemu-devel@nongnu.org; Tue, 01 Apr 2014 08:12:13 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <alex.bennee@linaro.org>) id 1WUxXv-0006Uu-10
	for qemu-devel@nongnu.org; Tue, 01 Apr 2014 08:12:09 -0400
Received: from static.88-198-71-155.clients.your-server.de
	([88.198.71.155]:44840 helo=socrates.bennee.com)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <alex.bennee@linaro.org>) id 1WUxXu-0006Un-R9
	for qemu-devel@nongnu.org; Tue, 01 Apr 2014 08:12:02 -0400
References: <1396052834-26834-1-git-send-email-rth@twiddle.net>
	<1396052834-26834-3-git-send-email-rth@twiddle.net>
From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
In-reply-to: <1396052834-26834-3-git-send-email-rth@twiddle.net>
Date: Tue, 01 Apr 2014 13:12:32 +0100
Message-ID: <87lhvps0y7.fsf@linaro.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Subject: Re: [Qemu-devel] [PATCH 2/8] tcg: Avoid stores to unaligned
	addresses
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Richard Henderson <rth@twiddle.net>
Cc: peter.maydell@linaro.org, qemu-devel@nongnu.org, aurelien@aurel32.net


Richard Henderson <rth@twiddle.net> writes:

> From: Peter Maydell <peter.maydell@linaro.org>
>
> Avoid stores to unaligned addresses in TCG code generation, by using the
> usual memcpy() approach. (Using bswap.h would drag a lot of QEMU baggage
> into TCG, so it's simpler just to do direct memcpy() here.)

I notice bswap.h has an interesting exultation to the efficiency of
inline memcpy's which I hope is justified.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>


>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  tcg/tcg.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tcg/tcg.c b/tcg/tcg.c
> index f1e0763..60f06c5 100644
> --- a/tcg/tcg.c
> +++ b/tcg/tcg.c
> @@ -125,21 +125,21 @@ static inline void tcg_out8(TCGContext *s, uint8_t v)
>  static inline void tcg_out16(TCGContext *s, uint16_t v)
>  {
>      uint8_t *p = s->code_ptr;
> -    *(uint16_t *)p = v;
> +    memcpy(p, &v, sizeof(v));
>      s->code_ptr = p + 2;
>  }
>  
>  static inline void tcg_out32(TCGContext *s, uint32_t v)
>  {
>      uint8_t *p = s->code_ptr;
> -    *(uint32_t *)p = v;
> +    memcpy(p, &v, sizeof(v));
>      s->code_ptr = p + 4;
>  }
>  
>  static inline void tcg_out64(TCGContext *s, uint64_t v)
>  {
>      uint8_t *p = s->code_ptr;
> -    *(uint64_t *)p = v;
> +    memcpy(p, &v, sizeof(v));
>      s->code_ptr = p + 8;
>  }

-- 
Alex Bennée