From: Richard Henderson <rth@twiddle.net>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Blue Swirl <blauwirbel@gmail.com>,
qemu-devel <qemu-devel@nongnu.org>,
Aurelien Jarno <aurelien@aurel32.net>
Subject: Re: [Qemu-devel] [PATCH v2] tcg-i386: Introduce limited deposit support
Date: Thu, 29 Sep 2011 07:58:13 -0700 [thread overview]
Message-ID: <4E848785.6090604@twiddle.net> (raw)
In-Reply-To: <4E84570F.3040103@siemens.com>
On 09/29/2011 04:31 AM, Jan Kiszka wrote:
> x86 cannot provide an optimized generic deposit implementation. But at
> least for a few special cases, namely for writing bits 0..7, 8..15, and
> 0..15, versions using only a single instruction are feasible.
> Introducing such limited support improves emulating 16-bit x86 code on
> x86, but also rarer cases where 32-bit or 64-bit code accesses bytes or
> words.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>
> Changes in v2:
> - introduce restricting predicates TCG_TARGET_deposit_i32/64_valid
> to decide if deposit support can be used
> - express register constraints via new 'Q' symbol
That's what I had in mind, yes.
The only thing that's missing now is a default version of
> +#define TCG_TARGET_deposit_i32_valid(ofs, len) \
> + (((ofs) == 0 && (len) == 8) || ((ofs) == 8 && (len) == 8) || \
> + ((ofs) == 0 && (len) == 16))
> +#define TCG_TARGET_deposit_i64_valid TCG_TARGET_deposit_i32_valid
These.
r~
next prev parent reply other threads:[~2011-09-29 14:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-28 12:28 [Qemu-devel] [PATCH] tcg-i386: Introduce specific deposit helpers Jan Kiszka
2011-09-28 14:26 ` Richard Henderson
2011-09-28 14:33 ` Jan Kiszka
2011-09-28 15:19 ` Richard Henderson
2011-09-28 22:07 ` Jan Kiszka
2011-09-28 22:47 ` Richard Henderson
2011-09-29 11:31 ` [Qemu-devel] [PATCH v2] tcg-i386: Introduce limited deposit support Jan Kiszka
2011-09-29 14:58 ` Richard Henderson [this message]
2011-09-29 15:19 ` Jan Kiszka
2011-09-29 15:23 ` [Qemu-devel] [PATCH v3] " Jan Kiszka
2011-09-29 16:11 ` Richard Henderson
2011-09-29 16:52 ` [Qemu-devel] [PATCH v4] " Jan Kiszka
2011-09-29 19:50 ` Richard Henderson
2011-10-01 12:06 ` Blue Swirl
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