From: Ulrich Hecht <uli@suse.de>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: riku.voipio@iki.fi, qemu-devel@nongnu.org, agraf@suse.de
Subject: Re: [Qemu-devel] [PATCH 1/9] TCG "sync" op
Date: Mon, 19 Oct 2009 19:17:33 +0200 [thread overview]
Message-ID: <200910191917.34021.uli@suse.de> (raw)
In-Reply-To: <20091016172908.GG4127@hall.aurel32.net>
On Friday 16 October 2009, Aurelien Jarno wrote:
> This example is a bit biased, as registers are only saved, and never
> reused. Let's comment on it though.
Yeah, well, I searched from the top for the first case where it makes a
difference. If it's of any help, I can upload a complete dump of both
versions somewhere.
> and I don't understand what is the gain compared to
> the use of tcg_gen_ld/st.
There are two sets of TCG values, tcgregs (which would arguably better
called tcgregs64) and tcgregs32. When doing a 32-bit access, tcgregs(64)
is synced, which is a nop if tcgregs(64) hasn't been touched. When doing
a 64-bit access, tcgregs32 is synced, which is a nop if tcgregs32 hasn't
been touched. In practice, 32-bit accesses followed by 64-bit accesses
and vice versa are very rare, so in most cases, sync is a nop.
tcg_gen_ld/st is never a nop. That's the benefit.
CU
Uli
--
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
next prev parent reply other threads:[~2009-10-19 17:17 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-16 12:38 [Qemu-devel] [PATCH 0/9] S/390 support updated Ulrich Hecht
2009-10-16 12:38 ` [Qemu-devel] [PATCH 1/9] TCG "sync" op Ulrich Hecht
2009-10-16 12:38 ` [Qemu-devel] [PATCH 2/9] S/390 CPU emulation Ulrich Hecht
2009-10-16 12:38 ` [Qemu-devel] [PATCH 3/9] S/390 host/target build system support Ulrich Hecht
2009-10-16 12:38 ` [Qemu-devel] [PATCH 4/9] S/390 host support for TCG Ulrich Hecht
2009-10-16 12:38 ` [Qemu-devel] [PATCH 5/9] linux-user: S/390 64-bit (s390x) support Ulrich Hecht
2009-10-16 12:38 ` [Qemu-devel] [PATCH 6/9] linux-user: don't do locking in single-threaded processes Ulrich Hecht
2009-10-16 12:38 ` [Qemu-devel] [PATCH 7/9] linux-user: dup3, fallocate syscalls Ulrich Hecht
2009-10-16 12:38 ` [Qemu-devel] [PATCH 8/9] linux-user: define a couple of syscalls for non-uid16 targets Ulrich Hecht
2009-10-16 12:38 ` [Qemu-devel] [PATCH 9/9] linux-user: getpriority errno fix Ulrich Hecht
2009-10-17 10:44 ` [Qemu-devel] [PATCH 3/9] S/390 host/target build system support Aurelien Jarno
2009-10-17 10:42 ` [Qemu-devel] [PATCH 2/9] S/390 CPU emulation Aurelien Jarno
2009-10-19 17:17 ` Ulrich Hecht
2009-10-22 21:28 ` Aurelien Jarno
2009-11-02 15:16 ` Ulrich Hecht
2009-11-02 18:42 ` Aurelien Jarno
2009-11-02 19:03 ` Laurent Desnogues
2009-11-09 16:55 ` Ulrich Hecht
2009-11-10 16:02 ` Aurelien Jarno
2009-11-11 10:46 ` Ulrich Hecht
2009-10-16 15:52 ` [Qemu-devel] [PATCH 1/9] TCG "sync" op Aurelien Jarno
2009-10-16 16:37 ` Ulrich Hecht
2009-10-16 17:29 ` Aurelien Jarno
2009-10-19 17:17 ` Ulrich Hecht [this message]
2009-10-17 8:59 ` Edgar E. Iglesias
2009-10-19 17:17 ` Ulrich Hecht
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