From: Paul Menage <menage-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
To: Andi Kleen <ak-l3A5Bk7waGM@public.gmane.org>
Cc: "Yu, Luming" <luming.yu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: Re: ACPI global lock macros
Date: Thu, 11 Dec 2003 00:27:54 -0800 [thread overview]
Message-ID: <3FD82A8A.9050307@google.com> (raw)
In-Reply-To: <20031211090716.0c3662d3.ak-l3A5Bk7waGM@public.gmane.org>
Andi Kleen wrote:
>
> It has even more bugs, e.g. it doesn't tell gcc that GLptr is modified (this hurts with
> newer versions that optimize more aggressively)
GLptr itself isn't modified - *GLptr is, but none of the actual C code
accesses *GLptr, so how does this affect the compiler's optimization
efforts? Is it because gcc treats the call as a pure function that maps
a pointer to an acquired value, and hence believes that it can move it
around? There aren't any instances of ACPI_ACQUIRE_GLOBAL_LOCK being
called twice in the same function, so it wouldn't be able to cache a
result. But I agree that it ought to declare that it clobbers memory.
Paul
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WARNING: multiple messages have this Message-ID (diff)
From: Paul Menage <menage@google.com>
To: Andi Kleen <ak@suse.de>
Cc: "Yu, Luming" <luming.yu@intel.com>,
linux-kernel@vger.kernel.org, acpi-devel@lists.sourceforge.net
Subject: Re: [ACPI] ACPI global lock macros
Date: Thu, 11 Dec 2003 00:27:54 -0800 [thread overview]
Message-ID: <3FD82A8A.9050307@google.com> (raw)
In-Reply-To: <20031211090716.0c3662d3.ak@suse.de>
Andi Kleen wrote:
>
> It has even more bugs, e.g. it doesn't tell gcc that GLptr is modified (this hurts with
> newer versions that optimize more aggressively)
GLptr itself isn't modified - *GLptr is, but none of the actual C code
accesses *GLptr, so how does this affect the compiler's optimization
efforts? Is it because gcc treats the call as a pure function that maps
a pointer to an acquired value, and hence believes that it can move it
around? There aren't any instances of ACPI_ACQUIRE_GLOBAL_LOCK being
called twice in the same function, so it wouldn't be able to cache a
result. But I agree that it ought to declare that it clobbers memory.
Paul
next prev parent reply other threads:[~2003-12-11 8:27 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-11 7:06 ACPI global lock macros Yu, Luming
2003-12-11 7:06 ` [ACPI] " Yu, Luming
2003-12-11 8:07 ` Andi Kleen
[not found] ` <20031211090716.0c3662d3.ak-l3A5Bk7waGM@public.gmane.org>
2003-12-11 8:27 ` Paul Menage [this message]
2003-12-11 8:27 ` Paul Menage
[not found] ` <3ACA40606221794F80A5670F0AF15F8401720C21-SRlDPOYGfgogGBtAFL8yw7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
2003-12-11 8:20 ` Paul Menage
2003-12-11 8:20 ` [ACPI] " Paul Menage
-- strict thread matches above, loose matches on Subject: below --
2003-12-11 7:27 Yu, Luming
[not found] ` <3ACA40606221794F80A5670F0AF15F8401720C22-SRlDPOYGfgogGBtAFL8yw7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
2003-12-11 17:46 ` Nate Lawson
2003-12-09 18:20 [ACPI] " Grover, Andrew
[not found] ` <F760B14C9561B941B89469F59BA3A8470255EFB3-sBd4vmA9Se4Lll3ZsUKC9FDQ4js95KgL@public.gmane.org>
2003-12-09 19:04 ` Paul Menage
2003-12-09 9:22 Paul Menage
2003-12-09 9:22 ` Paul Menage
[not found] ` <3FD59441.2000202-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2003-12-09 9:36 ` Arjan van de Ven
2003-12-09 9:36 ` Arjan van de Ven
[not found] ` <1070962573.5223.2.camel-PDvaWZGbcxi0rsOeZxrteAC/G2K4zDHf@public.gmane.org>
2003-12-09 9:42 ` Paul Menage
2003-12-09 9:42 ` Paul Menage
[not found] ` <3FD5990A.9020908-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2003-12-09 9:43 ` Arjan van de Ven
2003-12-09 9:43 ` Arjan van de Ven
[not found] ` <20031209094356.GA19702-s/M1imWmeEoQw3kMeb7FcACJwEvxM/w9@public.gmane.org>
2003-12-09 9:50 ` Paul Menage
2003-12-09 9:50 ` Paul Menage
2003-12-10 7:45 ` Andi Kleen
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