From: Will Newton <will.newton@linaro.org>
To: "Joseph S. Myers" <joseph@codesourcery.com>
Cc: "libc-ports@sourceware.org" <libc-ports@sourceware.org>,
Patch Tracking <patches@linaro.org>
Subject: Re: [PATCH] sysdeps/arm/armv7/multiarch/memcpy_impl.S: Improve performance.
Date: Fri, 30 Aug 2013 18:46:00 -0000 [thread overview]
Message-ID: <CANu=DmhtNsWyOppdp0d2scw_y9cWDOXBph2LJM6Be+FY-n2JPg@mail.gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.64.1308301513370.17271@digraph.polyomino.org.uk>
On 30 August 2013 16:18, Joseph S. Myers <joseph@codesourcery.com> wrote:
> On Fri, 30 Aug 2013, Will Newton wrote:
>
>> > There are various comments regarding alignment, whether stating "LDRD/STRD
>> > support unaligned word accesses" or referring to the mutual alignment that
>> > applies for particular code. Does this patch make any of them out of
>> > date? (If code can now only be reached with common 64-bit alignment, but
>> > in fact requires only 32-bit alignment, the comment should probably state
>> > both those things explicitly.)
>>
>> I've reviewed the comments and they all look ok as far as I can tell.
>
> Are you sure? For example, where it says "SRC and DST have the same
> mutual 32-bit alignment", is it not in fact the case after the patch that
> they now have the same mutual 64-bit alignment, even if this code doesn't
> currently rely on that? I think the comments in each place should be
> explicit about both things - what preconditions the code relies on, and
> what possibly stronger preconditions are in fact true given the other code
> in this file. Saying the mutual alignment is 32-bit when the reader can
> see from the code not far above that it's 64-bit just seems liable to
> confuse the reader, even if the comment is still formally true.
> Similarly for the requirements on unaligned word accesses - after this
> patch, which uses of ldrd/strd do require that?
Yes, you're right, that needs more thought. I'll have a look at it next week.
--
Will Newton
Toolchain Working Group, Linaro
prev parent reply other threads:[~2013-08-30 18:46 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-12 7:55 Will Newton
2013-08-27 7:46 ` Will Newton
2013-08-30 17:14 ` Carlos O'Donell
2013-08-30 18:48 ` Will Newton
2013-08-30 19:26 ` Carlos O'Donell
2013-09-02 14:18 ` Will Newton
2013-09-03 16:14 ` Carlos O'Donell
[not found] ` <CANu=DmhA9QvSe6RS72Db2P=yyjC72fsE8d4QZKHEcNiwqxNMvw@mail.gmail.com>
2013-09-02 14:18 ` benchmark improvements (Was: Re: [PATCH] sysdeps/arm/armv7/multiarch/memcpy_impl.S: Improve performance.) Siddhesh Poyarekar
2013-09-03 13:46 ` Will Newton
2013-09-03 17:48 ` Ondřej Bílka
2013-09-02 19:57 ` [PATCH] sysdeps/arm/armv7/multiarch/memcpy_impl.S: Improve performance Ondřej Bílka
2013-09-03 16:18 ` Carlos O'Donell
2013-09-03 17:37 ` Ondřej Bílka
2013-09-03 17:52 ` Carlos O'Donell
2013-09-03 18:57 ` Ondřej Bílka
2013-09-03 19:15 ` Carlos O'Donell
2013-09-04 7:27 ` Siddhesh Poyarekar
2013-09-04 11:03 ` Ondřej Bílka
2013-09-04 11:43 ` Siddhesh Poyarekar
2013-09-04 17:37 ` Ryan S. Arnold
2013-09-05 8:04 ` Ondřej Bílka
2013-09-04 15:30 ` Carlos O'Donell
2013-09-04 17:35 ` Ryan S. Arnold
2013-09-05 11:07 ` Ondřej Bílka
2013-09-05 11:54 ` Joseph S. Myers
2013-09-03 19:34 ` Ryan S. Arnold
2013-09-07 11:55 ` Ondřej Bílka
2013-09-03 19:31 ` Ryan S. Arnold
2013-09-03 19:54 ` Carlos O'Donell
2013-09-03 20:56 ` Ryan S. Arnold
2013-09-03 23:29 ` Ondřej Bílka
2013-09-03 23:31 ` Carlos O'Donell
2013-09-03 22:27 ` Ondřej Bílka
2013-08-29 23:58 ` Joseph S. Myers
2013-08-30 14:56 ` Will Newton
2013-08-30 15:18 ` Joseph S. Myers
2013-08-30 18:46 ` Will Newton [this message]
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