From: Junio C Hamano <gitster@pobox.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: demerphq <demerphq@gmail.com>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Martin Ågren" <martin.agren@gmail.com>,
"Andreas Schwab" <schwab@suse.de>,
"Lars Schneider" <larsxschneider@gmail.com>,
"Git Mailing List" <git@vger.kernel.org>,
"Marc Stevens" <marc@marc-stevens.nl>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>
Subject: Re: Unaligned accesses in sha1dc
Date: Sat, 03 Jun 2017 09:13:19 +0900 [thread overview]
Message-ID: <xmqq4lvyx71c.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <CA+55aFwL9LQfx8t7tixYgV+2w_=_dAABxk54_GLJoGod-w=mbw@mail.gmail.com> (Linus Torvalds's message of "Fri, 2 Jun 2017 14:53:59 -0700")
Linus Torvalds <torvalds@linux-foundation.org> writes:
> Dereferencing an unaligned pointer may be "undefined" in some
> technical meaning, but it sure as hell isn't undefined in reality, and
> compilers that willfully do stupid things should not be catered to
> overly. Reality is a lot more important.
Thanks for succinctly putting it this way. I think you said the
above number of times, and I was looking for one of them to include
a reference to in the response I was preparing, but this message
made it unnecessary ;-)
> And I think gcc can be tweaked to use "movbe" on x86 with the right
> magic incantation (ie not just __builtin_bswap32(), but also the
> switch to enable the new instructions). So having code to detect gcc
> and using __builtin_bswap32() would indeed be a good thing.
next prev parent reply other threads:[~2017-06-03 0:13 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-01 8:28 Unaligned accesses in sha1dc Andreas Schwab
[not found] ` <CDB32E2C-48AF-4636-B921-4C45B614FD35@marc-stevens.nl>
2017-06-01 9:05 ` Andreas Schwab
2017-06-01 9:15 ` Junio C Hamano
2017-06-01 9:15 ` Andreas Schwab
2017-06-01 9:34 ` Junio C Hamano
2017-06-01 9:18 ` brian m. carlson
2017-06-01 9:32 ` Andreas Schwab
2017-06-01 9:21 ` Lars Schneider
2017-06-01 9:53 ` Junio C Hamano
2017-06-01 10:08 ` Andreas Schwab
2017-06-01 10:26 ` Martin Ågren
2017-06-01 10:33 ` Ævar Arnfjörð Bjarmason
2017-06-01 11:53 ` Martin Ågren
2017-06-01 15:57 ` Martin Ågren
2017-06-02 0:15 ` Junio C Hamano
2017-06-02 8:51 ` Ævar Arnfjörð Bjarmason
2017-06-02 9:49 ` Martin Ågren
2017-06-02 19:32 ` Ævar Arnfjörð Bjarmason
2017-06-02 20:11 ` Martin Ågren
2017-06-02 20:14 ` Ævar Arnfjörð Bjarmason
2017-06-02 20:25 ` demerphq
2017-06-02 20:17 ` demerphq
2017-06-02 20:38 ` Ævar Arnfjörð Bjarmason
2017-06-02 21:53 ` Linus Torvalds
2017-06-03 0:13 ` Junio C Hamano [this message]
2017-06-02 14:46 ` Liam R. Howlett
2017-06-02 16:53 ` Ævar Arnfjörð Bjarmason
2017-06-03 0:15 ` Junio C Hamano
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