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From: Andreas Schwab <schwab@suse.de>
To: Junio C Hamano <gitster@pobox.com>
Cc: "Lars Schneider" <larsxschneider@gmail.com>,
	git@vger.kernel.org, "Marc Stevens" <marc@marc-stevens.nl>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: Re: Unaligned accesses in sha1dc
Date: Thu, 01 Jun 2017 12:08:40 +0200	[thread overview]
Message-ID: <mvmmv9st3yv.fsf@suse.de> (raw)
In-Reply-To: <xmqqwp8w3uff.fsf@gitster.mtv.corp.google.com> (Junio C. Hamano's message of "Thu, 01 Jun 2017 18:53:56 +0900")

On Jun 01 2017, Junio C Hamano <gitster@pobox.com> wrote:

> Depending on the model of "ARM" (or "SPARC") emulated with QEMU, and
> depending on the OS that runs on such an "ARM" or "SPARC", we may
> not see this---if the emulated OS has the "software unaligned-access
> emulation" our userland may not see a SIGBUS.

Even if the architecture implements unaligned accesses in hardware, it
is still undefined behaviour, and the compiler will (eventually) take
advantage of it.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

  reply	other threads:[~2017-06-01 10:08 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 [this message]
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
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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