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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>,
        =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason <avarab@gmail.com>
Subject: Re: Unaligned accesses in sha1dc
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Date:   Thu, 01 Jun 2017 12:08:40 +0200
In-Reply-To: <xmqqwp8w3uff.fsf@gitster.mtv.corp.google.com> (Junio C. Hamano's
        message of "Thu, 01 Jun 2017 18:53:56 +0900")
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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."