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Date:      Fri, 26 Dec 2014 13:55:20 +0100
From:      Thomas Zander <riggs@freebsd.org>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        "freebsd-ports@freebsd.org" <ports@freebsd.org>, multimedia@freebsd.org
Subject:   Re: [CFT] New upstream version of mplayer + mencoder
Message-ID:  <CAFU734z3Aw6K18eLNrxn7qbY3LQed-SAqQg=-taVfCkAQM8ozg@mail.gmail.com>
In-Reply-To: <20141226101504.GG1754@kib.kiev.ua>
References:  <20141225134226.GA78595@marvin2011.fritz.box> <20141225150940.GF1754@kib.kiev.ua> <CAFU734wkwxGPmxigiyA9JhiWQ7adX5_fVzFSCFxVOSaCM1iKOw@mail.gmail.com> <20141226101504.GG1754@kib.kiev.ua>

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On 26 December 2014 at 11:15, Konstantin Belousov <kostikbel@gmail.com> wrote:

> It seems that everything makes circles around stack alignment and SSE.
> At least, this is strongly suggested by references to OCFLAGS and the
> fact that -fomit-frame-pointer implicitely changes stack alignment.
> SIGBUS is somewhat consistent with this observation.

Sounds sensible to me. Thanks for taking a look.

> This might be a compiler bug (what compiler ?  I cannot find a conclusive
> answer in the PR), or more likely, it is a bug in inline assembler code,
> which probably makes unwarranted assumptions about stack alignment.

Presumably the reporters used the default compiler for the mplayer
port, which is clang on 9.x and 10.x on i386 and amd64.
The mplayer code (it bundles ffmpeg) assumes various alignments here
and there, including 16 byte alignment in various handcrafted SSE code
snippets.

Let's try the stackrealign option and observe the results. I'll update
the PR accordingly.
Best
Riggs



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