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Subject: Re: Segfault with Faster MDCT patch and -fPIC

Re: Segfault with Faster MDCT patch and -fPIC

From: RafaŽl Carrť <rafael.carre_at_gmail.com>
Date: Fri, 17 Sep 2010 12:49:57 +0200

On Fri, 17 Sep 2010 10:34:06 +0100
Dave Hooper <dave_at_beermex.com> wrote:

> That's very interesting indeed. I too observed a segfault when trying
> to use the fastermdct patch on top of a libtremor used by an MPD
> server but couldn't pinpoint the reason. That's one of the reasons
> this patch hasn't hit upstream Tremor.
>
> I know the code well but that line seems very mysterious (I.e.
> harmless - it should work unless something has corrupted the
> stack/address pointer, I think).
> Can any arm gurus see if I am misusing any registers in a way that
> prevents shared library usage, or anything along those lines?

From a very quick look on google, ARM seems to need r10 as PIC
register, and at least some TRANSFORM_* macros assign variables to r10
explicitely.

Why isn't 'register FFTSample x' enough?

Attached patch remove explicit naming of registers, and is also updated
to Tremor svn. I just tried a build on x86 but not on ARM.

Can you see if it works?

> > Unfortunately, I don't have gdb built for this platform (I managed

You could post the preprocessed source, output of gcc -E and gcc -S,

-- 
RafaŽl Carrť

Received on 2010-09-17

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