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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 14:39:25 +0200

On Fri, 17 Sep 2010 14:01:48 +0200
Slawomir Testowy <slawomir.testowy_at_gmail.com> wrote:

> Hi,
>
> thanks for quick response.
>
> 2010/9/17 RafaŽl Carrť <rafael.carre_at_gmail.com>:
> > I think the OP should post .S output of gcc and also give
> > us compiler version and options being used
> >
> > --
> > RafaŽl Carrť
> >
>
> Here it is:
>
> /opt/freescale/usr/local/gcc-4.1.2-glibc-2.5-nptl-3/arm-none-linux-gnue
> abi/bin/arm-none-linux-gnueabi-gcc --version
> arm-none-linux-gnueabi-gcc (GCC) 4.1.2
> Copyright (C) 2006 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions. There
> is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
> PARTICULAR PURPOSE.
>
> Exact command line:
>
> /opt/freescale/usr/local/gcc-4.1.2-glibc-2.5-nptl-3/arm-none-linux-gnue
> abi/bin/arm-none-linux-gnueabi-gcc -std=gnu89 -fPIC -DHAVE_CONFIG_H
> -I. -I./ -O2 -D_ARM_ASSEM_ -fsigned-char -ffast-math
> -fsingle-precision-constant -D_REENTRANT -DUSE_MEMORY_H -MT
> fft-ffmpeg.lo -MD -MP -MF .deps/fft-ffmpeg.Tpo -c fft-ffmpeg.c -o
> fft-ffmpeg.o
>
> Outputs of gcc -S and gcc -E are included in attachments.
>
> I'm afraid I won't be able to test proposed patch today. I'll try on
> Monday.

I think the patch wouldn't compile on ARM because I missed the ldmia
ordering constraints like Dave mentioned

otherwise I see that fft8_dispatch only differs on 1 register (-fPIC
use r9 and without it uses r10==sl) but I don't see r10/sl being used
as a pointer.. perhaps it's only done at linking phase?

BTW building gdb should be as simple as:
./configure --target=arm-none-linux-gnueabi ; make

-- 
RafaŽl Carrť
Received on 2010-09-17

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