[Buildroot] [PATCH 10/21] libtorrent: use the proper BR2_TOOLCHAIN_HAS_SYNC_x symbols

[Yann E. MORIN <yann.morin.1998@free.fr>]

thomas, All,

On 2016-01-25 23:07 +0100, Thomas Petazzoni spake thusly:
> On Mon, 25 Jan 2016 22:45:29 +0100, Yann E. MORIN wrote:
> 
> > On 2016-01-25 00:07 +0100, Thomas Petazzoni spake thusly:
> > > libtorrent uses 1 bytes and 4 bytes __sync built-ins, so let's use the
> > > appropriate BR2_TOOLCHAIN_HAS_SYNC_x symbols instead of
> > > BR2_ARCH_HAS_ATOMICS. The rtorrent package, which is a reverse
> > > dependency of libtorrent, gets fixed as well.
> > > 
> > > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> > > ---
> > >  package/libtorrent/Config.in | 4 ++--
> > >  package/rtorrent/Config.in   | 4 ++--
> > >  2 files changed, 4 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/package/libtorrent/Config.in b/package/libtorrent/Config.in
> > > index 17a1f23..4787f9c 100644
> > > --- a/package/libtorrent/Config.in
> > > +++ b/package/libtorrent/Config.in
> > > @@ -2,7 +2,7 @@ config BR2_PACKAGE_LIBTORRENT
> > >  	bool "libtorrent"
> > >  	depends on BR2_INSTALL_LIBSTDCPP
> > >  	depends on BR2_TOOLCHAIN_HAS_THREADS
> > > -	depends on BR2_ARCH_HAS_ATOMICS
> > > +	depends on BR2_TOOLCHAIN_HAS_SYNC_1 && BR2_TOOLCHAIN_HAS_SYNC_4
> > 
> > The original build failure that prompted adding the atomics dependency
> > only reported errors about the __sunc_*_4() functions, but libtorrent
> > has been bumped sinc ethen.
> > 
> > I was not able to easily reproduce a failure so far, but I will try with
> > an arc toolchain (which is lacking __sync_*_1() functions...
> 
> Beware with ARC: you need to have a toolchain with BR2_ARC_ATOMIC_EXT
> disabled, otherwise the __sync built-ins are provided. And by default,
> BR2_ARC_ATOMIC_EXT is enabled.

Yep, I know and the toolchain I built does not have them.

Thanks for the hint anyway. :-)

> Regarding libtorrent, if you want to test:
> 
>  1/ Remove the dependency on BR2_TOOLCHAIN_HAS_SYNC_<x> (or
>     BR2_ARCH_HAS_ATOMICS in the current Buildroot)

What I did.

>  2/ Build it with the br-sparc-glibc.config pointed above.

Doing so for ARC...

>  3/ Test the following:
> 
> $ echo "int main(void) { return 0; }" >> foo.c
> $ ./output/host/usr/bin/sparc-linux-gcc -o foo foo.c -ltorrent -lpthread
> 
> You get:
> 
> /home/thomas/projets/buildroot/output/host/usr/sparc-buildroot-linux-gnu/sysroot/usr/lib/libtorrent.so: undefined reference to `__sync_sub_and_fetch_4'
> /home/thomas/projets/buildroot/output/host/usr/sparc-buildroot-linux-gnu/sysroot/usr/lib/libtorrent.so: undefined reference to `__sync_bool_compare_and_swap_1'
> /home/thomas/projets/buildroot/output/host/usr/sparc-buildroot-linux-gnu/sysroot/usr/lib/libtorrent.so: undefined reference to `__sync_or_and_fetch_4'
> /home/thomas/projets/buildroot/output/host/usr/sparc-buildroot-linux-gnu/sysroot/usr/lib/libtorrent.so: undefined reference to `__sync_bool_compare_and_swap_4'
> /home/thomas/projets/buildroot/output/host/usr/sparc-buildroot-linux-gnu/sysroot/usr/lib/libtorrent.so: undefined reference to `__sync_add_and_fetch_4'
> /home/thomas/projets/buildroot/output/host/usr/sparc-buildroot-linux-gnu/sysroot/usr/lib/libtorrent.so: undefined reference to `__sync_fetch_and_or_4'
> /home/thomas/projets/buildroot/output/host/usr/sparc-buildroot-linux-gnu/sysroot/usr/lib/libtorrent.so: undefined reference to `__sync_fetch_and_and_4'
> collect2: error: ld returned 1 exit status
> 
> See the __sync_bool_compare_and_swap_1() ?
> 
> And now, you can test it with a Microblaze toolchain, which implements
> the 4-byte __sync builtins, but not the 1-byte builtins. And you get:
> 
> $ ./output/host/usr/bin/microblazeel-linux-gcc -o foo foo.c -ltorrent -lpthread
> /home/thomas/projets/buildroot/output/host/usr/microblazeel-buildroot-linux-gnu/sysroot/usr/lib/libtorrent.so: undefined reference to `__sync_bool_compare_and_swap_1'
> collect2: error: ld returned 1 exit status

Ah, I see my tests are no longer needed! Thanks for that!

(Note: I was not trying to turn your patch down, I was just trying to
confirm the _1 stuff).

Regards,
Yann E. MORIN.

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