Re: [patch libstdc++] Optimize synchronization in std::future if futexes are available.

[Sandra Loosemore <sandra at codesourcery dot com>]

On 01/17/2015 03:36 PM, Jonathan Wakely wrote:
> On 17/01/15 15:22 -0700, Sandra Loosemore wrote:
> [snip snip]
> > I'm getting a different series of build errors with this patch --
> > starting with
> >
> > In file included from
> > /scratch/sandra/arm-fsf2/src/gcc-mainline/libstdc++-v3/src/c++11/futex.cc:27:0:
> >
> > /scratch/sandra/arm-fsf2/obj/gcc-mainline-0-arm-none-linux-gnueabi-i686-pc-linux-gnu/arm-none-linux-gnueabi/libstdc++-v3/include/bits/atomic_futex.h:221:5:
> > error: 'mutex' does not name a type
> >     mutex _M_mutex;
> >     ^
> > /scratch/sandra/arm-fsf2/obj/gcc-mainline-0-arm-none-linux-gnueabi-i686-pc-linux-gnu/arm-none-linux-gnueabi/libstdc++-v3/include/bits/atomic_futex.h:222:5:
> > error: 'condition_variable' does not name a type
> >     condition_variable _M_condvar;
> >     ^
> > /scratch/sandra/arm-fsf2/obj/gcc-mainline-0-arm-none-linux-gnueabi-i686-pc-linux-gnu/arm-none-linux-gnueabi/libstdc++-v3/include/bits/atomic_futex.h:
> > In member function 'unsigned int
> > std::__atomic_futex_unsigned<_Waiter_bit>::_M_load(std::memory_
> > order)':
> > /scratch/sandra/arm-fsf2/obj/gcc-mainline-0-arm-none-linux-gnueabi-i686-pc-linux-gnu/arm-none-linux-gnueabi/libstdc++-v3/include/bits/atomic_futex.h:230:7:
> > error: 'unique_lock' was not declared in this scope
> >       unique_lock<mutex> __lock(_M_mutex);
> >       ^
> > and going on for several screenfuls.
>
> Odd, that should already be fixed at rev 219799.
>
> Are you still at a revision older than that?

My source tree is at r219802 now.
> > Maybe the patch(es) causing all these problems should be reverted
> > until the breakage is tracked down and fixed and regression-tested on
> > a variety of targets?  It's not really blocking me at the moment, but
> > it seems unfortunate that trunk is so unstable as we're entering Stage
> > 4.....

-Sandra