On Mon, 11 Sept 2023 at 15:12, Jonathan Wakely <jwak...@redhat.com> wrote:
> On Mon, 11 Sept 2023 at 13:36, Christophe Lyon > <christophe.l...@linaro.org> wrote: > > > > > > > > On Mon, 11 Sept 2023 at 12:59, Jonathan Wakely <jwak...@redhat.com> > wrote: > >> > >> On Sun, 10 Sept 2023 at 20:31, Christophe Lyon > >> <christophe.l...@linaro.org> wrote: > >> > > >> > Some targets like arm-eabi with newlib and default settings rely on > >> > __sync_synchronize() to ensure synchronization. Newlib does not > >> > implement it by default, to make users aware they have to take special > >> > care. > >> > > >> > This makes a few tests fail to link. > >> > >> Does this mean those features are unusable on the target, or just that > >> users need to provide their own __sync_synchronize to use them? > > > > > > IIUC the user is expected to provide them. > > Looks like we discussed this in the past :-) > > In https://gcc.gnu.org/legacy-ml/gcc-patches/2016-10/msg01632.html, > > see the pointer to Ramana's comment: > https://gcc.gnu.org/ml/gcc-patches/2015-05/msg02751.html > > Oh yes, thanks for the reminder! > > > > > The default arch for arm-eabi is armv4t which is very old. > > When running the testsuite with something more recent (either as default > by configuring GCC --with-arch=XXX or by forcing -march/-mcpu via dejagnu's > target-board), the compiler generates barrier instructions and there are no > such errors. > > Ah yes, that's fine then. > > > For instance, here is a log with the defaults: > > > https://git.linaro.org/toolchain/ci/base-artifacts/tcwg_gnu_embed_check_gcc/master-arm_eabi.git/tree/00-sumfiles?h=linaro-local/ci/tcwg_gnu_embed_check_gcc/master-arm_eabi > > and a log when we target cortex-m0 which is still a very small cpu but > has barriers: > > > https://git.linaro.org/toolchain/ci/base-artifacts/tcwg_gnu_embed_check_gcc/master-thumb_m0_eabi.git/tree/00-sumfiles?h=linaro-local/ci/tcwg_gnu_embed_check_gcc/master-thumb_m0_eabi > > > > I somehow wanted to get rid of such errors with the default > configuration.... > > Yep, that makes sense, and we'll still be testing them for newer > arches on the target, so it's not completely disabling those parts of > the testsuite. > > But I'm still curious why some of those tests need this change. I > think the ones I noted below are probably failing for some other > reasons. > > Just looked at 23_containers/span/back_assert_neg.cc, the linker says it needs arm-eabi/libstdc++-v3/src/.libs/libstdc++.a(debug.o) to resolve ./back_assert_neg-back_assert_neg.o (std::__glibcxx_assert_fail(char const*, int, char const*, char const*)) and indeed debug.o has a reference to __sync_synchronize > > >> > >> > > >> > This patch requires the missing thread-fence effective target in the > >> > tests that need it, making them UNSUPPORTED instead of FAIL and > >> > UNRESOLVED. > >> > >> Some of the modified tests should not be using > >> __gnu_debug::_Safe_sequence_base::_M_detach_all(), because they don't > >> use the Debug Mode. I don't know where those linker errors come from. > >> For example, the 23_containers/span/*assert_neg.cc and > >> 26_numerics/valarray/* tests shouldn't use debug iterators or atomics. > >> Neither should 25_algorithms/sample/2.cc nor > >> 26_numerics/bit/bit.pow.two/bit_ceil_neg.cc > > > > > > Ouch! I had the feeling this patch wouldn't count as obvious :-) > > > > I confess I didn't analyze the linker map for every single test updated > by this patch.... > > I can have a deeper look based on your comment below, excluding those > that look "OK" > > > >> > >> The last three in the patch shouldn't use it either: > >> > >> > diff --git > a/libstdc++-v3/testsuite/experimental/net/timer/waitable/dest.cc > b/libstdc++-v3/testsuite/experimental/net/timer/waitable/dest.cc > >> > index cb818708aef..372ed6e0c00 100644 > >> > --- a/libstdc++-v3/testsuite/experimental/net/timer/waitable/dest.cc > >> > +++ b/libstdc++-v3/testsuite/experimental/net/timer/waitable/dest.cc > >> > @@ -18,6 +18,7 @@ > >> > // { dg-do run { target c++14 } } > >> > // { dg-add-options libatomic } > >> > // { dg-xfail-if "poll not available" { *-*-rtems* } } > >> > +// { dg-require-thread-fence "" } // needed by > __gnu_debug::_Safe_sequence_base::_M_detach_all() > >> > > >> > #include <experimental/timer> > >> > #include <testsuite_hooks.h> > >> > diff --git > a/libstdc++-v3/testsuite/experimental/net/timer/waitable/ops.cc > b/libstdc++-v3/testsuite/experimental/net/timer/waitable/ops.cc > >> > index ae51979c3b4..8383e0be6a4 100644 > >> > --- a/libstdc++-v3/testsuite/experimental/net/timer/waitable/ops.cc > >> > +++ b/libstdc++-v3/testsuite/experimental/net/timer/waitable/ops.cc > >> > @@ -18,6 +18,7 @@ > >> > // { dg-do run { target c++14 } } > >> > // { dg-add-options libatomic } > >> > // { dg-xfail-if "poll not available" { *-*-rtems* } } > >> > +// { dg-require-thread-fence "" } // needed by > __gnu_debug::_Safe_sequence_base::_M_detach_all() > >> > > >> > #include <experimental/timer> > >> > #include <testsuite_hooks.h> > >> > diff --git > a/libstdc++-v3/testsuite/experimental/polymorphic_allocator/construct_pair.cc > b/libstdc++-v3/testsuite/experimental/polymorphic_allocator/construct_pair.cc > >> > index 960c1d253b5..42de45619a8 100644 > >> > --- > a/libstdc++-v3/testsuite/experimental/polymorphic_allocator/construct_pair.cc > >> > +++ > b/libstdc++-v3/testsuite/experimental/polymorphic_allocator/construct_pair.cc > >> > @@ -16,6 +16,7 @@ > >> > // <http://www.gnu.org/licenses/>. > >> > > >> > // { dg-do run { target c++14 } } > >> > +// { dg-require-thread-fence "" } // needed by > __gnu_debug::_Safe_sequence_base::_M_detach_all() > >> > > >> > #include <experimental/memory_resource> > >> > #include <utility> > >> > >> > >> I'm concerned with how much of the testsuite is being completely > >> disabled for this target. > > > > I think that depends on which "flavour" of arm-eabi we are looking at. > > I'm trying to cleanup some of the "obvious" failures, and that proves to > be tedious: > > - quite a few gcc/g++ tests have problems when overriding -mcpu/-march > with dejagnu's target-board > > - so I thought a first step could be to clean the default configuration, > but as said above it targets a very old architecture > > > >> > >> > >> Any tests with "debug" in the path are probably relying on the debug > >> mode, and any that use -D_GLIBCXX_DEBUG in dg-options are. And I > >> suppose it's expected that 29_atomics/* tests rely on atomic > >> synchronization, but it's unfortunate that those now can't be tested > >> for arm-eabi, and I don't understand why it only affects eight of the > > > > that's only the "default" arm-eabi, it does not happen in other > non-default arm-eabi (well I didn't check all possible cases) > > > >> > >> atomics tests not all the other ones. > >> > >> Something doesn't seem right here. > >> > > > > Thanks, > > > > Christophe > > > >
