On Wed, 17 May 2023 at 10:32, Martin Jambor wrote: > Hello, > > On Tue, May 16 2023, Jonathan Wakely via Gcc-patches wrote: > > Tested powerpc64le-linux. Builds OK on djgpp too. > > > > Pushed to trunk. > > > > -- >8 -- > > > > DJGPP (and maybe other targets) uses MAX_OFILE_ALIGNMENT=16 which means > > that globals (and static objects) can't have alignment greater than 16. > > This causes an error for the locks defined in src/c++11/shared_ptr.cc > > because we try to align them to the cacheline size, to avoid false > > sharing. > > > > Add a configure check for the increased alignment, and live with false > > sharing where we can't increase the alignment. > > > > libstdc++-v3/ChangeLog: > > > > PR libstdc++/109741 > > * acinclude.m4 (GLIBCXX_CHECK_ALIGNAS_CACHELINE): Define. > > * config.h.in: Regenerate. > > * configure: Regenerate. > > * configure.ac: Use GLIBCXX_CHECK_ALIGNAS_CACHELINE. > > * src/c++11/shared_ptr.cc (__gnu_internal::get_mutex): Do not > > align lock table if not supported. use __GCC_DESTRUCTIVE_SIZE > > instead of hardcoded 64. > > The periodic tests that Martin Liška left behind for me (for now) to > look at are now complaining that the configure and configure.ac in > libstdc++ are not in sync, the difference being (drum roll): > > diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure > index 188be08d716..412c4bf0e85 100755 > --- a/libstdc++-v3/configure > +++ b/libstdc++-v3/configure > @@ -71957,6 +71957,7 @@ _ACEOF > fi > > > +# For src/c++11/shared_ptr.cc alignment. > > > ac_ext=cpp >
Oh no! I was worried I'd actually broken something when I saw the email land in my inbox :-) Looks like I added that comment to configure.ac and then forgot to re-run autoreconf. > Can I commit this change or do I need to attempt to adjust the script to > ignore comments in configure or what would be the correct way to deal > with this? (Option requiring work on my side may take some time during > which the otherwise useful tests would not work, I am afraid). > > The "correct" fix is to run autoreconf in the libstdc++-v3 dir to regen the configure script, but for something this trivial it would also be fine to just make the change manually. I've pushed the regenerated file now, as r14-930-g7ddbc6171b383c Thanks for running those checks!
