https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86735
--- Comment #21 from janus at gcc dot gnu.org --- (In reply to Jakub Jelinek from comment #20) > Tried again, this time on real hw (i9-7960X) and still can't reproduce, Thanks for the data point, Jakub. Could you please share your kernel and glibc version? H.J.'s comment 15 sounds like the kernel version might make a difference. (Unfortunately I am stuck with kernel 4.15 right now and cannot verify this.) In any case, I still see the problem with current trunk and this config: * Ubuntu 18.04, kernel 4.15.0 * Intel(R) Core(TM) i9-7980XE CPU * glibc 2.27, binutils 2.30 My trunk build has been configured with: configure --program-suffix=-9 --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --with-arch=skylake-avx512 --prefix=/ --enable-languages=c,c++,fortran --disable-multilib