control: tag -1 + fixed-upstream On 2018-01-15 00:22, Aurelien Jarno wrote: > clone 887169 -1 > reassign -1 gcc-7 > retitle -1 gcc-7: missed optimization of glibc strspn SSE 4.2 variant > forwarded -1 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81481 > block 887169 by -1 > thanks > > On 2018-01-14 10:35, James Lu wrote: > > Package: libc6 > > Version: 2.26-3 > > Severity: normal > > > > Dear maintainers, > > > > On a recent glibc upgrade on buster/sid (first to 2.26-2 and then > > 2.26-3), one Steam game (Civilization V) consistently segfaults on startup. > > > > Similar issues have been reported in Arch Linux[1], Fedora[2], and > > OpenSUSE[3], where the consensus was that building glibc with > > From what I get about the above reported issues, this bug is caused by: > - the Steam games not following the Linux/x86 ABI wrt stack alignement > - the SSE4.2 version of the strspn function needing to push an SSE > register to the stack when build with GCC 7, due to a missed > optimization. > > > -mstackrealign fixed the issue. (I haven't been able to get such a local > > build working though) > > I don't think it is actually the consensus, only Arch Linux has chosen > this solution, and building the whole glibc with this option will have > an impact of the performances for all binaries, not only the broken > Steam ones. I therefore don't think it's the right way to fix the bug. > > Instead it looks like fixing PR81481 [1] on the GCC 7 side, and then > rebuilding glibc is the way to go. I am therefore cloning this bug to > gcc-7 so that it can happens.
Note that the bug has now been fixed upstream. Tagging this bug as such. Aurelien -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurel...@aurel32.net http://www.aurel32.net
