binary segfault when compiled with gcc 4.5 on linux x86_64

[albumasar]

See http://bugs.archlinux.org/task/20199
Note that the compilation process itself is fine (see attached log file).

[albumasar (albumasar)]

The file dvisvgm-texlive2010-build.log.gz was added: Build log for dvisvgm (TL 2010)

[Martin Gieseking (martin-gieseking)]

Thanks for telling me about this problem. However, the reason for the segfault seems to be a compiler bug. I currently have no idea why the program crashes at that part of the code when using gcc 4.5.0. Thus, it's difficult to provide a fix or a workaround at the moment. I'll investigate the issue in more detail in the next couple of days.

[Martin Gieseking (martin-gieseking)]

I've tracked down the GCC issue and filed a bug report:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45008

[albumasar (albumasar)]

Thanks Martin for doing this. In the meanwhile someone came up with a temporary fix on our bug tracker:
http://bugs.archlinux.org/task/20199#comment64195
which I have not tried yet. The patch seems to work, but I'd prefer not to patch the original code and thus I'll probably use gcc 4.4.4 instead for re-compiling our texlive-bin package. Unless of course you think that patch is perfectly ok.

[Martin Gieseking (martin-gieseking)]

Francois, thanks for the hint. The patch only affects a part of the relevant code and leaves similar constructions untouched. Thus, the same issue may still occur with different dvi files. Since the suggested fix messes up the sources, I'm a bit reluctant to move all local class definitions around. Currently, I would recommend not to build dvisvgm with gcc 4.5.0 but use a previous version instead. Hopefully, the bug gets fixed in gcc 4.5.1.

[albumasar (albumasar)]

Hi, the maintainer of gcc for our Linux distro, after an intensive session of git-bisecting, found the commit which fixes this: see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45008#c6
We will see if this can be cleanly backported to 4.5.0 and I will use it then to recompile texlive-bin, which shall then provide a working binary of dvisvgm.

[Martin Gieseking (martin-gieseking)]

Thanks to Allan for isolating the critical changeset from the gcc repository.
The issue has been added to the list of serious regressions and will be fixed in gcc 4.5.1. The latter is probably going to be released next week:
http://gcc.gnu.org/ml/gcc/2010-07/msg00323.html

[Martin Gieseking (martin-gieseking)]

The bug has been fixed in the GCC repo, so I close here.