Something seems to have been broken in llvm 3.5 after svn revision 209067.
What I am experiencing is that the system is stable for desktop usage but after
a few minutes from launching a game (I have tried with CKII, Witcher 2,
Watelands 2, Cities in motion, Deadfall Adventures and Serious Sam 3) or just
after a few seconds after exiting the game the desktop freezes, the screen goes
black (can't switch to vt to kill the game/desktop session) and the system
becomes unresponsive. I'm afraid I cannot obtain a dmesg log due to that
unresponsiveness.
If a dmesg log is needed to know the system's specs, the following attachement
of another bug report may be of use:
https://bugs.freedesktop.org/attachment.cgi?id=97787
I am using a llvm ppa to install llvm 3.5 git. I've tried to compile llvm with
no luck, so I cannot bisect. However, I still have in /var/cache/apt/archives
the deb packages for svn revisions 209564, 209581 and 209600 and those
revisions hang the system in the way described above. So judging by the R600
llvm backend activity
(https://github.com/llvm-mirror/llvm/commits/master/lib/Target/R600) and my
experience with those svn .deb packages I still have in the apt cache, it seems
the culprit must be a commit after 16 May.