https://bugs.freedesktop.org/show_bug.cgi?id=91993
--- Comment #17 from MC Return mc.return@gmx.net --- I can confirm that updating and recompiling of the AstroMenace source (Version 1.3.3 svn build 140929 now) now fully fixed the problem for me \o/ (radeonsi, R390X here).
Thanks a lot to everyone helping with this !