Created attachment 140824 [details]
backtrace

RX 480, mesa git e68fe445f51, libdrm git.

Tabs in firefox nightly randomly crash, see backtrace.
Everything else seems to work fine.

Without debug symbols the backtrace went through glPrimitiveBoundingBox for
some reason 

Core was generated by `/opt/firefox-nightly/firefox -contentproc -childID 4
-isForBrowser -prefsLen 43'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000000406d30 in ?? ()
[Current thread is 1 (Thread 0x7efc14152740 (LWP 14385))]
(gdb) bt
#0  0x0000000000406d30 in  ()
#1  0x00007efbe0647be0 in drmFreeDevice () at /usr/lib/libdrm.so.2
#2  0x00007efbe0ade8ae in glPrimitiveBoundingBox () at /usr/lib/libGL.so.1
#3  0x00007efbe0ad5bd5 in  () at /usr/lib/libGL.so.1
#4  0x00007efbe0abe350 in  () at /usr/lib/libGL.so.1
#5  0x00007efbe0ab9d81 in glXQueryVersion () at /usr/lib/libGL.so.1

but in the attached backtrace with full debugging enabled it looks a bit
different.