Comment 8 for bug 954783

Yes, currently investigating why -O3 affects this (probably a call to __aeabi_llsr in an underlying library is optimized away by -O3, causing the underlying library not to drag the symbol in at link time (it's supposed to come from libgcc.a)).

There may be a simple fix along the lines of

mv libUMP.so libBrokenUMP.so
arm-linux-androideabi-gcc -shared -o libUMP.so -L. -lBrokenUMP -lgcc

But of course that's rather ugly...