https://bugs.freedesktop.org/show_bug.cgi?id=93352
--- Comment #13 from Ilia Mirkin imirkin@alum.mit.edu --- I've pushed out a fix for the issue that triggers this assertion:
GridAutosport: ../../../../src/mesa/state_tracker/st_glsl_to_tgsi.cpp:2342: virtual void glsl_to_tgsi_visitor::visit(ir_dereference_variable*): Assertion `var->data.location != -1' failed.
But it sounds like there are additional issues too? I would encourage you to continue using --enable-debug as that is a lot better at identifying problems at their source.