Comment # 1 on bug 67046 from Michel Dänzer

AFAICT the real problem is this, visible with a debugging build of Mesa:

../../../../src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c:2190:lp_emit_declaration_soa:
Assertion `idx < 256' failed.

This can be avoided by bumping LP_MAX_TGSI_TEMPS, but it looks like the app
and/or glsl-to-tgsi aren't paying attention to the maximum number of
temporaries advertised by the driver.