https://bugs.freedesktop.org/show_bug.cgi?id=29762
--- Comment #2 from Marek Olšák maraeo@gmail.com 2010-08-25 18:35:47 PDT --- The compiler error is valid. Relative addressing (array indexing) is not implemented for fragment shaders.
The hardware only suppports relative addressing using the loop counter and only on r500. The loop counter register type has been removed in Gallium so it cannot be implemented directly. Some non-trivial work is needed in the compiler.