This fixes 8 fs-interpolateat* piglit crashes on radeonsi, because it can't handle non-input operands in interpolateAt*. Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com> Acked-by: Matt Turner <mattst88@gmail.com> Acked-by: Jose Fonseca <jfonseca@vmware.com>