Comment # 4 on bug 95130 from Nicolai H�hnle

As a temporary workaround, the error should disappear when you run with the
environment variable setting R600_DEBUG=mono.

The cause is that with non-monolithic shaders, input interpolation happens in
the prolog. However, when we compile the prolog we do not see the derivative
computations and therefore fail to turn the helper pixels on.