glsl-predication-on-large-array: Test predication on values from large array

Big local arrays may be handled differently than smaller ones, e.g. stored in a global memory. However drivers may have a subtle error combining this optimization with helper invocations of fragment shader.

Since all side-effects of helper invocations are being ignored - driver may also erroneously ignore stores to a local array which was lowered to a global memory.

This may cause an issue when a control flow in helper invocation depends on the value written to such array.

To test this we make a loop which depends on a value written to a big local array, so if stores are being ignored - the loop will become infinite, causing a hang.

Tests: mesa#3256 (closed) Signed-off-by: Yevhenii Kharchenko yevhenii.kharchenko@globallogic.com