Spir-v specifies shifts by values more than bit width to be undefined. This means removing the AND by (bitwidth-1) is invalid for zink. This opt produced ishl by constant (-1) when using soft fp64. This caused failures in a bunch of cts cases involving fp64 with softfp64 like: KHR-GL46.gpu_shader_fp64.builtin.ceil_double.
Cc: mesa-stable