Blender Git Loki

Fix T92972: Cycles HIP wrong render display after a recent refactor

It's unclear why this fails. Maybe the size of half4 is not the expected
8 bytes and adjacent pixels are overwritten. Or there is some bug in the
HIP compiler writing a struct into global memory, which we probably don't
do elsewhere in the kernel.

Thanks to Thomas, William and Jeroen for helping investigate this.