WIP: nir: lower int64 in a single pass.
Lowering passes should remove all occurrences of the instructions which are to be lowered. As lower_int64 emits other 64bit instructions while lowering, this hasn't been true. As this pass is fairly simple, it should work to lower all requested int64 instructions in a single pass. WIP because I'm not sure if I caught all combinations of options.
Edited by Daniel Schürmann