Function ballot

Returns a bitfield (u32 or u64) containing the result of its i1 argument in all active lanes, and zero in all inactive lanes.

This intrinsic does not behave like a normal function call; it is a "convergent" operation and as such has non-standard control-flow effects which need special treatment by the language. Rust currently does not properly support convergent operations. This operation is hence provided on a best-effort basis. Using it may result in incorrect code under some circumstances.