There's a difference between speed and correctness. If you promise something in the spec (e.g. unreachable control flow not mattering), in practice, that promis

There's a difference between speed and correctness. If you promise something in the spec (e.g. unreachable control flow not mattering), in practice, that promise should be upheld. If it's upheld with a 32x slowdown (e.g. warp divergence), then so be it, but the code should still run correctly according to the spec.