Internal compiler error (unhandled IO exception).: diffStm.convert: (to_bits32, i32, f32)

[rowanG077]

Using:

https://github.com/diku-dk/sorts/blob/master/lib/github.com/diku-dk/sorts/radix_sort.fut

With this reproducer, I expect due to get_bit:

import "radix_sort"

entry foo [n] (xs: [n]f32) (offset: f32): f32 =
  let go o = f32.sum (radix_sort_float f32.num_bits f32.get_bit (map (o +) xs))
  in vjp go offset 1

Due to this error:

Internal compiler error (unhandled IO exception).
Please report this at https://github.com/diku-dk/futhark/issues
diffStm.convert: (to_bits32, i32, f32)
CallStack (from HasCallStack):
  error, called at src/Futhark/AD/Rev.hs:233:27 in futhark-0.25.31-BiAOjOG8YPHE7SVcE6pZGA:Futhark.AD.Rev

[athas]

This will be an easy fix when I return to a computer, but I did think we had systematic unit tests for this. A little disturbing that we have overlooked something.

[athas]

Smaller case:

entry fwd (x: f32) = jvp (f32.to_bits) x 1

entry rev (x: f32) = vjp (f32.to_bits) x 1