Annotations for -ddump-exec

When running an accelerate-cuda program with -ddump-exec I get to see a lot of 'map', 'generate', 'fold1'. It would be nice to get more specific information. E.g. if I write

```
A.annotate "myfunc" $ A.replicate x y z
```

I expect to see "myfunc" in the output of -ddump-exec. However, I have no idea whether this still works in the presence of fusion.