ISPC missing symbol macOS

[maedoc]

Using the ISPC backend I've got a missing symbol (the C backend works fine, and plain futhark bench --backend=ispc bench_epiloss.fut also works),

ImportError                               Traceback (most recent call last)
/Users/duke/src/tvb-fut/bench_epiloss.ipynb Cell 5 in <cell line: 2>()
      1 from futhark_ffi import Futhark
----> 2 import _bench_epiloss
      3 epinet = Futhark(_bench_epiloss)
      4 w = np.loadtxt('weights.txt').astype('f')

ImportError: dlopen(/Users/duke/src/tvb-fut/_bench_epiloss.cpython-310-darwin.so, 0x0002): symbol not found in flat namespace (_futhark_mc_loop_ispc_57637)

I'll poke at it, but wanted to report.

[athas]

This is because the ISPC kernels are in a separate .o file. futhark-pycffi will have to be modified to also include that in the .so that gets built. (I don't actually remember who builds the .so.)

[maedoc]

when doing ISPC classically (i.e. hand written / without Futhark), I used ISPC to build the .o, c++ to build tasksys.cpp (does Futhark use this or it's still single core only?), and then c++ -shared to build the .so.

[athas]

Futhark's ISPC backend uses its own scheduler, not tasksys.cpp.

[pepijndevos]

Probably a clause needs to be added here to link the correct stuff

https://github.com/pepijndevos/futhark-pycffi/blob/bb2ca15ca6473e2a3dbe4c8d915781f7d4913077/futhark_ffi/build.py#L32-L40