[Crocus] crocus example does not work

[bongjunj]

Hi, I'm running the examples of crocus (cranelift/isle/veri/veri_engine).
The doc says I can test crocus using the following command:

cargo build --package=veri_engine # build crocus

path/to/pcrocus -i cranelift/isle/veri/veri_engine/examples/mid-end/broken_bor_band_consts.isle -t simplify --codegen cranelift/codegen/ --x64

(I added --x64 part since the error message tells me to do so)

But it fails with the following error messages

Writing generated file: /home/llfuzz/transopt-experiment/wasmtime/output/clif_opt.isle
Writing generated file: /home/llfuzz/transopt-experiment/wasmtime/output/clif_lower.isle
Missing term type instantiation for simplify

But the input ISLE file does have instantiation for simplify.

// wasmtime/cranelift/isle/veri/veri_engine/examples/mid-end/broken_bor_band_consts.isle
// ...

(spec (simplify x) (provide (= x result)))
(instantiate simplify
    ((args (bv 8)) (ret (bv 8)) (canon (bv 8)))
    ((args (bv 16)) (ret (bv 16)) (canon (bv 16)))
    ((args (bv 32)) (ret (bv 32)) (canon (bv 32)))
    ((args (bv 64)) (ret (bv 64)) (canon (bv 64)))
)
(decl simplify (Value) Value)

// ...

I think the parsing part is not working for crocus.

[cfallin]

cc @avanhatt or @mmcloughlin , any thoughts?