Fix web version (infinite loop)

[mitschabaude]

The web version of snarkyjs is reported to go into an infinite loop when compiling, cc @maht0rz @jackryanservia

one difference to node is that for web, there's some manually written "table" of functions that are run from workers. if that table got out of date, we had the web version break sometimes
here: https://github.com/o1-labs/snarkyjs/blob/main/src/chrome_bindings/worker_run.js

[maht0rz]

Are there any pointers as to how this can be fixed? I'd like to help

[mitschabaude]

I see two possible strategies for fixing:

1. Look at the recent history of the file bindings.js in the Mina repo, to see if functions where added / changed that got out of date with that function table mentioned above. Try to fix by updating the table
2. Try to figure out where the infinite loop happens. I usually do that with "log bisection". That probably requires to build snarkyjs from source and put print_endline statements in ocaml code (e.g. snarky_js_bindings_lib.ml in the Mina repo). Snarkyjs is built by running 'make snarkyjs' from the Mina repo

[maht0rz]

@mitschabaude is this the file you've mentioned above? I'll try comparing it manually
https://github.com/MinaProtocol/mina/blob/develop/src/lib/crypto/kimchi_bindings/js/bindings.js

[mitschabaude]

@mitschabaude is this the file you've mentioned above? I'll try comparing it manually https://github.com/MinaProtocol/mina/blob/develop/src/lib/crypto/kimchi_bindings/js/bindings.js

Yes, @maht0rz, this is it! That file is huge so I recommend looking at its recent git history for guessing relevant changes.

[maht0rz]

Thanks to @gregor#5446's instructions i've noticed a discrepancy in the web/chrome bindings, introduced in the following commit: MinaProtocol/mina@99dc99e#diff-c2c0ff175c607b726ab7857e08ab0d7389d6c6f2b2fb1039583a0505c47b28e9R1217

Seems to me like caml_pasta_fp_plonk_index_create now also accepts a new argument prev_challenges, but this isn't reflected in worker_run.js

Attempting to fix 🎢

[maht0rz]

Here are two profiler outputs from firefox, before the fix and after the attempted fix.

I've added undefined since i was not able to find a coresponding WASM-ish value in the plonk_wasm argument.

caml_pasta_fp_plonk_index_create: {
        args: [
          plonk_wasm.WasmFpGateVector,
          undefined /* number */,
          undefined, // this is what i've added
          plonk_wasm.WasmFpSrs,
        ],
        res: plonk_wasm.WasmPastaFpPlonkIndex,
      },

You can see the stack trace / calls changing after i've added the extra argument in the binding but i am still unable to compile my contract.

[mitschabaude]

awesome! undefined seems to be fine because prev_challenges is an integer. I think you just need to fix caml_pasta_fq_plonk_index_create in addition to caml_pasta_fp_plonk_index_create (note: fq vs fp)

[maht0rz]

It works, i will issue a PR right now! :)