Stream: general

Topic: incorrectly using wasmbuilder.app

view this post on Zulip Daniel Macovei (May 11 2023 at 21:33):

I made two components using cargo-component here, one in the big folder and one in the hello folder. https://github.com/macovedj/builder-examples
I also used wasmbuilder to link them with the following diagram
Screenshot-2023-05-11-at-4.30.18-PM.png
I ran this jco command: jco transpile big-greet.wasm --map 'wasi-*=@bytecodealliance/preview2-shim/*' -o big-greet
It's been a bit since I used jco, so I'm guessing that's where the issue is, but there were a lot of steps so not totally sure where I went wrong, I got the following error. Would love to debug on my own, but I'm not sure how to use the error to figure out which thing I'm missing an implementation for. I would expect the map flag to provide all of the wasi interfaces that are needed. Any help is greatly appreciated, but I realize this might be a bit on the complicated side... Happy to provide more info I missed.

panicked at 'not implemented', crates/js-component-bindgen/src/bindgen.rs:1029:49
(jsct transpile) RuntimeError: unreachable
    at __rust_start_panic (wasm://wasm/0122631e:wasm-function[3490]:0x1fdc92)
    at rust_panic (wasm://wasm/0122631e:wasm-function[3486]:0x1fdc3f)
    at _ZN3std9panicking20rust_panic_with_hook17h1e5f3993ce22fe2aE (wasm://wasm/0122631e:wasm-function[3485]:0x1fdc0f)
    at _ZN3std9panicking19begin_panic_handler28_$u7b$$u7b$closure$u7d$$u7d$17h757395b3caa1a881E (wasm://wasm/0122631e:wasm-function[3471]:0x1fcbd6)
    at _ZN3std10sys_common9backtrace26__rust_end_short_backtrace17h3e911ea98537fbdbE (wasm://wasm/0122631e:wasm-function[3470]:0x1fcb38)
    at rust_begin_unwind (wasm://wasm/0122631e:wasm-function[3480]:0x1fd866)
    at _ZN4core9panicking9panic_fmt17he9c46855d60d636eE (wasm://wasm/0122631e:wasm-function[3604]:0x206c27)
    at _ZN4core9panicking5panic17hf333278c14c20b5eE (wasm://wasm/0122631e:wasm-function[3610]:0x207190)
    at _ZN20js_component_bindgen7bindgen9JsBindgen11instantiate17hfe4cbb5545331156E (wasm://wasm/0122631e:wasm-function[101]:0xf8e0)
    at _ZN20js_component_bindgen9component8generate17h2fb6336405b47ca9E (wasm://wasm/0122631e:wasm-function[198]:0x280ae)
GitHub - macovedj/builder-examples
Contribute to macovedj/builder-examples development by creating an account on GitHub.

view this post on Zulip Daniel Macovei (May 11 2023 at 21:39):

After some thought, I'll try and use a locally built jco to log out whatever implementation was expected

view this post on Zulip Daniel Macovei (May 11 2023 at 21:44):

Ah, looks like I need an implementation of this https://github.com/bytecodealliance/jco/blob/main/crates/js-component-bindgen/src/transpile_bindgen.rs#L350

jco/transpile_bindgen.rs at main · bytecodealliance/jco
JavaScript tooling for working with WebAssembly Components - jco/transpile_bindgen.rs at main · bytecodealliance/jco

view this post on Zulip Guy Bedford (May 11 2023 at 21:52):

@Daniel Macovei are you definitely using different string encodings between inputs and outputs of the component?

view this post on Zulip Guy Bedford (May 11 2023 at 21:52):

we can definitely add transcoding support, was just waiting for it to be needed

view this post on Zulip Guy Bedford (May 11 2023 at 21:53):

feel free to post an issue!

view this post on Zulip Daniel Macovei (May 11 2023 at 22:04):

I would have guessed not since I'm using cargo-component to create each component. Will dig in a little bit tomorrow and likely post something. Thanks!

view this post on Zulip Daniel Macovei (May 11 2023 at 22:08):

I don't have a huge need or anything. Was mostly just trying to play with the wasmbuilder app using the simplest imports and exports I could think of. One component just exports a hello world function, and the other imports that greeting and uppercases it

view this post on Zulip Guy Bedford (May 11 2023 at 22:18):

if you're able to share the generated component in a jco issue it would be good to look into the exact scenario further

view this post on Zulip Daniel Macovei (May 12 2023 at 18:00):

I opened this this morning. Working on a few things, but I also intend to look into this myself. https://github.com/bytecodealliance/jco/issues/75

jco doesn't support wasmbuilder.app composed components with string parameter and return values · Issue #75 · bytecodealliance/jco
This thread provides an example that should be easy to reproduce. The component generated from wasmbuilder can be found here

view this post on Zulip Daniel Macovei (May 12 2023 at 21:51):

fwiw when building locally, it looks like the very first wasm export that gets called by js is generate from js-component-bindgen-component. In the bindings for that component, it looks like it fails as soon as it calls into the generate function. Seems like a surprise to me because I thought the issue wouldn't happen until instantiate gets called, but I can't even log anything from the very first line of generate. I may not be building correctly, but I think I am. Have gone through most of the build scripts defined in the package.json

view this post on Zulip Daniel Macovei (May 15 2023 at 16:46):

I made some passthrough functions for some of the unimplemented logic for transcoding and instance flags. This way I was able to transpile without getting an error, but obviously had some issues in my bindings. This is what gets fed to instantiateCore in the result bindings, which appears to just be an alias of WebAssembly.instantiate. Was looking for flags and transcode fields in the mdn docs on WebAssembly.instantiate, and I'm guessing that these fields aren't used by WebAssembly.instantiate? Instead instantiateCore will get logic that calls WebAssembly.instantiate in different ways, depending on the field values? Happy to try and help out here if I've got an accurate perception of what needs doing.

({ exports: exports7 } = await instantiateCore(await module8, {
    callee: {
      adapter0: exports1['hello-world'],
    },
    flags: {
      instance1: ,
      instance2: ,
    },
    memory: {
      '': exports5.memory,
    },
    post_return: {
      adapter0: exports1['cabi_post_hello-world'],
    },
    realloc: {
      '': exports5.cabi_realloc,
    },
    transcode: {
      'utf8-to-utf8 (mem0 => mem1)': ,
      'utf8-to-utf8 (mem1 => mem0)': ,
    },
  }));

view this post on Zulip Guy Bedford (May 15 2023 at 21:55):

@Daniel Macovei I believe this will involve authoring some kind of createTranscoder(fromMem, toMem, encoding) => function (fromPtr, fromLen, toRealloc) intrinsic that returns a function with the core signature expected by the transcoding adapter. Where JS code would then do the memory copy in this case. I'm not sure the exact core signature or how the realloc function index is passed.

view this post on Zulip Guy Bedford (May 15 2023 at 21:56):

if you want to create a draft PR with your work on stubbing out the implementation errors happy to collaborate on it as well

view this post on Zulip Daniel Macovei (May 15 2023 at 21:57):

Happy to! At the moment the stubs basically just print debug statements and return empty strings, but I can still push it up

view this post on Zulip Guy Bedford (May 15 2023 at 22:03):

just having a test case wired in would be a huge help

view this post on Zulip Daniel Macovei (May 15 2023 at 22:14):

https://github.com/bytecodealliance/jco/pull/76

transcode stub by macovedj · Pull Request #76 · bytecodealliance/jco
This branch stubs a transcoding implementation, along with a few other changes so as to find an implementation for this issue. Building jco locally enables one to transpile the component found her...

view this post on Zulip Daniel Macovei (May 15 2023 at 22:15):

Was considering pulling the components themselves into the repo, but didn't want to clutter things. Kindof tricky describing an issue across repos, but I think I provided all the links needed.

Last updated: Dec 23 2024 at 12:05 UTC