HelloWasm app is busted

[alexreinking]

The HelloWasm app isn't working right.

The build itself is broken and only happens to work. The core.cpp file uses the headers from a Halide filter library that it doesn't depend on. This can be observed by running cmake --build build --target wasm.

Then, the threaded versions don't work in-browser. Running Chrome with the following two flags enabled:

1. chrome://flags/#enable-javascript-experimental-shared-memory
2. chrome://flags/#enable-experimental-webassembly-features

shows an error in the generated emscripten code along the lines of TypeError: wait.value.then is not a function.

Emscripten error

Uncaught (in promise) TypeError: wait.value.then is not a function
    at __emscripten_thread_mailbox_await (index_threads.js:1:77532)
    at index_threads.wasm:0x3c555
    at callRuntimeCallbacks (index_threads.js:1:24660)
    at initRuntime (index_threads.js:1:7833)
    at doRun (index_threads.js:1:204130)
    at run (index_threads.js:1:204373)
    at runCaller (index_threads.js:1:203667)
    at removeRunDependency (index_threads.js:1:8897)
    at receiveInstance (index_threads.js:1:10976)
    at receiveInstantiationResult (index_threads.js:1:11116)
__emscripten_thread_mailbox_await @ index_threads.js:1
$Kd @ index_threads.wasm:0x3c555
callRuntimeCallbacks @ index_threads.js:1
initRuntime @ index_threads.js:1
doRun @ index_threads.js:1
run @ index_threads.js:1
runCaller @ index_threads.js:1
removeRunDependency @ index_threads.js:1
receiveInstance @ index_threads.js:1
receiveInstantiationResult @ index_threads.js:1

This is using the latest EMSDK, cloned from upstream as of this morning.

[abadams]

This threaded version works for me on linux chrome, but freezes on os x chrome: https://halide-lang.org/wasm_demo/index.html?simd&threads

It used to work on both.

[alexreinking]

https://halide-lang.org/wasm_demo/index.html?simd&threads

I'm sure that was compiled with an older version of EMSDK, too.

[steven-johnson]

Hmm, it works perfectly on my Mac using Chrome using today's EMCC and the wasm experimental features enabled in Chrome. What specific cmake configure command did you use? I did

mkdir build
cd build
Halide_DIR=~/halide-19-install/ cmake ..
ninja

[steven-johnson]

This can be observed by running cmake --build build --target wasm.

What's with the --target wasm part? I don't see any target of that name.

[steven-johnson]

FYI, I have Experimental JavaScript shared memory features set to default

[steven-johnson]

(I built with today's EMCC, btw... maybe there was a temporary buggy version?)