This repository is trying to demonstrate an issue when trying to compile a multi-theaded Rust program targeting wasm32-unknown-emscripten. To reproduce the error, you will need to have a very recent (git) version of LLVM in Emscripten, to get around this issue.
When using a nightly 1.59.0-dev, from 2021-12-06 I get a wasm file that works as expected. When using rust 1.60.0-nightly, I get the error:
[parse exception: attempted pop from empty stack / beyond block start boundary at 24770 (at 0:24770)]
Fatal: error in parsing input
emcc: error: '/home/greg/Extras/temp/emsdk/binaryen/main_64bit_binaryen/bin/wasm-emscripten-finalize --minimize-wasm-changes /home/greg/rust-examples/wasm-threads/target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm -o /home/greg/rust-examples/wasm-threads/target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm --detect-features' failed (returned 1)
...running wasm-emscripten-finalize with --debug on the "broken" *.wasm results in:
$ wasm-emscripten-finalize --minimize-wasm-changes target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm -o target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm --detect-features --debug
<snip>
readExpression seeing 16
zz node: Call
<==
getInt8: 128 (at 24764)
getInt8: 128 (at 24765)
getInt8: 128 (at 24766)
getInt8: 128 (at 24767)
getInt8: 0 (at 24768)
getU32LEB: 0 ==>
== popExpression
== popExpression
== popExpression
zz recurse from 3 at 24769
zz recurse into 3 at 24769
getInt8: 26 (at 24769)
readExpression seeing 26
zz node: Drop
== popExpression
== popExpression
== popExpression
== popExpression
== popExpression
== popExpression
[parse exception: attempted pop from empty stack / beyond block start boundary at 24770 (at 0:24770)]
Fatal: error in parsing input
wasm-validate doesn't seem to like the input to wasm-emscripten-finalize either:
$ wasm-validate --enable-threads target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:00060c2: error: type mismatch in drop, expected [any] but got []
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0006494: error: type mismatch at end of function, expected [] but got [i64]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0006f27: error: type mismatch in drop, expected [any] but got []
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:00072a1: error: type mismatch at end of function, expected [] but got [i32, i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:00073b5: error: type mismatch at end of function, expected [] but got [i32, i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0007529: error: type mismatch at end of function, expected [] but got [i32, i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0007940: error: type mismatch at end of function, expected [] but got [i32, i32, i32]
```
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000798a: error: type mismatch at end of function, expected [] but got [i32, i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0007a32: error: type mismatch in drop, expected [any] but got []
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0007db3: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0008f73: error: type mismatch in drop, expected [any] but got []
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0009169: error: type mismatch in drop, expected [any] but got []
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000952c: error: type mismatch in drop, expected [any] but got []
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0009752: error: type mismatch in drop, expected [any] but got []
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000a273: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000baaa: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000c327: error: type mismatch at end of function, expected [] but got [i32, i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000c376: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000c3f8: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000c534: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000d7e3: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000d8c2: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000d9b7: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000dea8: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000df5a: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000e00d: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000e0bd: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000e420: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000e6a3: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000f52d: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000fa38: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:000ff14: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:001053c: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0010938: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0010cab: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0010d72: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0011356: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0011a27: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0011e1b: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0011f04: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0012078: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:001232e: error: type mismatch in implicit return, expected [i32] but got [... i64]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:001232e: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0012557: error: type mismatch at end of function, expected [] but got [i32, i32, i64]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:00128d8: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0013d86: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0013f18: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:00140a3: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0014d73: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0015182: error: type mismatch at end of function, expected [] but got [... i32, i32, i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0015bea: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:00173ee: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0017802: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0017dc6: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:001817f: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0018272: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:00184ab: error: type mismatch at end of function, expected [] but got [i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:001864a: error: type mismatch at end of function, expected [] but got [i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:0018c22: error: type mismatch at end of function, expected [] but got [i32, i32, i32, i32]
target/wasm32-unknown-emscripten/release/deps/wasm_threads.wasm:00191b1: error: type mismatch at end of function, expected [] but got [i32]
```
The working wasm file compiled with 1.59.0 is included in the repository, it can be run with either:
node --experimental-wasm-threads --experimental-wasm-bulk-memory target/wasm32-unknown-emscripten/release/deps/wasm_threads.js
...or...
emrun index-wasm.html
...and the broken version (compiled with 1.6.0) of the wasm file that chokes wasm-emscripten-finalize is at: target/wasm32-unknown-emscripten/release/deps/broken_wasm_threads.wasm
Versions:
$ rustc +nightly --version --verbose
rustc 1.60.0-nightly (a00e130da 2022-01-29)
binary: rustc
commit-hash: a00e130dae74a213338e2b095ec855156d8f3d8a
commit-date: 2022-01-29
host: x86_64-unknown-linux-gnu
release: 1.60.0-nightly
LLVM version: 13.0.0
$ rustc +nightly-2021-12-06 --version --verbose
rustc 1.59.0-nightly (e2116acae 2021-12-05)
binary: rustc
commit-hash: e2116acae59654bfab2a9729a024f3e2fd6d4b02
commit-date: 2021-12-05
host: x86_64-unknown-linux-gnu
release: 1.59.0-nightly
LLVM version: 13.0.0
$ emcc --version
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.3-git (a1a755948a6e25c0fa62fc8fdcb89dc372618a63)
Copyright (C) 2014 the Emscripten authors (see AUTHORS.txt)
This is free and open source software under the MIT license.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ wasm-validate --version
1.0.13
...you will also need to compile the gxx_personality_v0_stub.cpp file in the src/ directory:
emcc -c gxx_personality_v0_stub.cpp -pthread
Running cargo-bisect-rustc results in the following regression report for this issue:
searched nightlies: from nightly-2021-12-06 to nightly-2022-02-03
regressed nightly: nightly-2022-01-25
searched commit range: https://github.com/rust-lang/rust/compare/84322efad553c7a79c80189f2d1b9197c1aa005f...51126be1b260216b41143469086e6e6ee567647e
regressed commit: https://github.com/rust-lang/rust/commit/42313dd29b3edb0ab453a0d43d12876ec7e48ce0
<details>
<summary>bisected with <a href='https://github.com/rust-lang/cargo-bisect-rustc'>cargo-bisect-rustc</a> v0.6.1</summary>
Host triple: x86_64-unknown-linux-gnu
Reproduce with:
```bash
cargo bisect-rustc -vv --start=2021-12-06 --with-src -- build --release