Bug 285902 – REGRESSION (287397@main..288804@main): Wasm optimization/interpretation bug affecting dart2wasm

• Component: WebAssembly
• Status: RESOLVED FIXED

[Martin Kustermann]

Created attachment 473897 [details]
Wasm optimization bug seemingly introduced between JSC version [287397..288804]

We upgraded from JSC version 287397 to 288804 and started hitting issues in our tests for the dart2wasm compiler.

Here's one example where a miscompilation seems to happen, first we unpack the attached file:
```
% tar xvzf ~/sdk3/jsc_bug.tar.gz
regress.wasm
regress.mjs
pkg/dart2wasm/bin/run_wasm.js
```

Now we run it with normal JSC
```
% jsc  $PWD/pkg/dart2wasm/bin/run_wasm.js -- $PWD/regress.mjs $PWD/regress.wasm --
Bad state: No element
module0.wasm-function[Error._throwWithCurrentStackTrace]@[wasm code]
module0.wasm-function[closure wrapper at file:///usr/local/google/home/kustermann/repositories/sdk-gclient3/sdk/tests/corelib/string_codeunits_test.dart:9:26 trampoline]@[wasm code]
module0.wasm-function[expectThrowsStateError]@[wasm code]
module0.wasm-function[main]@[wasm code]
module0.wasm-function[_invokeMain]@[wasm code]
invokeMain@/tmp/jsc/regress.mjs:276:48
@/tmp/jsc/pkg/dart2wasm/bin/run_wasm.js:425:31
Error: [object WebAssembly.Exception]
Stack: undefined
```

It seemingly fails to catch this exception in a try/catch. The same code runs fine in Chrome/D8 & Firefox/JSShell.

Now fiddling with the flags, it seems when using `--useWasmIPInt=false` the issue goes away
```
% jsc --useWasmIPInt=false $PWD/pkg/dart2wasm/bin/run_wasm.js -- $PWD/regress.mjs $PWD/regress.wasm --
% echo $?
0
```

[Alexey Proskuryakov]

I verified the regression range, and that "--useWasmIPInt=false" fixes this. Also verified that this is still reproducing as of 288846@main.

[Radar WebKit Bug Importer]

<rdar://problem/142892203>

Pull request: https://github.com/WebKit/WebKit/pull/39103

Thank you for reporting this issue! I've checked the PR above against the test provided, and I confirmed it runs correctly with `--useWasmIPInt=1` now.

[EWS]

Committed 289082@main (a8ba8390855b): <https://commits.webkit.org/289082@main>

Reviewed commits have been landed. Closing PR #39103 and removing active labels.