[WASM] Jiterpreter crash using `System.Text.JSON` and `WasmNativeStrip` usage.

[nickwinder]

Description

Crash in the Jiterpreter using System.Text.JSON serialization or deserialization when native WASM is stripped or a high Emscripten optimization level is chosen.

Setting WasmNativeStrip to false rectifies the issue, so it seems the strip command is too aggressive, or is disobeying the EMSCRIPTEN_KEEP_ALIVE annotation on the mono_wasm_copy_managed_pointer symbol.

Reproduction Steps

Minimal repo highlighting the issue can be found at https://github.com/nickwinder/dotnet-8-webassembly-bug

Basically, use System.Text.JSON using WasmNativeStrip and Emscripten optimization of O3.

I've found other mixtures of settings cause the same issue, but this was the simplest and easiest to reproduce.

Expected behavior

Calling System.Text.JSON serialization/deserialization should not crash, even when native binary is stripped, or highly optimized.

Actual behavior

Crashes with the following error log.

raw cwrap mono_wasm_copy_managed_pointer not found

      at Ja (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter-support.ts:1862:15)
      at Ja (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter.ts:264:31)
      at $i (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter.ts:703:26)
      at ../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter.ts:736:9
      at Ul (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter.ts:1049:19)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:322624)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1589606)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1548333)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:791465)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:122212)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:85466)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:66234)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:301784)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1589606)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1548333)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:791465)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:122212)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:85466)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:241702)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:791302)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:324116)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1589606)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1548333)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:791465)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:122212)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:622449)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1525334)
      at Object.apply [as mono_wasm_invoke_method_bound] (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/dotnet.native.js:8:96257)
      at mono_wasm_invoke_method_bound (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/invoke-cs.ts:273:29)
      at Object.kr (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/invoke-cs.ts:184:13)
      at Object.DoSomething (tests/init-test.js:5:40)

Regression?

.NET7 still allows this combination of optimization and features.

Known Workarounds

No response

Configuration

.NET8
Env : Chrome browser (likely others) and Node.js environments.
Arch : WASM

Other information

No response

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

Crash in the Jiterpreter using System.Text.JSON serialization or deserialization when native WASM is stripped or a high Emscripten optimization level is chosen.

Setting WasmNativeStrip to false rectifies the issue, so it seems the strip command is too aggressive, or is disobeying the EMSCRIPTEN_KEEP_ALIVE annotation on the mono_wasm_copy_managed_pointer symbol.

Reproduction Steps

Minimal repo highlighting the issue can be found at https://github.com/nickwinder/dotnet-8-webassembly-bug

Basically, use System.Text.JSON using WasmNativeStrip and Emscripten optimization of O3.

I've found other mixtures of settings cause the same issue, but this was the simplest and easiest to reproduce.

Expected behavior

Calling System.Text.JSON serialization/deserialization should not crash, even when native binary is stripped, or highly optimized.

Actual behavior

Crashes with the following error log.

raw cwrap mono_wasm_copy_managed_pointer not found

      at Ja (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter-support.ts:1862:15)
      at Ja (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter.ts:264:31)
      at $i (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter.ts:703:26)
      at ../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter.ts:736:9
      at Ul (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/jiterpreter.ts:1049:19)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:322624)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1589606)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1548333)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:791465)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:122212)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:85466)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:66234)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:301784)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1589606)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1548333)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:791465)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:122212)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:85466)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:241702)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:791302)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:324116)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1589606)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1548333)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:791465)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:122212)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:622449)
      at null.<anonymous> (wasm:/wasm/00a3bc76:1:1525334)
      at Object.apply [as mono_wasm_invoke_method_bound] (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/dotnet.native.js:8:96257)
      at mono_wasm_invoke_method_bound (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/invoke-cs.ts:273:29)
      at Object.kr (../WasmStripBug/WasmStripBug/bin/Release/net8.0/browser-wasm/AppBundle/https:/raw.githubusercontent.com/dotnet/runtime/5535e31a712343a63f5d7d796cd874e563e5ac14/src/mono/wasm/runtime/invoke-cs.ts:184:13)
      at Object.DoSomething (tests/init-test.js:5:40)

Regression?

.NET7 still allows this combination of optimization and features.

Known Workarounds

No response

Configuration

.NET8
Env : Chrome browser (likely others) and Node.js environments.
Arch : WASM

Other information

No response

Author:	nickwinder
Assignees:	-
Labels:	arch-wasm, untriaged, area-Build-mono, area-VM-meta-mono
Milestone:	-

[radical]

cc @kg

[kg]

Hi,
Thanks for the report! The good news is that this isn't formally a crash, and is instead a compatibility issue with emscripten's optimizer where the function we're looking for is getting renamed. So while we work on a long-term fix, it should be safe and reliable to use a workaround like the one you've come up with (disabling NativeStrip) or a different suitable workaround. An optimization level of 1 would also prevent this renaming from happening (O2 and O3 enable it), I believe. You could also try passing -s ASSERTIONS=1 to the linker, but I haven't tested it myself - just a guess from reading emscripten's source code.

[nickwinder]

Thanks @kg. The issue with all the workaround is that they all produce huge binaries, so it's not usable in production.
If there are any lower level workarounds which don't involved manipulating the stripping/optimization I'd love to explore them. But as of now, I wasn't able to find one.
Thanks

[kg]

Try adding -lexports.js to your EmccLinkOptimizationFlag and see what happens

[nickwinder]

Awesome that does the trick! Thanks so much.