[wasm] Add test checking that disabiling SIMD actually disables it

[radekdoulik]

The SIMD cannot be disabled anymore. These are the 2 parts we need to fix:

• [x] do not put -msimd128 to emcc-default.rsp, otherwise we compile with SIMD even when WasmEnableSIMD is false. Instead add it conditionally in src/mono/wasm/wasm.proj, src/mono/wasm/runtime/CMakeLists.txt and src/mono/wasm/build/WasmApp.Native.targets
• [x] do not build our mono runtime with -msimd128 or provide multiple native libraries versions

optionally:

• [ ] do not pass '--enable-simd' to wasm-opt. I think this doesn't add any SIMD instructions, so we probably don't need it. We should check it though.

following step:

• [ ] add WBT test to check that build with SIMD disabled produces .wasm files without SIMD instructions. This can be done easily once we have the wa-info tool in the runtime repo.
• [ ] Run SIMD WBT with older Firefox (88) or Chrome to check it works on runtime
• [ ] Disable SIMD and WASM EH in Jiterpreter if it was disabled during build
• [ ] AOT complication produces some SIMD althought it was disabled

[radekdoulik]

@kg do we need add_compile_options(-msimd128) in the src/mono/CMakeLists.txt for the interpreter to work with SIMD? if not, we can probably remove it. I think the performance will not be affected much by this. Otherwise we would need multiple versions of mono native libs I think.

[vargaz]

I think --enable-simd is needed by wasm-opt to be able to read an input file which uses simd opcodes.

[kg]

@kg do we need add_compile_options(-msimd128) in the src/mono/CMakeLists.txt for the interpreter to work with SIMD? if not, we can probably remove it. I think the performance will not be affected much by this. Otherwise we would need multiple versions of mono native libs I think.

Without -msimd128 no code that uses wasm intrinsics will compile, even if we don't run it. So we would need to ifdef everything relevant out I think.

Part of the problem is that -msimd128 isn't just an 'enable support' flag, unfortunately it turns a bunch of other stuff on by default and that's probably the source of the sections or opcodes that are breaking things for people.

I don't think the switch specifically needs to be there; I tried a bunch of things to try and get SIMD to work and that was the only simple solution I found that worked.

[ghost]

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

Issue Details

---

The SIMD cannot be disabled anymore. These are the 2 parts we need to fix: - [ ] do not put `-msimd128` to `emcc-default.rsp`, otherwise we compile with SIMD even when `WasmEnableSIMD` is `false`. Instead add it conditionally in `src/mono/wasm/wasm.proj`, `src/mono/wasm/runtime/CMakeLists.txt` and `src/mono/wasm/build/WasmApp.Native.targets` - [ ] do not build our mono runtime with `-msimd128` or provide multiple native libraries versions optionally: - [ ] do not pass '--enable-simd' to `wasm-opt`. I think this doesn't add any SIMD instructions, so we probably don't need it. We should check it though. following step: - [ ] add WBT test to check that build with SIMD disabled produces `.wasm` files without SIMD instructions. This can be done easily once we have the `wa-info` tool in the runtime repo.

Author:	radekdoulik
Assignees:	radekdoulik
Labels:	`arch-wasm`, `area-Build-mono`
Milestone:	8.0.0

[radekdoulik]

For mono libs and src/mono/CMakeLists.txt I will try to extract the interp simd code to a separate library, similar to what we do for exception handling, and link it conditionally.

[radekdoulik]

remaining parts can be done in net9

[KubaGluszkiewicz]

Hello, since our browser wasm application is deployed into various TV Systems like Tizen or WebOS which are internally baked by older chromium versions, disabling SIMD support is crucial for us. I'm trying to follow issues here (at least 2 were open related to enabling SIMD by default), and i see you are trying to fix it. I'm using version .net8 preview 7 and i'm not able to switch off SIMD support using csproj settings. Question is it possible in Preview7 to fully disable SIMD? If not, it will be possible in upcoming RC1 version?

My project settings:

<TargetFramework>net8.0</TargetFramework>
<RuntimeIdentifier>browser-wasm</RuntimeIdentifier>
<OutputType>Exe</OutputType>
<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
<WasmEnableExceptionHandling>False</WasmEnableExceptionHandling>
<WasmEnableSIMD>False</WasmEnableSIMD>
<WasmBuildNative>True</WasmBuildNative>

At program launch i'm getting bunch of errors like this:

MONO_WASM: instantiate_wasm_module() failed CompileError: WebAssembly.instantiateStreaming(): Compiling function #104:"19" failed: Invalid opcode (enable with --experimental-wasm-simd) @+28002
nt @ dotnet.runtime.js:3
dotnet.js:3 MONO_WASM: CompileError: WebAssembly.instantiateStreaming(): Compiling function #104:"19" failed: Invalid opcode (enable with --experimental-wasm-simd) @+28002
l @ dotnet.js:3
main.js:26 Error initializing dotnet: CompileError: WebAssembly.instantiateStreaming(): Compiling function #104:"19" failed: Invalid opcode (enable with --experimental-wasm-simd) @+28002
(anonymous) @ main.js:26
dotnet.js:3 Error in mono_download_assets: CompileError: WebAssembly.instantiateStreaming(): Compiling function #104:"19" failed: Invalid opcode (enable with --experimental-wasm-simd) @+28002
(anonymous) @ dotnet.js:3
4dotnet.js:3 Uncaught (in promise) CompileError: WebAssembly.instantiateStreaming(): Compiling function #104:"19" failed: Invalid opcode (enable with --experimental-wasm-simd) @+28002
dotnet.runtime.js:3 Uncaught (in promise) CompileError: WebAssembly.instantiateStreaming(): Compiling function #104:"19" failed: Invalid opcode (enable with --experimental-wasm-simd) @+28002
2index.html:1 Uncaught (in promise) CompileError: WebAssembly.instantiateStreaming(): Compiling function #104:"19" failed: Invalid opcode (enable with --experimental-wasm-simd) @+28002

not sure what i can do more to get rid of SIMD support in .Net8

[maraf]

@KubaGluszkiewicz Just a note, use lower case true/false in MSBuild properties.

[lewing]

<WasmEnableSIMD>false</WasmEnableSIMD> should be the only thing required to disable simd (and eh since it defaults to the simd setting) and the setting is fully functional now.

[maraf]

<WasmEnableSIMD>false</WasmEnableSIMD> should be the only thing required to disable simd (and eh since it defaults to the simd setting) and the setting is fully functional now.

I have it on my list. Using chrome 85 on CI should be enough

[lewing]

add WBT test to check that build with SIMD disabled produces .wasm files without SIMD instructions. This can be done easily once we have the wa-info tool in the runtime repo.

Running wasm-opt without --enable- is an easy way to see what is in use

[paulguz-datapa]

We have customers hitting this on Windows 10 machines. What is the timescale for the fix?

[maraf]

@paulguz-datapa Disabling SIMD should be working, they this issue open only to make an automated test. Are you setting both WasmEnableExceptionHandling and WasmEnableSIMD to false? I have published a simple with disabled SIMD here https://maraf.github.io/dotnet-wasm-nosimd/. Can you check it works in your environment?

[paulguz-datapa]

@maraf Yes, those flags work, thanks.

[lewing]

Closing as completed if this is incorrect please reopen

[luccawilli]

@maraf unfortunately your fix does not fix our problem. We got a small project running on blazor webassemly and after the update to .net8, we received feedback that the website was no longer working for them. As mentioned in this Issue, we decided to disable SIMD (the error message also pointed it out) via adding the Wasm Section to our project file.

<WasmEnableSIMD>false</WasmEnableSIMD>
<WasmEnableExceptionHandling>false</WasmEnableExceptionHandling>

Unfortunately, this does not solve the actual problem. We received still the same error.

Our test environment runs on "Microsoft Windows Server 2019 Standard - 10.0.17763" is a Virtual Machine with the processor "Intel64 Family 6 Model 85 Stepping 7 GenuineIntel" (Unfortunately without SIMD support). Hosting seems to be unrelated, I get the error in the IIS as well as in the Docker Image hosted Variant.

Unfortunately, I am not allowed to share the project code with you, so I have created a sample application that at least also outputs a SIMD error message. Unfortunately I can't get the same error as in the project above. https://github.com/luccawilli/dotnet-wasm-nosimd

It works on my personal machine ;)

Nevertheless, I suspect that SIMD is still included in the published Version somewhere. Do you have an idea what could go wrong?

[maraf]

@luccawilli If I understand it correctly, you are able to reproduce the error in your test environment, right? Can we please verify that https://maraf.github.io/dotnet-wasm-nosimd/ works on the machine without SIMD?

[luccawilli]

@maraf correct, your example works without an error. But it does not use any Pages or Components.

[maraf]

But it does not use any Pages or Components.

It's plain WebAssembly without blazor.

And your sample with Blazor doesn't work https://github.com/luccawilli/dotnet-wasm-nosimd, right? Do you have wasm-tools workload installed? (dotnet workload install wasm-tools)

[luccawilli]

@maraf Yes correct, mine does not work. And yes i installed wasm-tools.

[maraf]

Thanks! I'm getting the same "AllowRange" error on my machine. I'll investigate it

[LostBeard]

I have created demonstration projects showing how to build Blazor WASM apps with both SIMD enabled and disabled. And then loading the appropriate build at runtime based on the environment.

Blazor Web App SIMD Detect Example
BlazorWebAppSIMDDetectExample

Blazor WebAssembly Standalone SIMD Detect Example BlazorWASMSIMDDetectExample

[maraf]

@luccawilli The "AllowRange" error comes from the Jiterpreter that is testing what capabilities it can use. We'll prepare a fix for it not to test SIMD on runtime when it was disabled during compilation.

Anyway, with disable SIMD during build (WasmEnableSIMD=false and WasmEnableExceptionHandling=false) the app works despite it prints error to the console (the Blazor UI renders and all interactions work). You can get rid of the error with the following setting

<BlazorWebAssemblyRuntimeOptions>--no-jiterpreter-simd-enabled --no-jiterpreter-wasm-eh-enabled</BlazorWebAssemblyRuntimeOptions>

[LostBeard]

My comment here

Interesting note. I have noticed that my devices or browsers that do not support SIMD also throw an error MONO_WASM: Disabling jiterpreter after 2 failures if BlazorWebAssemblyJiterpreter is not also disabled. (The app still runs with the error.) Disabling both SIMD and the jiterpreter when SIMD is not supported works without any further issues on my test devices.

I found that disabling SIMD without also disabling BlazorWebAssemblyJiterpreter gave an error but still allowed the app to run.

@maraf You "cc@kg" my above comment on that thread. maraf quoting my above comment

[maraf]

I found that disabling SIMD without also disabling BlazorWebAssemblyJiterpreter gave an error but still allowed the app to run.

You actually don't need to disable the whole jiterpreter, just the SIMD and EH

[luccawilli]

@maraf Thank you for the investigation. As i see the error in my test app has vanished :)

Unfortunately, the change does not yet solve any problems in our main project. I will try to improve my test app, so that i can show you my main problem.

[luccawilli]

So I have improved my example. It now shows the same error that we get in our main project. https://github.com/luccawilli/dotnet-wasm-nosimd-try2

I also added the publish result and the folder publish profile.

The error shown in my test system:

No errors on my system (with SIMD support) (except for the missing icon)

@maraf Can you also investigate this one? Thanks alot :)

[maraf]

Why are you setting WasmBuildNative=false? This setting disables relinking .NET runtime and thus makes all the other settings void. We are improving the experience in 9 to produce an error when incompatible settings are used

[luccawilli]

Oh damn, okay alright. I didn't know that. I had to add it because my build agent (a linux machine) had thrown the following error: WasmApp.Native.targets(737,5): error : MarshalingPInvokeScanner.Assemblies cannot be empty

But I think I can ignore that, since it only needs to be published in my Docker-Image. Btw. to build and publish it in a Docker-Image, i had to install python3. (Maybe that also a problem on my build agent.) RUN apt-get update RUN apt-get install -y python3

Thank you once again Best regards