[wasm] Improvements to startup performance of mono_wasm_get_assembly_exports

[kg]

Generated JSImport/JSExport initializer does an Environment.Version check to see if we're on NET7. That check is tremendously expensive, because it fetches a CustomAttribute instance off of something in corlib, then parses the version string (parsing version strings initializes a bunch of stuff). This PR removes that check and adds a linker dependency to keep the registration method alive so it can be called when needed.

We will also need to document that DLLs (in nugets?) generated by this new version of the generator won't work on NET7 runtimes, since the relevant logic to perform automatic registration on that version.

[kg]

Requesting review to get feedback. I hope someone knows trimming better than me and can suggest how to fix this. Put a dependency attribute of some kind on the generated module initializer, maybe?

[pavelsavara]

Could you please show the generated code ?

[kg]

Could you please show the generated code ?

    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute]
    unsafe class __GeneratedInitializer
    {
        [global::System.ThreadStaticAttribute]
        static bool initialized;
        [global::System.Runtime.CompilerServices.ModuleInitializerAttribute, global::System.Diagnostics.CodeAnalysis.DynamicDependencyAttribute(global::System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.PublicMethods | global::System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.NonPublicMethods, typeof(__GeneratedInitializer))]
        static internal void __Net7SelfInit_()
        {
        }

        [global::System.Diagnostics.CodeAnalysis.DynamicDependencyAttribute("__Wrapper_PrepareToRender_1401412665", "MainJS", "RayTracer")]
        [global::System.Diagnostics.CodeAnalysis.DynamicDependencyAttribute("__Wrapper_OnClick_1317452459", "MainJS", "RayTracer")]
        static void __Register_()
        {
            if (initialized || global::System.Runtime.InteropServices.RuntimeInformation.OSArchitecture != global::System.Runtime.InteropServices.Architecture.Wasm)
                return;
            initialized = true;
            global::System.Runtime.InteropServices.JavaScript.JSFunctionBinding.BindManagedFunction("[RayTracer]MainJS:PrepareToRender", 1401412665, new global::System.Runtime.InteropServices.JavaScript.JSMarshalerType[] { global::System.Runtime.InteropServices.JavaScript.JSMarshalerType.ArraySegment(global::System.Runtime.InteropServices.JavaScript.JSMarshalerType.Byte), global::System.Runtime.InteropServices.JavaScript.JSMarshalerType.Int32, global::System.Runtime.InteropServices.JavaScript.JSMarshalerType.Int32 });
            global::System.Runtime.InteropServices.JavaScript.JSFunctionBinding.BindManagedFunction("[RayTracer]MainJS:OnClick", 1317452459, new global::System.Runtime.InteropServices.JavaScript.JSMarshalerType[] { global::System.Runtime.InteropServices.JavaScript.JSMarshalerType.Task() });
        }
    }

[pavelsavara]

Let's rename __Net7SelfInit_ to something like __DontTrimRegister_. Also please update description on top of this PR.

[pavelsavara]

Here we are removing support for 3rd party library/nuget generated by Net9 SDK from being able to run on Net7 runtime.
I think it's OK. @lewing thoughts ?

[maraf]

Here we are removing support for 3rd party library/nuget generated by Net9 SDK from being able to run on Net7 runtime. I think it's OK. @lewing thoughts ?

.NET 7 is EOL on May 14, 2024. Removing support seems reasonable to me

[radekdoulik]

works nicely