[mono][wasm] Add interpreter support for calls to UnmanagedCallersOnly EntryPoint without managed delegate reference

[lewing]

#94615 (comment)

#94615 added EntryPoint support to UCO on wasm (it was missing before)

 
        [UnmanagedCallersOnly(EntryPoint = "display_meaning")]
        public static void DisplayMeaningExport(int meaning)
        {
            Console.WriteLine($"The meaning of life is {meaning}");
        }

but there is currently an issue with when invoking the export from unmanaged when there is no managed delegate pointing to it and something akin to the following workaround is required:

   Intptr workaround = (IntPtr)(delegate* unmanaged<int,void>)&display_meaning;  // needs to be in method loaded by interp prior to unmanaged call 

This is because get_native_to_interp must be called before attempting to invoke the unmanaged entry point or the call will fail. Without the call wasm_native_to_interp_ftndescs is never initialized. For the workaround to work the delegate * does not need to be reached/reachable, the interpreter simply needs to resolve the method prior to calling it from unmanaged.

Tagging subscribers to 'arch-wasm': @lewing
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Issue Details

---

#94615 (comment)

#94615 added EntryPoint support to UCO

 
        [UnmanagedCallersOnly(EntryPoint = "display_meaning")]
        public static void DisplayMeaningExport(int meaning)
        {
            Console.WriteLine($"The meaning of life is {meaning}");
        }

but there is currently an issue with when invoking the export from unmanaged when there is no managed delegate pointing to it.

   Intptr workaround = (IntPtr)(delegate* unmanaged<int,void>)&display_meaning;  // needs to be in method loaded by interp prior to unmanaged call 

Author:	lewing
Assignees:	-
Labels:	arch-wasm, area-VM-meta-mono
Milestone:	9.0.0

Tagging subscribers to this area: @BrzVlad, @kotlarmilos
See info in area-owners.md if you want to be subscribed.

Issue Details

---

#94615 (comment)

#94615 added EntryPoint support to UCO

 
        [UnmanagedCallersOnly(EntryPoint = "display_meaning")]
        public static void DisplayMeaningExport(int meaning)
        {
            Console.WriteLine($"The meaning of life is {meaning}");
        }

but there is currently an issue with when invoking the export from unmanaged when there is no managed delegate pointing to it.

   Intptr workaround = (IntPtr)(delegate* unmanaged<int,void>)&display_meaning;  // needs to be in method loaded by interp prior to unmanaged call 

unless get_native_to_interp is called before attempting to invoke the unmanaged entry point the call will fail because the n2m entry slot is not initialized.

Author:	lewing
Assignees:	lewing
Labels:	arch-wasm, area-Codegen-Interpreter-mono, area-VM-meta-mono, os-wasi, os-browser
Milestone:	9.0.0