ExecutionEngineException in Unity3d IL2CPP iOS

[mjokipii]

Running code using Infer.NET fails with an ExecutionEngineException on iOS when built with IL2CPP from Unity3d. Some of the instantiations of generic types used internally don't exist during compile time which causes the corresponding iOS AOT code to be missing at runtime.

Details:
Unity 2018.3
Microsoft.ML.Probabilistic.dll
Microsoft.ML.Probabilistic.Compiler.dll

ExecutionEngineException: Attempting to call method 'Microsoft.ML.Probabilistic.Models.ModelBuilder::SearchExpression<System.Boolean>' for which no ahead of time (AOT) code was generated.
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Utilities.Util.Invoke (System.Reflection.MethodBase method, System.Object target, System.Object[] parameters) [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Models.ModelBuilder.Build (Microsoft.ML.Probabilistic.Models.InferenceEngine engine, System.Boolean inferOnlySpecifiedVars, System.Collections.Generic.IEnumerable`1[T] vars) [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Models.InferenceEngine.BuildAndCompile (System.Boolean inferOnlySpecifiedVars, System.Collections.Generic.IEnumerable`1[T] vars) [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Models.InferenceEngine.GetCompiledInferenceAlgorithm (System.Boolean inferOnlySpecifiedVars, Microsoft.ML.Probabilistic.Models.IVariable var) [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Models.InferenceEngine.Infer (Microsoft.ML.Probabilistic.Models.IVariable var) [0x00000] in <00000000000000000000000000000000>:0 
  at Main.TwoCoins () [0x00000] in <00000000000000000000000000000000>:0 
  at Main.Start () [0x00000] in <00000000000000000000000000000000>:0 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Utilities.Util.Invoke (System.Reflection.MethodBase method, System.Object target, System.Object[] parameters) [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Models.ModelBuilder.Build (Microsoft.ML.Probabilistic.Models.InferenceEngine engine, System.Boolean inferOnlySpecifiedVars, System.Collections.Generic.IEnumerable`1[T] vars) [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Models.InferenceEngine.BuildAndCompile (System.Boolean inferOnlySpecifiedVars, System.Collections.Generic.IEnumerable`1[T] vars) [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Models.InferenceEngine.GetCompiledInferenceAlgorithm (System.Boolean inferOnlySpecifiedVars, Microsoft.ML.Probabilistic.Models.IVariable var) [0x00000] in <00000000000000000000000000000000>:0 
  at Microsoft.ML.Probabilistic.Models.InferenceEngine.Infer (Microsoft.ML.Probabilistic.Models.IVariable var) [0x00000] in <00000000000000000000000000000000>:0 
  at Main.TwoCoins () [0x00000] in <00000000000000000000000000000000>:0 
  at Main.Start () [0x00000] in <00000000000000000000000000000000>:0 
 
(Filename: currently not available on il2cpp Line: -1)```

[a-vishar]

Does this error occur only on the device and not in the simulator? Also, do you have a small repro project?

…

On 18 May 2019, at 10:21, mjokipii ***@***.***> wrote: Running code using Infer.NET fails with an ExecutionEngineException on iOS when built with IL2CPP from Unity3d. Some of the instantiations of generic types used internally don't exist during compile time which causes the corresponding iOS AOT code to be missing at runtime. Details: Unity 2018.3 Microsoft.ML.Probabilistic.dll Microsoft.ML.Probabilistic.Compiler.dll ExecutionEngineException: Attempting to call method 'Microsoft.ML.Probabilistic.Models.ModelBuilder::SearchExpression<System.Boolean>' for which no ahead of time (AOT) code was generated. at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Utilities.Util.Invoke (System.Reflection.MethodBase method, System.Object target, System.Object[] parameters) [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Models.ModelBuilder.Build (Microsoft.ML.Probabilistic.Models.InferenceEngine engine, System.Boolean inferOnlySpecifiedVars, System.Collections.Generic.IEnumerable`1[T] vars) [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Models.InferenceEngine.BuildAndCompile (System.Boolean inferOnlySpecifiedVars, System.Collections.Generic.IEnumerable`1[T] vars) [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Models.InferenceEngine.GetCompiledInferenceAlgorithm (System.Boolean inferOnlySpecifiedVars, Microsoft.ML.Probabilistic.Models.IVariable var) [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Models.InferenceEngine.Infer (Microsoft.ML.Probabilistic.Models.IVariable var) [0x00000] in <00000000000000000000000000000000>:0 at Main.TwoCoins () [0x00000] in <00000000000000000000000000000000>:0 at Main.Start () [0x00000] in <00000000000000000000000000000000>:0 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Utilities.Util.Invoke (System.Reflection.MethodBase method, System.Object target, System.Object[] parameters) [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Models.ModelBuilder.Build (Microsoft.ML.Probabilistic.Models.InferenceEngine engine, System.Boolean inferOnlySpecifiedVars, System.Collections.Generic.IEnumerable`1[T] vars) [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Models.InferenceEngine.BuildAndCompile (System.Boolean inferOnlySpecifiedVars, System.Collections.Generic.IEnumerable`1[T] vars) [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Models.InferenceEngine.GetCompiledInferenceAlgorithm (System.Boolean inferOnlySpecifiedVars, Microsoft.ML.Probabilistic.Models.IVariable var) [0x00000] in <00000000000000000000000000000000>:0 at Microsoft.ML.Probabilistic.Models.InferenceEngine.Infer (Microsoft.ML.Probabilistic.Models.IVariable var) [0x00000] in <00000000000000000000000000000000>:0 at Main.TwoCoins () [0x00000] in <00000000000000000000000000000000>:0 at Main.Start () [0x00000] in <00000000000000000000000000000000>:0 (Filename: currently not available on il2cpp Line: -1)``` — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[mjokipii]

This error occurs only when ran on a device that executes only AOT code like the IL2CPP compiled Xcode build on any iOS device. The library performs correctly in the editor that executes managed code. I have a small Unity3d repro. Where should i deliver the project?

[a-vishar]

You can either attach it here (25MB limit) or use a third party host. Please include a full set of steps required to repro. I’m not sure this is something we can fix, it seems like it is either a limitation, or a bug in another tool. However, we can certainly take a look!

…

On 18 May 2019, at 13:09, mjokipii ***@***.***> wrote: This error occurs only when ran on a device that executes only AOT code like the IL2CPP compiled Xcode build on any iOS device. The library performs correctly in the editor that executes managed code. I have a small Unity3d repro. Where should i deliver the project? — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[mjokipii]

Yes, this is due to a known limitation of the IL2CPP compiler used in Unity3d and concerns only generic types with value type parameter. Please see:

https://stackoverflow.com/questions/56183606/invoke-generic-method-via-reflection-in-c-sharp-il2cpp-on-ios/56185978#56185978

Unfortunately that includes just about every use of Infer.Net.

I'll post the repro in a minute.

[mjokipii]

InferAheadOfTimeException.zip

1. Unzip the InferAheadOfTimeException.zip archive
2. Open the contained folder in Unity3d
3. In Unity editor, open the Assets/Scenes/Main scene
4. Open the build settings from File/Build Settings
5. Select Platform iOS and click Switch Platform
6. Press Play button in editor
7. Observe correct output from Scripts/Main.cs in Console
8. Press Play button again to exit playmode in editor
9. Click Build button in the Build Settings window and choose the target location
10. After the build is finished, open the resulting Unity-iPhone.xcodeproj in Xcode
11. Build and run on an iOS device
12. Observe the reported error appear in the debug panel

Reproduced on iOS 12.1.4 and iOS 10.2.1 using Unity3d 2018.3.10f1 and Xcode 10.2.1.

[mjokipii]

Hi there, any chance for a fix or a workaround to allow Infer.NET on Unity iOS?

[msdmkats]

Hi!
I see, the error happens during the compilation of the Infer.Net model. Do you actually need to run the compilation on the iOS device or, maybe, inference would be enough? In the latter case you could compile the model into C# code on your development machine, and then only put that code and Infer.Net runtime into the iOS code. This way all the necessary generic instantiations would probably (I don't have an iOS device anywhere nearby to check) exist at compile time.

See User guide on precompiling models

[mjokipii]

That sounds promising. After a quick look to the instructions, if ican can update the model parameters and data without recompiling, i think inference is all i need in the iOS side. I will look into this and see if i can make this work. Thanks a lot!