Attempting to JIT compile method in System.Text.Json tests on iOS devices

[akoeplinger]

When running the System.Text.Json tests on iOS arm64 devices with full AOT we're seeing the following methods where it attempts to JIT compile them, causing an ExecutionEngineException:

bool System.Text.Json.Serialization.Converters.IAsyncEnumerableOfTConverter`2<System.Collections.Generic.IAsyncEnumerable`1<int>, int>:OnWriteResume (System.Text.Json.Utf8JsonWriter,System.Collections.Generic.IAsyncEnumerable`1<int>,System.Text.Json.JsonSerializerOptions,System.Text.Json.WriteStack&)
bool System.Text.Json.Serialization.Converters.IAsyncEnumerableOfTConverter`2<System.Text.Json.Serialization.Tests.CollectionTests/MockedAsyncEnumerable`1<int>, int>:OnWriteResume (System.Text.Json.Utf8JsonWriter,System.Text.Json.Serialization.Tests.CollectionTests/MockedAsyncEnumerable`1<int>,System.Text.Json.JsonSerializerOptions,System.Text.Json.WriteStack&)
void System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<System.Collections.Concurrent.ConcurrentDictionary`2<int, int>, int, int>:Add (int,int modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)
void System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<System.Collections.Concurrent.ConcurrentDictionary`2<string, System.Text.Json.Serialization.Tests.StreamTests/ImmutableStructWithStrings>, string, System.Text.Json.Serialization.Tests.StreamTests/ImmutableStructWithStrings>:Add (string,System.Text.Json.Serialization.Tests.StreamTests/ImmutableStructWithStrings modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)
void System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<System.Collections.Concurrent.ConcurrentDictionary`2<string, int>, string, int>:Add (string,int modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)
void System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<System.Collections.Concurrent.ConcurrentDictionary`2<string, ulong>, string, ulong>:Add (string,ulong modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)
void System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<System.Collections.Generic.IDictionary`2<string, System.Nullable`1<System.DateTime>>, string, System.Nullable`1<System.DateTime>>:Add (string,System.Nullable`1<System.DateTime> modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)
void System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<System.Collections.Generic.IDictionary`2<string, int>, string, int>:Add (string,int modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)
void System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<System.Text.Json.Serialization.Tests.CollectionTests/DictionaryThatOnlyImplementsIDictionaryOfStringTValue`1<int>, string, int>:Add (string,int modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)
void System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<System.Text.Json.Serialization.Tests.GenericStructIDictionaryWrapper`2<string, string>, string, string>:Add (string,string modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)
void System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<System.Text.Json.Serialization.Tests.NullableTests/MyIDictionaryWrapper`1<System.Nullable`1<single>>, string, System.Nullable`1<single>>:Add (string,System.Nullable`1<single> modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)

It's not clear why these fail, needs to be investigated.

/cc @lambdageek

[marek-safar]

@SamMonoRT who is working on this?

[SamMonoRT]

@marek-safar - at the moment no one, but believe @imhameed has a PR up for fullaot and may have seen this error ?

[imhameed]

I've seen this for several runtime tests (see #57350), but I don't know what the cause or causes are yet.

[lambdageek]

@imhameed all these disabled STJ tests use dynamic in C# in some way or another. I didn't dig into how we AOT dynamic function calls, yet, but it's possible we either don't support it, or we're missing some pattern that the STJ serialization is using.

Nevermind. I misunderstood what #58276 was doing

[akoeplinger]

@lambdageek no, the issues here are not in tests using dynamic. They happen in "normal" System.Text.Json tests.

[BrzVlad]

I wasn't able to deploy the test app to device. I'll investigate next week once I'm added to Microsoft iOS Development Team

[akoeplinger]

Yup, the command for that is: ./dotnet.sh build /t:Test /p:TargetOS=iOS /p:TargetArchitecture=arm64 /p:RunAOTCompilation=true /p:DevTeamProvisioning=UBF8T346G9 /p:MonoEnableLLVM=false src/libraries/System.Text.Json/tests/System.Text.Json.Tests

(note that we currently have a bug where we don't recognize that we ILStripped the binaries so if you run this a second time it'll try to AOT the stripped binaries which will fail, probably best to just comment out the <ILStrip /> in tests.mobile.targets)

[BrzVlad]

These failures are caused by limitations in gsharedvt existing since its implementation. The limitation is reproduced with a constrained call with a signature containing multiple gsharedvt args. (https://github.com/dotnet/runtime/blob/main/src/mono/mono/mini/method-to-ir.c#L3684)

This issue can be reproduced from the iOS sample when executing this code

    private static T AssertThrows<T> (Action act) where T : Exception
    {       
            try {
                 act ();
            } catch (T e) {
                 return e;
            }
            throw new Exception ("Was supposed to throw");
    }
    private static void TestMethod ()
    {       
            AssertThrows<JsonException>(() => JsonSerializer.Deserialize<IList<object>>("[1,"));
            AssertThrows<JsonException>(() => JsonSerializer.Deserialize<IList<int>>("[1,"));
            AssertThrows<JsonException>(() => JsonSerializer.Deserialize<IList<int>>("[1")); 
            AssertThrows<JsonException>(() => JsonSerializer.Deserialize<IDictionary<string, int>>("{\"key\":1,"));
            AssertThrows<JsonException>(() => JsonSerializer.Deserialize<IDictionary<string, int>>("{\"key\":1"));
    }

When aot compilling System.Text.Json.dll, an example of a method hitting this limitation is System.Text.Json.Serialization.Converters.IDictionaryOfTKeyTValueConverter`3<TDictionary_GSHAREDVT, TKey_GSHAREDVT, TValue_GSHAREDVT>:Add (TKey_GSHAREDVT,TValue_GSHAREDVT modreq(System.Runtime.InteropServices.InAttribute)&,System.Text.Json.JsonSerializerOptions,System.Text.Json.ReadStack&)

@vargaz will take a look at this but the fix is likely not trivial so I don't see this making 6.0

[SamMonoRT]

Moving to 7.0 based on above comments.

[lambdageek]

@vargaz Does #59182 seem risky overall?

@SamMonoRT @akoeplinger @layomia Are the testcases here something contrived or possibly something that real users could run into? (@layomia it's the ones from #58276)

[vargaz]

It's somewhat risky, if this is needed for 6.0, we can create a version where the new code is ifdef ios|android, and the old code is used on wasm.

[lambdageek]

It's somewhat risky, if this is needed for 6.0, we can create a version where the new code is ifdef ios|android, and the old code is used on wasm.

I think we should hold off unless we get some customer reports that this is a problem in practice.