Remove GenericArraySortHelper from ILLinkTrim xml

[joperezr]

Remove the GenericArraySortHelper from ILLinkTrim and instead move them into attributes where they are being used.

[ghost]

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[joperezr]

I have validated that if I trim a simple Console app that calls Array.Sort methods these don't get trimmed.

@MichalStrehovsky @sbomer if I remove the Array.Sort calls I was expecting the .ctor of those types to get trimmed but that wasn't the case, and when I analyzed the dumped report I got that the linker kept them because:

--- TypeDef:System.Collections.Generic.GenericArraySortHelper`1:System.Private.CoreLib.dll dependencies ---
Dependency #1
        TypeDef:System.Collections.Generic.GenericArraySortHelper`1:System.Private.CoreLib.dll
        | TypeSpec:System.Collections.Generic.GenericArraySortHelper`1<System.String>:System.Private.CoreLib.dll [1 deps]
        | Method:System.Collections.Generic.IArraySortHelper`1<T> System.Collections.Generic.ArraySortHelper`1::CreateArraySortHelper() [1 deps]
        | MemberRef:System.Collections.Generic.IArraySortHelper`1<T> System.Collections.Generic.ArraySortHelper`1<T>::CreateArraySortHelper() [1 deps]
        | Method:System.Void System.Collections.Generic.ArraySortHelper`1::.cctor() [1 deps]
        | Field:System.Collections.Generic.IArraySortHelper`1<T> System.Collections.Generic.ArraySortHelper`1::s_defaultArraySortHelper [1 deps]
        | MemberRef:System.Collections.Generic.IArraySortHelper`1<T> System.Collections.Generic.ArraySortHelper`1<T>::s_defaultArraySortHelper [2 deps]
        | Method:System.Collections.Generic.IArraySortHelper`1<T> System.Collections.Generic.ArraySortHelper`1::get_Default() [1 deps]
        | MemberRef:System.Collections.Generic.IArraySortHelper`1<T> System.Collections.Generic.ArraySortHelper`1<T>::get_Default() [2 deps]
        | Method:System.Int32 System.Array::BinarySearch(T[],System.Int32,System.Int32,T,System.Collections.Generic.IComparer`1<T>) [1 deps]
        | MethodSpec:System.Int32 System.Array::BinarySearch<T>(T[],System.Int32,System.Int32,T,System.Collections.Generic.IComparer`1<T>) [1 deps]
        | Method:System.Int32 System.Array::BinarySearch(T[],T) [1 deps]
        | MethodSpec:System.Int32 System.Array::BinarySearch<System.UInt64>(T[],T) [3 deps]
        | Method:System.Boolean System.RuntimeType::IsEnumDefined(System.Object) [1 deps]
        | TypeDef:System.RuntimeType:System.Private.CoreLib.dll [456 deps]
        | Method:System.String System.Enum::ToString() [1 deps]
        | TypeDef:System.Enum [272 deps]
        | TypeDef:System.Diagnostics.DebuggableAttribute/DebuggingModes [8 deps]
        | Method:System.Void System.Diagnostics.DebuggableAttribute::.ctor(System.Diagnostics.DebuggableAttribute/DebuggingModes)

The wierd part here, is that if I remove the attributes I'm adding in this PR, and don't use Array.Sort, I would have expected the .ctor to still be kept as found by the report above given there is still something rooting it, but the .ctor is actually not present. Is this by design?

[MichalStrehovsky]

The wierd part here, is that if I remove the attributes I'm adding in this PR, and don't use Array.Sort, I would have expected the .ctor to still be kept as found by the report above given there is still something rooting it, but the .ctor is actually not present. Is this by design?

Type is getting rooted by the typeof - linker cannot remove a type referenced statically by a typeof, but the members on the type are fair game.

The PreserveDependency ensures the constructor is kept (even though the code as-is won't actually use the ctor because RuntimeTypeHandle.Allocate below actually allocates a new instance without running a constructor - but keeping a constructor forces linker to keep a couple other things on the class that are actually important - I wish we had a "pretend this type was allocated" annotation).

[ghost]

Hello @joperezr!

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