Remove HMFs from JIT helpers

[AaronRobinsonMSFT]

Remove unused JIT_StressGC.
Convert JIT_GetRuntimeFieldStub and JIT_GetRuntimeMethodStub to C#.

Contributes to #95695

Copilot reviewed 2 out of 10 changed files in this pull request and generated no comments.

Files not reviewed (8)

• src/coreclr/inc/jithelpers.h: Language not supported
• src/coreclr/vm/corelib.h: Language not supported
• src/coreclr/vm/field.cpp: Language not supported
• src/coreclr/vm/field.h: Language not supported
• src/coreclr/vm/frames.h: Language not supported
• src/coreclr/vm/interpreter.cpp: Language not supported
• src/coreclr/vm/jithelpers.cpp: Language not supported
• src/coreclr/vm/runtimehandles.cpp: Language not supported

Comments suppressed due to low confidence (2)

src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs:929

• Ensure that the behavior of the new method FromPtr in RuntimeMethodInfoStub is covered by tests.

internal static object FromPtr(IntPtr pMD)

src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs:1397

• Ensure that the behavior of the new method FromPtr in RuntimeFieldInfoStub is covered by tests.

internal static object FromPtr(IntPtr pFD)

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[AaronRobinsonMSFT]

@jkotas I couldn't find any obvious way to emit a ldtoken for a method or field via C#, so I didn't measure any potential performance impact here. Suggestions are welcome.

[jkotas]

@EgorBot -windows_intel

using System;
using System.Reflection;
using System.Reflection.Emit;
using BenchmarkDotNet.Attributes;

public class Bench
{
    Func<RuntimeMethodHandle> d = Init();

    static Func<RuntimeMethodHandle> Init()
    {
        DynamicMethod dm = new DynamicMethod("My", typeof(RuntimeMethodHandle), null, typeof(string).Module);

        MethodInfo randomMethod = typeof(object).GetMethod("ReferenceEquals");

        ILGenerator il = dm.GetILGenerator();
        il.Emit(OpCodes.Ldtoken, randomMethod);
        il.Emit(OpCodes.Ret);

        return dm.CreateDelegate<Func<RuntimeMethodHandle>>();
    }

    [Benchmark]
    public RuntimeMethodHandle LdToken() => d();
}

[jkotas]

I couldn't find any obvious way to emit a ldtoken for a method or field via C#

C# emits ldtoken for methods/fields as part of expression trees, but it is wrapped by a bunch of code that would obfuscate the perf measurement.

I have a posted a microbenchmark using DynamicMethods. I am not worried about the perf impact of this change. I expect this change to be a perf improvement.

[jkotas]

Thanks