Use reflection metadata to represent methods/fields in native layout

src/coreclr/nativeaot/System.Private.CoreLib/src/CompatibilitySuppressions.xml

@@ -717,18 +717,6 @@
     <DiagnosticId>CP0001</DiagnosticId>
     <Target>T:Internal.Runtime.CompilerServices.OpenMethodResolver</Target>
   </Suppression>
-  <Suppression>
-    <DiagnosticId>CP0001</DiagnosticId>
-    <Target>T:Internal.Runtime.CompilerServices.RuntimeFieldHandleInfo</Target>
-  </Suppression>
-  <Suppression>
-    <DiagnosticId>CP0001</DiagnosticId>
-    <Target>T:Internal.Runtime.CompilerServices.RuntimeMethodHandleInfo</Target>
-  </Suppression>
-  <Suppression>
-    <DiagnosticId>CP0001</DiagnosticId>
-    <Target>T:Internal.Runtime.CompilerServices.RuntimeSignature</Target>
-  </Suppression>
   <Suppression>
     <DiagnosticId>CP0001</DiagnosticId>
     <Target>T:Internal.Runtime.TypeManagerHandle</Target>
@@ -753,6 +741,14 @@
     <DiagnosticId>CP0001</DiagnosticId>
     <Target>T:System.MDArray</Target>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:System.FieldHandleInfo</Target>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:System.MethodHandleInfo</Target>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0001</DiagnosticId>
     <Target>T:System.Reflection.BinderBundle</Target>

src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/Augments/TypeLoaderCallbacks.cs

@@ -19,13 +19,10 @@ public abstract class TypeLoaderCallbacks
         public abstract bool TryGetConstructedGenericTypeForComponents(RuntimeTypeHandle genericTypeDefinitionHandle, RuntimeTypeHandle[] genericTypeArgumentHandles, out RuntimeTypeHandle runtimeTypeHandle);
         public abstract IntPtr GetThreadStaticGCDescForDynamicType(TypeManagerHandle handle, int index);
         public abstract IntPtr GenericLookupFromContextAndSignature(IntPtr context, IntPtr signature, out IntPtr auxResult);
-        public abstract bool GetRuntimeMethodHandleComponents(RuntimeMethodHandle runtimeMethodHandle, out RuntimeTypeHandle declaringTypeHandle, out MethodNameAndSignature nameAndSignature, out RuntimeTypeHandle[] genericMethodArgs);
-        public abstract RuntimeMethodHandle GetRuntimeMethodHandleForComponents(RuntimeTypeHandle declaringTypeHandle, string methodName, RuntimeSignature methodSignature, RuntimeTypeHandle[] genericMethodArgs);
-        public abstract bool CompareMethodSignatures(RuntimeSignature signature1, RuntimeSignature signature2);
+        public abstract RuntimeMethodHandle GetRuntimeMethodHandleForComponents(RuntimeTypeHandle declaringTypeHandle, MethodHandle handle, RuntimeTypeHandle[] genericMethodArgs);
         public abstract IntPtr TryGetDefaultConstructorForType(RuntimeTypeHandle runtimeTypeHandle);
         public abstract IntPtr ResolveGenericVirtualMethodTarget(RuntimeTypeHandle targetTypeHandle, RuntimeMethodHandle declMethod);
-        public abstract bool GetRuntimeFieldHandleComponents(RuntimeFieldHandle runtimeFieldHandle, out RuntimeTypeHandle declaringTypeHandle, out string fieldName);
-        public abstract RuntimeFieldHandle GetRuntimeFieldHandleForComponents(RuntimeTypeHandle declaringTypeHandle, string fieldName);
+        public abstract RuntimeFieldHandle GetRuntimeFieldHandleForComponents(RuntimeTypeHandle declaringTypeHandle, FieldHandle handle);
         public abstract bool TryGetPointerTypeForTargetType(RuntimeTypeHandle pointeeTypeHandle, out RuntimeTypeHandle pointerTypeHandle);
         public abstract bool TryGetArrayTypeForElementType(RuntimeTypeHandle elementTypeHandle, bool isMdArray, int rank, out RuntimeTypeHandle arrayTypeHandle);
         /// <summary>

src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/CompilerServices/MethodNameAndSignature.cs

@@ -0,0 +1,57 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Diagnostics;
+
+using Internal.Metadata.NativeFormat;
+
+namespace Internal.Runtime.CompilerServices
+{
+    [CLSCompliant(false)]
+    public class MethodNameAndSignature
+    {
+        public MetadataReader Reader { get; }
+        public MethodHandle Handle { get; }
+
+        public MethodNameAndSignature(MetadataReader reader, MethodHandle handle)
+        {
+            Reader = reader;
+            Handle = handle;
+        }
+
+        public string GetName()
+        {
+            Method method = Reader.GetMethod(Handle);
+            return Reader.GetString(method.Name);
+        }
+
+        public override bool Equals(object? compare)
+        {
+            if (compare == null)
+                return false;
+
+            MethodNameAndSignature? other = compare as MethodNameAndSignature;
+            if (other == null)
+                return false;
+
+            // Comparing handles is enough if there's only one metadata blob
+            // (Same assumption in GetHashCode below!)
+            Debug.Assert(Reader == other.Reader);
+
+            Method thisMethod = Reader.GetMethod(Handle);
+            Method otherMethod = other.Reader.GetMethod(other.Handle);
+
+            return thisMethod.Signature.Equals(otherMethod.Signature)
+                && thisMethod.Name.Equals(otherMethod.Name);
+        }
+
+        public override int GetHashCode()
+        {
+            Method method = Reader.GetMethod(Handle);
+
+            // Assumes we only have one metadata blob
+            return method.Signature.GetHashCode() ^ method.Name.GetHashCode();
+        }
+    }
+}

src/coreclr/nativeaot/System.Private.CoreLib/src/System.Private.CoreLib.csproj

@@ -119,9 +119,7 @@
     <Compile Include="Internal\Runtime\CompilerHelpers\MathHelpers.cs" />
     <Compile Include="Internal\Runtime\CompilerServices\FunctionPointerOps.cs" />
     <Compile Include="Internal\Runtime\CompilerServices\GenericMethodDescriptor.cs" />
-    <Compile Include="Internal\Runtime\CompilerServices\RuntimeFieldHandleInfo.cs" />
-    <Compile Include="Internal\Runtime\CompilerServices\RuntimeMethodHandleInfo.cs" />
-    <Compile Include="Internal\Runtime\CompilerServices\RuntimeSignature.cs" />
+    <Compile Include="Internal\Runtime\CompilerServices\MethodNameAndSignature.cs" />
     <Compile Include="Internal\Runtime\CompilerServices\OpenMethodResolver.cs" />
     <Compile Include="Internal\Runtime\TypeLoaderExceptionHelper.cs" />
     <Compile Include="Internal\DeveloperExperience\DeveloperExperience.cs" />

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/FieldInfos/NativeFormat/NativeFormatRuntimeFieldInfo.cs

@@ -130,7 +130,7 @@ public sealed override RuntimeFieldHandle FieldHandle
             {
                 return RuntimeAugments.TypeLoaderCallbacks.GetRuntimeFieldHandleForComponents(
                     DeclaringType.TypeHandle,
-                    Name);
+                    _fieldHandle);
             }
         }
 

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/MethodInfos/NativeFormat/NativeFormatMethodCommon.cs

@@ -201,12 +201,9 @@ public RuntimeMethodHandle GetRuntimeMethodHandle(Type[] genericArgs)
                 genericArgHandles = null;
             }
 
-            TypeManagerHandle typeManager = RuntimeAugments.TypeLoaderCallbacks.GetModuleForMetadataReader(Reader);
-
             return RuntimeAugments.TypeLoaderCallbacks.GetRuntimeMethodHandleForComponents(
                 DeclaringType.TypeHandle,
-                Name,
-                RuntimeSignature.CreateFromMethodHandle(typeManager, MethodHandle.AsInt()),
+                _methodHandle,
                 genericArgHandles);
         }