Remove Helper Method Frames (HMF) from Reflection (#110211)

Create general purpose RuntimeTypeHandle.InternalAlloc() and RuntimeTypeHandle.InternalAllocNoChecks().
Convert RuntimeMethodHandle::ReboxToNullable() to managed.
Convert RuntimeMethodHandle::ReboxFromNullable() to managed.
Convert RuntimeMethodHandle::InvokeMethod() to QCall.

Author: AaronRobinsonMSFT

src/coreclr/System.Private.CoreLib/src/System/Delegate.CoreCLR.cs

@@ -434,23 +434,10 @@ private bool BindToMethodInfo(object? target, IRuntimeMethodInfo method, Runtime
 
         private static MulticastDelegate InternalAlloc(RuntimeType type)
         {
-            MulticastDelegate? d = null;
-            InternalAlloc(new QCallTypeHandle(ref type), ObjectHandleOnStack.Create(ref d));
-            return d!;
+            Debug.Assert(type.IsAssignableTo(typeof(MulticastDelegate)));
+            return Unsafe.As<MulticastDelegate>(RuntimeTypeHandle.InternalAlloc(type));
         }
 
-        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "Delegate_InternalAlloc")]
-        private static partial void InternalAlloc(QCallTypeHandle type, ObjectHandleOnStack d);
-
-        internal static MulticastDelegate InternalAllocLike(MulticastDelegate d)
-        {
-            InternalAllocLike(ObjectHandleOnStack.Create(ref d));
-            return d;
-        }
-
-        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "Delegate_InternalAllocLike")]
-        private static partial void InternalAllocLike(ObjectHandleOnStack d);
-
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         internal static unsafe bool InternalEqualTypes(object a, object b)
         {

src/coreclr/System.Private.CoreLib/src/System/MulticastDelegate.CoreCLR.cs

@@ -167,7 +167,7 @@ private static bool TrySetSlot(object?[] a, int index, object o)
         private MulticastDelegate NewMulticastDelegate(object[] invocationList, int invocationCount, bool thisIsMultiCastAlready)
         {
             // First, allocate a new multicast delegate just like this one, i.e. same type as the this object
-            MulticastDelegate result = InternalAllocLike(this);
+            MulticastDelegate result = Unsafe.As<MulticastDelegate>(RuntimeTypeHandle.InternalAllocNoChecks((RuntimeType)GetType()));
 
             // Performance optimization - if this already points to a true multicast delegate,
             // copy _methodPtr and _methodPtrAux fields rather than calling into the EE to get them

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/CastHelpers.cs

@@ -596,6 +596,32 @@ internal static void Unbox_Nullable(ref byte destPtr, MethodTable* typeMT, objec
             }
         }
 
+        [DebuggerHidden]
+        internal static object? ReboxFromNullable(MethodTable* srcMT, object src)
+        {
+            Debug.Assert(srcMT->IsNullable);
+
+            ref byte nullableData = ref src.GetRawData();
+
+            // If 'hasValue' is false, return null.
+            if (!Unsafe.As<byte, bool>(ref nullableData))
+                return null;
+
+            // Allocate a new instance of the T in Nullable<T>.
+            MethodTable* dstMT = srcMT->InstantiationArg0();
+            object dst = RuntimeTypeHandle.InternalAlloc(dstMT);
+
+            // Copy data from the Nullable<T>.
+            ref byte srcData = ref Unsafe.Add(ref nullableData, srcMT->NullableValueAddrOffset);
+            ref byte dstData = ref RuntimeHelpers.GetRawData(dst);
+            if (dstMT->ContainsGCPointers)
+                Buffer.BulkMoveWithWriteBarrier(ref dstData, ref srcData, dstMT->GetNumInstanceFieldBytesIfContainsGCPointers());
+            else
+                SpanHelpers.Memmove(ref dstData, ref srcData, dstMT->GetNumInstanceFieldBytes());
+
+            return dst;
+        }
+
         [DebuggerHidden]
         [MethodImpl(MethodImplOptions.NoInlining)]
         private static ref byte Unbox_Helper(MethodTable* pMT1, object obj)

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

@@ -269,6 +269,36 @@ private static partial void CreateInstanceForAnotherGenericParameter(
             int cTypeHandles,
             ObjectHandleOnStack instantiatedObject);
 
+        internal static unsafe object InternalAlloc(MethodTable* pMT)
+        {
+            object? result = null;
+            InternalAlloc(pMT, ObjectHandleOnStack.Create(ref result));
+            return result!;
+        }
+
+        internal static object InternalAlloc(RuntimeType type)
+        {
+            Debug.Assert(!type.GetNativeTypeHandle().IsTypeDesc);
+            object result = InternalAlloc(type.GetNativeTypeHandle().AsMethodTable());
+            GC.KeepAlive(type);
+            return result;
+        }
+
+        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "RuntimeTypeHandle_InternalAlloc")]
+        private static unsafe partial void InternalAlloc(MethodTable* pMT, ObjectHandleOnStack result);
+
+        internal static object InternalAllocNoChecks(RuntimeType type)
+        {
+            Debug.Assert(!type.GetNativeTypeHandle().IsTypeDesc);
+            object? result = null;
+            InternalAllocNoChecks(type.GetNativeTypeHandle().AsMethodTable(), ObjectHandleOnStack.Create(ref result));
+            GC.KeepAlive(type);
+            return result!;
+        }
+
+        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "RuntimeTypeHandle_InternalAllocNoChecks")]
+        private static unsafe partial void InternalAllocNoChecks(MethodTable* pMT, ObjectHandleOnStack result);
+
         /// <summary>
         /// Given a RuntimeType, returns information about how to activate it via calli
         /// semantics. This method will ensure the type object is fully initialized within
@@ -1026,14 +1056,59 @@ internal static MdUtf8String GetUtf8Name(RuntimeMethodHandleInternal method)
 
         [DebuggerStepThrough]
         [DebuggerHidden]
-        [MethodImpl(MethodImplOptions.InternalCall)]
-        internal static extern object? InvokeMethod(object? target, void** arguments, Signature sig, bool isConstructor);
+        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "RuntimeMethodHandle_InvokeMethod")]
+        private static partial void InvokeMethod(ObjectHandleOnStack target, void** arguments, ObjectHandleOnStack sig, Interop.BOOL isConstructor, ObjectHandleOnStack result);
 
-        [MethodImpl(MethodImplOptions.InternalCall)]
-        internal static extern object? ReboxFromNullable(object? src);
+        [DebuggerStepThrough]
+        [DebuggerHidden]
+        internal static object? InvokeMethod(object? target, void** arguments, Signature sig, bool isConstructor)
+        {
+            object? result = null;
+            InvokeMethod(
+                ObjectHandleOnStack.Create(ref target),
+                arguments,
+                ObjectHandleOnStack.Create(ref sig),
+                isConstructor ? Interop.BOOL.TRUE : Interop.BOOL.FALSE,
+                ObjectHandleOnStack.Create(ref result));
+            return result;
+        }
 
-        [MethodImpl(MethodImplOptions.InternalCall)]
-        internal static extern object ReboxToNullable(object? src, RuntimeType destNullableType);
+        /// <summary>
+        /// For a true boxed Nullable{T}, re-box to a boxed {T} or null, otherwise just return the input.
+        /// </summary>
+        internal static object? ReboxFromNullable(object? src)
+        {
+            // If src is null or not NullableOfT, just return that state.
+            if (src is null)
+            {
+                return null;
+            }
+
+            MethodTable* pMT = RuntimeHelpers.GetMethodTable(src);
+            if (!pMT->IsNullable)
+            {
+                return src;
+            }
+
+            return CastHelpers.ReboxFromNullable(pMT, src);
+        }
+
+        /// <summary>
+        /// Convert a boxed value of {T} (which is either {T} or null) to a true boxed Nullable{T}.
+        /// </summary>
+        internal static object ReboxToNullable(object? src, RuntimeType destNullableType)
+        {
+            Debug.Assert(destNullableType.IsNullableOfT);
+            MethodTable* pMT = destNullableType.GetNativeTypeHandle().AsMethodTable();
+            object obj = RuntimeTypeHandle.InternalAlloc(pMT);
+            GC.KeepAlive(destNullableType); // The obj instance will keep the type alive.
+
+            CastHelpers.Unbox_Nullable(
+                ref obj.GetRawData(),
+                pMT,
+                src);
+            return obj;
+        }
 
         [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "RuntimeMethodHandle_GetMethodInstantiation")]
         private static partial void GetMethodInstantiation(RuntimeMethodHandleInternal method, ObjectHandleOnStack types, Interop.BOOL fAsRuntimeTypeArray);

src/coreclr/vm/comdelegate.cpp

@@ -2024,36 +2024,6 @@ Stub* COMDelegate::GetInvokeMethodStub(EEImplMethodDesc* pMD)
     }
 }
 
-extern "C" void QCALLTYPE Delegate_InternalAlloc(QCall::TypeHandle pType, QCall::ObjectHandleOnStack d)
-{
-    QCALL_CONTRACT;
-
-    BEGIN_QCALL;
-
-    GCX_COOP();
-
-    _ASSERTE(pType.AsTypeHandle().AsMethodTable()->IsDelegate());
-
-    d.Set(pType.AsTypeHandle().AsMethodTable()->Allocate());
-
-    END_QCALL;
-}
-
-extern "C" void QCALLTYPE Delegate_InternalAllocLike(QCall::ObjectHandleOnStack d)
-{
-    QCALL_CONTRACT;
-
-    BEGIN_QCALL;
-
-    GCX_COOP();
-
-    _ASSERTE(d.Get()->GetMethodTable()->IsDelegate());
-
-    d.Set(d.Get()->GetMethodTable()->AllocateNoChecks());
-
-    END_QCALL;
-}
-
 void COMDelegate::ThrowIfInvalidUnmanagedCallersOnlyUsage(MethodDesc* pMD)
 {
     CONTRACTL

src/coreclr/vm/comdelegate.h

@@ -123,10 +123,6 @@ extern "C" BOOL QCALLTYPE Delegate_BindToMethodName(QCall::ObjectHandleOnStack d
 extern "C" BOOL QCALLTYPE Delegate_BindToMethodInfo(QCall::ObjectHandleOnStack d, QCall::ObjectHandleOnStack target,
     MethodDesc * method, QCall::TypeHandle pMethodType, DelegateBindingFlags flags);
 
-extern "C" void QCALLTYPE Delegate_InternalAlloc(QCall::TypeHandle pType, QCall::ObjectHandleOnStack d);
-
-extern "C" void QCALLTYPE Delegate_InternalAllocLike(QCall::ObjectHandleOnStack d);
-
 extern "C" void QCALLTYPE Delegate_FindMethodHandle(QCall::ObjectHandleOnStack d, QCall::ObjectHandleOnStack retMethodInfo);
 
 extern "C" BOOL QCALLTYPE Delegate_InternalEqualMethodHandles(QCall::ObjectHandleOnStack left, QCall::ObjectHandleOnStack right);

src/coreclr/vm/ecalllist.h

@@ -146,9 +146,6 @@ FCFuncStart(gSignatureNative)
 FCFuncEnd()
 
 FCFuncStart(gRuntimeMethodHandle)
-    FCFuncElement("InvokeMethod", RuntimeMethodHandle::InvokeMethod)
-    FCFuncElement("ReboxFromNullable", RuntimeMethodHandle::ReboxFromNullable)
-    FCFuncElement("ReboxToNullable", RuntimeMethodHandle::ReboxToNullable)
     FCFuncElement("GetImplAttributes", RuntimeMethodHandle::GetImplAttributes)
     FCFuncElement("GetAttributes", RuntimeMethodHandle::GetAttributes)
     FCFuncElement("GetMethodTable", RuntimeMethodHandle::GetMethodTable)

src/coreclr/vm/methodtable.cpp

@@ -3940,18 +3940,17 @@ void MethodTable::CheckRunClassInitAsIfConstructingThrowing()
         THROWS;
         GC_TRIGGERS;
         MODE_ANY;
+        PRECONDITION(HasPreciseInitCctors());
     }
     CONTRACTL_END;
-    if (HasPreciseInitCctors())
+
+    MethodTable *pMTCur = this;
+    while (pMTCur != NULL)
     {
-        MethodTable *pMTCur = this;
-        while (pMTCur != NULL)
-        {
-            if (!pMTCur->GetClass()->IsBeforeFieldInit())
-                pMTCur->CheckRunClassInitThrowing();
+        if (!pMTCur->GetClass()->IsBeforeFieldInit())
+            pMTCur->CheckRunClassInitThrowing();
 
-            pMTCur = pMTCur->GetParentMethodTable();
-        }
+        pMTCur = pMTCur->GetParentMethodTable();
     }
 }
 

src/coreclr/vm/methodtable.h

@@ -2676,8 +2676,8 @@ class MethodTable
     // This flavor of Allocate is more efficient, but can only be used
     // if CheckInstanceActivated(), IsClassInited() are known to be true.
     // A sufficient condition is that another instance of the exact same type already
-    // exists in the same appdomain. It's currently called only from Delegate.Combine
-    // via COMDelegate::InternalAllocLike.
+    // exists in the same ALC. It's currently called only from Delegate.Combine
+    // via RuntimeTypeHandle_InternalAllocNoChecks.
     OBJECTREF AllocateNoChecks();
 
     OBJECTREF Box(void* data);
@@ -3921,12 +3921,11 @@ public :
         TADDR         m_ElementTypeHnd;
     };
     public:
-    union 
+    union
     {
         PTR_InterfaceInfo   m_pInterfaceMap;
         TADDR               m_encodedNullableUnboxData; // Used for Nullable<T> to represent the offset to the value field, and the size of the value field
     };
-    
 
     // VTable slots go here
 

src/coreclr/vm/methodtable.inl

@@ -1230,7 +1230,7 @@ inline OBJECTREF MethodTable::AllocateNoChecks()
     }
     CONTRACTL_END;
 
-    // we know an instance of this class already exists in the same appdomain
+    // We know an instance of this class already exists
     // therefore, some checks become redundant.
     // this currently only happens for Delegate.Combine
 
@@ -1239,7 +1239,6 @@ inline OBJECTREF MethodTable::AllocateNoChecks()
     return AllocateObject(this);
 }
 
-
 #ifndef DACCESS_COMPILE
 //==========================================================================================
 // unbox src into dest, No checks are done