Support async generic virtual methods (#121524)

* Since generic virtual method dispatch is based on
`RuntimeMethodHandle`, we need a `RuntimeMethodHandle` for async
variants. Emit the bit in the compiler, at runtime (when type loading),
and read it when needed. Reflection stack should never see this
`RuntimeMethodHandle`.
* Add `AsyncVariant` property on `MethodDesc` (since runtime type system
does this for unboxing methods too).
* Add a flag that distinguishes async variants in native layout. This is
not specific to GVMs, it also covers other cases of runtime generic
dictionary building, such as `MakeGenericMethod`.
* Add a flag that distinguishes these in generic method dictionary
hashtables (both static and built at runtime)
* Lots of piping through the extra bool

Author: MichalStrehovsky

src/coreclr/nativeaot/System.Private.CoreLib/src/System/RuntimeMethodHandle.cs

@@ -49,7 +49,7 @@ public unsafe bool Equals(RuntimeMethodHandle handle)
                 return false;
             if (!thisInfo->Handle.Equals(thatInfo->Handle))
                 return false;
-            if (thisInfo->NumGenericArgs != thatInfo->NumGenericArgs)
+            if (thisInfo->_numGenericArgsAndFlag != thatInfo->_numGenericArgsAndFlag)
                 return false;
 
             RuntimeTypeHandle* thisFirstArg = &thisInfo->FirstArgument;
@@ -123,7 +123,19 @@ public struct MethodHandleInfo
     {
         public RuntimeTypeHandle DeclaringType;
         public MethodHandle Handle;
-        public int NumGenericArgs;
+        internal int _numGenericArgsAndFlag;
         public RuntimeTypeHandle FirstArgument;
+
+        public int NumGenericArgs
+        {
+            get => _numGenericArgsAndFlag & ~RuntimeMethodHandleConstants.IsAsyncVariant;
+            set => _numGenericArgsAndFlag = (_numGenericArgsAndFlag & RuntimeMethodHandleConstants.IsAsyncVariant) | value;
+        }
+
+        public bool IsAsyncVariant
+        {
+            get => (_numGenericArgsAndFlag & RuntimeMethodHandleConstants.IsAsyncVariant) != 0;
+            set => _numGenericArgsAndFlag = value ? _numGenericArgsAndFlag | RuntimeMethodHandleConstants.IsAsyncVariant : _numGenericArgsAndFlag & ~RuntimeMethodHandleConstants.IsAsyncVariant;
+        }
     }
 }

src/coreclr/nativeaot/System.Private.Reflection.Execution/src/Internal/Reflection/Execution/ExecutionEnvironmentImplementation.MappingTables.cs

@@ -695,7 +695,8 @@ private unsafe bool TryGetMethodForOriginalLdFtnResult_InvokeMap_Inner(NativeFor
         private static unsafe bool TryGetMethodForOriginalLdFtnResult_GenericMethodWithInstantiationArgument(IntPtr instantiationArgument, ref RuntimeTypeHandle declaringTypeHandle, out QMethodDefinition methodHandle, out RuntimeTypeHandle[] genericMethodTypeArgumentHandles)
         {
             MethodNameAndSignature nameAndSig;
-            bool success = TypeLoaderEnvironment.Instance.TryGetGenericMethodComponents(instantiationArgument, out declaringTypeHandle, out nameAndSig, out genericMethodTypeArgumentHandles);
+            bool success = TypeLoaderEnvironment.Instance.TryGetGenericMethodComponents(instantiationArgument, out declaringTypeHandle, out nameAndSig, out genericMethodTypeArgumentHandles, out bool isAsyncVariant);
+            Debug.Assert(!isAsyncVariant, "Async variants should not be visible to reflection");
             if (success)
             {
                 if (TypeLoaderEnvironment.Instance.TryGetMetadataForTypeMethodNameAndSignature(declaringTypeHandle, nameAndSig, out methodHandle))

src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/Runtime/TypeLoader/GenericDictionaryCell.cs

@@ -328,7 +328,8 @@ internal override unsafe IntPtr Create(TypeBuilder builder)
                 RuntimeMethodHandle handle = TypeLoaderEnvironment.Instance.GetRuntimeMethodHandleForComponents(
                     builder.GetRuntimeTypeHandle(Method.OwningType),
                     Method.NameAndSignature.Handle,
-                    genericArgHandles);
+                    genericArgHandles,
+                    Method.AsyncVariant);
 
                 return *(IntPtr*)&handle;
             }

src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/Runtime/TypeLoader/NativeLayoutInfoLoadContext.cs

@@ -189,17 +189,18 @@ internal MethodDesc GetMethod(ref NativeParser parser)
             MethodNameAndSignature nameAndSignature = new MethodNameAndSignature(_module.MetadataReader, token.AsHandle().ToMethodHandle(_module.MetadataReader));
 
             bool unboxingStub = (flags & MethodFlags.IsUnboxingStub) != 0;
+            bool asyncVariant = (flags & MethodFlags.IsAsyncVariant) != 0;
 
             MethodDesc retVal;
             if ((flags & MethodFlags.HasInstantiation) != 0)
             {
                 TypeDesc[] typeArguments = GetTypeSequence(ref parser);
                 Debug.Assert(typeArguments.Length > 0);
-                retVal = this._typeSystemContext.ResolveGenericMethodInstantiation(unboxingStub, containingType, nameAndSignature, new Instantiation(typeArguments));
+                retVal = this._typeSystemContext.ResolveGenericMethodInstantiation(unboxingStub, asyncVariant, containingType, nameAndSignature, new Instantiation(typeArguments));
             }
             else
             {
-                retVal = this._typeSystemContext.ResolveRuntimeMethod(unboxingStub, containingType, nameAndSignature);
+                retVal = this._typeSystemContext.ResolveRuntimeMethod(unboxingStub, asyncVariant, containingType, nameAndSignature);
             }
 
             if ((flags & MethodFlags.HasFunctionPointer) != 0)

src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/Runtime/TypeLoader/TypeBuilder.cs

@@ -286,7 +286,7 @@ internal void ParseNativeLayoutInfo(InstantiatedMethod method)
             if (!method.UnboxingStub && method.OwningType.IsValueType && !TypeLoaderEnvironment.IsStaticMethodSignature(method.NameAndSignature))
             {
                 // Make it an unboxing stub, note the first parameter which is true
-                nonTemplateMethod = (InstantiatedMethod)method.Context.ResolveGenericMethodInstantiation(true, (DefType)method.OwningType, method.NameAndSignature, method.Instantiation);
+                nonTemplateMethod = (InstantiatedMethod)method.Context.ResolveGenericMethodInstantiation(true, method.AsyncVariant, (DefType)method.OwningType, method.NameAndSignature, method.Instantiation);
             }
 
             uint nativeLayoutInfoToken;
@@ -802,6 +802,7 @@ private void FinishRuntimeType(TypeDesc type)
                     _declaringTypeHandle = GetRuntimeTypeHandle(method.OwningType),
                     _genericMethodArgumentHandles = GetRuntimeTypeHandles(method.Instantiation),
                     _methodNameAndSignature = method.NameAndSignature,
+                    _isAsyncVariant = method.AsyncVariant,
                     _methodDictionary = method.RuntimeMethodDictionary
                 };
             }

src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/Runtime/TypeLoader/TypeLoaderEnvironment.ConstructedGenericMethodsLookup.cs

@@ -7,6 +7,7 @@
 using System.Reflection.Runtime.General;
 using System.Threading;
 
+using Internal.Metadata.NativeFormat;
 using Internal.NativeFormat;
 using Internal.Runtime.CompilerServices;
 using Internal.TypeSystem;
@@ -19,6 +20,7 @@ internal class GenericMethodEntry
         {
             private int? _hashCode;
             public bool _isRegisteredSuccessfully;
+            public bool _isAsyncVariant;
             public IntPtr _methodDictionary;
             public RuntimeTypeHandle _declaringTypeHandle;
             public MethodNameAndSignature _methodNameAndSignature;
@@ -45,6 +47,9 @@ public virtual bool IsEqualToEntryByComponentsComparison(GenericMethodEntry othe
                 if (!other._declaringTypeHandle.Equals(_declaringTypeHandle))
                     return false;
 
+                if (_isAsyncVariant != other._isAsyncVariant)
+                    return false;
+
                 if (!other._methodNameAndSignature.Equals(_methodNameAndSignature))
                     return false;
 
@@ -150,8 +155,14 @@ internal override bool MatchParsedEntry(ref NativeParser entryParser, ref Extern
                 if (_methodToLookup.OwningType != parsedDeclaringType)
                     return false;
 
-                // Hash table names / sigs are indirected through to the native layout info
-                MethodNameAndSignature nameAndSignature = TypeLoaderEnvironment.GetMethodNameAndSignatureFromToken(moduleHandle, entryParser.GetUnsigned());
+                int flagsAndToken = (int)entryParser.GetUnsigned();
+                bool isAsyncVariant = (flagsAndToken & GenericMethodsHashtableConstants.IsAsyncVariant) != 0;
+                if (_methodToLookup.AsyncVariant != isAsyncVariant)
+                    return false;
+
+                int token = ((int)HandleType.Method << 25) | (flagsAndToken & ~GenericMethodsHashtableConstants.IsAsyncVariant);
+
+                MethodNameAndSignature nameAndSignature = TypeLoaderEnvironment.GetMethodNameAndSignatureFromToken(moduleHandle, (uint)token);
                 if (!_methodToLookup.NameAndSignature.Equals(nameAndSignature))
                     return false;
 
@@ -178,6 +189,9 @@ internal override bool MatchGenericMethodEntry(GenericMethodEntry entry)
                 if (_methodToLookup.OwningType != parsedDeclaringType)
                     return false;
 
+                if (_methodToLookup.AsyncVariant != entry._isAsyncVariant)
+                    return false;
+
                 if (!_methodToLookup.NameAndSignature.Equals(entry._methodNameAndSignature))
                     return false;
 
@@ -208,11 +222,11 @@ internal bool TryLookupGenericMethodDictionary(GenericMethodLookupData lookupDat
             return true;
         }
 
-        public bool TryGetGenericMethodComponents(IntPtr methodDictionary, out RuntimeTypeHandle declaringType, out MethodNameAndSignature nameAndSignature, out RuntimeTypeHandle[] genericMethodArgumentHandles)
+        public bool TryGetGenericMethodComponents(IntPtr methodDictionary, out RuntimeTypeHandle declaringType, out MethodNameAndSignature nameAndSignature, out RuntimeTypeHandle[] genericMethodArgumentHandles, out bool isAsyncVariant)
         {
-            if (!TryGetDynamicGenericMethodComponents(methodDictionary, out declaringType, out nameAndSignature, out genericMethodArgumentHandles))
+            if (!TryGetDynamicGenericMethodComponents(methodDictionary, out declaringType, out nameAndSignature, out genericMethodArgumentHandles, out isAsyncVariant))
             {
-                if (!TryGetStaticGenericMethodComponents(methodDictionary, out declaringType, out nameAndSignature, out genericMethodArgumentHandles))
+                if (!TryGetStaticGenericMethodComponents(methodDictionary, out declaringType, out nameAndSignature, out genericMethodArgumentHandles, out isAsyncVariant))
                     return false;
             }
 
@@ -222,8 +236,8 @@ public bool TryGetGenericMethodComponents(IntPtr methodDictionary, out RuntimeTy
         public static bool TryGetGenericMethodComponents(IntPtr methodDictionary, out RuntimeTypeHandle declaringType, out RuntimeTypeHandle[] genericMethodArgumentHandles)
         {
             TypeLoaderEnvironment instance = TypeLoaderEnvironment.InstanceOrNull;
-            if (instance == null || !instance.TryGetDynamicGenericMethodComponents(methodDictionary, out declaringType, out _, out genericMethodArgumentHandles))
-                if (!TryGetStaticGenericMethodComponents(methodDictionary, out declaringType, out _, out genericMethodArgumentHandles))
+            if (instance == null || !instance.TryGetDynamicGenericMethodComponents(methodDictionary, out declaringType, out _, out genericMethodArgumentHandles, out _))
+                if (!TryGetStaticGenericMethodComponents(methodDictionary, out declaringType, out _, out genericMethodArgumentHandles, out _))
                     return false;
 
             return true;
@@ -286,7 +300,7 @@ public bool TryGetGenericVirtualMethodPointer(InstantiatedMethod method, out Int
             if (!method.UnboxingStub && method.OwningType.IsValueType && !IsStaticMethodSignature(method.NameAndSignature))
             {
                 // Make it an unboxing stub, note the first parameter which is true
-                nonTemplateMethod = (InstantiatedMethod)method.Context.ResolveGenericMethodInstantiation(true, (DefType)method.OwningType, method.NameAndSignature, method.Instantiation);
+                nonTemplateMethod = (InstantiatedMethod)method.Context.ResolveGenericMethodInstantiation(true, method.AsyncVariant, (DefType)method.OwningType, method.NameAndSignature, method.Instantiation);
             }
 
             // If we cannot find an exact method entry point, look for an equivalent template and compute the generic dictionary
@@ -371,11 +385,12 @@ private static bool TryGetStaticGenericMethodDictionary(GenericMethodLookupData
             return false;
         }
 
-        private bool TryGetDynamicGenericMethodComponents(IntPtr methodDictionary, out RuntimeTypeHandle declaringType, out MethodNameAndSignature methodNameAndSignature, out RuntimeTypeHandle[] genericMethodArgumentHandles)
+        private bool TryGetDynamicGenericMethodComponents(IntPtr methodDictionary, out RuntimeTypeHandle declaringType, out MethodNameAndSignature methodNameAndSignature, out RuntimeTypeHandle[] genericMethodArgumentHandles, out bool isAsyncVariant)
         {
             declaringType = default(RuntimeTypeHandle);
             methodNameAndSignature = null;
             genericMethodArgumentHandles = null;
+            isAsyncVariant = false;
 
             using (_dynamicGenericsLock.EnterScope())
             {
@@ -389,10 +404,12 @@ private bool TryGetDynamicGenericMethodComponents(IntPtr methodDictionary, out R
                 declaringType = entry._declaringTypeHandle;
                 methodNameAndSignature = entry._methodNameAndSignature;
                 genericMethodArgumentHandles = entry._genericMethodArgumentHandles;
+                isAsyncVariant = entry._isAsyncVariant;
                 return true;
             }
         }
-        private static unsafe bool TryGetStaticGenericMethodComponents(IntPtr methodDictionary, out RuntimeTypeHandle declaringType, out MethodNameAndSignature nameAndSignature, out RuntimeTypeHandle[] genericMethodArgumentHandles)
+
+        private static unsafe bool TryGetStaticGenericMethodComponents(IntPtr methodDictionary, out RuntimeTypeHandle declaringType, out MethodNameAndSignature nameAndSignature, out RuntimeTypeHandle[] genericMethodArgumentHandles, out bool isAsyncVariant)
         {
             // Generic method dictionaries have a header that has the hash code in it. Locate the header
             IntPtr dictionaryHeader = IntPtr.Subtract(methodDictionary, IntPtr.Size);
@@ -420,7 +437,12 @@ private static unsafe bool TryGetStaticGenericMethodComponents(IntPtr methodDict
                     // We have a match - fill in the results
                     declaringType = externalReferencesLookup.GetRuntimeTypeHandleFromIndex(entryParser.GetUnsigned());
 
-                    int token = (int)entryParser.GetUnsigned();
+
+                    int flagsAndToken = (int)entryParser.GetUnsigned();
+                    isAsyncVariant = (flagsAndToken & GenericMethodsHashtableConstants.IsAsyncVariant) != 0;
+
+                    int token = ((int)HandleType.Method << 25) | (flagsAndToken & ~GenericMethodsHashtableConstants.IsAsyncVariant);
+
                     nameAndSignature = new MethodNameAndSignature(module.MetadataReader, token.AsHandle().ToMethodHandle(module.MetadataReader));
 
                     uint arity = entryParser.GetSequenceCount();
@@ -438,6 +460,7 @@ private static unsafe bool TryGetStaticGenericMethodComponents(IntPtr methodDict
             declaringType = default(RuntimeTypeHandle);
             nameAndSignature = null;
             genericMethodArgumentHandles = null;
+            isAsyncVariant = false;
             return false;
         }
 

src/coreclr/nativeaot/System.Private.TypeLoader/src/Internal/Runtime/TypeLoader/TypeLoaderEnvironment.GVMResolution.cs

@@ -311,7 +311,7 @@ private static InstantiatedMethod FindMatchingInterfaceSlot(NativeFormatModuleIn
                                     Debug.Assert(interfaceImplType != null);
                                 }
 
-                                return (InstantiatedMethod)context.ResolveGenericMethodInstantiation(false, interfaceImplType, targetMethodNameAndSignature, slotMethod.Instantiation);
+                                return (InstantiatedMethod)context.ResolveGenericMethodInstantiation(false, slotMethod.AsyncVariant, interfaceImplType, targetMethodNameAndSignature, slotMethod.Instantiation);
                             }
                         }
                     }
@@ -502,7 +502,7 @@ private static InstantiatedMethod ResolveGenericVirtualMethodTarget(DefType targ
                     Debug.Assert(targetMethodNameAndSignature != null);
 
                     TypeSystemContext context = slotMethod.Context;
-                    return (InstantiatedMethod)context.ResolveGenericMethodInstantiation(false, targetType, targetMethodNameAndSignature, slotMethod.Instantiation);
+                    return (InstantiatedMethod)context.ResolveGenericMethodInstantiation(false, slotMethod.AsyncVariant, targetType, targetMethodNameAndSignature, slotMethod.Instantiation);
                 }
             }