Remove MethodDescCallSite in comutilnative.cpp (#123986)

huoyaoyuan · AaronRobinsonMSFT · jkotas · web-flow · commit afe05405dff6 · 2026-02-11T10:14:46.000-08:00
Contributes to #123864. Adds support for returning value. --------- Co-authored-by: Aaron R Robinson <arobins@microsoft.com> Co-authored-by: Jan Kotas <jkotas@microsoft.com>
diff --git a/src/coreclr/System.Private.CoreLib/src/System/Exception.CoreCLR.cs b/src/coreclr/System.Private.CoreLib/src/System/Exception.CoreCLR.cs
@@ -257,8 +257,45 @@ private bool CanSetRemoteStackTrace()
             return true;
         }
 
+#if FEATURE_COMINTEROP
         // used by vm
-        internal string? GetHelpContext(out uint helpContext)
+        [UnmanagedCallersOnly]
+        internal static unsafe IntPtr GetDescriptionBstr(Exception* obj, Exception* pException)
+        {
+            try
+            {
+                string message = obj->Message;
+                if (string.IsNullOrEmpty(message))
+                    message = obj->GetClassName();
+
+                // Allocate the description BSTR.
+                return Marshal.StringToBSTR(message);
+            }
+            catch (Exception ex)
+            {
+                *pException = ex;
+                return IntPtr.Zero;
+            }
+        }
+
+        // used by vm
+        [UnmanagedCallersOnly]
+        internal static unsafe IntPtr GetSourceBstr(Exception* obj, Exception* pException)
+        {
+            try
+            {
+                string? source = obj->Source;
+
+                return Marshal.StringToBSTR(source);
+            }
+            catch (Exception ex)
+            {
+                *pException = ex;
+                return IntPtr.Zero;
+            }
+        }
+
+        private string? GetHelpContext(out uint helpContext)
         {
             helpContext = 0;
             string? helpFile = HelpLink;
@@ -283,5 +320,23 @@ private bool CanSetRemoteStackTrace()
 
             return helpFile;
         }
+
+        // used by vm
+        [UnmanagedCallersOnly]
+        internal static unsafe void GetHelpContextBstr(Exception* obj, IntPtr* bstr, uint* helpContext, Exception* pException)
+        {
+            *bstr = IntPtr.Zero;
+            try
+            {
+                string? helpFile = obj->GetHelpContext(out *helpContext);
+
+                *bstr = Marshal.StringToBSTR(helpFile);
+            }
+            catch (Exception ex)
+            {
+                *pException = ex;
+            }
+        }
+#endif
     }
 }
diff --git a/src/coreclr/vm/callhelpers.h b/src/coreclr/vm/callhelpers.h
@@ -746,6 +746,57 @@ class UnmanagedCallersOnlyCaller final
 
         GCPROTECT_END();
     }
+
+    template<typename Ret, typename... Args>
+    Ret InvokeThrowing_Ret(Args... args)
+    {
+        CONTRACTL
+        {
+            THROWS;
+            GC_TRIGGERS;
+            MODE_COOPERATIVE;
+        }
+        CONTRACTL_END;
+        
+        // Sanity check - UnmanagedCallersOnly methods must be in CoreLib.
+        // See below load level override.
+        _ASSERTE(_pMD->GetModule()->IsSystem());
+
+        // We're invoking an CoreLib method, so lift the restriction on type load limits. These calls are
+        // limited to CoreLib and only into UnmanagedCallersOnly methods.
+        OVERRIDE_TYPE_LOAD_LEVEL_LIMIT(CLASS_LOADED);
+
+        Ret ret;
+
+        struct
+        {
+            OBJECTREF Exception;
+        } gc;
+        gc.Exception = NULL;
+        GCPROTECT_BEGIN(gc);
+
+        {
+            GCX_PREEMP();
+
+            PCODE methodEntry = _pMD->GetSingleCallableAddrOfCodeForUnmanagedCallersOnly();
+            _ASSERTE(methodEntry != (PCODE)NULL);
+
+            // Cast the function pointer to the appropriate type.
+            // Note that we append the exception handle argument.
+            auto fptr = reinterpret_cast<Ret(*)(Args..., OBJECTREF*)>(methodEntry);
+
+            // The last argument is the implied exception handle for any exceptions.
+            ret = fptr(args..., &gc.Exception);
+        }
+
+        // If an exception was thrown, propagate it
+        if (gc.Exception != NULL)
+            COMPlusThrow(gc.Exception);
+
+        GCPROTECT_END();
+
+        return ret;
+    }
 };
 
 #endif //!DACCESS_COMPILE
diff --git a/src/coreclr/vm/comutilnative.cpp b/src/coreclr/vm/comutilnative.cpp
@@ -124,30 +124,6 @@ extern "C" void QCALLTYPE ExceptionNative_GetFrozenStackTrace(QCall::ObjectHandl
 
 #ifdef FEATURE_COMINTEROP
 
-static BSTR BStrFromString(STRINGREF s)
-{
-    CONTRACTL
-    {
-        THROWS;
-    }
-    CONTRACTL_END;
-
-    WCHAR *wz;
-    int cch;
-    BSTR bstr;
-
-    if (s == NULL)
-        return NULL;
-
-    s->RefInterpretGetStringValuesDangerousForGC(&wz, &cch);
-
-    bstr = SysAllocString(wz);
-    if (bstr == NULL)
-        COMPlusThrowOM();
-
-    return bstr;
-}
-
 static BSTR GetExceptionDescription(OBJECTREF objException)
 {
     CONTRACTL
@@ -161,31 +137,12 @@ static BSTR GetExceptionDescription(OBJECTREF objException)
 
     BSTR bstrDescription;
 
-    STRINGREF MessageString = NULL;
-    GCPROTECT_BEGIN(MessageString)
     GCPROTECT_BEGIN(objException)
     {
-        // read Exception.Message property
-        MethodDescCallSite getMessage(METHOD__EXCEPTION__GET_MESSAGE, &objException);
-
-        ARG_SLOT GetMessageArgs[] = { ObjToArgSlot(objException)};
-        MessageString = getMessage.Call_RetSTRINGREF(GetMessageArgs);
-
-        // if the message string is empty then use the exception classname.
-        if (MessageString == NULL || MessageString->GetStringLength() == 0) {
-            // call GetClassName
-            MethodDescCallSite getClassName(METHOD__EXCEPTION__GET_CLASS_NAME, &objException);
-            ARG_SLOT GetClassNameArgs[] = { ObjToArgSlot(objException)};
-            MessageString = getClassName.Call_RetSTRINGREF(GetClassNameArgs);
-            _ASSERTE(MessageString != NULL && MessageString->GetStringLength() != 0);
-        }
-
-        // Allocate the description BSTR.
-        int DescriptionLen = MessageString->GetStringLength();
-        bstrDescription = SysAllocStringLen(MessageString->GetBuffer(), DescriptionLen);
+        UnmanagedCallersOnlyCaller getDescriptionBstr(METHOD__EXCEPTION__GET_DESCRIPTION_BSTR);
+        bstrDescription = getDescriptionBstr.InvokeThrowing_Ret<BSTR>(&objException);
     }
     GCPROTECT_END();
-    GCPROTECT_END();
 
     return bstrDescription;
 }
@@ -200,19 +157,17 @@ static BSTR GetExceptionSource(OBJECTREF objException)
         PRECONDITION( IsException(objException->GetMethodTable()) );
     }
     CONTRACTL_END;
+    
+    BSTR bstrSource;
 
-    STRINGREF refRetVal;
     GCPROTECT_BEGIN(objException)
-
-    // read Exception.Source property
-    MethodDescCallSite getSource(METHOD__EXCEPTION__GET_SOURCE, &objException);
-
-    ARG_SLOT GetSourceArgs[] = { ObjToArgSlot(objException)};
-
-    refRetVal = getSource.Call_RetSTRINGREF(GetSourceArgs);
-
+    {
+        UnmanagedCallersOnlyCaller getSourceBstr(METHOD__EXCEPTION__GET_SOURCE_BSTR);
+        bstrSource = getSourceBstr.InvokeThrowing_Ret<BSTR>(&objException);
+    }
     GCPROTECT_END();
-    return BStrFromString(refRetVal);
+
+    return bstrSource;
 }
 
 static void GetExceptionHelp(OBJECTREF objException, BSTR *pbstrHelpFile, DWORD *pdwHelpContext)
@@ -229,20 +184,11 @@ static void GetExceptionHelp(OBJECTREF objException, BSTR *pbstrHelpFile, DWORD
     }
     CONTRACTL_END;
 
-    *pdwHelpContext = 0;
-
-    GCPROTECT_BEGIN(objException);
-
-    // call managed code to parse help context
-    MethodDescCallSite getHelpContext(METHOD__EXCEPTION__GET_HELP_CONTEXT, &objException);
-
-    ARG_SLOT GetHelpContextArgs[] =
+    GCPROTECT_BEGIN(objException)
     {
-        ObjToArgSlot(objException),
-        PtrToArgSlot(pdwHelpContext)
-    };
-    *pbstrHelpFile = BStrFromString(getHelpContext.Call_RetSTRINGREF(GetHelpContextArgs));
-
+        UnmanagedCallersOnlyCaller getHelpContextBstr(METHOD__EXCEPTION__GET_HELP_CONTEXT_BSTR);
+        getHelpContextBstr.InvokeThrowing(&objException, pbstrHelpFile, pdwHelpContext);
+    }
     GCPROTECT_END();
 }
 
diff --git a/src/coreclr/vm/corelib.h b/src/coreclr/vm/corelib.h
@@ -301,11 +301,11 @@ DEFINE_FIELD_U(_xcode,             ExceptionObject,    _xcode)
 DEFINE_FIELD_U(_HResult,           ExceptionObject,    _HResult)
 DEFINE_CLASS(EXCEPTION,             System,                 Exception)
 DEFINE_METHOD(EXCEPTION,            INTERNAL_PRESERVE_STACK_TRACE, InternalPreserveStackTrace, IM_RetVoid)
-// Following Exception members are only used when FEATURE_COMINTEROP
-DEFINE_METHOD(EXCEPTION,            GET_CLASS_NAME,         GetClassName,               IM_RetStr)
-DEFINE_PROPERTY(EXCEPTION,          MESSAGE,                Message,                    Str)
-DEFINE_PROPERTY(EXCEPTION,          SOURCE,                 Source,                     Str)
-DEFINE_METHOD(EXCEPTION,            GET_HELP_CONTEXT,       GetHelpContext,             IM_RefUInt_RetStr)
+#ifdef FEATURE_COMINTEROP
+DEFINE_METHOD(EXCEPTION,            GET_DESCRIPTION_BSTR,   GetDescriptionBstr,         SM_PtrException_PtrException_RetIntPtr)
+DEFINE_METHOD(EXCEPTION,            GET_SOURCE_BSTR,        GetSourceBstr,              SM_PtrException_PtrException_RetIntPtr)
+DEFINE_METHOD(EXCEPTION,            GET_HELP_CONTEXT_BSTR,  GetHelpContextBstr,         SM_PtrException_PtrIntPtr_PtrUInt_PtrException_RetVoid)
+#endif // FEATURE_COMINTEROP
 
 
 DEFINE_CLASS(SYSTEM_EXCEPTION,      System,                 SystemException)
diff --git a/src/coreclr/vm/metasig.h b/src/coreclr/vm/metasig.h
@@ -399,7 +399,10 @@ DEFINE_METASIG_T(SM(IntPtr_RetRuntimeType, I , C(CLASS)))
 DEFINE_METASIG_T(IM(RuntimeArgumentHandle_PtrVoid_RetVoid, g(ARGUMENT_HANDLE) P(v), v))
 
 // Exception
-DEFINE_METASIG(IM(RefUInt_RetStr, r(K), s))
+#ifdef FEATURE_COMINTEROP
+DEFINE_METASIG_T(SM(PtrException_PtrException_RetIntPtr, P(C(EXCEPTION)) P(C(EXCEPTION)), I))
+DEFINE_METASIG_T(SM(PtrException_PtrIntPtr_PtrUInt_PtrException_RetVoid, P(C(EXCEPTION)) P(I) P(K) P(C(EXCEPTION)), v))
+#endif //FEATURE_COMINTEROP
 
 #ifdef FEATURE_COMINTEROP
 // The signature of the method System.Runtime.InteropServices.ICustomQueryInterface.GetInterface
