[runtime] Treat calling a non-virtual method through an open delegate the same as the normal case instead of the OPEN_VIRTUAL case. (#17832)

* [runtime] Treat calling a non-virtual method through an open delegate the same as the normal case instead of the OPEN_VIRTUAL case.

* [amd64] Fix the return value mapping in gsharedvt calls, the return address might be in different registers in the caller and callee.

* [runtime] Always initialize del->method_ptr even if interp_method is set, JITted code makes calls through it in mixed mode.

* Add a test for open delegates and gsharedvt.

* Increase nrgctx trampoline count, its needed by dynamic-method-churn.exe in full-aot-interp mode.

5 files changed, 32 insertions, 4 deletions

diff --git a/configure.ac b/configure.ac
index 7ad189a7473..5eb2cf9beca 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1347,7 +1347,7 @@ enable_cooperative_suspend_default=no
 enable_hybrid_suspend_default=no
 
 # For the sake of clearer error messages, these numbers should all be different from each other.
-INVARIANT_AOT_OPTIONS=nimt-trampolines=2000,ntrampolines=10000,nrgctx-fetch-trampolines=256,ngsharedvt-trampolines=4400,nftnptr-arg-trampolines=4000
+INVARIANT_AOT_OPTIONS=nimt-trampolines=2000,ntrampolines=10000,nrgctx-fetch-trampolines=256,ngsharedvt-trampolines=4400,nftnptr-arg-trampolines=4000,nrgctx-trampolines=21000
 
 AOT_BUILD_ATTRS=$INVARIANT_AOT_OPTIONS
 
diff --git a/mono/metadata/marshal.c b/mono/metadata/marshal.c
index df783091919..59a0c2eb9d2 100644
--- a/mono/metadata/marshal.c
+++ b/mono/metadata/marshal.c
@@ -2329,7 +2329,11 @@ mono_marshal_get_delegate_invoke (MonoMethod *method, MonoDelegate *del)
 	sig = mono_signature_no_pinvoke (method);
 
 	if (del && !del->target && del->method && mono_method_signature_internal (del->method)->hasthis) {
-		callvirt = TRUE;
+		if (!(del->method->flags & METHOD_ATTRIBUTE_VIRTUAL) && !m_class_is_valuetype (del->method->klass) && sig->param_count ==  mono_method_signature_internal (del->method)->param_count + 1) {
+			/* The first argument of the delegate is passed as this, the normal invoke code can handle this */
+		} else {
+			callvirt = TRUE;
+		}
 		target_method = del->method;
 	}
 
diff --git a/mono/mini/gshared.cs b/mono/mini/gshared.cs
index 13cb8a55866..abcec7e2bd6 100644
--- a/mono/mini/gshared.cs
+++ b/mono/mini/gshared.cs
@@ -2217,6 +2217,30 @@ public class Tests
 		var s = new AStruct () { a = 1, b = 2 };
 		return iface.foo<AStruct> (s);
 	}
+
+	interface IFaceOpenDel {
+		object AMethod<T> ();
+	}
+
+	class ClassOpenDel : IFaceOpenDel {
+		public Nullable<int> field;
+
+		public Nullable<int> getField () {
+			return field;
+		}
+
+		public object AMethod<T> () {
+			var d = (Func<ClassOpenDel, T>)Delegate.CreateDelegate (typeof (Func<ClassOpenDel, T>), typeof (ClassOpenDel).GetMethod ("getField"));
+			return d (this);
+		}
+	}
+
+	// Open instance delegate returning a gsharedvt value
+	public static int test_0_open_delegate () {
+		IFaceOpenDel iface = new ClassOpenDel () { field = 42 };
+		var res = (Nullable<int>)iface.AMethod<Nullable<int>> ();
+		return res == 42 ? 0 : 1;
+	}
 }
 
 // #13191
diff --git a/mono/mini/mini-amd64-gsharedvt.c b/mono/mini/mini-amd64-gsharedvt.c
index 3bd23b6d04e..03c79149dbe 100644
--- a/mono/mini/mini-amd64-gsharedvt.c
+++ b/mono/mini/mini-amd64-gsharedvt.c
@@ -411,7 +411,7 @@ mono_arch_get_gsharedvt_call_info (gpointer addr, MonoMethodSignature *normal_si
 	if (cinfo->ret.storage == ArgValuetypeAddrInIReg) {
 		/* Both the caller and the callee pass the vtype ret address in r8 (System V) and RCX or RDX (Windows) */
 		g_assert (gcinfo->ret.storage == ArgValuetypeAddrInIReg || gcinfo->ret.storage == ArgGsharedvtVariableInReg);
-		add_to_map (map, map_reg (cinfo->ret.reg), map_reg (cinfo->ret.reg));
+		add_to_map (map, map_reg (caller_cinfo->ret.reg), map_reg (callee_cinfo->ret.reg));
 	}
 
 	info = mono_domain_alloc0 (mono_domain_get (), sizeof (GSharedVtCallInfo) + (map->len * sizeof (int)));
diff --git a/mono/mini/mini-runtime.c b/mono/mini/mini-runtime.c
index 3122bbe750e..a14a0a38702 100644
--- a/mono/mini/mini-runtime.c
+++ b/mono/mini/mini-runtime.c
@@ -3568,7 +3568,7 @@ mini_init_delegate (MonoDelegateHandle delegate, MonoError *error)
 		g_assert (del->method);
 		/* del->method_ptr might already be set to no_llvmonly_interp_method_pointer if the delegate was created from the interpreter */
 		del->method_ptr = mini_llvmonly_load_method_delegate (del->method, FALSE, FALSE, &del->extra_arg, error);
-	} else if (!del->method_ptr && !del->interp_method) {
+	} else if (!del->method_ptr) {
 		del->method_ptr = create_delegate_method_ptr (del->method, error);
 		return_if_nok (error);
 	}