From 3adc3c69603a2c3d27c762504d4523d1397960b9 Mon Sep 17 00:00:00 2001
From: Steve Pfister <stpfiste@microsoft.com>
Date: Mon, 8 Jul 2024 09:48:23 -0400
Subject: [PATCH 1/9] Call composite_type_to_reduced_element_type all the time

---
 src/mono/mono/metadata/class.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/mono/mono/metadata/class.c b/src/mono/mono/metadata/class.c
index 043338c14899d9..b379f637999a7f 100644
--- a/src/mono/mono/metadata/class.c
+++ b/src/mono/mono/metadata/class.c
@@ -4284,13 +4284,9 @@ mono_class_is_assignable_from_general (MonoClass *klass, MonoClass *oklass, gboo
 
 		MonoClass *eclass;
 		MonoClass *eoclass;
-		if (signature_assignment) {
-			eclass = composite_type_to_reduced_element_type (klass);
-			eoclass = composite_type_to_reduced_element_type (oklass);
-		} else {
-			eclass = m_class_get_cast_class (klass);
-			eoclass = m_class_get_cast_class (oklass);
-		}
+
+		eclass = composite_type_to_reduced_element_type (klass);
+		eoclass = composite_type_to_reduced_element_type (oklass);
 
 		*result = (eclass == eoclass);
 		return;

From ccb82a15fb480968e6b95d1217e9acec63ced0e6 Mon Sep 17 00:00:00 2001
From: Steve Pfister <stpfiste@microsoft.com>
Date: Mon, 8 Jul 2024 15:00:40 -0400
Subject: [PATCH 2/9] Work path to set values

---
 .../tests/System.Runtime.Tests/System/ArrayTests.cs        | 1 -
 src/mono/System.Private.CoreLib/src/System/Array.Mono.cs   | 7 +------
 src/mono/mono/metadata/icall.c                             | 5 -----
 3 files changed, 1 insertion(+), 12 deletions(-)

diff --git a/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/ArrayTests.cs b/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/ArrayTests.cs
index 998094377be4f4..ccaba707130386 100644
--- a/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/ArrayTests.cs
+++ b/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/ArrayTests.cs
@@ -1599,7 +1599,6 @@ public static void Copy_SourceAndDestinationNeverConvertible_ThrowsArrayTypeMism
         }
 
         [Fact]
-        [SkipOnMono("https://github.com/dotnet/runtime/issues/104197")]
         public static unsafe void Copy_CompatiblePointers()
         {
             // Can copy between compatible pointers
diff --git a/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs b/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs
index cded34be47b1f8..ac1a31a9c94088 100644
--- a/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs
+++ b/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs
@@ -169,6 +169,7 @@ private static void CopySlow(Array sourceArray, int sourceIndex, Array destinati
             if (reliable)
             {
                 if (!dst_type.Equals(src_type) &&
+                    !(dst_type.IsPointer && src_type.IsPointer) &&
                     !(dst_type.IsPrimitive && src_type.IsPrimitive &&
                       CanChangePrimitive(ObjectHandleOnStack.Create(ref dst_type), ObjectHandleOnStack.Create(ref src_type), true)))
                 {
@@ -329,9 +330,6 @@ private unsafe nint GetFlattenedIndex(ReadOnlySpan<int> indices)
 
         internal object? InternalGetValue(nint index)
         {
-            if (GetType().GetElementType()!.IsPointer)
-                throw new NotSupportedException(SR.NotSupported_Type);
-
             Array self = this;
             object? res = null;
             GetValueImpl(ObjectHandleOnStack.Create(ref self), ObjectHandleOnStack.Create(ref res), (int)index);
@@ -340,9 +338,6 @@ private unsafe nint GetFlattenedIndex(ReadOnlySpan<int> indices)
 
         internal void InternalSetValue(object? value, nint index)
         {
-            if (GetType().GetElementType()!.IsPointer)
-                throw new NotSupportedException(SR.NotSupported_Type);
-
             Array self = this;
             SetValueImpl(ObjectHandleOnStack.Create(ref self), ObjectHandleOnStack.Create(ref value), (int)index);
         }
diff --git a/src/mono/mono/metadata/icall.c b/src/mono/mono/metadata/icall.c
index 67cd6470df19db..a30dda9fffb0c3 100644
--- a/src/mono/mono/metadata/icall.c
+++ b/src/mono/mono/metadata/icall.c
@@ -199,11 +199,6 @@ ves_icall_System_Array_GetValueImpl (MonoObjectHandleOnStack array_handle, MonoO
 	MonoClass * const array_class = mono_object_class (array);
 	MonoClass * const element_class = m_class_get_element_class (array_class);
 
-	if (m_class_is_native_pointer (element_class)) {
-		mono_error_set_not_supported (error, NULL);
-		return;
-	}
-
 	if (m_class_is_valuetype (element_class)) {
 		gsize element_size = mono_array_element_size (array_class);
 		gpointer element_address = mono_array_addr_with_size_fast (array, element_size, (gsize)pos);

From 047d4ad7717b08b38dbf4babcd3e76ca30dff59a Mon Sep 17 00:00:00 2001
From: Steve Pfister <stpfiste@microsoft.com>
Date: Tue, 9 Jul 2024 10:59:34 -0400
Subject: [PATCH 3/9] Revert slow path changes - make fast path work

---
 src/mono/System.Private.CoreLib/src/System/Array.Mono.cs | 1 -
 src/mono/mono/metadata/class.c                           | 4 ++++
 src/mono/mono/metadata/icall.c                           | 5 +----
 src/mono/mono/metadata/object.c                          | 2 +-
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs b/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs
index ac1a31a9c94088..c85c6d4b89efc5 100644
--- a/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs
+++ b/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs
@@ -169,7 +169,6 @@ private static void CopySlow(Array sourceArray, int sourceIndex, Array destinati
             if (reliable)
             {
                 if (!dst_type.Equals(src_type) &&
-                    !(dst_type.IsPointer && src_type.IsPointer) &&
                     !(dst_type.IsPrimitive && src_type.IsPrimitive &&
                       CanChangePrimitive(ObjectHandleOnStack.Create(ref dst_type), ObjectHandleOnStack.Create(ref src_type), true)))
                 {
diff --git a/src/mono/mono/metadata/class.c b/src/mono/mono/metadata/class.c
index b379f637999a7f..5fab235e63173a 100644
--- a/src/mono/mono/metadata/class.c
+++ b/src/mono/mono/metadata/class.c
@@ -3582,6 +3582,10 @@ mono_class_is_subclass_of_internal (MonoClass *klass, MonoClass *klassc,
 				    gboolean check_interfaces)
 {
 	MONO_REQ_GC_UNSAFE_MODE;
+
+	if (mono_class_is_pointer(klass) && mono_class_is_pointer(klassc))
+		return TRUE;
+	
 	/* FIXME test for interfaces with variant generic arguments */
 	if (check_interfaces) {
 		mono_class_init_internal (klass);
diff --git a/src/mono/mono/metadata/icall.c b/src/mono/mono/metadata/icall.c
index a30dda9fffb0c3..acef2351a8b44e 100644
--- a/src/mono/mono/metadata/icall.c
+++ b/src/mono/mono/metadata/icall.c
@@ -199,7 +199,7 @@ ves_icall_System_Array_GetValueImpl (MonoObjectHandleOnStack array_handle, MonoO
 	MonoClass * const array_class = mono_object_class (array);
 	MonoClass * const element_class = m_class_get_element_class (array_class);
 
-	if (m_class_is_valuetype (element_class)) {
+	if (m_class_is_valuetype (element_class) || mono_class_is_pointer (element_class)) {
 		gsize element_size = mono_array_element_size (array_class);
 		gpointer element_address = mono_array_addr_with_size_fast (array, element_size, (gsize)pos);
 		MonoObject *res = mono_value_box_checked (element_class, element_address, error);
@@ -871,9 +871,6 @@ ves_icall_System_Array_FastCopy (MonoObjectHandleOnStack source_handle, int sour
 		/* It's only safe to copy between arrays if we can ensure the source will always have a subtype of the destination. We bail otherwise. */
 		if (!mono_class_is_subclass_of_internal (src_class, dest_class, FALSE))
 			return FALSE;
-
-		if (m_class_is_native_pointer (src_class) || m_class_is_native_pointer (dest_class))
-			return FALSE;
 	}
 
 	if (m_class_is_valuetype (dest_class)) {
diff --git a/src/mono/mono/metadata/object.c b/src/mono/mono/metadata/object.c
index 2a0e9e9834e094..1c1a632a4003e7 100644
--- a/src/mono/mono/metadata/object.c
+++ b/src/mono/mono/metadata/object.c
@@ -6529,7 +6529,7 @@ mono_value_box_handle (MonoClass *klass, gpointer value, MonoError *error)
 
 	error_init (error);
 
-	g_assert (m_class_is_valuetype (klass));
+	g_assert (m_class_is_valuetype (klass) || mono_class_is_pointer (klass));
 	g_assert (value != NULL);
 	if (G_UNLIKELY (m_class_is_byreflike (klass))) {
 		char *full_name = mono_type_get_full_name (klass);

From 6494a32fb841434950f54bc430d2d9a0610d6057 Mon Sep 17 00:00:00 2001
From: Steve Pfister <stpfiste@microsoft.com>
Date: Tue, 9 Jul 2024 11:55:21 -0400
Subject: [PATCH 4/9] Removed wrong NSE checks

---
 src/mono/System.Private.CoreLib/src/System/Array.Mono.cs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs b/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs
index c85c6d4b89efc5..cded34be47b1f8 100644
--- a/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs
+++ b/src/mono/System.Private.CoreLib/src/System/Array.Mono.cs
@@ -329,6 +329,9 @@ private unsafe nint GetFlattenedIndex(ReadOnlySpan<int> indices)
 
         internal object? InternalGetValue(nint index)
         {
+            if (GetType().GetElementType()!.IsPointer)
+                throw new NotSupportedException(SR.NotSupported_Type);
+
             Array self = this;
             object? res = null;
             GetValueImpl(ObjectHandleOnStack.Create(ref self), ObjectHandleOnStack.Create(ref res), (int)index);
@@ -337,6 +340,9 @@ private unsafe nint GetFlattenedIndex(ReadOnlySpan<int> indices)
 
         internal void InternalSetValue(object? value, nint index)
         {
+            if (GetType().GetElementType()!.IsPointer)
+                throw new NotSupportedException(SR.NotSupported_Type);
+
             Array self = this;
             SetValueImpl(ObjectHandleOnStack.Create(ref self), ObjectHandleOnStack.Create(ref value), (int)index);
         }

From 5ea2e7696d7fccab8e8573b16f7b2fed43ad9646 Mon Sep 17 00:00:00 2001
From: Steve Pfister <stpfiste@microsoft.com>
Date: Tue, 9 Jul 2024 14:14:53 -0400
Subject: [PATCH 5/9] Guard against incompatible types

---
 src/mono/mono/metadata/icall.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/mono/mono/metadata/icall.c b/src/mono/mono/metadata/icall.c
index acef2351a8b44e..187d57f885814e 100644
--- a/src/mono/mono/metadata/icall.c
+++ b/src/mono/mono/metadata/icall.c
@@ -867,6 +867,9 @@ ves_icall_System_Array_FastCopy (MonoObjectHandleOnStack source_handle, int sour
 		if (m_class_is_valuetype (dest_class) || m_class_is_enumtype (dest_class) ||
 		 	m_class_is_valuetype (src_class) || m_class_is_valuetype (src_class))
 			return FALSE;
+		
+		if (!mono_class_is_assignable_from_internal(dest_class, src_class))
+			return FALSE;
 
 		/* It's only safe to copy between arrays if we can ensure the source will always have a subtype of the destination. We bail otherwise. */
 		if (!mono_class_is_subclass_of_internal (src_class, dest_class, FALSE))

From 5ff76e596b5b904c7bec16d788ec80aa33033d7d Mon Sep 17 00:00:00 2001
From: Steve Pfister <stpfiste@microsoft.com>
Date: Tue, 9 Jul 2024 16:24:17 -0400
Subject: [PATCH 6/9] Feedback

---
 src/mono/mono/metadata/class.c |  3 ---
 src/mono/mono/metadata/icall.c | 15 +++++++++------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/mono/mono/metadata/class.c b/src/mono/mono/metadata/class.c
index 5fab235e63173a..2117c94c06a840 100644
--- a/src/mono/mono/metadata/class.c
+++ b/src/mono/mono/metadata/class.c
@@ -3583,9 +3583,6 @@ mono_class_is_subclass_of_internal (MonoClass *klass, MonoClass *klassc,
 {
 	MONO_REQ_GC_UNSAFE_MODE;
 
-	if (mono_class_is_pointer(klass) && mono_class_is_pointer(klassc))
-		return TRUE;
-	
 	/* FIXME test for interfaces with variant generic arguments */
 	if (check_interfaces) {
 		mono_class_init_internal (klass);
diff --git a/src/mono/mono/metadata/icall.c b/src/mono/mono/metadata/icall.c
index 187d57f885814e..c0d381ea32f6ec 100644
--- a/src/mono/mono/metadata/icall.c
+++ b/src/mono/mono/metadata/icall.c
@@ -868,12 +868,15 @@ ves_icall_System_Array_FastCopy (MonoObjectHandleOnStack source_handle, int sour
 		 	m_class_is_valuetype (src_class) || m_class_is_valuetype (src_class))
 			return FALSE;
 		
-		if (!mono_class_is_assignable_from_internal(dest_class, src_class))
-			return FALSE;
-
-		/* It's only safe to copy between arrays if we can ensure the source will always have a subtype of the destination. We bail otherwise. */
-		if (!mono_class_is_subclass_of_internal (src_class, dest_class, FALSE))
-			return FALSE;
+		if (mono_class_is_pointer (dest_class) && mono_class_is_pointer (src_class)) {
+			/* if we're copying between two arrays of pointers, only allow it if both dest_class is assignable from src_class (checked above, and src_class is assignable from dest_class).  This should only be true if both src_class and dest_class have a common cast_class. (for example: int*[] and uint*[] are ok, but void*[] and int*[] are not)). */
+			if (!mono_class_is_assignable_from_internal (src_class, dest_class, FALSE))
+				return FALSE;
+		} else {
+			/* It's only safe to copy between arrays if we can ensure the source will always have a subtype of the destination. We bail otherwise. */
+			if (!mono_class_is_subclass_of_internal (src_class, dest_class, FALSE))
+				return FALSE;
+		}
 	}
 
 	if (m_class_is_valuetype (dest_class)) {

From 461b0fd254f2242aa8b1f9bf3eafd5ac297d5ab8 Mon Sep 17 00:00:00 2001
From: Steve Pfister <stpfiste@microsoft.com>
Date: Tue, 9 Jul 2024 16:49:27 -0400
Subject: [PATCH 7/9] Mistaken param

---
 src/mono/mono/metadata/icall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mono/mono/metadata/icall.c b/src/mono/mono/metadata/icall.c
index c0d381ea32f6ec..8069eb89e1378f 100644
--- a/src/mono/mono/metadata/icall.c
+++ b/src/mono/mono/metadata/icall.c
@@ -870,7 +870,7 @@ ves_icall_System_Array_FastCopy (MonoObjectHandleOnStack source_handle, int sour
 		
 		if (mono_class_is_pointer (dest_class) && mono_class_is_pointer (src_class)) {
 			/* if we're copying between two arrays of pointers, only allow it if both dest_class is assignable from src_class (checked above, and src_class is assignable from dest_class).  This should only be true if both src_class and dest_class have a common cast_class. (for example: int*[] and uint*[] are ok, but void*[] and int*[] are not)). */
-			if (!mono_class_is_assignable_from_internal (src_class, dest_class, FALSE))
+			if (!mono_class_is_assignable_from_internal (src_class, dest_class))
 				return FALSE;
 		} else {
 			/* It's only safe to copy between arrays if we can ensure the source will always have a subtype of the destination. We bail otherwise. */

From 1f08798d1357100c51670a45be6d5ba9a9b3fcda Mon Sep 17 00:00:00 2001
From: Steve Pfister <stpfiste@microsoft.com>
Date: Tue, 9 Jul 2024 17:45:52 -0400
Subject: [PATCH 8/9] Flip params

---
 src/mono/mono/metadata/icall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mono/mono/metadata/icall.c b/src/mono/mono/metadata/icall.c
index 8069eb89e1378f..b03d69e0ff949c 100644
--- a/src/mono/mono/metadata/icall.c
+++ b/src/mono/mono/metadata/icall.c
@@ -870,7 +870,7 @@ ves_icall_System_Array_FastCopy (MonoObjectHandleOnStack source_handle, int sour
 		
 		if (mono_class_is_pointer (dest_class) && mono_class_is_pointer (src_class)) {
 			/* if we're copying between two arrays of pointers, only allow it if both dest_class is assignable from src_class (checked above, and src_class is assignable from dest_class).  This should only be true if both src_class and dest_class have a common cast_class. (for example: int*[] and uint*[] are ok, but void*[] and int*[] are not)). */
-			if (!mono_class_is_assignable_from_internal (src_class, dest_class))
+			if (!mono_class_is_assignable_from_internal (dest_class, src_class))
 				return FALSE;
 		} else {
 			/* It's only safe to copy between arrays if we can ensure the source will always have a subtype of the destination. We bail otherwise. */

From e6690489a78207028bf46bd80ec76fa4146b9227 Mon Sep 17 00:00:00 2001
From: Steve Pfister <stpfiste@microsoft.com>
Date: Tue, 9 Jul 2024 20:22:54 -0400
Subject: [PATCH 9/9] Do assignable check if src or dest is a pointer type

---
 src/mono/mono/metadata/icall.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/mono/mono/metadata/icall.c b/src/mono/mono/metadata/icall.c
index b03d69e0ff949c..43f3d32653f321 100644
--- a/src/mono/mono/metadata/icall.c
+++ b/src/mono/mono/metadata/icall.c
@@ -868,8 +868,8 @@ ves_icall_System_Array_FastCopy (MonoObjectHandleOnStack source_handle, int sour
 		 	m_class_is_valuetype (src_class) || m_class_is_valuetype (src_class))
 			return FALSE;
 		
-		if (mono_class_is_pointer (dest_class) && mono_class_is_pointer (src_class)) {
-			/* if we're copying between two arrays of pointers, only allow it if both dest_class is assignable from src_class (checked above, and src_class is assignable from dest_class).  This should only be true if both src_class and dest_class have a common cast_class. (for example: int*[] and uint*[] are ok, but void*[] and int*[] are not)). */
+		if (mono_class_is_pointer (dest_class) || mono_class_is_pointer (src_class)) {
+			/* if we're copying between at least one array of pointers, only allow it if both dest_class is assignable from src_class (checked above, and src_class is assignable from dest_class).  This should only be true if both src_class and dest_class have a common cast_class. (for example: int*[] and uint*[] are ok, but void*[] and int*[] are not)). */
 			if (!mono_class_is_assignable_from_internal (dest_class, src_class))
 				return FALSE;
 		} else {