tlopex commented on code in PR #684:
URL: https://github.com/apache/tvm-ffi/pull/684#discussion_r3642494889
##########
rust/tvm-ffi-macros/src/object_macros.rs:
##########
@@ -192,23 +195,24 @@ pub fn derive_object_ref(input: proc_macro::TokenStream)
-> TokenStream {
}
}
+ #[inline(always)]
unsafe fn move_to_any(
src: Self,
data: &mut #tvm_ffi_crate::tvm_ffi_sys::TVMFFIAny
) {
type ContainerType = <#struct_name as
#tvm_ffi_crate::object::ObjectRefCore>
::ContainerType;
- let type_index =
- <ContainerType as
#tvm_ffi_crate::object::ObjectCore>::type_index();
- data.type_index = type_index as i32;
- data.small_str_len = 0;
let data_ptr = #tvm_ffi_crate::object::ObjectArc::into_raw(
src.data
);
- data.data_union.v_obj =
- data_ptr as *mut ContainerType as *mut
#tvm_ffi_crate::tvm_ffi_sys::TVMFFIObject;
+ let object_ptr =
+ data_ptr as *mut ContainerType as *mut
#tvm_ffi_crate::tvm_ffi_sys::TVMFFIObject;
Review Comment:
We need the object pointer first because the type index is now read from the
runtime object header instead of ContainerType::type_index(), which preserves
the dynamic subtype after an upcast.
##########
rust/tvm-ffi/src/object.rs:
##########
@@ -95,13 +99,120 @@ pub unsafe trait ObjectCoreWithExtraItems: ObjectCore {
/// used by the ffi Any system and not user facing
///
/// We mark as unsafe since it moves out the internal of the ObjectRef
+///
+/// # Safety
+///
+/// `data`, `into_data`, and `from_data` must preserve the same object
+/// allocation and form an ownership-preserving round trip. That allocation
must
+/// start with a valid `TVMFFIObject` header whose registered object-range
+/// runtime type index correctly describes its layout and inheritance.
+///
+/// When `Self` also implements [`AnyCompatible`], `copy_to_any_view` must
+/// produce a non-owning view, while `move_to_any` must transfer ownership of
+/// the same object pointer and dynamic type index. `move_from_any_after_check`
+/// must be able to reclaim that owned representation exactly once, and a true
+/// `check_any_strict` result must guarantee that both after-check constructors
+/// are valid for it.
pub unsafe trait ObjectRefCore: Sized + Clone {
type ContainerType: ObjectCore;
fn data(this: &Self) -> &ObjectArc<Self::ContainerType>;
fn into_data(this: Self) -> ObjectArc<Self::ContainerType>;
fn from_data(data: ObjectArc<Self::ContainerType>) -> Self;
}
+/// Check whether a runtime type index refers to `target_type_index` or one of
+/// its subtypes.
+///
+/// The subtype relation lives in the process-wide type table maintained by the
+/// tvm-ffi library: every registered type records its depth in the single
+/// inheritance tree together with the chain of its ancestors. The check is
+/// O(1) — if `target` really is an ancestor, it must appear in the candidate's
+/// ancestor array exactly at `target`'s depth.
+///
+/// This is a hidden support function for derive-generated object checks.
Object
+/// indices in the registered range must refer to entries in the runtime type
+/// table.
+#[doc(hidden)]
+#[inline(always)]
+pub fn is_instance_of(object_type_index: i32, target_type_index: i32) -> bool {
+ if object_type_index == target_type_index {
+ return true;
+ }
+ let object_begin = TypeIndex::kTVMFFIStaticObjectBegin as i32;
+ // Every registered object is an instance of the root Object type.
+ if target_type_index == object_begin {
Review Comment:
I think it is. this is the root object fast path. Every object-range type
must cast to objectref, and the C++ uses the same range check while avoiding
type-table lookups.
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