From dedb6123d6bea756f0074f2913dcf830ca3564d9 Mon Sep 17 00:00:00 2001
From: Peter Zhu <peter@peterzhu.ca>
Date: Fri, 2 Oct 2026 18:07:17 +0900
Subject: [PATCH] Implement mmtk_is_pinned

---
 gc/mmtk/mmtk.c     | 3 +--
 gc/mmtk/mmtk.h     | 2 ++
 gc/mmtk/src/api.rs | 5 +++++
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/gc/mmtk/mmtk.c b/gc/mmtk/mmtk.c
index a7d0544..6311a60 100644
--- a/gc/mmtk/mmtk.c
+++ b/gc/mmtk/mmtk.c
@@ -1221,8 +1221,7 @@ rb_gc_impl_object_moved_p(void *objspace_ptr, VALUE obj)
 bool
 rb_gc_impl_pinned_p(void *objspace_ptr, VALUE obj)
 {
-    /* MMTk tracks pinning separately */
-    return false;
+    return mmtk_is_pinned((MMTk_ObjectReference)obj);
 }
 
 VALUE
diff --git a/gc/mmtk/mmtk.h b/gc/mmtk/mmtk.h
index 7f330b8..b81cf91 100644
--- a/gc/mmtk/mmtk.h
+++ b/gc/mmtk/mmtk.h
@@ -140,6 +140,8 @@ size_t mmtk_weak_references_count(void);
 
 void mmtk_register_pinning_obj(MMTk_ObjectReference obj);
 
+bool mmtk_is_pinned(MMTk_ObjectReference object);
+
 void mmtk_object_reference_write_post(MMTk_Mutator *mutator, MMTk_ObjectReference object);
 
 void mmtk_register_wb_unprotected_object(MMTk_ObjectReference object);
diff --git a/gc/mmtk/src/api.rs b/gc/mmtk/src/api.rs
index c8d83d3..ae341d0 100644
--- a/gc/mmtk/src/api.rs
+++ b/gc/mmtk/src/api.rs
@@ -414,6 +414,11 @@ pub extern "C" fn mmtk_register_pinning_obj(obj: ObjectReference) {
     crate::binding().pinning_registry.register(obj);
 }
 
+#[unsafe(no_mangle)]
+pub extern "C" fn mmtk_is_pinned(object: ObjectReference) -> bool {
+    memory_manager::is_pinned(object)
+}
+
 // =============== Write barriers ===============
 
 #[unsafe(no_mangle)]