Implement heap walking

Author: peterzhu2118

gc/mmtk.c

@@ -218,6 +218,7 @@ rb_gc_impl_new_obj(void *objspace_ptr, void *cache_ptr, VALUE klass, VALUE flags
     if (alloc_size > 24) alloc_obj[3] = v2;
     if (alloc_size > 32) alloc_obj[4] = v3;
 
+    mmtk_post_alloc(cache_ptr, (void*)alloc_obj, alloc_size + 8, MMTK_ALLOCATION_SEMANTICS_DEFAULT);
 
     if (rb_gc_shutdown_call_finalizer_p((VALUE)alloc_obj)) {
         mmtk_add_obj_free_candidate(alloc_obj);
@@ -337,7 +338,38 @@ void rb_gc_impl_writebarrier(void *objspace_ptr, VALUE a, VALUE b) { }
 void rb_gc_impl_writebarrier_unprotect(void *objspace_ptr, VALUE obj) { }
 void rb_gc_impl_writebarrier_remember(void *objspace_ptr, VALUE obj) { }
 // Heap walking
-void rb_gc_impl_each_objects(void *objspace_ptr, int (*callback)(void *, void *, size_t, void *), void *data) { }
+struct each_objects_data {
+    bool stop;
+    int (*callback)(void *, void *, size_t, void *);
+    void *data;
+};
+
+static void
+each_objects_i(MMTk_ObjectReference obj, void *d)
+{
+    struct each_objects_data *data = d;
+
+    if (data->stop) return;
+
+    size_t slot_size = rb_gc_impl_obj_slot_size((VALUE)obj);
+
+    if (data->callback(obj, (void *)((char *)obj + slot_size), slot_size, data->data) != 0) {
+        data->stop = true;
+    }
+}
+
+void
+rb_gc_impl_each_objects(void *objspace_ptr, int (*callback)(void *, void *, size_t, void *), void *data)
+{
+    struct each_objects_data each_objects_data = {
+        .stop = false,
+        .callback = callback,
+        .data = data,
+    };
+
+    mmtk_enumerate_objects(each_objects_i, &each_objects_data);
+}
+
 void rb_gc_impl_each_object(void *objspace_ptr, void (*func)(VALUE obj, void *data), void *data) { }
 // Finalizers
 void

gc/mmtk.h

@@ -125,8 +125,15 @@ MMTk_Address mmtk_alloc(MMTk_Mutator *mutator,
                         size_t offset,
                         MMTk_AllocationSemantics semantics);
 
+void mmtk_post_alloc(MMTk_Mutator *mutator,
+                     MMTk_ObjectReference refer,
+                     size_t bytes,
+                     MMTk_AllocationSemantics semantics);
+
 void mmtk_add_obj_free_candidate(MMTk_ObjectReference object);
 
+void mmtk_enumerate_objects(void (*callback)(MMTk_ObjectReference, void*), void *data);
+
 struct MMTk_RawVecOfObjRef mmtk_get_all_obj_free_candidates(void);
 
 void mmtk_free_raw_vec_of_obj_ref(struct MMTk_RawVecOfObjRef raw_vec);

gc/mmtk/Cargo.lock

@@ -29,8 +29,8 @@ probe = "0.5"
 features = ["is_mmtk_object", "object_pinning", "sticky_immix_non_moving_nursery"]
 
 # Uncomment the following lines to use mmtk-core from the official repository.
-git = "https://github.com/mmtk/mmtk-core.git"
-rev = "a3a72f8e5795678eff06fdc1524f0b429a62ccc0"
+git = "https://github.com/wks/mmtk-core.git"
+rev = "7d3f79d4e50dacec881252562c8c7946e2513e55"
 
 # Uncomment the following line to use mmtk-core from a local repository.
 # path = "../../mmtk-core"

gc/mmtk/Cargo.toml

@@ -402,3 +402,10 @@ pub struct RubyUpcalls {
 }
 
 unsafe impl Sync for RubyUpcalls {}
+
+#[repr(C)]
+#[derive(Clone)]
+pub struct HeapBounds {
+    pub start: *mut libc::c_void,
+    pub end: *mut libc::c_void,
+}

gc/mmtk/src/abi.rs

@@ -77,12 +77,34 @@ pub extern "C" fn mmtk_alloc(
     )
 }
 
+#[no_mangle]
+pub extern "C" fn mmtk_post_alloc(
+    mutator: *mut RubyMutator,
+    refer: ObjectReference,
+    bytes: usize,
+    semantics: AllocationSemantics,
+) {
+    memory_manager::post_alloc::<Ruby>(unsafe { &mut *mutator }, refer, bytes, semantics)
+}
+
 // TODO: Replace with buffered mmtk_add_obj_free_candidates
 #[no_mangle]
 pub extern "C" fn mmtk_add_obj_free_candidate(object: ObjectReference) {
     binding().weak_proc.add_obj_free_candidate(object)
 }
 
+// =============== Heap walking ===============
+
+#[no_mangle]
+pub extern "C" fn mmtk_enumerate_objects(
+    callback: extern "C" fn(ObjectReference, *mut libc::c_void),
+    data: *mut libc::c_void,
+) {
+    crate::mmtk().enumerate_objects(|object| {
+        callback(object, data);
+    })
+}
+
 // =============== Finalizers ===============
 
 #[no_mangle]

gc/mmtk/src/api.rs

@@ -28,7 +28,7 @@ impl Scanning<Ruby> for VMScanning {
         object_tracer: &mut OT,
     ) {
         debug_assert!(
-            mmtk::memory_manager::is_mmtk_object(object.to_raw_address()),
+            mmtk::memory_manager::is_mmtk_object(object.to_raw_address()).is_some(),
             "Not an MMTk object: {object}",
         );
         let gc_tls = unsafe { GCThreadTLS::from_vwt_check(tls) };
@@ -40,7 +40,7 @@ impl Scanning<Ruby> for VMScanning {
                 if pin { " pin" } else { "" }
             );
             debug_assert!(
-                mmtk::memory_manager::is_mmtk_object(target_object.to_raw_address()),
+                mmtk::memory_manager::is_mmtk_object(target_object.to_raw_address()).is_some(),
                 "Destination is not an MMTk object. Src: {object} dst: {target_object}"
             );
             let forwarded_target = object_tracer.trace_object(target_object);
@@ -173,7 +173,7 @@ impl VMScanning {
                 }
             );
             debug_assert!(
-                mmtk::memory_manager::is_mmtk_object(object.to_raw_address()),
+                mmtk::memory_manager::is_mmtk_object(object.to_raw_address()).is_some(),
                 "Root does not point to MMTk object.  object: {object}"
             );
             buffer.push(object);

gc/mmtk/src/scanning.rs

@@ -230,7 +230,7 @@ trait GlobalTableProcessingWork {
         // of `trace_object` due to the way it is used in `UPDATE_IF_MOVED`.
         let forward_object = |_worker, object: ObjectReference, _pin| {
             debug_assert!(
-                mmtk::memory_manager::is_mmtk_object(object.to_address::<Ruby>()),
+                mmtk::memory_manager::is_mmtk_object(object.to_address::<Ruby>()).is_some(),
                 "{} is not an MMTk object",
                 object
             );