WIP

Author: byroot

gc.c

@@ -4145,6 +4145,18 @@ rb_gc_update_vm_references(void *objspace)
 #endif
 }
 
+void
+rb_gc_update_moved_object(void *objspace, VALUE dest, VALUE src)
+{
+    if (RB_TYPE_P(dest, T_IMEMO)) {
+        return;
+    }
+
+    if (FL_TEST_RAW(dest, RUBY_FL_ADDRESS_SEEN)) {
+        rb_obj_set_stable_address(dest, src);
+    }
+}
+
 void
 rb_gc_update_object_references(void *objspace, VALUE obj)
 {

gc/default/default.c

@@ -5453,25 +5453,22 @@ gc_compact_move(rb_objspace_t *objspace, rb_heap_t *heap, VALUE src)
     GC_ASSERT(gc_is_moveable_obj(objspace, src));
 
     rb_heap_t *dest_pool = gc_compact_destination_pool(objspace, heap, src);
+    uint32_t orig_shape = 0;
+    uint32_t new_shape = 0;
 
     if (gc_compact_heap_cursors_met_p(dest_pool)) {
         return dest_pool != heap;
     }
 
-    uint32_t orig_shape, new_shape;
-    VALUE dest = rb_gc_impl_location(objspace, src);
-
-    if (RB_TYPE_P(src, T_IMEMO)) {
-        new_shape = orig_shape = 0;
-    }
-    else {
-        new_shape = orig_shape = rb_gc_get_shape(src);
-    }
-
     if (RB_TYPE_P(src, T_OBJECT)) {
+        orig_shape = rb_gc_get_shape(src);
+
         if (dest_pool != heap) {
             new_shape = rb_gc_rebuild_shape(src, dest_pool - heaps);
-            dest_pool = heap;
+
+            if (new_shape == 0) {
+                dest_pool = heap;
+            }
         }
     }
 
@@ -5500,19 +5497,13 @@ gc_compact_move(rb_objspace_t *objspace, rb_heap_t *heap, VALUE src)
         }
     }
 
-    if (FL_TEST_RAW(dest, RUBY_FL_ADDRESS_SEEN) && !rb_shape_has_old_address(new_shape)) {
-        DURING_GC_COULD_MALLOC_REGION_START();
-        {
-            new_shape = rb_shape_transition_old_address(new_shape);
-            rb_obj_field_set(dest, new_shape, 0, src);
+    if (orig_shape != 0) {
+        if (new_shape != 0) {
+            VALUE dest = rb_gc_impl_location(objspace, src);
+            rb_gc_set_shape(dest, new_shape);
         }
-        DURING_GC_COULD_MALLOC_REGION_END();
-    }
-
-    if (new_shape != orig_shape) {
-        rb_gc_set_shape(dest, new_shape);
+        RMOVED(src)->original_shape_id = orig_shape;
     }
-    RMOVED(src)->original_shape_id = orig_shape;
 
     return true;
 }
@@ -7031,9 +7022,11 @@ gc_ref_update(void *vstart, void *vend, size_t stride, rb_objspace_t *objspace,
         asan_unpoisoning_object(v) {
             switch (BUILTIN_TYPE(v)) {
               case T_NONE:
-              case T_MOVED:
               case T_ZOMBIE:
                 break;
+              case T_MOVED:
+                rb_gc_update_moved_object(objspace, rb_gc_location(v), v);
+                break;
               default:
                 if (RVALUE_WB_UNPROTECTED(objspace, v)) {
                     page->flags.has_uncollectible_wb_unprotected_objects = TRUE;

gc/gc.h

@@ -75,6 +75,7 @@ MODULAR_GC_FN size_t rb_gc_obj_optimal_size(VALUE obj);
 MODULAR_GC_FN void rb_gc_mark_children(void *objspace, VALUE obj);
 MODULAR_GC_FN void rb_gc_vm_weak_table_foreach(vm_table_foreach_callback_func callback, vm_table_update_callback_func update_callback, void *data, bool weak_only, enum rb_gc_vm_weak_tables table);
 MODULAR_GC_FN void rb_gc_update_object_references(void *objspace, VALUE obj);
+MODULAR_GC_FN void rb_gc_update_moved_object(void *objspace, VALUE dest, VALUE src);
 MODULAR_GC_FN void rb_gc_update_vm_references(void *objspace);
 MODULAR_GC_FN void rb_gc_event_hook(VALUE obj, rb_event_flag_t event);
 MODULAR_GC_FN void *rb_gc_get_objspace(void);

internal/variable.h

@@ -55,6 +55,7 @@ VALUE rb_obj_field_get(VALUE obj, shape_id_t target_shape_id);
 void rb_ivar_set_internal(VALUE obj, ID id, VALUE val);
 void rb_obj_field_set(VALUE obj, shape_id_t target_shape_id, ID field_name, VALUE val);
 st_index_t rb_obj_stable_address(VALUE obj);
+void rb_obj_set_stable_address(VALUE obj, VALUE old_address);
 
 RUBY_SYMBOL_EXPORT_BEGIN
 /* variable.c (export) */

variable.c

@@ -4789,14 +4789,43 @@ rb_obj_stable_address(VALUE obj)
     RUBY_ASSERT(FL_ABLE(obj));
     RUBY_ASSERT(!RB_TYPE_P(obj, T_IMEMO));
 
-    if (!FL_TEST_RAW(obj, RUBY_FL_ADDRESS_SEEN)) {
+    if (FL_TEST_RAW(obj, RUBY_FL_ADDRESS_SEEN)) {
+        shape_id_t shape_id = RBASIC_SHAPE_ID(obj);
+        if (UNLIKELY(rb_shape_has_old_address(shape_id))) {
+            VALUE old_address = rb_obj_field_get(obj, rb_shape_old_address(shape_id));
+#if SIZEOF_LONG == SIZEOF_VOIDP
+            return (st_index_t)NUM2LONG(old_address);
+#elif SIZEOF_LONG_LONG == SIZEOF_VOIDP
+            return (st_index_t)NUM2LL(old_address);
+#else
+#error "Unexpected VALUE size"
+#endif
+        }
+    }
+    else {
         FL_SET_RAW(obj, RUBY_FL_ADDRESS_SEEN);
     }
 
+    return (st_index_t)obj;
+}
+
+void
+rb_obj_set_stable_address(VALUE obj, VALUE old_address)
+{
+    RUBY_ASSERT(FL_ABLE(obj));
+    RUBY_ASSERT(!RB_TYPE_P(obj, T_IMEMO));
+    RUBY_ASSERT(FL_TEST_RAW(obj, RUBY_FL_ADDRESS_SEEN));
+
     shape_id_t shape_id = RBASIC_SHAPE_ID(obj);
-    if (rb_shape_has_old_address(shape_id)) {
-        return (st_index_t)rb_obj_field_get(obj, rb_shape_old_address(shape_id));
-    }
 
-    return (st_index_t)obj;
+    if (!rb_shape_has_old_address(shape_id)) {
+#if SIZEOF_LONG == SIZEOF_VOIDP
+        old_address = LONG2NUM(old_address);
+#elif SIZEOF_LONG_LONG == SIZEOF_VOIDP
+        old_address = LL2NUM(old_address);
+#else
+#error "Unexpected VALUE size"
+#endif
+        rb_obj_field_set(obj, rb_shape_transition_old_address(shape_id), 0, old_address);
+    }
 }