Implement object shapes for T_CLASS and T_MODULE (#6637)

* Avoid RCLASS_IV_TBL in marshal.c
* Avoid RCLASS_IV_TBL for class names
* Avoid RCLASS_IV_TBL for autoload
* Avoid RCLASS_IV_TBL for class variables
* Avoid copying RCLASS_IV_TBL onto ICLASSes
* Use object shapes for Class and Module IVs

1 files changed, 10 insertions, 13 deletions

diff --git a/gc.c b/gc.c
index 76a1f0f2de..75b330ede5 100644
--- a/gc.c
+++ b/gc.c
@@ -3447,8 +3447,8 @@ obj_free(rb_objspace_t *objspace, VALUE obj)
       case T_CLASS:
         rb_id_table_free(RCLASS_M_TBL(obj));
         cc_table_free(objspace, obj, FALSE);
-        if (RCLASS_IV_TBL(obj)) {
-            st_free_table(RCLASS_IV_TBL(obj));
+        if (RCLASS_IVPTR(obj)) {
+            xfree(RCLASS_IVPTR(obj));
         }
         if (RCLASS_CONST_TBL(obj)) {
             rb_free_const_table(RCLASS_CONST_TBL(obj));
@@ -4865,15 +4865,11 @@ obj_memsize_of(VALUE obj, int use_all_types)
             if (RCLASS_M_TBL(obj)) {
                 size += rb_id_table_memsize(RCLASS_M_TBL(obj));
             }
-            if (RCLASS_IV_TBL(obj)) {
-                size += st_memsize(RCLASS_IV_TBL(obj));
-            }
+            // class IV sizes are allocated as powers of two
+            size += SIZEOF_VALUE << bit_length(RCLASS_IV_COUNT(obj));
             if (RCLASS_CVC_TBL(obj)) {
                 size += rb_id_table_memsize(RCLASS_CVC_TBL(obj));
             }
-            if (RCLASS_EXT(obj)->iv_tbl) {
-                size += st_memsize(RCLASS_EXT(obj)->iv_tbl);
-            }
             if (RCLASS_EXT(obj)->const_tbl) {
                 size += rb_id_table_memsize(RCLASS_EXT(obj)->const_tbl);
             }
@@ -7212,7 +7208,9 @@ gc_mark_children(rb_objspace_t *objspace, VALUE obj)
 
         mark_m_tbl(objspace, RCLASS_M_TBL(obj));
         cc_table_mark(objspace, obj);
-        mark_tbl_no_pin(objspace, RCLASS_IV_TBL(obj));
+        for (attr_index_t i = 0; i < RCLASS_IV_COUNT(obj); i++) {
+            gc_mark(objspace, RCLASS_IVPTR(obj)[i]);
+        }
         mark_const_tbl(objspace, RCLASS_CONST_TBL(obj));
         break;
 
@@ -10439,7 +10437,9 @@ gc_update_object_references(rb_objspace_t *objspace, VALUE obj)
         update_cvc_tbl(objspace, obj);
         update_superclasses(objspace, obj);
 
-        gc_update_tbl_refs(objspace, RCLASS_IV_TBL(obj));
+        for (attr_index_t i = 0; i < RCLASS_IV_COUNT(obj); i++) {
+            UPDATE_IF_MOVED(objspace, RCLASS_IVPTR(obj)[i]);
+        }
 
         update_class_ext(objspace, RCLASS_EXT(obj));
         update_const_tbl(objspace, RCLASS_CONST_TBL(obj));
@@ -10454,9 +10454,6 @@ gc_update_object_references(rb_objspace_t *objspace, VALUE obj)
             UPDATE_IF_MOVED(objspace, RCLASS(obj)->super);
         }
         if (!RCLASS_EXT(obj)) break;
-        if (RCLASS_IV_TBL(obj)) {
-            gc_update_tbl_refs(objspace, RCLASS_IV_TBL(obj));
-        }
         update_class_ext(objspace, RCLASS_EXT(obj));
         update_m_tbl(objspace, RCLASS_CALLABLE_M_TBL(obj));
         update_cc_tbl(objspace, obj);