1 files changed, 15 insertions, 10 deletions
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 24709eee2e..7efcdba8a4 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -1213,9 +1213,10 @@ ALWAYS_INLINE(static VALUE vm_getivar(VALUE, ID, const rb_iseq_t *, IVC, const s
 static inline VALUE
 vm_getivar(VALUE obj, ID id, const rb_iseq_t *iseq, IVC ic, const struct rb_callcache *cc, int is_attr, VALUE default_value)
 {
+    VALUE fields_obj;
 #if OPT_IC_FOR_IVAR
     VALUE val = Qundef;
-    VALUE * ivar_list;
+    VALUE *ivar_list;
 
     if (SPECIAL_CONST_P(obj)) {
         return default_value;
@@ -1247,11 +1248,17 @@ vm_getivar(VALUE obj, ID id, const rb_iseq_t *iseq, IVC ic, const struct rb_call
                 }
             }
 
-            ivar_list = RCLASS_PRIME_FIELDS(obj);
+            fields_obj = RCLASS_WRITABLE_FIELDS_OBJ(obj);
+            if (!fields_obj) {
+                return default_value;
+            }
+            ivar_list = rb_imemo_class_fields_ptr(fields_obj);
+            shape_id = rb_obj_shape_id(fields_obj);
+
             break;
         }
       default:
-        if (FL_TEST_RAW(obj, FL_EXIVAR)) {
+        if (rb_obj_exivar_p(obj)) {
             struct gen_fields_tbl *fields_tbl;
             rb_gen_fields_tbl_get(obj, id, &fields_tbl);
             ivar_list = fields_tbl->as.shape.fields;
@@ -1318,7 +1325,7 @@ vm_getivar(VALUE obj, ID id, const rb_iseq_t *iseq, IVC ic, const struct rb_call
             switch (BUILTIN_TYPE(obj)) {
               case T_CLASS:
               case T_MODULE:
-                table = (st_table *)RCLASS_FIELDS_HASH(obj);
+                table = rb_imemo_class_fields_complex_tbl(fields_obj);
                 break;
 
               case T_OBJECT:
@@ -1374,6 +1381,7 @@ vm_getivar(VALUE obj, ID id, const rb_iseq_t *iseq, IVC ic, const struct rb_call
         RUBY_ASSERT(!UNDEF_P(val));
     }
 
+    RB_GC_GUARD(fields_obj);
     return val;
 
 general_path:
@@ -1455,9 +1463,7 @@ vm_setivar_default(VALUE obj, ID id, VALUE val, shape_id_t dest_shape_id, attr_i
         RUBY_ASSERT(dest_shape_id != INVALID_SHAPE_ID && shape_id != INVALID_SHAPE_ID);
     }
     else if (dest_shape_id != INVALID_SHAPE_ID) {
-        rb_shape_t *dest_shape = RSHAPE(dest_shape_id);
-
-        if (shape_id == dest_shape->parent_id && dest_shape->edge_name == id && RSHAPE_CAPACITY(shape_id) == RSHAPE_CAPACITY(dest_shape_id)) {
+        if (shape_id == RSHAPE_PARENT(dest_shape_id) && RSHAPE_EDGE_NAME(dest_shape_id) == id && RSHAPE_CAPACITY(shape_id) == RSHAPE_CAPACITY(dest_shape_id)) {
             RUBY_ASSERT(index < RSHAPE_CAPACITY(dest_shape_id));
         }
         else {
@@ -1498,10 +1504,9 @@ vm_setivar(VALUE obj, ID id, VALUE val, shape_id_t dest_shape_id, attr_index_t i
                 VM_ASSERT(!rb_ractor_shareable_p(obj));
             }
             else if (dest_shape_id != INVALID_SHAPE_ID) {
-                rb_shape_t *dest_shape = RSHAPE(dest_shape_id);
-                shape_id_t source_shape_id = dest_shape->parent_id;
+                shape_id_t source_shape_id = RSHAPE_PARENT(dest_shape_id);
 
-                if (shape_id == source_shape_id && dest_shape->edge_name == id && RSHAPE_CAPACITY(shape_id) == RSHAPE_CAPACITY(dest_shape_id)) {
+                if (shape_id == source_shape_id && RSHAPE_EDGE_NAME(dest_shape_id) == id && RSHAPE_CAPACITY(shape_id) == RSHAPE_CAPACITY(dest_shape_id)) {
                     RUBY_ASSERT(dest_shape_id != INVALID_SHAPE_ID && shape_id != INVALID_SHAPE_ID);
 
                     RBASIC_SET_SHAPE_ID(obj, dest_shape_id);