Stop managing valid class serials

`mjit_valid_class_serial_p` has no longer been used since b9007b6c54.

gc.c

@@ -2820,7 +2820,6 @@ obj_free(rb_objspace_t *objspace, VALUE obj)
         break;
       case T_MODULE:
       case T_CLASS:
-        mjit_remove_class_serial(RCLASS_SERIAL(obj));
 	rb_id_table_free(RCLASS_M_TBL(obj));
         cc_table_free(objspace, obj, FALSE);
 	if (RCLASS_IV_TBL(obj)) {

mjit.c

@@ -521,19 +521,6 @@ init_header_filename(void)
     return true;
 }
 
-static enum rb_id_table_iterator_result
-valid_class_serials_add_i(ID key, VALUE v, void *unused)
-{
-    rb_const_entry_t *ce = (rb_const_entry_t *)v;
-    VALUE value = ce->value;
-
-    if (!rb_is_const_id(key)) return ID_TABLE_CONTINUE;
-    if (RB_TYPE_P(value, T_MODULE) || RB_TYPE_P(value, T_CLASS)) {
-        mjit_add_class_serial(RCLASS_SERIAL(value));
-    }
-    return ID_TABLE_CONTINUE;
-}
-
 #ifdef _WIN32
 UINT rb_w32_system_tmpdir(WCHAR *path, UINT len);
 #endif
@@ -738,16 +725,6 @@ mjit_init(const struct mjit_options *opts)
     // rb_fiber_init_mjit_cont again with mjit_enabled=true to set the root_fiber's mjit_cont.
     rb_fiber_init_mjit_cont(GET_EC()->fiber_ptr);
 
-    // Initialize class_serials cache for compilation
-    valid_class_serials = rb_hash_new();
-    rb_obj_hide(valid_class_serials);
-    rb_gc_register_mark_object(valid_class_serials);
-    mjit_add_class_serial(RCLASS_SERIAL(rb_cObject));
-    mjit_add_class_serial(RCLASS_SERIAL(CLASS_OF(rb_vm_top_self())));
-    if (RCLASS_CONST_TBL(rb_cObject)) {
-        rb_id_table_foreach(RCLASS_CONST_TBL(rb_cObject), valid_class_serials_add_i, NULL);
-    }
-
     // Initialize worker thread
     start_worker();
 }
@@ -996,28 +973,4 @@ mjit_mark_cc_entries(const struct rb_iseq_constant_body *const body)
     }
 }
 
-// A hook to update valid_class_serials.
+#endif // USE_MJIT
-void
-mjit_add_class_serial(rb_serial_t class_serial)
-{
-    if (!mjit_enabled)
-        return;
-
-    // Do not wrap CRITICAL_SECTION here. This function is only called in main thread
-    // and guarded by GVL, and `rb_hash_aset` may cause GC and deadlock in it.
-    rb_hash_aset(valid_class_serials, LONG2FIX(class_serial), Qtrue);
-}
-
-// A hook to update valid_class_serials.
-void
-mjit_remove_class_serial(rb_serial_t class_serial)
-{
-    if (!mjit_enabled)
-        return;
-
-    CRITICAL_SECTION_START(3, "in mjit_remove_class_serial");
-    rb_hash_delete_entry(valid_class_serials, LONG2FIX(class_serial));
-    CRITICAL_SECTION_FINISH(3, "in mjit_remove_class_serial");
-}
-
-#endif

mjit.h

@@ -101,8 +101,6 @@ extern void mjit_update_references(const rb_iseq_t *iseq);
 extern void mjit_mark(void);
 extern struct mjit_cont *mjit_cont_new(rb_execution_context_t *ec);
 extern void mjit_cont_free(struct mjit_cont *cont);
-extern void mjit_add_class_serial(rb_serial_t class_serial);
-extern void mjit_remove_class_serial(rb_serial_t class_serial);
 extern void mjit_mark_cc_entries(const struct rb_iseq_constant_body *const body);
 
 // A threshold used to reject long iseqs from JITting as such iseqs
@@ -206,8 +204,6 @@ static inline void mjit_gc_start_hook(void){}
 static inline void mjit_gc_exit_hook(void){}
 static inline void mjit_free_iseq(const rb_iseq_t *iseq){}
 static inline void mjit_mark(void){}
-static inline void mjit_add_class_serial(rb_serial_t class_serial){}
-static inline void mjit_remove_class_serial(rb_serial_t class_serial){}
 static inline VALUE mjit_exec(rb_execution_context_t *ec) { return Qundef; /* unreachable */ }
 static inline void mjit_child_after_fork(void){}
 

mjit_worker.c

@@ -240,9 +240,6 @@ static bool worker_stopped;
 
 // Path of "/tmp", which can be changed to $TMP in MinGW.
 static char *tmp_dir;
-// Hash like { 1 => true, 2 => true, ... } whose keys are valid `class_serial`s.
-// This is used to invalidate obsoleted CALL_CACHE.
-static VALUE valid_class_serials;
 
 // Used C compiler path.
 static const char *cc_path;
@@ -488,16 +485,6 @@ real_ms_time(void)
 }
 #endif
 
-// Return true if class_serial is not obsoleted. This is used by mjit_compile.c.
-bool
-mjit_valid_class_serial_p(rb_serial_t class_serial)
-{
-    CRITICAL_SECTION_START(3, "in valid_class_serial_p");
-    bool found_p = rb_hash_stlike_lookup(valid_class_serials, LONG2FIX(class_serial), NULL);
-    CRITICAL_SECTION_FINISH(3, "in valid_class_serial_p");
-    return found_p;
-}
-
 // Return the best unit from list.  The best is the first
 // high priority unit or the unit whose iseq has the biggest number
 // of calls so far.

vm.c

@@ -366,7 +366,6 @@ rb_serial_t
 rb_next_class_serial(void)
 {
     rb_serial_t class_serial = NEXT_CLASS_SERIAL();
-    mjit_add_class_serial(class_serial);
     return class_serial;
 }