per-method serial number

Methods and their definitions can be allocated/deallocated on-the-fly.
One pathological situation is when a method is deallocated then another
one is allocated immediately after that.  Address of those old/new method
entries/definitions can be the same then, depending on underlying
malloc/free implementation.

So pointer comparison is insufficient.  We have to check the contents.
To do so we introduce def->method_serial, which is an integer unique to
that specific method definition.

PS: Note that method_serial being uintptr_t rather than rb_serial_t is
intentional.  This is because rb_serial_t can be bigger than a pointer
on a 32bit system (rb_serial_t is at least 64bit).  In order to preserve
old packing of struct rb_call_cache, rb_serial_t is inappropriate.

1 files changed, 1 insertions, 1 deletions

diff --git a/vm_insnhelper.h b/vm_insnhelper.h
index 1a3dbc0326..18a670bf14 100644
--- a/vm_insnhelper.h
+++ b/vm_insnhelper.h
@@ -132,7 +132,7 @@ static inline void
 CC_SET_ME(CALL_CACHE cc, const rb_callable_method_entry_t *me)
 {
     cc->me = me;
-    cc->def = me ? me->def : NULL;
+    cc->method_serial = me ? me->def->method_serial : 0;
 }
 
 #define GET_BLOCK_HANDLER() (GET_LEP()[VM_ENV_DATA_INDEX_SPECVAL])