make `overloaded_cme_table` truly weak key map

`overloaded_cme_table` keeps cme -> monly_cme pairs to manage
corresponding `monly_cme` for `cme`. The lifetime of the `monly_cme`
should be longer than `monly_cme`, but the previous patch losts the
reference to the living `monly_cme`.

Now `overloaded_cme_table` values are always root (keys are only weak
reference), it means `monly_cme` does not freed until corresponding
`cme` is invalidated.

To make managing easy, move `overloaded_cme_table` to `rb_vm_t`.

1 files changed, 1 insertions, 0 deletions

diff --git a/vm_core.h b/vm_core.h
index 6bbce23078..11866b85e5 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -714,6 +714,7 @@ typedef struct rb_vm_struct {
     int builtin_inline_index;
 
     struct rb_id_table *negative_cme_table;
+    st_table *overloaded_cme_table; // cme -> overloaded_cme
 
 #ifndef VM_GLOBAL_CC_CACHE_TABLE_SIZE
 #define VM_GLOBAL_CC_CACHE_TABLE_SIZE 1023