`mandatory_only_cme` should not be in `def`

`def` (`rb_method_definition_t`) is shared by multiple callable
method entries (cme, `rb_callable_method_entry_t`).

There are two issues:

* old -> young reference: `cme1->def->mandatory_only_cme = monly_cme`
  if `cme1` is young and `monly_cme` is young, there is no problem.
  Howevr, another old `cme2` can refer `def`, in this case, old `cme2`
  points young `monly_cme` and it violates gengc assumption.
* cme can have different `defined_class` but `monly_cme` only has
  one `defined_class`. It does not make sense and `monly_cme`
  should be created for a cme (not `def`).

To solve these issues, this patch allocates `monly_cme` per `cme`.
`cme` does not have another room to store a pointer to the `monly_cme`,
so this patch introduces `overloaded_cme_table`, which is weak key map
`[cme] -> [monly_cme]`.

`def::body::iseqptr::monly_cme` is deleted.

The first issue is reported by Alan Wu.

1 files changed, 11 insertions, 5 deletions

diff --git a/vm_callinfo.h b/vm_callinfo.h
index 700fd3dc6c..09f755c818 100644
--- a/vm_callinfo.h
+++ b/vm_callinfo.h
@@ -449,6 +449,10 @@ struct rb_class_cc_entries {
 };
 
 #if VM_CHECK_MODE > 0
+
+const rb_callable_method_entry_t *rb_vm_lookup_overloaded_cme(const rb_callable_method_entry_t *cme);
+void rb_vm_dump_overloaded_cme_table(void);
+
 static inline bool
 vm_ccs_p(const struct rb_class_cc_entries *ccs)
 {
@@ -459,15 +463,17 @@ static inline bool
 vm_cc_check_cme(const struct rb_callcache *cc, const rb_callable_method_entry_t *cme)
 {
     if (vm_cc_cme(cc) == cme ||
-        (cme->def->iseq_overload && vm_cc_cme(cc) == cme->def->body.iseq.mandatory_only_cme)) {
+        (cme->def->iseq_overload && vm_cc_cme(cc) == rb_vm_lookup_overloaded_cme(cme))) {
         return true;
     }
     else {
 #if 1
-        fprintf(stderr, "iseq_overload:%d mandatory_only_cme:%p eq:%d\n",
-                (int)cme->def->iseq_overload,
-                (void *)cme->def->body.iseq.mandatory_only_cme,
-                vm_cc_cme(cc) == cme->def->body.iseq.mandatory_only_cme);
+        // debug print
+
+        fprintf(stderr, "iseq_overload:%d\n", (int)cme->def->iseq_overload);
+        rp(cme);
+        rp(vm_cc_cme(cc));
+        rb_vm_lookup_overloaded_cme(cme);
 #endif
         return false;
     }