vm_cc_new: don't assume cme is present.

[Bug #21694]

`vm_search_super_method` explictly calls `vm_cc_new` with `cme=NULL`
when there is no super class.

Author: byroot

test/ruby/test_super.rb

@@ -759,4 +759,19 @@ def initialize
     inherited = inherited_class.new
     assert_equal 2, inherited.test # it may read index=1 while it should be index=2
   end
+
+  def test_super_in_basic_object
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
+    begin;
+      class ::BasicObject
+        def no_super
+          super()
+        rescue ::NameError
+          :ok
+        end
+      end
+
+      assert_equal :ok, "[Bug #21694]".no_super
+    end;
+  end
 end

vm_callinfo.h

@@ -302,6 +302,7 @@ struct rb_callcache {
 #define VM_CALLCACHE_REFINEMENT IMEMO_FL_USER3
 #define VM_CALLCACHE_UNMARKABLE IMEMO_FL_USER4
 #define VM_CALLCACHE_ON_STACK   IMEMO_FL_USER5
+#define VM_CALLCACHE_INVALID_SUPER IMEMO_FL_USER6
 
 enum vm_cc_type {
     cc_type_normal, // chained from ccs
@@ -344,8 +345,6 @@ vm_cc_new(VALUE klass,
     *((struct rb_callable_method_entry_struct **)&cc->cme_) = (struct rb_callable_method_entry_struct *)cme;
     *((vm_call_handler *)&cc->call_) = call;
 
-    VM_ASSERT(RB_TYPE_P(klass, T_CLASS) || RB_TYPE_P(klass, T_ICLASS));
-
     switch (type) {
       case cc_type_normal:
         break;
@@ -358,8 +357,13 @@ vm_cc_new(VALUE klass,
         break;
     }
 
-    if (cme->def->type == VM_METHOD_TYPE_ATTRSET || cme->def->type == VM_METHOD_TYPE_IVAR) {
-        vm_cc_attr_index_initialize(cc, INVALID_SHAPE_ID);
+    if (cme) {
+        if (cme->def->type == VM_METHOD_TYPE_ATTRSET || cme->def->type == VM_METHOD_TYPE_IVAR) {
+            vm_cc_attr_index_initialize(cc, INVALID_SHAPE_ID);
+        }
+    }
+    else {
+        *(VALUE *)&cc->flags |= VM_CALLCACHE_INVALID_SUPER;
     }
 
     RB_DEBUG_COUNTER_INC(cc_new);
@@ -405,6 +409,14 @@ vm_cc_markable(const struct rb_callcache *cc)
     return FL_TEST_RAW((VALUE)cc, VM_CALLCACHE_UNMARKABLE) == 0;
 }
 
+static inline bool
+vm_cc_invalid_super(const struct rb_callcache *cc)
+{
+    VM_ASSERT(IMEMO_TYPE_P(cc, imemo_callcache));
+    // Set when calling super and there is no superclass.
+    return FL_TEST_RAW((VALUE)cc, VM_CALLCACHE_INVALID_SUPER);
+}
+
 static inline bool
 vm_cc_valid(const struct rb_callcache *cc)
 {
@@ -418,10 +430,11 @@ static inline const struct rb_callable_method_entry_struct *
 vm_cc_cme(const struct rb_callcache *cc)
 {
     VM_ASSERT(IMEMO_TYPE_P(cc, imemo_callcache));
-    VM_ASSERT(cc->klass != Qundef || !vm_cc_markable(cc));
+    VM_ASSERT(cc->klass != Qundef || !vm_cc_markable(cc) || vm_cc_invalid_super(cc));
     VM_ASSERT(cc_check_class(cc->klass));
     VM_ASSERT(cc->call_ == NULL   || // not initialized yet
               !vm_cc_markable(cc) ||
+              vm_cc_invalid_super(cc) ||
               cc->cme_ != NULL);
 
     return cc->cme_;
@@ -432,7 +445,7 @@ vm_cc_call(const struct rb_callcache *cc)
 {
     VM_ASSERT(IMEMO_TYPE_P(cc, imemo_callcache));
     VM_ASSERT(cc->call_ != NULL);
-    VM_ASSERT(cc->klass != Qundef || !vm_cc_markable(cc));
+    VM_ASSERT(cc->klass != Qundef || !vm_cc_markable(cc) || vm_cc_invalid_super(cc));
     VM_ASSERT(cc_check_class(cc->klass));
     return cc->call_;
 }

vm_insnhelper.c

@@ -5164,7 +5164,7 @@ vm_search_super_method(const rb_control_frame_t *reg_cfp, struct rb_call_data *c
 
     if (!klass) {
         /* bound instance method of module */
-        cc = vm_cc_new(klass, NULL, vm_call_method_missing, cc_type_super);
+        cc = vm_cc_new(Qundef, NULL, vm_call_method_missing, cc_type_super);
         RB_OBJ_WRITE(reg_cfp->iseq, &cd->cc, cc);
     }
     else {