7 files changed, 58 insertions, 19 deletions
diff --git a/eval.c b/eval.c
index 6fc3969690..efac69735b 100644
--- a/eval.c
+++ b/eval.c
@@ -1341,7 +1341,7 @@ rb_using_module(const rb_cref_t *cref, VALUE module)
 {
     Check_Type(module, T_MODULE);
     using_module_recursive(cref, module);
-    rb_clear_method_cache_all();
+    rb_clear_all_refinement_method_cache();
 }
 
 /*
diff --git a/gc.c b/gc.c
index 916e08eb03..b686bbbaa4 100644
--- a/gc.c
+++ b/gc.c
@@ -3187,6 +3187,8 @@ vm_ccs_free(struct rb_class_cc_entries *ccs, int alive, rb_objspace_t *objspace,
                     asan_poison_object((VALUE)cc);
                 }
             }
+
+            VM_ASSERT(!vm_cc_super_p(cc) && !vm_cc_refinement_p(cc));
             vm_cc_invalidate(cc);
         }
         ruby_xfree(ccs->entries);
diff --git a/method.h b/method.h
index d33ab5053c..6b60a49a3a 100644
--- a/method.h
+++ b/method.h
@@ -249,6 +249,6 @@ void rb_scope_visibility_set(rb_method_visibility_t);
 VALUE rb_unnamed_parameters(int arity);
 
 void rb_clear_method_cache(VALUE klass_or_module, ID mid);
-void rb_clear_method_cache_all(void);
+void rb_clear_all_refinement_method_cache(void);
 
 #endif /* RUBY_METHOD_H */
diff --git a/test/ruby/test_refinement.rb b/test/ruby/test_refinement.rb
index 56f33ae00a..7cddfce6bd 100644
--- a/test/ruby/test_refinement.rb
+++ b/test/ruby/test_refinement.rb
@@ -2626,6 +2626,24 @@ class TestRefinement < Test::Unit::TestCase
     assert_equal([], Refinement.used_modules)
   end
 
+  def test_inlinecache
+    assert_separately([], <<-"end;")
+      module R
+        refine String do
+          def to_s = :R
+        end
+      end
+
+      2.times{|i|
+        s = ''.to_s
+        assert_equal '', s if i == 0
+        assert_equal :R, s if i == 1
+        using R            if i == 0
+        assert_equal :R, ''.to_s
+      }
+    end;
+  end
+
   private
 
   def eval_using(mod, s)
diff --git a/vm_callinfo.h b/vm_callinfo.h
index 914f1eafdf..91c92854d7 100644
--- a/vm_callinfo.h
+++ b/vm_callinfo.h
@@ -296,13 +296,15 @@ struct rb_callcache {
 #define VM_CALLCACHE_UNMARKABLE FL_FREEZE
 #define VM_CALLCACHE_ON_STACK   FL_EXIVAR
 
-#define VM_CALLCACHE_IVAR  IMEMO_FL_USER0
-#define VM_CALLCACHE_BF    IMEMO_FL_USER1
-#define VM_CALLCACHE_SUPER IMEMO_FL_USER2
+#define VM_CALLCACHE_IVAR       IMEMO_FL_USER0
+#define VM_CALLCACHE_BF         IMEMO_FL_USER1
+#define VM_CALLCACHE_SUPER      IMEMO_FL_USER2
+#define VM_CALLCACHE_REFINEMENT IMEMO_FL_USER3
 
 enum vm_cc_type {
     cc_type_normal, // chained from ccs
     cc_type_super,
+    cc_type_refinement,
 };
 
 extern const struct rb_callcache *rb_vm_empty_cc(void);
@@ -332,6 +334,9 @@ vm_cc_new(VALUE klass,
       case cc_type_super:
         *(VALUE *)&cc->flags |= VM_CALLCACHE_SUPER;
         break;
+      case cc_type_refinement:
+        *(VALUE *)&cc->flags |= VM_CALLCACHE_REFINEMENT;
+        break;
     }
 
     vm_cc_attr_index_initialize(cc, INVALID_SHAPE_ID);
@@ -345,6 +350,12 @@ vm_cc_super_p(const struct rb_callcache *cc)
     return (cc->flags & VM_CALLCACHE_SUPER) != 0;
 }
 
+static inline bool
+vm_cc_refinement_p(const struct rb_callcache *cc)
+{
+    return (cc->flags & VM_CALLCACHE_REFINEMENT) != 0;
+}
+
 #define VM_CC_ON_STACK(clazz, call, aux, cme) \
     (struct rb_callcache) {                   \
         .flags = T_IMEMO |                    \
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 5e52207d81..6291e13fec 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -2003,6 +2003,8 @@ vm_ccs_verify(struct rb_class_cc_entries *ccs, ID mid, VALUE klass)
         VM_ASSERT(IMEMO_TYPE_P(cc, imemo_callcache));
         VM_ASSERT(vm_cc_class_check(cc, klass));
         VM_ASSERT(vm_cc_check_cme(cc, ccs->cme));
+        VM_ASSERT(!vm_cc_super_p(cc));
+        VM_ASSERT(!vm_cc_refinement_p(cc));
     }
     return TRUE;
 }
@@ -4193,12 +4195,19 @@ search_refined_method(rb_execution_context_t *ec, rb_control_frame_t *cfp, struc
 static VALUE
 vm_call_refined(rb_execution_context_t *ec, rb_control_frame_t *cfp, struct rb_calling_info *calling)
 {
-    struct rb_callcache *ref_cc =  &VM_CC_ON_STACK(Qundef, vm_call_general, {{ 0 }},
-                                                   search_refined_method(ec, cfp, calling));
+    const rb_callable_method_entry_t *ref_cme = search_refined_method(ec, cfp, calling);
 
-    if (vm_cc_cme(ref_cc)) {
-        calling->cc= ref_cc;
-        return vm_call_method(ec, cfp, calling);
+    if (ref_cme) {
+        if (calling->cd->cc) {
+            const struct rb_callcache *cc = calling->cc = vm_cc_new(vm_cc_cme(calling->cc)->defined_class, ref_cme, vm_call_general, cc_type_refinement);
+            RB_OBJ_WRITE(cfp->iseq, &calling->cd->cc, cc);
+            return vm_call_method(ec, cfp, calling);
+        }
+        else {
+            struct rb_callcache *ref_cc =  &VM_CC_ON_STACK(Qundef, vm_call_general, {{ 0 }}, ref_cme);
+            calling->cc= ref_cc;
+            return vm_call_method(ec, cfp, calling);
+        }
     }
     else {
         return vm_call_method_nome(ec, cfp, calling);
diff --git a/vm_method.c b/vm_method.c
index 221f184267..a65c676cfc 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -307,19 +307,19 @@ rb_clear_method_cache(VALUE klass_or_module, ID mid)
 void rb_cc_table_free(VALUE klass);
 
 static int
-invalidate_all_cc(void *vstart, void *vend, size_t stride, void *data)
+invalidate_all_refinement_cc(void *vstart, void *vend, size_t stride, void *data)
 {
     VALUE v = (VALUE)vstart;
     for (; v != (VALUE)vend; v += stride) {
         void *ptr = asan_poisoned_object_p(v);
         asan_unpoison_object(v, false);
+
         if (RBASIC(v)->flags) { // liveness check
-            if (RB_TYPE_P(v, T_CLASS) ||
-                RB_TYPE_P(v, T_ICLASS)) {
-                if (RCLASS_CC_TBL(v)) {
-                    rb_cc_table_free(v);
+            if (imemo_type_p(v, imemo_callcache)) {
+                const struct rb_callcache *cc = (const struct rb_callcache *)v;
+                if (vm_cc_refinement_p(cc) && cc->klass) {
+                    vm_cc_invalidate(cc);
                 }
-                RCLASS_CC_TBL(v) = NULL;
             }
         }
 
@@ -331,10 +331,9 @@ invalidate_all_cc(void *vstart, void *vend, size_t stride, void *data)
 }
 
 void
-rb_clear_method_cache_all(void)
+rb_clear_all_refinement_method_cache(void)
 {
-    rb_objspace_each_objects(invalidate_all_cc, NULL);
-
+    rb_objspace_each_objects(invalidate_all_refinement_cc, NULL);
     rb_yjit_invalidate_all_method_lookup_assumptions();
 }