Migrate StablePtr to KRefSharedHolder (#3966)

This PR also fixes tests from #3969

backend.native/tests/build.gradle

@@ -2742,6 +2742,10 @@ standaloneTest("memory_only_gc") {
     source = "runtime/memory/only_gc.kt"
 }
 
+task memory_stable_ref_cross_thread_check(type: KonanLocalTest) {
+    source = "runtime/memory/stable_ref_cross_thread_check.kt"
+}
+
 standaloneTest("cycle_collector") {
     disabled = project.globalTestArgs.contains('-opt') || (project.testTarget == 'wasm32') // Needs debug build.
     flags = ['-g']

backend.native/tests/runtime/memory/stable_ref_cross_thread_check.kt

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package runtime.memory.stable_ref_cross_thread_check
+
+import kotlin.test.*
+
+import kotlin.native.concurrent.*
+import kotlinx.cinterop.*
+
+@Test
+fun runTest1() {
+    val worker = Worker.start()
+
+    val future = worker.execute(TransferMode.SAFE, { }) {
+        StableRef.create(Any())
+    }
+    val ref = future.result
+    assertFailsWith<IncorrectDereferenceException> {
+        val value = ref.get()
+        println(value.toString())
+    }
+
+    worker.requestTermination().result
+}
+
+@Test
+fun runTest2() {
+    val worker = Worker.start()
+
+    val mainThreadRef = StableRef.create(Any())
+    // Simulate this going through interop as raw C pointer.
+    val pointerValue: Long = mainThreadRef.asCPointer().toLong()
+    val future = worker.execute(TransferMode.SAFE, { pointerValue }) {
+        val pointer: COpaquePointer = it.toCPointer()!!
+        assertFailsWith<IncorrectDereferenceException> {
+            // Even attempting to convert a pointer to StableRef should fail.
+            val otherThreadRef: StableRef<Any> = pointer.asStableRef()
+            println(otherThreadRef.toString())
+        }
+        Unit
+    }
+    future.result
+
+    worker.requestTermination().result
+}

runtime/src/main/cpp/Interop.cpp

@@ -18,21 +18,28 @@
 #include <stdio.h>
 #include <stdint.h>
 
+#include "Alloc.h"
 #include "Memory.h"
+#include "MemorySharedRefs.hpp"
 #include "Types.h"
 
 extern "C" {
 
 KNativePtr Kotlin_Interop_createStablePointer(KRef any) {
-    return CreateStablePointer(any);
+  KRefSharedHolder* holder = konanConstructInstance<KRefSharedHolder>();
+  holder->init(any);
+  return holder;
 }
 
 void Kotlin_Interop_disposeStablePointer(KNativePtr pointer) {
-  DisposeStablePointer(pointer);
+  KRefSharedHolder* holder = reinterpret_cast<KRefSharedHolder*>(pointer);
+  holder->dispose();
+  konanDestructInstance(holder);
 }
 
 OBJ_GETTER(Kotlin_Interop_derefStablePointer, KNativePtr pointer) {
-  RETURN_RESULT_OF(DerefStablePointer, pointer);
+  KRefSharedHolder* holder = reinterpret_cast<KRefSharedHolder*>(pointer);
+  RETURN_OBJ(holder->ref());
 }
 
 }

runtime/src/main/cpp/Memory.cpp

@@ -2279,10 +2279,7 @@ void disposeStablePointer(KNativePtr pointer) {
 
 OBJ_GETTER(derefStablePointer, KNativePtr pointer) {
   KRef ref = reinterpret_cast<KRef>(pointer);
-#if USE_GC
-  if (IsStrictMemoryModel && ref != nullptr)
-    rememberNewContainer(ref->container());
-#endif  // USE_GC
+  AdoptReferenceFromSharedVariable(ref);
   RETURN_OBJ(ref);
 }
 
@@ -2758,6 +2755,13 @@ bool IsForeignRefAccessible(ObjHeader* object, ForeignRefContext context) {
   return isForeignRefAccessible(object, context);
 }
 
+void AdoptReferenceFromSharedVariable(ObjHeader* object) {
+#if USE_GC
+  if (IsStrictMemoryModel && object != nullptr && isShareable(object->container()))
+    rememberNewContainer(object->container());
+#endif  // USE_GC
+}
+
 // Public memory interface.
 MemoryState* InitMemory() {
   return initMemory();

runtime/src/main/cpp/MemoryPrivate.hpp

@@ -36,6 +36,10 @@ void DeinitForeignRef(ObjHeader* object, ForeignRefContext context);
 
 bool IsForeignRefAccessible(ObjHeader* object, ForeignRefContext context);
 
+// Should be used when reference is read from a possibly shared variable,
+// and there's nothing else keeping the object alive.
+void AdoptReferenceFromSharedVariable(ObjHeader* object);
+
 }  // extern "C"
 
 #endif // RUNTIME_MEMORYPRIVATE_HPP

runtime/src/main/cpp/MemorySharedRefs.cpp

@@ -22,6 +22,7 @@ void KRefSharedHolder::init(ObjHeader* obj) {
 
 ObjHeader* KRefSharedHolder::ref() const {
   ensureRefAccessible();
+  AdoptReferenceFromSharedVariable(obj_);
   return obj_;
 }
 
@@ -76,7 +77,8 @@ void BackRefFromAssociatedObject::addRef() {
 
 bool BackRefFromAssociatedObject::tryAddRef() {
   // Suboptimal but simple:
-  ObjHeader* obj = this->ref();
+  this->ensureRefAccessible();
+  ObjHeader* obj = this->obj_;
 
   if (!TryAddHeapRef(obj)) return false;
   this->addRef();
@@ -97,6 +99,12 @@ void BackRefFromAssociatedObject::releaseRef() {
   }
 }
 
+ObjHeader* BackRefFromAssociatedObject::ref() const {
+  ensureRefAccessible();
+  AdoptReferenceFromSharedVariable(obj_);
+  return obj_;
+}
+
 void BackRefFromAssociatedObject::ensureRefAccessible() const {
   ensureForeignRefAccessible(obj_, context_);
 }

runtime/src/main/cpp/MemorySharedRefs.hpp

@@ -35,10 +35,7 @@ class BackRefFromAssociatedObject {
 
   void releaseRef();
 
-  ObjHeader* ref() const {
-    ensureRefAccessible();
-    return obj_;
-  }
+  ObjHeader* ref() const;
 
   inline bool permanent() const {
     return obj_->permanent(); // Safe to query from any thread.