wasm gc: support ReferenceQueue

core/src/main/java/org/teavm/backend/wasm/WasmGCTarget.java

@@ -16,6 +16,8 @@
 package org.teavm.backend.wasm;
 
 import java.io.IOException;
+import java.lang.ref.Reference;
+import java.lang.ref.ReferenceQueue;
 import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.HashMap;
@@ -55,6 +57,7 @@
 import org.teavm.backend.wasm.transformation.gc.BaseClassesTransformation;
 import org.teavm.backend.wasm.transformation.gc.ClassLoaderResourceTransformation;
 import org.teavm.backend.wasm.transformation.gc.EntryPointTransformation;
+import org.teavm.backend.wasm.transformation.gc.ReferenceQueueTransformation;
 import org.teavm.dependency.DependencyAnalyzer;
 import org.teavm.dependency.DependencyListener;
 import org.teavm.interop.Platforms;
@@ -176,6 +179,7 @@ public List<ClassHolderTransformer> getTransformers() {
         return List.of(
                 new BaseClassesTransformation(),
                 new ClassLoaderResourceTransformation(),
+                new ReferenceQueueTransformation(),
                 entryPointTransformation
         );
     }
@@ -267,6 +271,12 @@ public void emit(ListableClassHolderSource classes, BuildTarget buildTarget, Str
             exceptionMessageFunction.setExportName("teavm.exceptionMessage");
         }
 
+        var refQueueSupplyRef = new MethodReference(ReferenceQueue.class, "supply", Reference.class, void.class);
+        if (controller.getDependencyInfo().getMethod(refQueueSupplyRef) != null) {
+            var refQueueSupplyFunction = declarationsGenerator.functions().forInstanceMethod(refQueueSupplyRef);
+            refQueueSupplyFunction.setExportName("teavm.reportGarbageCollectedValue");
+        }
+
         moduleGenerator.generate();
         customGenerators.contributeToModule(module);
         adjustModuleMemory(module);

core/src/main/java/org/teavm/backend/wasm/gc/WasmGCReferenceQueueDependency.java

@@ -15,13 +15,19 @@
  */
 package org.teavm.backend.wasm.gc;
 
+import java.lang.ref.Reference;
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
 import org.teavm.dependency.AbstractDependencyListener;
 import org.teavm.dependency.DependencyAgent;
 import org.teavm.dependency.DependencyNode;
 import org.teavm.dependency.MethodDependency;
+import org.teavm.model.MethodReference;
 
 public class WasmGCReferenceQueueDependency extends AbstractDependencyListener {
     private DependencyNode valueNode;
+    private boolean refQueuePassedToRef;
+    private boolean refQueuePoll;
 
     @Override
     public void started(DependencyAgent agent) {
@@ -33,12 +39,30 @@ public void methodReached(DependencyAgent agent, MethodDependency method) {
         if (method.getMethod().getOwnerName().equals("java.lang.ref.WeakReference")) {
             switch (method.getMethod().getName()) {
                 case "<init>":
+                    if (method.getMethod().parameterCount() == 2) {
+                        refQueuePassedToRef = true;
+                        checkRefQueue(agent);
+                    }
                     method.getVariable(1).connect(valueNode);
                     break;
                 case "get":
                     valueNode.connect(method.getResult());
                     break;
             }
+        } else if (method.getMethod().getOwnerName().equals(ReferenceQueue.class.getName())) {
+            if (method.getMethod().getName().equals("poll")) {
+                refQueuePoll = true;
+                checkRefQueue(agent);
+            }
+        }
+    }
+
+    private void checkRefQueue(DependencyAgent agent) {
+        if (refQueuePassedToRef && refQueuePoll) {
+            agent.linkMethod(new MethodReference(ReferenceQueue.class, "supply", Reference.class, void.class))
+                    .propagate(0, ReferenceQueue.class)
+                    .propagate(1, WeakReference.class)
+                    .use();
         }
     }
 }

core/src/main/java/org/teavm/backend/wasm/generators/gc/WeakReferenceGenerator.java

@@ -61,7 +61,8 @@ private void generateConstructor(WasmGCCustomGeneratorContext context, WasmFunct
         function.add(queueLocal);
 
         var weakRefConstructor = getCreateWeakReferenceFunction(context);
-        var weakRef = new WasmCall(weakRefConstructor, new WasmGetLocal(valueLocal), new WasmGetLocal(thisLocal));
+        var weakRef = new WasmCall(weakRefConstructor, new WasmGetLocal(valueLocal), new WasmGetLocal(thisLocal),
+                new WasmGetLocal(queueLocal));
         function.getBody().add(new WasmStructSet(weakRefStruct, new WasmGetLocal(thisLocal),
                 WasmGCClassInfoProvider.WEAK_REFERENCE_OFFSET, weakRef));
     }
@@ -97,7 +98,8 @@ private WasmFunction getCreateWeakReferenceFunction(WasmGCCustomGeneratorContext
             var function = new WasmFunction(context.functionTypes().of(
                     WasmType.Reference.EXTERN,
                     context.typeMapper().mapType(ValueType.parse(Object.class)),
-                    context.typeMapper().mapType(ValueType.parse(WeakReference.class))
+                    context.typeMapper().mapType(ValueType.parse(WeakReference.class)),
+                    context.typeMapper().mapType(ValueType.parse(ReferenceQueue.class))
             ));
             function.setName(context.names().topLevel("teavm@createWeakReference"));
             function.setImportName("createWeakRef");

core/src/main/java/org/teavm/backend/wasm/transformation/gc/ReferenceQueueEntry.java

@@ -0,0 +1,27 @@
+/*
+ *  Copyright 2024 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.backend.wasm.transformation.gc;
+
+import java.lang.ref.Reference;
+
+class ReferenceQueueEntry<T> {
+    final Reference<T> reference;
+    ReferenceQueueEntry<T> next;
+
+    ReferenceQueueEntry(Reference<T> reference) {
+        this.reference = reference;
+    }
+}

core/src/main/java/org/teavm/backend/wasm/transformation/gc/ReferenceQueueTemplate.java

@@ -0,0 +1,45 @@
+/*
+ *  Copyright 2024 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.backend.wasm.transformation.gc;
+
+import java.lang.ref.Reference;
+
+class ReferenceQueueTemplate<T> {
+    private ReferenceQueueEntry<T> start;
+    private ReferenceQueueEntry<T> end;
+
+    public Reference<T> poll() {
+        var result = start;
+        if (result == null) {
+            return null;
+        }
+        start = result.next;
+        if (start == null) {
+            end = null;
+        }
+        return result.reference;
+    }
+
+    public void supply(Reference<T> reference) {
+        var entry = new ReferenceQueueEntry<>(reference);
+        if (start == null) {
+            start = entry;
+        } else {
+            end.next = entry;
+        }
+        end = entry;
+    }
+}

core/src/main/java/org/teavm/backend/wasm/transformation/gc/ReferenceQueueTransformation.java

@@ -0,0 +1,80 @@
+/*
+ *  Copyright 2024 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.backend.wasm.transformation.gc;
+
+import java.lang.ref.ReferenceQueue;
+import org.teavm.model.ClassHolder;
+import org.teavm.model.ClassHolderTransformer;
+import org.teavm.model.ClassHolderTransformerContext;
+import org.teavm.model.FieldReference;
+import org.teavm.model.MethodHolder;
+import org.teavm.model.MethodReader;
+import org.teavm.model.instructions.GetFieldInstruction;
+import org.teavm.model.instructions.PutFieldInstruction;
+import org.teavm.model.util.ModelUtils;
+import org.teavm.model.util.ProgramUtils;
+
+public class ReferenceQueueTransformation implements ClassHolderTransformer {
+    @Override
+    public void transformClass(ClassHolder cls, ClassHolderTransformerContext context) {
+        if (cls.getName().equals(ReferenceQueue.class.getName())) {
+           transformReferenceQueue(cls, context);
+        }
+    }
+
+    private void transformReferenceQueue(ClassHolder cls, ClassHolderTransformerContext context) {
+        var templateClass = context.getHierarchy().getClassSource().get(ReferenceQueueTemplate.class.getName());
+        for (var method : templateClass.getMethods()) {
+            if (!method.getName().equals("<init>")) {
+                copyMethod(cls, method);
+            }
+        }
+        for (var field : templateClass.getFields()) {
+            cls.addField(ModelUtils.copyField(field));
+        }
+    }
+
+    private void copyMethod(ClassHolder cls, MethodReader method) {
+        var targetMethod = cls.getMethod(method.getDescriptor());
+        if (targetMethod == null) {
+            targetMethod = new MethodHolder(method.getDescriptor());
+            cls.addMethod(targetMethod);
+            targetMethod.getModifiers().addAll(method.readModifiers());
+            targetMethod.setLevel(method.getLevel());
+        }
+
+        var targetProgram = ProgramUtils.copy(method.getProgram());
+        targetMethod.setProgram(targetProgram);
+        for (var block : targetProgram.getBasicBlocks()) {
+            for (var instruction : block) {
+                if (instruction instanceof GetFieldInstruction) {
+                    var getField = (GetFieldInstruction) instruction;
+                    getField.setField(mapField(getField.getField()));
+                } else if (instruction instanceof PutFieldInstruction) {
+                    var putField = (PutFieldInstruction) instruction;
+                    putField.setField(mapField(putField.getField()));
+                }
+            }
+        }
+    }
+
+    private FieldReference mapField(FieldReference field) {
+        if (field.getClassName().equals(ReferenceQueueTemplate.class.getName())) {
+            return new FieldReference(ReferenceQueue.class.getName(), field.getFieldName());
+        }
+        return field;
+    }
+}

core/src/main/js/wasm-gc-runtime/runtime.js

@@ -124,8 +124,8 @@ function consoleImports(imports) {
 function coreImports(imports, context) {
     let finalizationRegistry = new FinalizationRegistry(heldValue => {
         let report = context.exports["teavm.reportGarbageCollectedValue"];
-        if (typeof report === "function") {
-            report(heldValue)
+        if (typeof report !== "undefined") {
+            report(heldValue.queue, heldValue.ref);
         }
     });
     let stringFinalizationRegistry = new FinalizationRegistry(heldValue => {
@@ -135,18 +135,16 @@ function coreImports(imports, context) {
         }
     });
     imports.teavm = {
-        createWeakRef(value, heldValue) {
-            let weakRef = new WeakRef(value);
-            if (heldValue !== null) {
-                finalizationRegistry.register(value, heldValue)
+        createWeakRef(value, ref, queue) {
+            if (queue !== null) {
+                finalizationRegistry.register(value, { ref: ref, queue: queue });
             }
-            return weakRef;
+            return new WeakRef(value);
         },
         deref: weakRef => weakRef.deref(),
         createStringWeakRef(value, heldValue) {
-            let weakRef = new WeakRef(value);
             stringFinalizationRegistry.register(value, heldValue)
-            return weakRef;
+            return new WeakRef(value);
         },
         stringDeref: weakRef => weakRef.deref(),
         takeStackTrace() {