From 1d5f5420fd57256e423ceaec10eb5fac4d47ad16 Mon Sep 17 00:00:00 2001
From: Christian Humer <christian.humer@oracle.com>
Date: Wed, 15 Jul 2026 17:05:29 +0200
Subject: [PATCH] Preinitialize inherited Truffle library dispatches

---
 .../svm/truffle/TruffleBaseFeature.java       | 43 +++++++++++++++++--
 1 file changed, 40 insertions(+), 3 deletions(-)

diff --git a/substratevm/src/com.oracle.svm.truffle/src/com/oracle/svm/truffle/TruffleBaseFeature.java b/substratevm/src/com.oracle.svm.truffle/src/com/oracle/svm/truffle/TruffleBaseFeature.java
index d6ad186297cb..7c379b469381 100644
--- a/substratevm/src/com.oracle.svm.truffle/src/com/oracle/svm/truffle/TruffleBaseFeature.java
+++ b/substratevm/src/com.oracle.svm.truffle/src/com/oracle/svm/truffle/TruffleBaseFeature.java
@@ -268,6 +268,8 @@ public boolean getAsBoolean() {
     private AnalysisMetaAccess metaAccess;
     private GraalGraphObjectReplacer graalGraphObjectReplacer;
     private final EconomicSet<Class<?>> registeredClasses = EconomicSet.create();
+    private final EconomicSet<Class<?>> registeredExportLibraryClasses = EconomicSet.create();
+    private final Set<Class<?>> pendingExportLibraryReceiverClasses = ConcurrentHashMap.newKeySet();
     private final Map<Class<?>, PossibleReplaceCandidatesSubtypeHandler> subtypeChecks = new HashMap<>();
     private boolean profilingEnabled;
     private Field uncachedDispatchField;
@@ -818,6 +820,13 @@ public void duringAnalysis(DuringAnalysisAccess a) {
             initializeTruffleLibrariesAtBuildTime(access, type);
             initializeDynamicObjectLayouts(type);
         }
+        /* Resolve reachable export subclasses once they are known to be instantiated. */
+        for (Class<?> receiverClass : pendingExportLibraryReceiverClasses) {
+            AnalysisType type = access.getMetaAccess().lookupJavaType(receiverClass);
+            if (type.isInstantiated() && pendingExportLibraryReceiverClasses.remove(receiverClass)) {
+                initializeTruffleLibraryReceiverAtBuildTime(receiverClass);
+            }
+        }
         access.rescanRoot(layoutInfoMapField, scanReason);
         access.rescanRoot(layoutMapField, scanReason);
         access.rescanRoot(libraryFactoryCacheField, scanReason);
@@ -983,12 +992,40 @@ private void initializeTruffleLibrariesAtBuildTime(DuringAnalysisAccessImpl acce
             access.rescanField(factory, uncachedDispatchField, scanReason);
         }
         if (AnnotationUtil.isAnnotationPresent(type, ExportLibrary.class) || AnnotationUtil.isAnnotationPresent(type, ExportLibrary.Repeat.class)) {
-            /* Eagerly resolve receiver type. */
-            invokeStaticMethod("com.oracle.truffle.api.library.LibraryFactory$ResolvedDispatch", "lookup",
-                            Collections.singleton(Class.class), type.getJavaClass());
+            Class<?> receiverClass = type.getJavaClass();
+            if (registeredExportLibraryClasses.add(receiverClass)) {
+                access.registerSubtypeReachabilityHandler(this::registerConcreteTruffleLibraryReceiver, receiverClass);
+                if (hasExplicitReceiverExport(type)) {
+                    /*
+                     * Exports with an explicit receiver can be used as dynamic dispatch targets
+                     * without the export class being instantiated.
+                     */
+                    initializeTruffleLibraryReceiverAtBuildTime(receiverClass);
+                }
+            }
+        }
+    }
+
+    private static boolean hasExplicitReceiverExport(AnalysisType type) {
+        for (ExportLibrary export : AnnotationUtil.getAnnotationsByType(type, ExportLibrary.class, ExportLibrary.Repeat.class, ExportLibrary.Repeat::value)) {
+            if (export.receiverType() != Void.class) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private void registerConcreteTruffleLibraryReceiver(@SuppressWarnings("unused") DuringAnalysisAccess access, Class<?> receiverClass) {
+        if (!Modifier.isAbstract(receiverClass.getModifiers())) {
+            pendingExportLibraryReceiverClasses.add(receiverClass);
         }
     }
 
+    private static void initializeTruffleLibraryReceiverAtBuildTime(Class<?> receiverClass) {
+        invokeStaticMethod("com.oracle.truffle.api.library.LibraryFactory$ResolvedDispatch", "lookup",
+                        Collections.singleton(Class.class), receiverClass);
+    }
+
     private final EconomicSet<Class<?>> dynamicObjectClasses = EconomicSet.create();
 
     private void initializeDynamicObjectLayouts(AnalysisType type) {