reduced LibGraalLoader API

dougxc · dougxc · commit 9ec1aec57beb · 2025-02-14T10:47:46.000+01:00
* renamed LibGraalLoader.getModuleMap to getClassModuleMap
* replaced LibGraalLoader.getJavaHome with a protocol shared between HostedLibGraalClassLoader and LibGraalFeature
* removed LibGraalLoader.getRuntimeClassLoader
* remove LibGraalLoader.getServiceModules
diff --git a/compiler/src/jdk.graal.compiler.libgraal.loader/src/jdk/graal/compiler/libgraal/loader/HostedLibGraalClassLoader.java b/compiler/src/jdk.graal.compiler.libgraal.loader/src/jdk/graal/compiler/libgraal/loader/HostedLibGraalClassLoader.java
@@ -57,12 +57,12 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
-import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 /**
  * A classloader that reads class files and resources from a jimage file and a module path at image
- * build time.
+ * build time. The {@code java.home} of the JDK containing the jimage can be obtained by converting
+ * the bytes of {@code getResourceAsStream("META-INF/libgraal.java.home")} to a string.
  */
 @Platforms(Platform.HOSTED_ONLY.class)
 public final class HostedLibGraalClassLoader extends ClassLoader implements LibGraalLoader {
@@ -73,6 +73,12 @@ public final class HostedLibGraalClassLoader extends ClassLoader implements LibG
      */
     private static final String LIBGRAAL_JAVA_HOME_PROPERTY_NAME = "libgraal.java.home";
 
+    /**
+     * The {@code java.home} of the JDK whose runtime image contains the Graal and JVMCI classes
+     * from which libgraal will be built.
+     */
+    private static final Path LIBGRAAL_JAVA_HOME = Path.of(System.getProperty(LIBGRAAL_JAVA_HOME_PROPERTY_NAME, System.getProperty("java.home")));
+
     /**
      * Name of the system property specifying a module path for the module(s) containing
      * {@code LibGraalFeature} and its dependencies that are not available in the runtime image.
@@ -167,30 +173,17 @@ byte[] readBytes() throws ClassNotFoundException {
     /**
      * Modules containing classes that can be annotated by {@code LibGraalService}.
      */
-    private static final Set<String> LIBGRAAL_SERVICES_MODULES = Set.of(
+    private static final Set<String> LIBGRAAL_MODULES = Set.of(
+                    "jdk.internal.vm.ci",
                     "jdk.graal.compiler",
                     "jdk.graal.compiler.libgraal",
                     "org.graalvm.truffle.compiler",
                     "com.oracle.graal.graal_enterprise");
 
-    /**
-     * Modules in which Graal and JVMCI classes are defined that this loader will load.
-     */
-    private static final Set<String> LIBGRAAL_MODULES = Stream.concat(
-                    LIBGRAAL_SERVICES_MODULES.stream(), Stream.of("jdk.internal.vm.ci")) //
-                    .collect(Collectors.toUnmodifiableSet());
-
     static {
         ClassLoader.registerAsParallelCapable();
     }
 
-    private final Path libgraalJavaHome = Path.of(System.getProperty(LIBGRAAL_JAVA_HOME_PROPERTY_NAME, System.getProperty("java.home")));
-
-    @Override
-    public Path getJavaHome() {
-        return libgraalJavaHome;
-    }
-
     /**
      * Converts the module path entry {@code s} to a {@link Path}.
      *
@@ -207,7 +200,7 @@ Path parseModulePathEntry(String s) {
     @SuppressWarnings("unused")
     public HostedLibGraalClassLoader() {
         // This loader delegates to the class loader that loaded its own class.
-        super(LibGraalClassLoader.LOADER_NAME, HostedLibGraalClassLoader.class.getClassLoader());
+        super("LibGraalClassLoader", HostedLibGraalClassLoader.class.getClassLoader());
 
         try {
             /*
@@ -226,7 +219,7 @@ public HostedLibGraalClassLoader() {
 
             Map<String, String> modulesMap = new HashMap<>();
 
-            Path imagePath = libgraalJavaHome.resolve(Path.of("lib", "modules"));
+            Path imagePath = LIBGRAAL_JAVA_HOME.resolve(Path.of("lib", "modules"));
             this.imageReader = BasicImageReader.open(imagePath);
             for (var entry : imageReader.getEntryNames()) {
                 int secondSlash = entry.indexOf('/', 1);
@@ -286,15 +279,10 @@ public HostedLibGraalClassLoader() {
      * name of its enclosing module.
      */
     @Override
-    public Map<String, String> getModuleMap() {
+    public Map<String, String> getClassModuleMap() {
         return modules;
     }
 
-    @Override
-    public Set<String> getServicesModules() {
-        return LIBGRAAL_SERVICES_MODULES;
-    }
-
     @Override
     protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
         if (!modules.containsKey(name)) {
@@ -328,6 +316,12 @@ protected Class<?> findClass(final String name) throws ClassNotFoundException {
      */
     private static final String SERVICE_PROTOCOL = "service-config";
 
+    /**
+     * Name of the protocol for accessing a file whose contents are the {@code java.home} of the JDK
+     * whose runtime image contains the Graal and JVMCI * classes from which libgraal will be built.
+     */
+    private static final String LIBGRAAL_JAVA_HOME_PROTOCOL = "libgraal-java-home";
+
     /**
      * Name of the protocol for accessing entries in {@link #resources}.
      */
@@ -341,7 +335,14 @@ protected URL findResource(String name) {
         if (handler == null) {
             this.serviceHandler = handler = new ImageURLStreamHandler();
         }
-        if (name.startsWith("META-INF/services/")) {
+        if (name.equals("META-INF/libgraal.java.home")) {
+            try {
+                var uri = new URI(LIBGRAAL_JAVA_HOME_PROTOCOL, "libgraal.java.home", null);
+                return URL.of(uri, handler);
+            } catch (URISyntaxException | MalformedURLException e) {
+                return null;
+            }
+        } else if (name.startsWith("META-INF/services/")) {
             String service = name.substring("META-INF/services/".length());
             if (services.containsKey(service)) {
                 try {
@@ -382,7 +383,12 @@ private class ImageURLStreamHandler extends URLStreamHandler {
         @Override
         public URLConnection openConnection(URL u) {
             String protocol = u.getProtocol();
-            if (protocol.equalsIgnoreCase(SERVICE_PROTOCOL)) {
+            if (protocol.equalsIgnoreCase(LIBGRAAL_JAVA_HOME_PROTOCOL)) {
+                if (!u.getPath().equals("libgraal.java.home")) {
+                    throw new IllegalArgumentException(u.toString());
+                }
+                return new ImageURLConnection(u, LIBGRAAL_JAVA_HOME.toString().getBytes());
+            } else if (protocol.equalsIgnoreCase(SERVICE_PROTOCOL)) {
                 List<String> providers = services.get(u.getPath());
                 if (providers != null) {
                     return new ImageURLConnection(u, String.join("\n", providers).getBytes());
@@ -434,9 +440,4 @@ public String getContentType() {
             return "application/octet-stream";
         }
     }
-
-    @Override
-    public ClassLoader getRuntimeClassLoader() {
-        return LibGraalClassLoader.singleton;
-    }
 }
diff --git a/compiler/src/jdk.graal.compiler.libgraal/src/jdk/graal/compiler/libgraal/GetJNIConfig.java b/compiler/src/jdk.graal.compiler.libgraal/src/jdk/graal/compiler/libgraal/GetJNIConfig.java
@@ -78,9 +78,9 @@ final class GetJNIConfig implements AutoCloseable {
 
     int lineNo;
 
-    private GetJNIConfig(ClassLoader loader) {
+    private GetJNIConfig(ClassLoader loader, Path libgraalJavaHome) {
         this.loader = loader;
-        Path javaExe = getJavaExe(Path.of(GraalServices.getSavedProperty("java.home")));
+        Path javaExe = getJavaExe(libgraalJavaHome);
         configFilePath = Path.of("libgraal_jniconfig.txt");
 
         String[] command = {javaExe.toFile().getAbsolutePath(), "-XX:+UnlockExperimentalVMOptions", "-XX:+EnableJVMCI", "-XX:JVMCILibDumpJNIConfig=" + configFilePath};
@@ -196,8 +196,8 @@ private GraalError error(String format, Object... args) {
      * @param loader used to resolve type names in the config
      */
     @SuppressWarnings("try")
-    public static void register(ClassLoader loader) {
-        try (GetJNIConfig source = new GetJNIConfig(loader)) {
+    public static void register(ClassLoader loader, Path libgraalJavaHome) {
+        try (GetJNIConfig source = new GetJNIConfig(loader, libgraalJavaHome)) {
             Map<String, Class<?>> classes = new HashMap<>();
             for (String line : source.lines) {
                 source.lineNo++;
diff --git a/compiler/src/jdk.graal.compiler.libgraal/src/jdk/graal/compiler/libgraal/LibGraalClassLoader.java b/compiler/src/jdk.graal.compiler.libgraal/src/jdk/graal/compiler/libgraal/LibGraalClassLoader.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,20 +22,17 @@
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
-package jdk.graal.compiler.libgraal.loader;
+package jdk.graal.compiler.libgraal;
 
 import org.graalvm.nativeimage.hosted.Feature.DuringSetupAccess;
 
 /**
  * The image runtime class loader that {@linkplain DuringSetupAccess#registerObjectReplacer
- * replaces} the build-time instance of {@link HostedLibGraalClassLoader}.
+ * replaces} the build-time instance of the {@link jdk.graal.nativeimage.LibGraalLoader}.
  */
-public final class LibGraalClassLoader extends ClassLoader {
+final class LibGraalClassLoader extends ClassLoader {
 
-    static final String LOADER_NAME = "LibGraalClassLoader";
-    static final LibGraalClassLoader singleton = new LibGraalClassLoader();
-
-    private LibGraalClassLoader() {
-        super(LOADER_NAME, null);
+    LibGraalClassLoader(String name) {
+        super(name, null);
     }
 }
diff --git a/compiler/src/jdk.graal.compiler.libgraal/src/jdk/graal/compiler/libgraal/LibGraalFeature.java b/compiler/src/jdk.graal.compiler.libgraal/src/jdk/graal/compiler/libgraal/LibGraalFeature.java
@@ -24,6 +24,8 @@
  */
 package jdk.graal.compiler.libgraal;
 
+import java.io.IOException;
+import java.io.InputStream;
 import java.lang.module.ModuleDescriptor;
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
@@ -114,7 +116,23 @@ public boolean getAsBoolean() {
         }
     }
 
+    /**
+     * See javadoc for {@code jdk.graal.compiler.libgraal.loader.HostedLibGraalClassLoader}.
+     */
+    private static Path readLibgraalJavaHome(ClassLoader cl) {
+        try (InputStream in = cl.getResourceAsStream("META-INF/libgraal.java.home")) {
+            if (in == null) {
+                throw new GraalError(cl.getClass().getName() + " does not support META-INF/libgraal.java.home protocol (see javadoc of HostedLibGraalClassLoader)");
+            }
+            return Path.of(new String(in.readAllBytes()));
+        } catch (IOException e) {
+            throw new GraalError(e);
+        }
+    }
+
     private final LibGraalLoader libgraalLoader = (LibGraalLoader) getClass().getClassLoader();
+    private final Path libgraalJavaHome = readLibgraalJavaHome(getClass().getClassLoader());
+
     private BeforeAnalysisAccess beforeAnalysisAccess;
     private BeforeCompilationAccess beforeCompilationAccess;
     private OptionCollector optionCollector;
@@ -126,7 +144,7 @@ public void afterRegistration(AfterRegistrationAccess access) {
         // All qualified exports to libgraal modules need to be further exported to
         // ALL-UNNAMED so that access is also possible when the libgraal classes
         // are loaded via the libgraal loader into unnamed modules.
-        Set<String> libgraalModules = Set.copyOf(libgraalLoader.getModuleMap().values());
+        Set<String> libgraalModules = Set.copyOf(libgraalLoader.getClassModuleMap().values());
         for (Module module : ModuleLayer.boot().modules()) {
             Set<ModuleDescriptor.Exports> exports = module.getDescriptor().exports();
             for (ModuleDescriptor.Exports e : exports) {
@@ -141,26 +159,43 @@ public void afterRegistration(AfterRegistrationAccess access) {
     public void duringSetup(DuringSetupAccess access) {
         optionCollector = new OptionCollector();
 
+        /*
+         * Replace HostedLibGraalClassLoader with a basic class loader at runtime that cuts out the
+         * parent class loader (i.e., NativeImageClassLoader) and is guaranteed not to make any
+         * additional types/methods/fields accidentally reachable.
+         */
+        String loaderName = ((ClassLoader) libgraalLoader).getName();
+        LibGraalClassLoader runtimeLibgraalLoader = new LibGraalClassLoader(loaderName);
+        access.registerObjectReplacer(obj -> obj == libgraalLoader ? runtimeLibgraalLoader : obj);
+
+        // Register reachability handler used to initialize OptionsParser.libgraalOptions.
         access.registerObjectReachabilityHandler(optionCollector::accept, OptionKey.class);
+
+        // Register reachability handler that marks the fields that are accessed via unsafe.
         access.registerObjectReachabilityHandler(fields -> {
             for (int i = 0; i < fields.getOffsets().length; i++) {
                 Field field = fields.getField(i);
                 beforeAnalysisAccess.registerAsUnsafeAccessed(field);
             }
         }, Fields.class);
+
+        // Register reachability handler that marks NodeClass subclasses as unsafe allocated
+        // (see jdk.graal.compiler.graph.NodeClass.allocateInstance).
         access.registerObjectReachabilityHandler(nodeClass -> {
             Class<?> clazz = nodeClass.getClazz();
             if (!Modifier.isAbstract(clazz.getModifiers())) {
                 /* Support for NodeClass.allocateInstance. */
                 beforeAnalysisAccess.registerAsUnsafeAllocated(clazz);
             }
         }, NodeClass.class);
-        GetJNIConfig.register((ClassLoader) libgraalLoader);
+
+        // Register the fields/methods/classes accessed via JNI.
+        GetJNIConfig.register((ClassLoader) libgraalLoader, libgraalJavaHome);
     }
 
     /**
      * Collects all instances of the LibGraalLoader loaded {@link OptionKey} class reached by the
-     * static analysis.
+     * static analysis and uses them to initialize {@link OptionsParser#libgraalOptions}.
      */
     private final class OptionCollector implements Consumer<OptionKey<?>> {
         private final Set<OptionKey<?>> options = Collections.newSetFromMap(new ConcurrentHashMap<>());
@@ -178,7 +213,7 @@ public void accept(OptionKey<?> option) {
 
         void afterAnalysis(AfterAnalysisAccess access) {
             sealed = true;
-            Map<String, String> modules = libgraalLoader.getModuleMap();
+            Map<String, String> modules = libgraalLoader.getClassModuleMap();
             for (OptionKey<?> option : options) {
                 OptionDescriptor descriptor = option.getDescriptor();
                 if (descriptor.isServiceLoaded()) {
@@ -272,8 +307,7 @@ public void beforeAnalysis(BeforeAnalysisAccess access) {
 
         doLegacyJVMCIInitialization();
 
-        Path libGraalJavaHome = libgraalLoader.getJavaHome();
-        GetCompilerConfig.Result configResult = GetCompilerConfig.from(libGraalJavaHome);
+        GetCompilerConfig.Result configResult = GetCompilerConfig.from(libgraalJavaHome);
         for (var e : configResult.opens().entrySet()) {
             Module module = ModuleLayer.boot().findModule(e.getKey()).orElseThrow();
             for (String source : e.getValue()) {
diff --git a/compiler/src/jdk.graal.compiler.libgraal/src/jdk/graal/compiler/libgraal/LibGraalSupportImpl.java b/compiler/src/jdk.graal.compiler.libgraal/src/jdk/graal/compiler/libgraal/LibGraalSupportImpl.java
@@ -32,7 +32,6 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
-import java.util.Set;
 import java.util.function.Supplier;
 
 import jdk.graal.compiler.core.common.LibGraalSupport;
@@ -152,14 +151,8 @@ private static long getJNIEnv() {
 
     @Platforms(Platform.HOSTED_ONLY.class)
     @Override
-    public Map<String, String> getModuleMap() {
-        return libGraalLoader.getModuleMap();
-    }
-
-    @Platforms(Platform.HOSTED_ONLY.class)
-    @Override
-    public Set<String> getServicesModules() {
-        return libGraalLoader.getServicesModules();
+    public Map<String, String> getClassModuleMap() {
+        return libGraalLoader.getClassModuleMap();
     }
 
     @Override
diff --git a/compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/core/common/LibGraalSupport.java b/compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/core/common/LibGraalSupport.java
@@ -34,7 +34,6 @@
 import java.lang.ref.ReferenceQueue;
 import java.util.Map;
 import java.util.ServiceLoader;
-import java.util.Set;
 import java.util.function.Supplier;
 
 /**
@@ -81,19 +80,14 @@ public interface LibGraalSupport {
     @Platforms(Platform.HOSTED_ONLY.class)
     Supplier<Long> createGlobal(long initialValue);
 
-    /**
-     * Gets the names of the modules containing classes that can be annotated by
-     * {@code LibGraalService}.
-     */
-    Set<String> getServicesModules();
-
     /**
      * Gets a map from the {@linkplain Class#forName(String) name} of a class to the name of its
-     * enclosing module. There is one entry in the map for each class compiled into libgraal.
+     * enclosing module. There is one entry in the map for each class loadable via the libgraal
+     * class loader.
      *
      * @return an unmodifiable map
      */
-    Map<String, String> getModuleMap();
+    Map<String, String> getClassModuleMap();
 
     /**
      * Notifies the runtime that the caller is at a point where the live set of objects is expected
diff --git a/compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/serviceprovider/GraalServices.java b/compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/serviceprovider/GraalServices.java
@@ -38,7 +38,6 @@
 import java.util.Properties;
 import java.util.ServiceConfigurationError;
 import java.util.ServiceLoader;
-import java.util.Set;
 
 import jdk.graal.compiler.core.ArchitectureSpecific;
 import jdk.graal.compiler.core.common.LibGraalSupport;
@@ -115,12 +114,8 @@ private static void addProviders(String arch, Class<?> service) {
         LibGraalSupport libgraal = LibGraalSupport.INSTANCE;
         if (libgraal != null) {
             libgraalServices = new HashMap<>();
-            Set<String> libgraalServicesModules = libgraal.getServicesModules();
-            Map<String, String> modules = libgraal.getModuleMap();
             String arch = getJVMCIArch();
-            modules.entrySet().stream()//
-                            .filter(e -> libgraalServicesModules.contains(e.getValue()))//
-                            .map(Map.Entry::getKey)//
+            libgraal.getClassModuleMap().keySet().stream()//
                             .map(GraalServices::loadClassOrNull)//
                             .filter(c -> c != null && c.getAnnotation(LibGraalService.class) != null)//
                             .forEach(service -> addProviders(arch, service));
diff --git a/sdk/src/jdk.graal.nativeimage/src/jdk/graal/nativeimage/LibGraalLoader.java b/sdk/src/jdk.graal.nativeimage/src/jdk/graal/nativeimage/LibGraalLoader.java
diff --git a/substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/ClassLoaderFeature.java b/substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/ClassLoaderFeature.java
diff --git a/substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/NativeImageClassLoaderSupport.java b/substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/NativeImageClassLoaderSupport.java
