[GR-65294] Fix Class.forName folding when respecting class loaders.

PullRequest: graal/20914

Author: gilles-duboscq

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/hub/registry/BootClassRegistry.java

@@ -69,6 +69,9 @@ public synchronized Class<?> doLoadClass(Symbol<Type> type) {
         // Only looking into the jimage for now. There could be appended elements.
         // see GraalServices.getSavedProperty("jdk.boot.class.path.append")
         String pkg = packageFromType(type);
+        if (pkg == null) {
+            return null;
+        }
         try {
             String moduleName = ClassRegistries.getBootModuleForPackage(pkg);
             if (moduleName == null) {

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/snippets/ReflectionPlugins.java

@@ -50,6 +50,7 @@
 
 import com.oracle.svm.core.TrackDynamicAccessEnabled;
 import com.oracle.svm.hosted.DynamicAccessDetectionFeature;
+import com.oracle.svm.hosted.NativeImageSystemClassLoader;
 import org.graalvm.nativeimage.ImageSingletons;
 import org.graalvm.nativeimage.hosted.RuntimeReflection;
 import org.graalvm.nativeimage.impl.RuntimeClassInitializationSupport;
@@ -343,7 +344,7 @@ public boolean apply(GraphBuilderContext b, ResolvedJavaMethod targetMethod, Rec
                         return false;
                     }
                     loader = (ClassLoader) unboxObjectConstant(b, classLoaderNode.asJavaConstant());
-                    if (loader == ClassLoader.getSystemClassLoader()) {
+                    if (loader == NativeImageSystemClassLoader.singleton().defaultSystemClassLoader) {
                         /*
                          * The run time's application class loader is the build time's image class
                          * loader.