Allow all classes to be used at image build time

Author: Christian Wimmer

substratevm/CHANGELOG.md

@@ -7,6 +7,7 @@ This changelog summarizes major changes to GraalVM Native Image.
 * (GR-45841) BellSoft added support for the JFR event ThreadCPULoad.
 * (GR-45994) Removed the option `-H:EnableSignalAPI`. Please use the runtime option `EnableSignalHandling` if it is necessary to enable or disable signal handling explicitly.
 * (GR-39406) Simulation of class initializer: Class initializer of classes that are not marked for initialization at image build time are simulated at image build time to avoid executing them at image run time.
+* (GR-39406) All classes can now be used at image build time, even when they are not explicitly configured as `--initialize-at-build-time`. Note, however, that still only classes configured as `--initialize-at-build-time` are allowed in the image heap.
 * (GR-46392) Add `--parallelism` option to control how many threads are used by the build process.
 * (GR-46392) Add build resources section to the build output that shows the memory and thread limits of the build process.
 

substratevm/mx.substratevm/mx_substratevm.py

@@ -1413,9 +1413,9 @@ def build_and_test_clinittest_image(native_image, args, new_class_init_policy):
         mkpath(build_dir)
 
         if new_class_init_policy:
-            policy_args = ['-H:+UseNewExperimentalClassInitialization', '-H:+SimulateClassInitializer', '-H:Features=com.oracle.svm.test.clinit.TestClassInitializationFeatureNewPolicyFeature']
+            policy_args = ['-H:-UseDeprecatedOldClassInitialization', '-H:+SimulateClassInitializer', '-H:Features=com.oracle.svm.test.clinit.TestClassInitializationFeatureNewPolicyFeature']
         else:
-            policy_args = ['-H:-UseNewExperimentalClassInitialization', '-H:-SimulateClassInitializer', '-H:Features=com.oracle.svm.test.clinit.TestClassInitializationFeatureOldPolicyFeature']
+            policy_args = ['-H:+UseDeprecatedOldClassInitialization', '-H:-SimulateClassInitializer', '-H:Features=com.oracle.svm.test.clinit.TestClassInitializationFeatureOldPolicyFeature']
 
         # Build and run the example
         native_image(

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/classinitialization/ClassInitializationOptions.java

@@ -100,8 +100,9 @@ private static class InitializationValueEager extends InitializationValueTransfo
     @Option(help = "Assert class initialization is specified for all classes.", type = OptionType.Debug)//
     public static final HostedOptionKey<Boolean> AssertInitializationSpecifiedForAllClasses = new HostedOptionKey<>(false);
 
-    @Option(help = "Use new class initialization strategy that allows all classes to be used at image build time.", type = OptionType.Expert)//
-    public static final HostedOptionKey<Boolean> UseNewExperimentalClassInitialization = new HostedOptionKey<>(false);
+    @Option(help = "Use the old class initialization strategy that does not allow all classes to be used at image build time.", type = OptionType.Expert, //
+                    deprecated = true, deprecationMessage = "Temporary flag to restore the class initialization behavior of older GraalVM versions. The old class initialization strategy will be removed in a future version of GraalVM.") //
+    public static final HostedOptionKey<Boolean> UseDeprecatedOldClassInitialization = new HostedOptionKey<>(false);
 
     @Option(help = "Simulate the effects of class initializer at image build time, to avoid class initialization at run time.", type = OptionType.Expert)//
     public static final HostedOptionKey<Boolean> SimulateClassInitializer = new HostedOptionKey<>(true);

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/classinitialization/ClassInitializationSupport.java

@@ -87,11 +87,11 @@ public abstract class ClassInitializationSupport implements RuntimeClassInitiali
     final MetaAccessProvider metaAccess;
 
     public static ClassInitializationSupport create(MetaAccessProvider metaAccess, ImageClassLoader loader) {
-        if (ClassInitializationOptions.UseNewExperimentalClassInitialization.getValue()) {
-            LogUtils.warning("Using new experimental class initialization strategy. Image size and peak performance are not optimized yet!");
-            return new AllowAllHostedUsagesClassInitializationSupport(metaAccess, loader);
+        if (ClassInitializationOptions.UseDeprecatedOldClassInitialization.getValue()) {
+            LogUtils.warning("Using old deprecated class initialization strategy. Only classes that are marked explicitly as '--initialize-at-build-time' can be used during image generation.");
+            return new ProvenSafeClassInitializationSupport(metaAccess, loader);
         }
-        return new ProvenSafeClassInitializationSupport(metaAccess, loader);
+        return new AllowAllHostedUsagesClassInitializationSupport(metaAccess, loader);
     }
 
     public static ClassInitializationSupport singleton() {

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/image/DisallowedImageHeapObjectFeature.java

@@ -168,11 +168,18 @@ private void checkDisallowedMBeanObjects(Object original) {
     }
 
     private RuntimeException error(String msg, Object obj, String initializerAction) {
+        String suffix = "";
+        if (!ClassInitializationOptions.UseDeprecatedOldClassInitialization.getValue()) {
+            suffix = System.lineSeparator() +
+                            "If you see this error while migrating to a newer GraalVM release, please note that the class initialization strategy has changed in GraalVM for JDK 21." +
+                            " All classes can now be used at image build time. However, only classes explicitly marked as --initialize-at-built-time are allowed to be in the image heap." +
+                            " This rule is now strictly enforced, i.e., the problem might be solvable by registering the reported type as --initialize-at-built-time.";
+        }
         throw new UnsupportedFeatureException(msg + " " + classInitialization.objectInstantiationTraceMessage(obj, initializerAction) + " " +
                         "The object was probably created by a class initializer and is reachable from a static field. " +
                         "You can request class initialization at image runtime by using the option " +
                         SubstrateOptionsParser.commandArgument(ClassInitializationOptions.ClassInitialization, "<class-name>", "initialize-at-run-time") + ". " +
-                        "Or you can write your own initialization methods and call them explicitly from your main entry point.");
+                        "Or you can write your own initialization methods and call them explicitly from your main entry point." + suffix);
     }
 
     private static boolean search(byte[] haystack, byte[] needle) {

substratevm/src/com.oracle.svm.test/src/com/oracle/svm/test/clinit/TestClassInitialization.java

@@ -714,8 +714,8 @@ public void afterImageWrite(AfterImageWriteAccess access) {
 }
 
 /**
- * For testing with {@link ClassInitializationOptions#UseNewExperimentalClassInitialization} set to
- * false and simulation of class initializer disabled.
+ * For testing with {@link ClassInitializationOptions#UseDeprecatedOldClassInitialization} set to
+ * true and simulation of class initializer disabled.
  */
 class TestClassInitializationFeatureOldPolicyFeature extends TestClassInitializationFeature {
 
@@ -752,8 +752,8 @@ void checkClass(Class<?> checkedClass, boolean checkSafeEarly, boolean checkSafe
 }
 
 /**
- * For testing with {@link ClassInitializationOptions#UseNewExperimentalClassInitialization} set to
- * true and simulation of class initializer enabled.
+ * For testing with {@link ClassInitializationOptions#UseDeprecatedOldClassInitialization} set to
+ * false and simulation of class initializer enabled.
  */
 class TestClassInitializationFeatureNewPolicyFeature extends TestClassInitializationFeature {
     @Override