[GR-64061] Footprint improvements in Native Image Builder.

sdk/src/org.graalvm.nativeimage/src/org/graalvm/nativeimage/c/function/CFunctionPointer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * The Universal Permissive License (UPL), Version 1.0

substratevm/src/com.oracle.graal.pointsto/src/com/oracle/graal/pointsto/meta/AnalysisMethod.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 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
@@ -119,6 +119,8 @@ public abstract class AnalysisMethod extends AnalysisElement implements WrappedJ
     private static final AtomicReferenceFieldUpdater<AnalysisMethod, Boolean> reachableInCurrentLayerUpdater = AtomicReferenceFieldUpdater
                     .newUpdater(AnalysisMethod.class, Boolean.class, "reachableInCurrentLayer");
 
+    public static final AnalysisMethod[] EMPTY_ARRAY = new AnalysisMethod[0];
+
     public record Signature(String name, AnalysisType[] parameterTypes) {
     }
 

substratevm/src/com.oracle.graal.pointsto/src/com/oracle/graal/pointsto/meta/AnalysisType.java

@@ -115,6 +115,8 @@ public abstract class AnalysisType extends AnalysisElement implements WrappedJav
 
     private static final AtomicReferenceFieldUpdater<AnalysisType, Object> RESOLVED_METHODS_UPDATER = AtomicReferenceFieldUpdater.newUpdater(AnalysisType.class, Object.class, "resolvedMethods");
 
+    public static final AnalysisType[] EMPTY_ARRAY = new AnalysisType[0];
+
     protected final AnalysisUniverse universe;
     private final ResolvedJavaType wrapped;
     private final String qualifiedName;
@@ -360,7 +362,7 @@ private AnalysisType[] convertTypes(ResolvedJavaType[] originalTypes) {
             }
             result.add(universe.lookup(originalType));
         }
-        return result.toArray(new AnalysisType[result.size()]);
+        return result.toArray(AnalysisType.EMPTY_ARRAY);
     }
 
     public AnalysisType getArrayClass(int dim) {

substratevm/src/com.oracle.graal.pointsto/src/com/oracle/graal/pointsto/meta/AnalysisUniverse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 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
@@ -471,7 +471,7 @@ public AnalysisMethod[] lookup(JavaMethod[] inputs) {
                 }
             }
         }
-        return result.toArray(new AnalysisMethod[result.size()]);
+        return result.toArray(AnalysisMethod.EMPTY_ARRAY);
     }
 
     @Override

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/CodeBreakdownProvider.java

@@ -36,7 +36,7 @@
 import com.oracle.svm.hosted.meta.HostedMethod;
 
 class CodeBreakdownProvider {
-    private final Map<String, Long> codeBreakdown;
+    private Map<String, Long> codeBreakdown;
 
     CodeBreakdownProvider(Collection<CompileTask> compilationTasks) {
         Map<String, Long> nameToSizeMap = new HashMap<>();
@@ -60,8 +60,17 @@ class CodeBreakdownProvider {
         codeBreakdown = Collections.unmodifiableMap(nameToSizeMap);
     }
 
-    public static Map<String, Long> get() {
-        return ImageSingletons.lookup(CodeBreakdownProvider.class).codeBreakdown;
+    /**
+     * Provides the code breakdown as map from name to size, and clears the cache to avoid memory
+     * footprint.
+     *
+     * @return the code breakdown
+     */
+    public static Map<String, Long> getAndClear() {
+        CodeBreakdownProvider singleton = ImageSingletons.lookup(CodeBreakdownProvider.class);
+        Map<String, Long> map = singleton.codeBreakdown;
+        singleton.codeBreakdown = null;
+        return map;
     }
 
     private static String findJARFile(Class<?> javaClass) {

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/ProgressReporter.java

@@ -641,7 +641,7 @@ private void printBreakdowns() {
             return;
         }
         l().printLineSeparator();
-        Map<String, Long> codeBreakdown = CodeBreakdownProvider.get();
+        Map<String, Long> codeBreakdown = CodeBreakdownProvider.getAndClear();
         Iterator<Entry<String, Long>> packagesBySize = codeBreakdown.entrySet().stream()
                         .sorted(Entry.comparingByValue(Comparator.reverseOrder())).iterator();
 

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/annotation/SubstrateAnnotationExtractor.java

@@ -279,6 +279,9 @@ private AnnotationValue[][] getParameterAnnotationDataFromRoot(Executable rootEl
             ByteBuffer buf = ByteBuffer.wrap(rawParameterAnnotations);
             try {
                 int numParameters = buf.get() & 0xFF;
+                if (numParameters == 0) {
+                    return NO_PARAMETER_ANNOTATIONS;
+                }
                 AnnotationValue[][] parameterAnnotations = new AnnotationValue[numParameters][];
                 for (int i = 0; i < numParameters; i++) {
                     List<AnnotationValue> parameterAnnotationList = new ArrayList<>();

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/code/CEntryPointData.java

@@ -91,7 +91,7 @@ public static CEntryPointData createCustomUnpublished() {
     private static CEntryPointData create(CEntryPoint annotation, CEntryPointOptions options, Supplier<String> alternativeNameSupplier) {
         String annotatedName = annotation.name();
         Class<? extends Function<String, String>> nameTransformation = DEFAULT_NAME_TRANSFORMATION;
-        String documentation = String.join(System.lineSeparator(), annotation.documentation());
+        String documentation = annotation.documentation().length == 0 ? "" : String.join(System.lineSeparator(), annotation.documentation());
         CEntryPoint.Builtin builtin = annotation.builtin();
         Class<?> prologue = DEFAULT_PROLOGUE;
         Class<?> prologueBailout = DEFAULT_PROLOGUE_BAILOUT;

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/code/RestrictHeapAccessCalleesImpl.java

@@ -114,7 +114,7 @@ public void aggregateMethods(Collection<AnalysisMethod> methods) {
         }
         MethodAggregator visitor = new MethodAggregator(aggregation, assertionErrorConstructorList);
         AnalysisMethodCalleeWalker walker = new AnalysisMethodCalleeWalker();
-        for (AnalysisMethod method : aggregation.keySet().toArray(new AnalysisMethod[0])) {
+        for (AnalysisMethod method : aggregation.keySet().toArray(AnalysisMethod.EMPTY_ARRAY)) {
             walker.walkMethod(method, visitor);
         }
         calleeToCallerMap = Collections.unmodifiableMap(aggregation);

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/code/RuntimeMetadataEncoderImpl.java

@@ -720,7 +720,8 @@ public void addRecordComponentsLookupError(HostedType declaringClass, Throwable
     }
 
     private static HostedType[] getParameterTypes(HostedMethod method) {
-        HostedType[] parameterTypes = new HostedType[method.getSignature().getParameterCount(false)];
+        int len = method.getSignature().getParameterCount(false);
+        HostedType[] parameterTypes = len == 0 ? HostedType.EMPTY_ARRAY : new HostedType[len];
         for (int i = 0; i < parameterTypes.length; ++i) {
             parameterTypes[i] = method.getSignature().getParameterType(i);
         }
@@ -737,7 +738,7 @@ private static String[] getParameterTypeNames(HostedMethod method) {
 
     private static HostedType[] getExceptionTypes(MetaAccessProvider metaAccess, Executable reflectMethod) {
         Class<?>[] exceptionClasses = reflectMethod.getExceptionTypes();
-        HostedType[] exceptionTypes = new HostedType[exceptionClasses.length];
+        HostedType[] exceptionTypes = exceptionClasses.length == 0 ? HostedType.EMPTY_ARRAY : new HostedType[exceptionClasses.length];
         for (int i = 0; i < exceptionClasses.length; ++i) {
             exceptionTypes[i] = (HostedType) metaAccess.lookupJavaType(exceptionClasses[i]);
         }

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

@@ -104,7 +104,7 @@ public NativeImageHeapWriter(NativeImageHeap heap, ImageHeapLayoutInfo heapLayou
     public long writeHeap(DebugContext debug, RelocatableBuffer buffer) {
         try (Indent perHeapIndent = debug.logAndIndent("NativeImageHeap.writeHeap:")) {
             for (ObjectInfo info : heap.getObjects()) {
-                assert !heap.isBlacklisted(info.getObject());
+                assert !heap.isBlacklisted(info.getObject()) : "Backlisted object: " + info.getObject();
                 if (info.getConstant().isWrittenInPreviousLayer()) {
                     /*
                      * Base layer constants already written in the base layer heap are only added to

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/meta/HostedArrayClass.java

@@ -81,7 +81,7 @@ public int getArrayDimension() {
 
     @Override
     public HostedField[] getInstanceFields(boolean includeSuperclasses) {
-        return new HostedField[0];
+        return HostedField.EMPTY_ARRAY;
     }
 
     @Override

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/meta/HostedField.java

@@ -43,6 +43,10 @@
  */
 public class HostedField extends HostedElement implements OriginalFieldProvider, SharedField, WrappedJavaField {
 
+    static final int LOC_UNMATERIALIZED_STATIC_CONSTANT = -10;
+
+    public static final HostedField[] EMPTY_ARRAY = new HostedField[0];
+
     public final AnalysisField wrapped;
 
     private final HostedType holder;
@@ -51,8 +55,6 @@ public class HostedField extends HostedElement implements OriginalFieldProvider,
     protected int location;
     private int installedLayerNum;
 
-    static final int LOC_UNMATERIALIZED_STATIC_CONSTANT = -10;
-
     public HostedField(AnalysisField wrapped, HostedType holder, HostedType type) {
         this.wrapped = wrapped;
         this.holder = holder;

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/meta/HostedInterface.java

@@ -36,6 +36,8 @@
  */
 public class HostedInterface extends HostedType {
 
+    public static final HostedInterface[] EMPTY_ARRAY = new HostedInterface[0];
+
     public HostedInterface(HostedUniverse universe, AnalysisType wrapped, JavaKind kind, JavaKind storageKind, HostedInterface[] interfaces) {
         super(universe, wrapped, kind, storageKind, null, interfaces);
     }
@@ -87,6 +89,6 @@ public int getArrayDimension() {
 
     @Override
     public HostedField[] getInstanceFields(boolean includeSuperclasses) {
-        return new HostedField[0];
+        return HostedField.EMPTY_ARRAY;
     }
 }

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/meta/HostedPrimitiveType.java

@@ -31,7 +31,7 @@
 public class HostedPrimitiveType extends HostedType {
 
     public HostedPrimitiveType(HostedUniverse universe, AnalysisType wrapped, JavaKind kind, JavaKind storageKind) {
-        super(universe, wrapped, kind, storageKind, null, new HostedInterface[0]);
+        super(universe, wrapped, kind, storageKind, null, HostedInterface.EMPTY_ARRAY);
     }
 
     @Override
@@ -81,7 +81,7 @@ public int getArrayDimension() {
 
     @Override
     public HostedField[] getInstanceFields(boolean includeSuperclasses) {
-        return new HostedField[0];
+        return HostedField.EMPTY_ARRAY;
     }
 
     @Override

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/meta/HostedUniverse.java

@@ -355,7 +355,7 @@ public HostedType optionalLookup(JavaType type) {
     }
 
     public HostedType[] optionalLookup(JavaType... javaTypes) {
-        HostedType[] result = new HostedType[javaTypes.length];
+        HostedType[] result = new HostedType[javaTypes.length]; // EMPTY_ARRAY failing here
         for (int i = 0; i < javaTypes.length; ++i) {
             result[i] = optionalLookup(javaTypes[i]);
             if (result[i] == null) {
@@ -421,7 +421,7 @@ public HostedMethod optionalLookup(JavaMethod method) {
     }
 
     public HostedMethod[] lookup(JavaMethod[] inputs) {
-        HostedMethod[] result = new HostedMethod[inputs.length];
+        HostedMethod[] result = new HostedMethod[inputs.length]; // EMPTY_ARRAY failing here
         for (int i = 0; i < result.length; i++) {
             result[i] = lookup(inputs[i]);
         }

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/meta/UniverseBuilder.java

@@ -45,6 +45,8 @@
 import java.util.stream.Collectors;
 
 import org.graalvm.nativeimage.ImageInfo;
+import org.graalvm.nativeimage.Platform;
+import org.graalvm.nativeimage.Platforms;
 import org.graalvm.nativeimage.c.function.CEntryPointLiteral;
 import org.graalvm.nativeimage.c.function.CFunction;
 import org.graalvm.nativeimage.c.function.CFunctionPointer;
@@ -119,6 +121,7 @@
 
 public class UniverseBuilder {
 
+    @Platforms(Platform.HOSTED_ONLY.class) private static final CFunctionPointer[] EMPTY_ARRAY = new CFunctionPointer[0];
     private final AnalysisUniverse aUniverse;
     private final AnalysisMetaAccess aMetaAccess;
     private final HostedUniverse hUniverse;
@@ -227,7 +230,7 @@ private HostedType makeType(AnalysisType aType) {
         assert !typeName.contains("/hosted/meta/") : "Hosted meta object in image " + typeName;
 
         AnalysisType[] aInterfaces = aType.getInterfaces();
-        HostedInterface[] sInterfaces = new HostedInterface[aInterfaces.length];
+        HostedInterface[] sInterfaces = aInterfaces.length == 0 ? HostedInterface.EMPTY_ARRAY : new HostedInterface[aInterfaces.length];
         for (int i = 0; i < aInterfaces.length; i++) {
             sInterfaces[i] = (HostedInterface) makeType(aInterfaces[i]);
         }
@@ -469,7 +472,7 @@ public static boolean isKnownImmutableType(Class<?> clazz) {
     private void layoutInstanceFields(int numTypeCheckSlots) {
         BitSet usedBytes = new BitSet();
         usedBytes.set(0, ConfigurationValues.getObjectLayout().getFirstFieldOffset());
-        layoutInstanceFields(hUniverse.getObjectClass(), new HostedField[0], usedBytes, numTypeCheckSlots);
+        layoutInstanceFields(hUniverse.getObjectClass(), HostedField.EMPTY_ARRAY, usedBytes, numTypeCheckSlots);
     }
 
     private static boolean mustReserveArrayFields(HostedInstanceClass clazz) {
@@ -640,7 +643,7 @@ private void layoutInstanceFields(HostedInstanceClass clazz, HostedField[] super
             clazz.setIdentityHashOffset(offset);
         }
 
-        clazz.instanceFieldsWithoutSuper = allFields.toArray(new HostedField[0]);
+        clazz.instanceFieldsWithoutSuper = allFields.toArray(HostedField.EMPTY_ARRAY);
         clazz.firstInstanceFieldOffset = firstInstanceFieldOffset;
         clazz.afterFieldsOffset = afterFieldsOffset;
         clazz.instanceSize = layout.alignUp(afterFieldsOffset);
@@ -840,13 +843,12 @@ private void layoutStaticFields() {
             fieldsOfTypes[typeId].add(field);
         }
 
-        HostedField[] noFields = new HostedField[0];
         for (HostedType type : hUniverse.getTypes()) {
             List<HostedField> fieldsOfType = fieldsOfTypes[type.getTypeID()];
             if (fieldsOfType != null) {
                 type.staticFields = fieldsOfType.toArray(new HostedField[fieldsOfType.size()]);
             } else {
-                type.staticFields = noFields;
+                type.staticFields = HostedField.EMPTY_ARRAY;
             }
         }
 
@@ -886,7 +888,7 @@ private void collectMethodImplementations() {
         for (HostedMethod method : hUniverse.methods.values()) {
 
             // Reuse the implementations from the analysis method.
-            method.implementations = hUniverse.lookup(method.wrapped.collectMethodImplementations(false).toArray(new AnalysisMethod[0]));
+            method.implementations = hUniverse.lookup(method.wrapped.collectMethodImplementations(false).toArray(AnalysisMethod.EMPTY_ARRAY));
             Arrays.sort(method.implementations, HostedUniverse.METHOD_COMPARATOR);
         }
     }
@@ -955,7 +957,7 @@ private void buildHubs() {
             hub.setSharedData(layoutHelper, monitorOffset, identityHashOffset, referenceMapIndex, type.isInstantiated());
 
             if (SubstrateOptions.useClosedTypeWorldHubLayout()) {
-                CFunctionPointer[] vtable = new CFunctionPointer[type.closedTypeWorldVTable.length];
+                CFunctionPointer[] vtable = type.closedTypeWorldVTable.length == 0 ? EMPTY_ARRAY : new CFunctionPointer[type.closedTypeWorldVTable.length];
                 for (int idx = 0; idx < type.closedTypeWorldVTable.length; idx++) {
                     /*
                      * We install a CodePointer in the vtable; when generating relocation info, we
@@ -994,7 +996,7 @@ private void buildHubs() {
                     typeSlotIdx += 2;
                 }
 
-                CFunctionPointer[] vtable = new CFunctionPointer[type.openTypeWorldDispatchTables.length];
+                CFunctionPointer[] vtable = type.openTypeWorldDispatchTables.length == 0 ? EMPTY_ARRAY : new CFunctionPointer[type.openTypeWorldDispatchTables.length];
                 for (int idx = 0; idx < type.openTypeWorldDispatchTables.length; idx++) {
                     /*
                      * We install a CodePointer in the open world vtable; when generating relocation

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/meta/VTableBuilder.java

@@ -430,8 +430,8 @@ private void buildClosedTypeWorldVTables() {
             if (type.isArray()) {
                 type.closedTypeWorldVTable = objectClass.closedTypeWorldVTable;
             }
-            if (type.closedTypeWorldVTable == null) {
-                assert type.isInterface() || type.isPrimitive();
+            if (type.closedTypeWorldVTable == null || type.closedTypeWorldVTable.length == 0) {
+                assert type.isInterface() || type.isPrimitive() || type.closedTypeWorldVTable.length == 0;
                 type.closedTypeWorldVTable = HostedMethod.EMPTY_ARRAY;
             }
 

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/reflect/ReflectionDataBuilder.java

@@ -965,7 +965,7 @@ private void registerTypesForAnnotations(AnnotatedElement annotatedElement) {
                         registerTypesForAnnotation(annotation);
                     }
                 }
-                filteredAnnotations.put(annotatedElement, includedAnnotations.toArray(new AnnotationValue[0]));
+                filteredAnnotations.put(annotatedElement, includedAnnotations.toArray(NO_ANNOTATIONS));
             }
         }
     }
@@ -974,7 +974,7 @@ private void registerTypesForParameterAnnotations(AnalysisMethod method) {
         if (method != null) {
             if (!filteredParameterAnnotations.containsKey(method)) {
                 AnnotationValue[][] parameterAnnotations = annotationExtractor.getParameterAnnotationData(method);
-                AnnotationValue[][] includedParameterAnnotations = new AnnotationValue[parameterAnnotations.length][];
+                AnnotationValue[][] includedParameterAnnotations = parameterAnnotations.length == 0 ? NO_PARAMETER_ANNOTATIONS : new AnnotationValue[parameterAnnotations.length][];
                 for (int i = 0; i < includedParameterAnnotations.length; ++i) {
                     AnnotationValue[] annotations = parameterAnnotations[i];
                     List<AnnotationValue> includedAnnotations = new ArrayList<>();
@@ -984,7 +984,7 @@ private void registerTypesForParameterAnnotations(AnalysisMethod method) {
                             registerTypesForAnnotation(annotation);
                         }
                     }
-                    includedParameterAnnotations[i] = includedAnnotations.toArray(new AnnotationValue[0]);
+                    includedParameterAnnotations[i] = includedAnnotations.toArray(NO_ANNOTATIONS);
                 }
                 filteredParameterAnnotations.put(method, includedParameterAnnotations);
             }
@@ -1001,7 +1001,7 @@ private void registerTypesForTypeAnnotations(AnnotatedElement annotatedElement)
                         registerTypesForAnnotation(typeAnnotation.getAnnotationData());
                     }
                 }
-                filteredTypeAnnotations.put(annotatedElement, includedTypeAnnotations.toArray(new TypeAnnotationValue[0]));
+                filteredTypeAnnotations.put(annotatedElement, includedTypeAnnotations.toArray(NO_TYPE_ANNOTATIONS));
             }
         }
     }