1 /*
  2  * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.  Oracle designates this
  8  * particular file as subject to the "Classpath" exception as provided
  9  * by Oracle in the LICENSE file that accompanied this code.
 10  *
 11  * This code is distributed in the hope that it will be useful, but WITHOUT
 12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 14  * version 2 for more details (a copy is included in the LICENSE file that
 15  * accompanied this code).
 16  *
 17  * You should have received a copy of the GNU General Public License version
 18  * 2 along with this work; if not, write to the Free Software Foundation,
 19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 20  *
 21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 22  * or visit www.oracle.com if you need additional information or have any
 23  * questions.
 24  */
 25 
 26 package java.lang.invoke;
 27 
 28 import jdk.internal.access.JavaLangInvokeAccess.ReflectableLambdaInfo;
 29 import jdk.internal.constant.ClassOrInterfaceDescImpl;
 30 import jdk.internal.misc.CDS;
 31 import jdk.internal.util.ClassFileDumper;
 32 import sun.invoke.util.VerifyAccess;
 33 
 34 import java.io.Serializable;
 35 import java.lang.classfile.ClassBuilder;
 36 import java.lang.classfile.ClassFile;
 37 import java.lang.classfile.CodeBuilder;
 38 import java.lang.classfile.Label;
 39 import java.lang.classfile.MethodBuilder;
 40 import java.lang.classfile.Opcode;
 41 import java.lang.classfile.TypeKind;
 42 import java.lang.classfile.constantpool.MethodHandleEntry;
 43 import java.lang.classfile.constantpool.NameAndTypeEntry;
 44 import java.lang.constant.ClassDesc;
 45 import java.lang.constant.MethodTypeDesc;
 46 import java.lang.reflect.Modifier;
 47 import java.util.LinkedHashSet;
 48 import java.util.List;
 49 import java.util.Set;
 50 import java.util.function.Consumer;
 51 
 52 import static java.lang.classfile.ClassFile.*;
 53 import java.lang.classfile.attribute.ExceptionsAttribute;
 54 import java.lang.classfile.constantpool.ClassEntry;
 55 import java.lang.classfile.constantpool.ConstantPoolBuilder;
 56 
 57 import static java.lang.constant.ConstantDescs.*;
 58 import static java.lang.invoke.MethodHandleNatives.Constants.NESTMATE_CLASS;
 59 import static java.lang.invoke.MethodHandleNatives.Constants.STRONG_LOADER_LINK;
 60 import jdk.internal.constant.ConstantUtils;
 61 import jdk.internal.constant.MethodTypeDescImpl;
 62 import jdk.internal.vm.annotation.Stable;
 63 import sun.invoke.util.Wrapper;
 64 
 65 /**
 66  * Lambda metafactory implementation which dynamically creates an
 67  * inner-class-like class per lambda callsite.
 68  *
 69  * @see LambdaMetafactory
 70  */
 71 /* package */ final class InnerClassLambdaMetafactory extends AbstractValidatingLambdaMetafactory {
 72     private static final String LAMBDA_INSTANCE_FIELD = "LAMBDA_INSTANCE$";
 73     private static final @Stable String[] ARG_NAME_CACHE = {"arg$1", "arg$2", "arg$3", "arg$4", "arg$5", "arg$6", "arg$7", "arg$8"};
 74     private static final ClassDesc[] EMPTY_CLASSDESC_ARRAY = ConstantUtils.EMPTY_CLASSDESC;
 75 
 76     // Static builders to avoid lambdas
 77     record MethodBody(Consumer<CodeBuilder> code) implements Consumer<MethodBuilder> {
 78         @Override
 79         public void accept(MethodBuilder mb) {
 80             mb.withCode(code);
 81         }
 82     };
 83 
 84     // For dumping generated classes to disk, for debugging purposes
 85     private static final ClassFileDumper lambdaProxyClassFileDumper;
 86 
 87     private static final boolean disableEagerInitialization;
 88 
 89     private static final String NAME_METHOD_QUOTED = "__internal_quoted";
 90     private static final String QUOTED_FIELD_NAME = "quoted";
 91     private static final String MODEL_FIELD_NAME = "model";
 92 
 93     static {
 94         // To dump the lambda proxy classes, set this system property:
 95         //    -Djdk.invoke.LambdaMetafactory.dumpProxyClassFiles
 96         // or -Djdk.invoke.LambdaMetafactory.dumpProxyClassFiles=true
 97         final String dumpProxyClassesKey = "jdk.invoke.LambdaMetafactory.dumpProxyClassFiles";
 98         lambdaProxyClassFileDumper = ClassFileDumper.getInstance(dumpProxyClassesKey, "DUMP_LAMBDA_PROXY_CLASS_FILES");
 99 
100         final String disableEagerInitializationKey = "jdk.internal.lambda.disableEagerInitialization";
101         disableEagerInitialization = Boolean.getBoolean(disableEagerInitializationKey);
102     }
103 
104     // See context values in AbstractValidatingLambdaMetafactory
105     private final ClassDesc implMethodClassDesc;     // Name of type containing implementation "CC"
106     private final String implMethodName;             // Name of implementation method "impl"
107     private final MethodTypeDesc implMethodDesc;     // Type descriptor for implementation methods "(I)Ljava/lang/String;"
108     private final MethodType constructorType;        // Generated class constructor type "(CC)void"
109     private final MethodTypeDesc constructorTypeDesc;// Type descriptor for the generated class constructor type "(CC)void"
110     private final ClassDesc[] argDescs;              // Type descriptors for the constructor arguments
111     private final String lambdaClassName;            // Generated name for the generated class "X$$Lambda$1"
112     private final ConstantPoolBuilder pool = ConstantPoolBuilder.of();
113     private final ClassEntry lambdaClassEntry;       // Class entry for the generated class "X$$Lambda$1"
114     private final boolean useImplMethodHandle;       // use MethodHandle invocation instead of symbolic bytecode invocation
115 
116     /**
117      * General meta-factory constructor, supporting both standard cases and
118      * allowing for uncommon options such as serialization or bridging.
119      *
120      * @param caller Stacked automatically by VM; represents a lookup context
121      *               with the accessibility privileges of the caller.
122      * @param factoryType Stacked automatically by VM; the signature of the
123      *                    invoked method, which includes the expected static
124      *                    type of the returned lambda object, and the static
125      *                    types of the captured arguments for the lambda.  In
126      *                    the event that the implementation method is an
127      *                    instance method, the first argument in the invocation
128      *                    signature will correspond to the receiver.
129      * @param interfaceMethodName Name of the method in the functional interface to
130      *                   which the lambda or method reference is being
131      *                   converted, represented as a String.
132      * @param interfaceMethodType Type of the method in the functional interface to
133      *                            which the lambda or method reference is being
134      *                            converted, represented as a MethodType.
135      * @param implementation The implementation method which should be called (with
136      *                       suitable adaptation of argument types, return types,
137      *                       and adjustment for captured arguments) when methods of
138      *                       the resulting functional interface instance are invoked.
139      * @param dynamicMethodType The signature of the primary functional
140      *                          interface method after type variables are
141      *                          substituted with their instantiation from
142      *                          the capture site
143      * @param isSerializable Should the lambda be made serializable?  If set,
144      *                       either the target type or one of the additional SAM
145      *                       types must extend {@code Serializable}.
146      * @param altInterfaces Additional interfaces which the lambda object
147      *                      should implement.
148      * @param altMethods Method types for additional signatures to be
149      *                   implemented by invoking the implementation method
150      * @throws LambdaConversionException If any of the meta-factory protocol
151      *         invariants are violated
152      */
153     public InnerClassLambdaMetafactory(MethodHandles.Lookup caller,
154                                        MethodType factoryType,
155                                        String interfaceMethodName,
156                                        MethodType interfaceMethodType,
157                                        MethodHandle implementation,
158                                        MethodType dynamicMethodType,
159                                        boolean isSerializable,
160                                        Class<?>[] altInterfaces,
161                                        MethodType[] altMethods,
162                                        ReflectableLambdaInfo reflectableLambdaInfo)
163             throws LambdaConversionException {
164         super(caller, factoryType, interfaceMethodName, interfaceMethodType,
165               implementation, dynamicMethodType,
166               isSerializable, altInterfaces, altMethods, reflectableLambdaInfo);
167         implMethodClassDesc = implClassDesc(implClass);
168         implMethodName = implInfo.getName();
169         implMethodDesc = methodDesc(implInfo.getMethodType());
170         constructorType = factoryType.changeReturnType(Void.TYPE);
171         lambdaClassName = lambdaClassName(targetClass);
172         lambdaClassEntry = pool.classEntry(ConstantUtils.internalNameToDesc(lambdaClassName));
173         // If the target class invokes a protected method inherited from a
174         // superclass in a different package, or does 'invokespecial', the
175         // lambda class has no access to the resolved method, or does
176         // 'invokestatic' on a hidden class which cannot be resolved by name.
177         // Instead, we need to pass the live implementation method handle to
178         // the proxy class to invoke directly. (javac prefers to avoid this
179         // situation by generating bridges in the target class)
180         useImplMethodHandle = (Modifier.isProtected(implInfo.getModifiers()) &&
181                                !VerifyAccess.isSamePackage(targetClass, implInfo.getDeclaringClass())) ||
182                                implKind == MethodHandleInfo.REF_invokeSpecial ||
183                                implKind == MethodHandleInfo.REF_invokeStatic && implClass.isHidden();
184         int parameterCount = factoryType.parameterCount();
185         ClassDesc[] argDescs;
186         MethodTypeDesc constructorTypeDesc;
187         if (parameterCount > 0) {
188             argDescs = new ClassDesc[parameterCount];
189             for (int i = 0; i < parameterCount; i++) {
190                 argDescs[i] = classDesc(factoryType.parameterType(i));
191             }
192             constructorTypeDesc = MethodTypeDescImpl.ofValidated(CD_void, argDescs);
193         } else {
194             argDescs = EMPTY_CLASSDESC_ARRAY;
195             constructorTypeDesc = MTD_void;
196         }
197         this.argDescs = argDescs;
198         this.constructorTypeDesc = constructorTypeDesc;
199     }
200 
201     private static String argName(int i) {
202         return i < ARG_NAME_CACHE.length ? ARG_NAME_CACHE[i] :  "arg$" + (i + 1);
203     }
204 
205     private static String sanitizedTargetClassName(Class<?> targetClass) {
206         String name = targetClass.getName();
207         if (targetClass.isHidden()) {
208             // use the original class name
209             name = name.replace('/', '_');
210         }
211         return name.replace('.', '/');
212     }
213 
214     private static String lambdaClassName(Class<?> targetClass) {
215         return sanitizedTargetClassName(targetClass).concat("$$Lambda");
216     }
217 
218     /**
219      * Build the CallSite. Generate a class file which implements the functional
220      * interface, define the class, if there are no parameters create an instance
221      * of the class which the CallSite will return, otherwise, generate handles
222      * which will call the class' constructor.
223      *
224      * @return a CallSite, which, when invoked, will return an instance of the
225      * functional interface
226      * @throws LambdaConversionException If properly formed functional interface
227      * is not found
228      */
229     @Override
230     CallSite buildCallSite() throws LambdaConversionException {
231         final Class<?> innerClass = spinInnerClass();
232         if (factoryType.parameterCount() == 0 && disableEagerInitialization) {
233             try {
234                 return new ConstantCallSite(caller.findStaticGetter(innerClass, LAMBDA_INSTANCE_FIELD,
235                                                                     factoryType.returnType()));
236             } catch (ReflectiveOperationException e) {
237                 throw new LambdaConversionException(
238                         "Exception finding " + LAMBDA_INSTANCE_FIELD + " static field", e);
239             }
240         } else {
241             try {
242                 MethodHandle mh = caller.findConstructor(innerClass, constructorType);
243                 if (factoryType.parameterCount() == 0) {
244                     // In the case of a non-capturing lambda, we optimize linkage by pre-computing a single instance
245                     Object inst = mh.invokeBasic();
246                     return new ConstantCallSite(MethodHandles.constant(interfaceClass, inst));
247                 } else {
248                     return new ConstantCallSite(mh.asType(factoryType));
249                 }
250             } catch (ReflectiveOperationException e) {
251                 throw new LambdaConversionException("Exception finding constructor", e);
252             } catch (Throwable e) {
253                 throw new LambdaConversionException("Exception instantiating lambda object", e);
254             }
255         }
256     }
257 
258     /**
259      * Spins the lambda proxy class.
260      *
261      * This first checks if a lambda proxy class can be loaded from CDS archive.
262      * Otherwise, generate the lambda proxy class. If CDS dumping is enabled, it
263      * registers the lambda proxy class for including into the CDS archive.
264      */
265     private Class<?> spinInnerClass() throws LambdaConversionException {
266         // CDS does not handle disableEagerInitialization or useImplMethodHandle
267         if (!disableEagerInitialization && !useImplMethodHandle) {
268             if (CDS.isUsingArchive()) {
269                 // load from CDS archive if present
270                 Class<?> innerClass = LambdaProxyClassArchive.find(targetClass,
271                                                                    interfaceMethodName,
272                                                                    factoryType,
273                                                                    interfaceMethodType,
274                                                                    implementation,
275                                                                    dynamicMethodType,
276                                                                    isSerializable,
277                                                                    altInterfaces,
278                                                                    altMethods);
279                 if (innerClass != null) return innerClass;
280             }
281 
282             // include lambda proxy class in CDS archive at dump time
283             if (CDS.isDumpingArchive()) {
284                 Class<?> innerClass = generateInnerClass();
285                 LambdaProxyClassArchive.register(targetClass,
286                                                  interfaceMethodName,
287                                                  factoryType,
288                                                  interfaceMethodType,
289                                                  implementation,
290                                                  dynamicMethodType,
291                                                  isSerializable,
292                                                  altInterfaces,
293                                                  altMethods,
294                                                  innerClass);
295                 return innerClass;
296             }
297 
298         }
299         return generateInnerClass();
300     }
301 
302     /**
303      * Generate a class file which implements the functional
304      * interface, define and return the class.
305      *
306      * @return a Class which implements the functional interface
307      * @throws LambdaConversionException If properly formed functional interface
308      * is not found
309      */
310     private Class<?> generateInnerClass() throws LambdaConversionException {
311         List<ClassDesc> interfaces;
312         ClassDesc interfaceDesc = classDesc(interfaceClass);
313         boolean accidentallySerializable = !isSerializable && Serializable.class.isAssignableFrom(interfaceClass);
314         if (altInterfaces.length == 0) {
315             interfaces = List.of(interfaceDesc);
316         } else {
317             // Assure no duplicate interfaces (ClassFormatError)
318             Set<ClassDesc> itfs = LinkedHashSet.newLinkedHashSet(altInterfaces.length + 1);
319             itfs.add(interfaceDesc);
320             for (Class<?> i : altInterfaces) {
321                 itfs.add(classDesc(i));
322                 accidentallySerializable |= !isSerializable && Serializable.class.isAssignableFrom(i);
323             }
324             interfaces = List.copyOf(itfs);
325         }
326         final boolean finalAccidentallySerializable = accidentallySerializable;
327         final byte[] classBytes = ClassFile.of().build(lambdaClassEntry, pool, new Consumer<ClassBuilder>() {
328             @Override
329             public void accept(ClassBuilder clb) {
330                 clb.withFlags(ACC_SUPER | ACC_FINAL | ACC_SYNTHETIC)
331                    .withInterfaceSymbols(interfaces);
332                 // Generate final fields to be filled in by constructor
333                 for (int i = 0; i < argDescs.length; i++) {
334                     clb.withField(argName(i), argDescs[i], ACC_PRIVATE | ACC_FINAL);
335                 }
336 
337                 if (reflectableLambdaInfo != null) {
338                     // the field that will hold the quoted instance
339                     clb.withField(QUOTED_FIELD_NAME, reflectableLambdaInfo.quotedClass(), ACC_PRIVATE);
340                     // the field that will hold the model
341                     clb.withField(MODEL_FIELD_NAME, reflectableLambdaInfo.funcOpClass(),
342                             ACC_PRIVATE | ACC_STATIC);
343                 }
344 
345                 generateConstructor(clb);
346 
347                 generateClassInitializationMethod(clb);
348 
349 
350                 // Forward the SAM method
351                 clb.withMethodBody(interfaceMethodName,
352                         methodDesc(interfaceMethodType),
353                         ACC_PUBLIC,
354                         forwardingMethod(interfaceMethodType));
355 
356                 // Forward the bridges
357                 if (altMethods != null) {
358                     for (MethodType mt : altMethods) {
359                         clb.withMethodBody(interfaceMethodName,
360                                 methodDesc(mt),
361                                 ACC_PUBLIC | ACC_BRIDGE,
362                                 forwardingMethod(mt));
363                     }
364                 }
365 
366                 if (isSerializable)
367                     generateSerializationFriendlyMethods(clb);
368                 else if (finalAccidentallySerializable)
369                     generateSerializationHostileMethods(clb);
370 
371                 if (reflectableLambdaInfo != null) {
372                     generateQuotedMethod(clb);
373                 }
374             }
375         });
376 
377         // Define the generated class in this VM.
378 
379         try {
380             // this class is linked at the indy callsite; so define a hidden nestmate
381             List<?> classdata;
382             if (useImplMethodHandle || reflectableLambdaInfo != null) {
383                 classdata = reflectableLambdaInfo == null ?
384                         List.of(implementation) :
385                         List.of(implementation, reflectableLambdaInfo.opHandle(), reflectableLambdaInfo.extractOpHandle());
386             } else {
387                 classdata = null;
388             }
389             return caller.makeHiddenClassDefiner(lambdaClassName, classBytes, lambdaProxyClassFileDumper, NESTMATE_CLASS | STRONG_LOADER_LINK)
390                          .defineClass(!disableEagerInitialization, classdata);
391 
392         } catch (Throwable t) {
393             throw new InternalError(t);
394         }
395     }
396 
397     private void generateClassInitializationMethod(ClassBuilder clb) {
398         if (!(factoryType.parameterCount() == 0 && disableEagerInitialization) && reflectableLambdaInfo == null) {
399             return;
400         }
401         clb.withMethodBody(CLASS_INIT_NAME, MTD_void, ACC_STATIC, new Consumer<CodeBuilder>() {
402             @Override
403             public void accept(CodeBuilder cob) {
404                 if (factoryType.parameterCount() == 0 && disableEagerInitialization) {
405                     ClassDesc lambdaTypeDescriptor = classDesc(factoryType.returnType());
406                     // Generate the static final field that holds the lambda singleton
407                     clb.withField(LAMBDA_INSTANCE_FIELD, lambdaTypeDescriptor, ACC_PRIVATE | ACC_STATIC | ACC_FINAL);
408                     cob.new_(lambdaClassEntry)
409                             .dup()
410                             .invokespecial(pool.methodRefEntry(lambdaClassEntry, pool.nameAndTypeEntry(INIT_NAME, constructorTypeDesc)))
411                             .putstatic(pool.fieldRefEntry(lambdaClassEntry, pool.nameAndTypeEntry(LAMBDA_INSTANCE_FIELD, lambdaTypeDescriptor)));
412                 }
413                 cob.return_();
414             }
415         });
416     }
417 
418     /**
419      * Generate the constructor for the class
420      */
421     private void generateConstructor(ClassBuilder clb) {
422         // Generate constructor
423         clb.withMethodBody(INIT_NAME, constructorTypeDesc, ACC_PRIVATE,
424                 new Consumer<>() {
425                     @Override
426                     public void accept(CodeBuilder cob) {
427                         cob.aload(0)
428                            .invokespecial(CD_Object, INIT_NAME, MTD_void);
429                         int parameterCount = factoryType.parameterCount();
430                         for (int i = 0; i < parameterCount; i++) {
431                             cob.aload(0)
432                                .loadLocal(TypeKind.from(factoryType.parameterType(i)), cob.parameterSlot(i))
433                                .putfield(pool.fieldRefEntry(lambdaClassEntry, pool.nameAndTypeEntry(argName(i), argDescs[i])));
434                         }
435                         cob.return_();
436                     }
437                 });
438     }
439 
440     private static class SerializationSupport {
441         // Serialization support
442         private static final ClassDesc CD_SerializedLambda = ClassOrInterfaceDescImpl.ofValidated("Ljava/lang/invoke/SerializedLambda;");
443         private static final ClassDesc CD_ObjectOutputStream = ClassOrInterfaceDescImpl.ofValidated("Ljava/io/ObjectOutputStream;");
444         private static final ClassDesc CD_ObjectInputStream = ClassOrInterfaceDescImpl.ofValidated("Ljava/io/ObjectInputStream;");
445         private static final MethodTypeDesc MTD_Object = MethodTypeDescImpl.ofValidated(CD_Object);
446         private static final MethodTypeDesc MTD_void_ObjectOutputStream = MethodTypeDescImpl.ofValidated(CD_void, CD_ObjectOutputStream);
447         private static final MethodTypeDesc MTD_void_ObjectInputStream = MethodTypeDescImpl.ofValidated(CD_void, CD_ObjectInputStream);
448 
449         private static final String NAME_METHOD_WRITE_REPLACE = "writeReplace";
450         private static final String NAME_METHOD_READ_OBJECT = "readObject";
451         private static final String NAME_METHOD_WRITE_OBJECT = "writeObject";
452 
453         static final ClassDesc CD_NotSerializableException = ClassOrInterfaceDescImpl.ofValidated("Ljava/io/NotSerializableException;");
454         static final MethodTypeDesc MTD_CTOR_NOT_SERIALIZABLE_EXCEPTION = MethodTypeDescImpl.ofValidated(CD_void, CD_String);
455         static final MethodTypeDesc MTD_CTOR_SERIALIZED_LAMBDA = MethodTypeDescImpl.ofValidated(CD_void,
456                 CD_Class, CD_String, CD_String, CD_String, CD_int, CD_String, CD_String, CD_String, CD_String, ConstantUtils.CD_Object_array);
457 
458     }
459 
460     /**
461      * Generate a writeReplace method that supports serialization
462      */
463     private void generateSerializationFriendlyMethods(ClassBuilder clb) {
464         clb.withMethodBody(SerializationSupport.NAME_METHOD_WRITE_REPLACE, SerializationSupport.MTD_Object, ACC_PRIVATE | ACC_FINAL,
465                 new Consumer<>() {
466                     @Override
467                     public void accept(CodeBuilder cob) {
468                         cob.new_(SerializationSupport.CD_SerializedLambda)
469                            .dup()
470                            .ldc(ClassDesc.ofInternalName(sanitizedTargetClassName(targetClass)))
471                            .ldc(factoryType.returnType().getName().replace('.', '/'))
472                            .ldc(interfaceMethodName)
473                            .ldc(interfaceMethodType.toMethodDescriptorString())
474                            .ldc(implInfo.getReferenceKind())
475                            .ldc(implInfo.getDeclaringClass().getName().replace('.', '/'))
476                            .ldc(implInfo.getName())
477                            .ldc(implInfo.getMethodType().toMethodDescriptorString())
478                            .ldc(dynamicMethodType.toMethodDescriptorString())
479                            .loadConstant(argDescs.length)
480                            .anewarray(CD_Object);
481                         for (int i = 0; i < argDescs.length; i++) {
482                             cob.dup()
483                                .loadConstant(i)
484                                .aload(0)
485                                .getfield(pool.fieldRefEntry(lambdaClassEntry, pool.nameAndTypeEntry(argName(i), argDescs[i])));
486                             TypeConvertingMethodAdapter.boxIfTypePrimitive(cob, TypeKind.from(argDescs[i]));
487                             cob.aastore();
488                         }
489                         cob.invokespecial(SerializationSupport.CD_SerializedLambda, INIT_NAME,
490                                           SerializationSupport.MTD_CTOR_SERIALIZED_LAMBDA)
491                            .areturn();
492                     }
493                 });
494     }
495 
496     /**
497     * Generate method #__internal_quoted()
498      */
499     private void generateQuotedMethod(ClassBuilder clb) {
500         clb.withMethod(NAME_METHOD_QUOTED, MethodTypeDesc.of(reflectableLambdaInfo.quotedClass()), ACC_PRIVATE, new MethodBody(new Consumer<CodeBuilder>() {
501             @Override
502             public void accept(CodeBuilder cob) {
503                 cob.aload(0)
504                         .invokevirtual(lambdaClassEntry.asSymbol(), "getQuoted", MethodTypeDesc.of(reflectableLambdaInfo.quotedClass()))
505                         .areturn();
506             }
507         }));
508         // generate helper methods
509         /*
510         synchronized Quoted getQuoted() {
511             Quoted v = quoted;
512             if (v == null) {
513                 v = quoted = Quoted.extractOp(getModel(), captures);
514             }
515             return v;
516         }
517         * */
518         clb.withMethod("getQuoted", MethodTypeDesc.of(reflectableLambdaInfo.quotedClass()),
519                 ACC_PRIVATE + ACC_SYNCHRONIZED,
520                 new MethodBody(new Consumer<CodeBuilder>() {
521                     @Override
522                     public void accept(CodeBuilder cob) {
523                         cob.aload(0)
524                                 .getfield(lambdaClassEntry.asSymbol(), QUOTED_FIELD_NAME, reflectableLambdaInfo.quotedClass())
525                                 .astore(1)
526                                 .aload(1)
527                                 .ifThen(Opcode.IFNULL, bcb -> {
528                                     bcb.aload(0); // will be used by putfield
529 
530                                     // load class data: MH to Quoted.extractOp
531                                     ConstantPoolBuilder cp = bcb.constantPool();
532                                     MethodHandleEntry bsmDataAt = cp.methodHandleEntry(BSM_CLASS_DATA_AT);
533                                     NameAndTypeEntry natMH = cp.nameAndTypeEntry(DEFAULT_NAME, CD_MethodHandle);
534                                     bcb.ldc(cp.constantDynamicEntry(cp.bsmEntry(bsmDataAt, List.of(cp.intEntry(2))), natMH));
535 
536                                     bcb.invokestatic(lambdaClassEntry.asSymbol(), "getModel", MethodTypeDesc.of(reflectableLambdaInfo.funcOpClass()));
537 
538                                     // load captured args in array
539                                     int capturedArity = factoryType.parameterCount();
540                                     bcb.loadConstant(capturedArity)
541                                             .anewarray(CD_Object);
542                                     for (int i = 0; i < capturedArity; i++) {
543                                         bcb.dup()
544                                                 .loadConstant(i)
545                                                 .aload(0)
546                                                 .getfield(lambdaClassEntry.asSymbol(), argName(i), argDescs[i]);
547                                         TypeConvertingMethodAdapter.boxIfTypePrimitive(bcb, TypeKind.from(argDescs[i]));
548                                         bcb.aastore();
549                                     }
550 
551                                     // invoke Quoted.extractOp
552                                     bcb.invokevirtual(CD_MethodHandle, "invokeExact", methodDesc(reflectableLambdaInfo.extractOpHandle().type()))
553                                             .dup_x1()
554                                             .putfield(lambdaClassEntry.asSymbol(), QUOTED_FIELD_NAME, reflectableLambdaInfo.quotedClass())
555                                             .astore(1);
556 
557                                 })
558                                 .aload(1)
559                                 .areturn();
560                     }
561                 }));
562 
563         /*
564         private static synchronized CoreOp.FuncOp getModel() {
565             FuncOp v = model;
566             if (v == null) {
567                 v = model = ...invoke lambda op building method...
568             }
569             return v;
570         }
571         * */
572         clb.withMethod("getModel", MethodTypeDesc.of(reflectableLambdaInfo.funcOpClass()),
573                 ACC_PRIVATE + ACC_STATIC + ACC_SYNCHRONIZED,
574                 new MethodBody(new Consumer<CodeBuilder>() {
575                     @Override
576                     public void accept(CodeBuilder cob) {
577                         ClassDesc funcOpClassDesc = reflectableLambdaInfo.funcOpClass();
578                         cob.getstatic(lambdaClassEntry.asSymbol(), MODEL_FIELD_NAME, funcOpClassDesc)
579                                 .astore(0)
580                                 .aload(0)
581                                 .ifThen(Opcode.IFNULL, bcb -> {
582                                     // load class data: MH to op building method
583                                     ConstantPoolBuilder cp = pool;
584                                     MethodHandleEntry bsmDataAt = cp.methodHandleEntry(BSM_CLASS_DATA_AT);
585                                     NameAndTypeEntry natMH = cp.nameAndTypeEntry(DEFAULT_NAME, CD_MethodHandle);
586                                     cob.ldc(cp.constantDynamicEntry(cp.bsmEntry(bsmDataAt, List.of(cp.intEntry(1))), natMH));
587                                     MethodType mtype = quotableOpGetterInfo.getMethodType();
588                                     cob.invokevirtual(CD_MethodHandle, "invokeExact", mtype.describeConstable().get())
589                                             .checkcast(funcOpClassDesc)
590                                             .dup()
591                                             .putstatic(lambdaClassEntry.asSymbol(), MODEL_FIELD_NAME, funcOpClassDesc)
592                                             .astore(0);
593                                 })
594                                 .aload(0)
595                                 .areturn();
596                     }
597                 }));
598     }
599 
600     /**
601      * Generate a readObject/writeObject method that is hostile to serialization
602      */
603     private void generateSerializationHostileMethods(ClassBuilder clb) {
604         var hostileMethod = new Consumer<MethodBuilder>() {
605             @Override
606             public void accept(MethodBuilder mb) {
607                 ConstantPoolBuilder cp = mb.constantPool();
608                 ClassEntry nseCE = cp.classEntry(SerializationSupport.CD_NotSerializableException);
609                 mb.with(ExceptionsAttribute.of(nseCE))
610                         .withCode(new Consumer<CodeBuilder>() {
611                             @Override
612                             public void accept(CodeBuilder cob) {
613                                 cob.new_(nseCE)
614                                         .dup()
615                                         .ldc("Non-serializable lambda")
616                                         .invokespecial(cp.methodRefEntry(nseCE, cp.nameAndTypeEntry(INIT_NAME,
617                                                 SerializationSupport.MTD_CTOR_NOT_SERIALIZABLE_EXCEPTION)))
618                                         .athrow();
619                             }
620                         });
621             }
622         };
623         clb.withMethod(SerializationSupport.NAME_METHOD_WRITE_OBJECT, SerializationSupport.MTD_void_ObjectOutputStream,
624                 ACC_PRIVATE + ACC_FINAL, hostileMethod);
625         clb.withMethod(SerializationSupport.NAME_METHOD_READ_OBJECT, SerializationSupport.MTD_void_ObjectInputStream,
626                 ACC_PRIVATE + ACC_FINAL, hostileMethod);
627     }
628 
629     /**
630      * This method generates a method body which calls the lambda implementation
631      * method, converting arguments, as needed.
632      */
633     Consumer<CodeBuilder> forwardingMethod(MethodType methodType) {
634         return new Consumer<>() {
635             @Override
636             public void accept(CodeBuilder cob) {
637                 if (implKind == MethodHandleInfo.REF_newInvokeSpecial) {
638                     cob.new_(implMethodClassDesc)
639                        .dup();
640                 }
641                 if (useImplMethodHandle) {
642                     ConstantPoolBuilder cp = cob.constantPool();
643                     cob.ldc(cp.constantDynamicEntry(cp.bsmEntry(cp.methodHandleEntry(BSM_CLASS_DATA_AT), List.of(cp.intEntry(0))),
644                                                     cp.nameAndTypeEntry(DEFAULT_NAME, CD_MethodHandle)));
645                 }
646                 for (int i = 0; i < argDescs.length; i++) {
647                     cob.aload(0)
648                        .getfield(pool.fieldRefEntry(lambdaClassEntry, pool.nameAndTypeEntry(argName(i), argDescs[i])));
649                 }
650 
651                 convertArgumentTypes(cob, methodType);
652 
653                 if (useImplMethodHandle) {
654                     MethodType mtype = implInfo.getMethodType();
655                     if (implKind != MethodHandleInfo.REF_invokeStatic) {
656                         mtype = mtype.insertParameterTypes(0, implClass);
657                     }
658                     cob.invokevirtual(CD_MethodHandle, "invokeExact", methodDesc(mtype));
659                 } else {
660                     // Invoke the method we want to forward to
661                     cob.invoke(invocationOpcode(), implMethodClassDesc, implMethodName, implMethodDesc, implClass.isInterface());
662                 }
663                 // Convert the return value (if any) and return it
664                 // Note: if adapting from non-void to void, the 'return'
665                 // instruction will pop the unneeded result
666                 Class<?> implReturnClass = implMethodType.returnType();
667                 Class<?> samReturnClass = methodType.returnType();
668                 TypeConvertingMethodAdapter.convertType(cob, implReturnClass, samReturnClass, samReturnClass);
669                 cob.return_(TypeKind.from(samReturnClass));
670             }
671         };
672     }
673 
674     private void convertArgumentTypes(CodeBuilder cob, MethodType samType) {
675         int samParametersLength = samType.parameterCount();
676         int captureArity = factoryType.parameterCount();
677         for (int i = 0; i < samParametersLength; i++) {
678             Class<?> argType = samType.parameterType(i);
679             cob.loadLocal(TypeKind.from(argType), cob.parameterSlot(i));
680             TypeConvertingMethodAdapter.convertType(cob, argType, implMethodType.parameterType(captureArity + i), dynamicMethodType.parameterType(i));
681         }
682     }
683 
684     private Opcode invocationOpcode() throws InternalError {
685         return switch (implKind) {
686             case MethodHandleInfo.REF_invokeStatic     -> Opcode.INVOKESTATIC;
687             case MethodHandleInfo.REF_newInvokeSpecial -> Opcode.INVOKESPECIAL;
688             case MethodHandleInfo.REF_invokeVirtual    -> Opcode.INVOKEVIRTUAL;
689             case MethodHandleInfo.REF_invokeInterface  -> Opcode.INVOKEINTERFACE;
690             case MethodHandleInfo.REF_invokeSpecial    -> Opcode.INVOKESPECIAL;
691             default -> throw new InternalError("Unexpected invocation kind: " + implKind);
692         };
693     }
694 
695     static ClassDesc implClassDesc(Class<?> cls) {
696         return cls.isHidden() ? null : ConstantUtils.referenceClassDesc(cls.descriptorString());
697     }
698 
699     static ClassDesc classDesc(Class<?> cls) {
700         return cls.isPrimitive() ? Wrapper.forPrimitiveType(cls).basicClassDescriptor()
701                                  : ConstantUtils.referenceClassDesc(cls.descriptorString());
702     }
703 
704     static MethodTypeDesc methodDesc(MethodType mt) {
705         var params = new ClassDesc[mt.parameterCount()];
706         for (int i = 0; i < params.length; i++) {
707             params[i] = classDesc(mt.parameterType(i));
708         }
709         return MethodTypeDescImpl.ofValidated(classDesc(mt.returnType()), params);
710     }
711 }