wip Stable and unique Lambda and LambdaForm class names

runtime/bcutil/ComparingCursor.cpp

@@ -428,29 +428,10 @@ ComparingCursor::shouldCheckForEquality(DataType dataType, U_32 u32Value)
 	}
 
 	switch (dataType) {
-	case SRP_TO_UTF8_CLASS_NAME:
-#if JAVA_SPEC_VERSION < 21
-		if (_context->isLambdaClass() && _romClassIsShared) {
-			/*
-			 * If the class is a lambda class, don't compare the class names because lambda
-			 * classes might have different index numbers from run to run.
-			 */
-			return false;
-		}
-#endif /* JAVA_SPEC_VERSION < 21 */
-		break;
+	case SRP_TO_UTF8_CLASS_NAME: /* fall through */
 	case BYTECODE: /* fall through */
 	case GENERIC: /* fall through */
 	case CLASS_FILE_SIZE: /* fall through */
-#if JAVA_SPEC_VERSION < 21
-		if ((CLASS_FILE_SIZE == dataType) 
-			&& _context->isLambdaClass()
-			&& _romClassIsShared
-		) {
-			/* If comparing a lambda class from the shared cache, class file size comparison is already done in ROMClassBuilder::compareROMClassForEquality().  */
-			return false;
-		}
-#endif /* JAVA_SPEC_VERSION < 21 */
 	case SRP_TO_DEBUG_DATA: /* fall through */
 	case SRP_TO_GENERIC: /* fall through */
 	case SRP_TO_UTF8: /* fall through */

runtime/bcutil/ROMClassBuilder.cpp

@@ -277,16 +277,6 @@ ROMClassBuilder::handleAnonClassName(J9CfrClassFile *classfile, ROMClassCreation
 	PORT_ACCESS_FROM_PORT(_portLibrary);
 
 #if defined(J9VM_OPT_OPENJDK_METHODHANDLE)
-	/*
-	 * Prevent generated LambdaForm classes from MethodHandles to be stored to the shared cache.
-	 * When there are a large number of such classes in the shared cache, they trigger a lot of class comparisons.
-	 * Performance can be much worse (compared to shared cache turned off).
-	 */
-	if (isLambdaFormClassName(originalStringBytes, originalStringLength, NULL/*deterministicPrefixLength*/)) {
-		context->addFindClassFlags(J9_FINDCLASS_FLAG_DO_NOT_SHARE);
-		context->addFindClassFlags(J9_FINDCLASS_FLAG_LAMBDAFORM);
-	}
-
 #if JAVA_SPEC_VERSION >= 15
 	/* InjectedInvoker is a hidden class without the strong attribute set. It
 	 * is created by MethodHandleImpl.makeInjectedInvoker on the OpenJDK side.
@@ -417,22 +407,6 @@ ROMClassBuilder::handleAnonClassName(J9CfrClassFile *classfile, ROMClassCreation
 	j9str_printf(PORTLIB, buf, ROM_ADDRESS_LENGTH + 1, ROM_ADDRESS_FORMAT, 0);
 	memcpy(constantPool[newUtfCPEntry].bytes + newHostPackageLength + originalStringLength + 1, buf, ROM_ADDRESS_LENGTH + 1);	
 
-	/* Mark if the class is a Lambda class. */
-#if defined(J9VM_OPT_OPENJDK_METHODHANDLE)
-	if (!context->isLambdaFormClass()
-		&& isLambdaClassName(reinterpret_cast<const char *>(_anonClassNameBuffer),
-		                     newAnonClassNameLength - 1, NULL/*deterministicPrefixLength*/)
-	) {
-		context->addFindClassFlags(J9_FINDCLASS_FLAG_LAMBDA);
-	}
-#else /* defined(J9VM_OPT_OPENJDK_METHODHANDLE) */
-	if (isLambdaClassName(reinterpret_cast<const char *>(_anonClassNameBuffer),
-	                      newAnonClassNameLength - 1, NULL/*deterministicPrefixLength*/)
-	) {
-		context->addFindClassFlags(J9_FINDCLASS_FLAG_LAMBDA);
-	}
-#endif /* defined(J9VM_OPT_OPENJDK_METHODHANDLE) */
-
 	/* search constantpool for all other identical classRefs. We have not actually
 	 * tested this scenario as javac will not output more than one classRef or utfRef of the
 	 * same kind.
@@ -590,18 +564,6 @@ ROMClassBuilder::prepareAndLaydown( BufferManager *bufferManager, ClassFileParse
 	getSizeInfo(context, &romClassWriter, &srpOffsetTable, &countDebugDataOutOfLine, &sizeInformation);
 
 	U_32 romSize = 0;
-#if JAVA_SPEC_VERSION < 21
-	U_32 sizeToCompareForLambda = 0;
-	if (context->isLambdaClass()) {
-		/* 
-		 * romSize calculated from getSizeInfo() does not involve StringInternManager. It is only accurate for string intern disabled classes. 
-		 * Lambda classes in java 15 and up are strong hidden classes (defined with Option.STONG), which has the same lifecycle as its
-		 * defining class loader. It is string intern enabled. So pass classFileSize instead of romSize to sizeToCompareForLambda.
-		 */
-		sizeToCompareForLambda = classFileOracle.getClassFileSize();
-	}
-#endif /* JAVA_SPEC_VERSION < 21 */
-
 	if (context->shouldCompareROMClassForEquality()) {
 		ROMClassVerbosePhase v(context, CompareHashtableROMClass);
 
@@ -624,9 +586,6 @@ ROMClassBuilder::prepareAndLaydown( BufferManager *bufferManager, ClassFileParse
 				modifiers,
 				extraModifiers,
 				optionalFlags,
-#if JAVA_SPEC_VERSION < 21
-				sizeToCompareForLambda,
-#endif /* JAVA_SPEC_VERSION < 21 */
 				context)
 		) {
 			return OK;
@@ -720,9 +679,6 @@ ROMClassBuilder::prepareAndLaydown( BufferManager *bufferManager, ClassFileParse
 						modifiers,
 						extraModifiers,
 						optionalFlags,
-#if JAVA_SPEC_VERSION < 21
-						sizeToCompareForLambda,
-#endif /* JAVA_SPEC_VERSION < 21 */
 						context)
 
 				) {
@@ -1479,55 +1435,19 @@ ROMClassBuilder::compareROMClassForEquality(
 		U_32 modifiers,
 		U_32 extraModifiers,
 		U_32 optionalFlags,
-#if JAVA_SPEC_VERSION < 21
-		U_32 sizeToCompareForLambda,
-#endif /* JAVA_SPEC_VERSION < 21 */
 		ROMClassCreationContext *context)
 {
 	bool ret = false;
+	ComparingCursor compareCursor(_javaVM, srpOffsetTable, srpKeyProducer, classFileOracle, romClass, romClassIsShared, context);
+	romClassWriter->writeROMClass(&compareCursor,
+			&compareCursor,
+			&compareCursor,
+			NULL,
+			NULL,
+			0, modifiers, extraModifiers, optionalFlags,
+			ROMClassWriter::WRITE);
 
-#if JAVA_SPEC_VERSION < 21
-	if (context->isLambdaClass()) {
-		/*
-		 * Lambda class names are in the format of HostClassName$$Lambda$<IndexNumber>/<zeroed out ROM_ADDRESS>.
-		 * When we reach this check, the host class names will be the same for both the classes because
-		 * of the earlier hash-key check. So, the only difference in the size will be the difference
-		 * between the number of digits of the index number. The same lambda class might have a
-		 * different index number from run to run and when the number of digits of the index number
-		 * increases by 1, classFileSize also increases by 1. The indexNumber is the counter for the number of
-		 * lambda classes defined so far. It is an int in the JCL side. So the it cannot vary more than max
-		 * integer vs 0, which is maxVariance (9 bytes). This check is different than the romSize check because
-		 * when the number of digits of the index number increases by 1, classFileSize also increases by 1 but
-		 * romSize increases by 2.
-		 */
-		int maxVariance = 9;
-		int variance = abs(static_cast<int>((sizeToCompareForLambda - reinterpret_cast<J9ROMClass *>(romClass)->classFileSize)));
-		if (variance <= maxVariance) {
-			ComparingCursor compareCursor(_javaVM, srpOffsetTable, srpKeyProducer, classFileOracle, romClass, romClassIsShared, context);
-			romClassWriter->writeROMClass(&compareCursor,
-					&compareCursor,
-					&compareCursor,
-					NULL,
-					NULL,
-					0, modifiers, extraModifiers, optionalFlags,
-					ROMClassWriter::WRITE);
-
-			ret = compareCursor.isEqual();
-		}
-	} else
-#endif /* JAVA_SPEC_VERSION < 21 */
-	{
-		ComparingCursor compareCursor(_javaVM, srpOffsetTable, srpKeyProducer, classFileOracle, romClass, romClassIsShared, context);
-		romClassWriter->writeROMClass(&compareCursor,
-				&compareCursor,
-				&compareCursor,
-				NULL,
-				NULL,
-				0, modifiers, extraModifiers, optionalFlags,
-				ROMClassWriter::WRITE);
-
-		ret = compareCursor.isEqual();
-	}
+	ret = compareCursor.isEqual();
 	J9UTF8* name = J9ROMCLASS_CLASSNAME((J9ROMClass *)romClass);
 	Trc_BCU_compareROMClassForEquality_event(ret, J9UTF8_LENGTH(name), J9UTF8_DATA(name));
 	return ret;

runtime/bcutil/ROMClassBuilder.hpp

@@ -169,9 +169,6 @@ class ROMClassBuilder
 			U_32 modifiers,
 			U_32 extraModifiers,
 			U_32 optionalFlags,
-#if JAVA_SPEC_VERSION < 21
-			U_32 sizeToCompareForLambda,
-#endif /* JAVA_SPEC_VERSION < 21 */
 			ROMClassCreationContext *context);
 
 	SharedCacheRangeInfo getSharedCacheSRPRangeInfo(void *address);

runtime/bcutil/ROMClassCreationContext.hpp

@@ -240,10 +240,6 @@ class ROMClassCreationContext
 	bool isHiddenClassOptNestmateSet() const { return J9_ARE_ALL_BITS_SET(_findClassFlags, J9_FINDCLASS_FLAG_CLASS_OPTION_NESTMATE); }
 	bool isHiddenClassOptStrongSet() const { return J9_ARE_ALL_BITS_SET(_findClassFlags, J9_FINDCLASS_FLAG_CLASS_OPTION_STRONG); }
 	bool isDoNotShareClassFlagSet() const {return J9_ARE_ALL_BITS_SET(_findClassFlags, J9_FINDCLASS_FLAG_DO_NOT_SHARE);}
-	bool isLambdaClass() const { return J9_ARE_ALL_BITS_SET(_findClassFlags, J9_FINDCLASS_FLAG_LAMBDA); }
-#if defined(J9VM_OPT_OPENJDK_METHODHANDLE)
-	bool isLambdaFormClass() const { return J9_ARE_ALL_BITS_SET(_findClassFlags, J9_FINDCLASS_FLAG_LAMBDAFORM); }
-#endif /* defined(J9VM_OPT_OPENJDK_METHODHANDLE) */
 
 	bool isClassUnmodifiable() const {
 		bool unmodifiable = false;
@@ -406,33 +402,11 @@ class ROMClassCreationContext
 			if (NULL != _className) {
 				U_16 classNameLenToCompare0 = static_cast<U_16>(_classNameLength);
 				U_16 classNameLenToCompare1 = classNameLength;
-				BOOLEAN misMatch = FALSE;
 				if (isClassHidden()) {
 					/* For hidden classes, className has the ROM address appended, _className does not. */
 					classNameLenToCompare1 = static_cast<U_16>(_classNameLength);
-#if JAVA_SPEC_VERSION < 21
-					if (isROMClassShareable()) {
-						/*
-						 * Before JDK21, Lambda class names are in the format:
-						 *	HostClassName$$Lambda$<IndexNumber>/<zeroed out ROM_ADDRESS>
-						 * Do not compare the IndexNumber as it can be different from run to run.
-						 */
-						U_8 *lambdaClass0 = reinterpret_cast<U_8 *>(getLastDollarSignOfLambdaClassName(
-									reinterpret_cast<const char *>(_className), _classNameLength));
-						U_8 *lambdaClass1 = reinterpret_cast<U_8 *>(getLastDollarSignOfLambdaClassName(
-									reinterpret_cast<const char *>(className), classNameLength));
-						if ((NULL != lambdaClass0) && (NULL != lambdaClass1)) {
-							classNameLenToCompare0 = static_cast<U_16>(lambdaClass0 - _className + 1);
-							classNameLenToCompare1 = static_cast<U_16>(lambdaClass1 - className + 1);
-						} else if ((NULL == lambdaClass0) != (NULL == lambdaClass1)) {
-							misMatch = TRUE;
-						}
-					}
-#endif /* JAVA_SPEC_VERSION < 21 */
 				}
-				if (misMatch
-				|| !J9UTF8_DATA_EQUALS(_className, classNameLenToCompare0, className, classNameLenToCompare1)
-				) {
+				if (!J9UTF8_DATA_EQUALS(_className, classNameLenToCompare0, className, classNameLenToCompare1)) {
 #define J9WRONGNAME " (wrong name: "
 					PORT_ACCESS_FROM_PORT(_portLibrary);
 					UDATA errorStringSize = _classNameLength + sizeof(J9WRONGNAME) + 1 + classNameLength;

runtime/jcl/CMakeLists.txt

@@ -92,6 +92,9 @@ target_link_libraries(jclse
 		j9vm_interface
 		j9vm_gc_includes
 
+		j9shrcommon
+		j9shrutil
+		j9zip
 		omrsig
 		j9hookable
 		j9zlib

runtime/jcl/common/java_lang_invoke_MethodHandleNatives.cpp

@@ -36,6 +36,9 @@
 #include <string.h>
 #include <assert.h>
 
+#undef UT_MODULE_LOADED
+#undef UT_MODULE_UNLOADED
+#include "CacheMap.hpp"
 #include "VMHelpers.hpp"
 
 extern "C" {
@@ -772,6 +775,115 @@ Java_java_lang_invoke_MethodHandleNatives_expand(JNIEnv *env, jclass clazz, jobj
 	vmFuncs->internalExitVMToJNI(currentThread);
 }
 
+/**
+ * Find a Lambda or customized LambdaForm class in the SCC.
+ * Requires non-null input arguments.
+ * Returns a pointer to a SCC-cached ROMClass if found, otherwise nullptr.
+ *
+ * Throws OutOfMemoryError upon failure to allocate memory.
+ */
+jobject JNICALL
+Java_java_lang_invoke_MethodHandleNatives_findInSCC(JNIEnv *env, jclass clazz, jstring classnameObject, jclass lookupClass)
+{
+#if defined(J9VM_OPT_SHARED_CLASSES)
+#if defined(J9VM_ENV_DATA64)
+#define J9_ROM_ADDRESS_SUFFIX "/0x0000000000000000"
+#else /* defined(J9VM_ENV_DATA64) */
+#define J9_ROM_ADDRESS_SUFFIX "/0x00000000"
+#endif /* defined(J9VM_ENV_DATA64) */
+
+	J9VMThread *currentThread = reinterpret_cast<J9VMThread*>(env);
+	J9JavaVM *vm = currentThread->javaVM;
+	const J9InternalVMFunctions *vmFuncs = vm->internalVMFunctions;
+	PORT_ACCESS_FROM_JAVAVM(vm);
+
+	vmFuncs->internalEnterVMFromJNI(currentThread);
+
+	J9Class *hostClass = J9VM_J9CLASS_FROM_HEAPCLASS(currentThread, J9_JNI_UNWRAP_REFERENCE(lookupClass));
+	J9ClassLoader *classloader = hostClass->classLoader;
+	if (nullptr == classloader) {
+		vmFuncs->internalEnterVMFromJNI(currentThread);
+		return nullptr;
+	}
+
+	j9object_t classname = J9_JNI_UNWRAP_REFERENCE(classnameObject);
+	IDATA classnameLength = vmFuncs->getStringUTF8Length(currentThread, classname);
+	UDATA romAddressSuffixLength = LITERAL_STRLEN(J9_ROM_ADDRESS_SUFFIX);
+	UDATA lookupKeyLength = classnameLength + romAddressSuffixLength + /* null terminator */ 1;
+	char *lookupKey = static_cast<char *>(j9mem_allocate_memory(lookupKeyLength, OMRMEM_CATEGORY_VM));
+
+	/* Memory cleanup and exit routine. */
+	auto cleanup = [=]() {
+		if (nullptr != lookupKey) {
+			j9mem_free_memory(lookupKey);
+		}
+		vmFuncs->internalExitVMToJNI(currentThread);
+	};
+
+	if (nullptr == lookupKey) {
+		vmFuncs->setNativeOutOfMemoryError(currentThread, 0, 0);
+		cleanup();
+		return nullptr;
+	}
+
+	vmFuncs->copyStringToUTF8Helper(currentThread, classname, J9_STR_NONE, 0, classnameLength, reinterpret_cast<U_8 *>(lookupKey), classnameLength);
+	memcpy(lookupKey + classnameLength, J9_ROM_ADDRESS_SUFFIX, romAddressSuffixLength);
+	lookupKey[lookupKeyLength - 1] = '\0';
+
+	J9SharedClassConfig *sconfig = currentThread->javaVM->sharedClassConfig;
+	if (nullptr == sconfig) {
+		cleanup();
+		return nullptr;
+	}
+
+	SH_CacheMap* cachemap = reinterpret_cast<SH_CacheMap*>(sconfig->sharedClassCache);
+	/* TODO Look to see if we should use a different API here. */
+	void *iterator = nullptr;
+	void *firstFound = nullptr;
+	omrthread_monitor_enter(vm->classMemorySegments->segmentMutex);
+	J9ROMClass *romClass = const_cast<J9ROMClass *>(cachemap->findNextROMClass(currentThread, iterator, firstFound, lookupKeyLength - 1, lookupKey));
+	omrthread_monitor_exit(vm->classMemorySegments->segmentMutex);
+
+	if (nullptr == romClass) {
+		cleanup();
+		return nullptr;
+	}
+
+	UDATA options = J9_FINDCLASS_FLAG_NO_CHECK_FOR_EXISTING_CLASS
+					| J9_FINDCLASS_FLAG_THROW_ON_FAIL
+					| J9_FINDCLASS_FLAG_UNSAFE
+					| J9_FINDCLASS_FLAG_HIDDEN
+					| J9_FINDCLASS_FLAG_ANON
+					| J9_FINDCLASS_FLAG_CLASS_OPTION_NESTMATE
+					| J9_FINDCLASS_FLAG_CLASS_OPTION_STRONG;
+
+	omrthread_monitor_enter(vm->classTableMutex);
+	/* internalCreateRAMClassFromROMClass will release the classTableMutex. */
+	J9Class *ramClass = vmFuncs->internalCreateRAMClassFromROMClass(currentThread,
+									classloader,
+									romClass,
+									options,
+									nullptr /* elementClass */,
+									nullptr /* protectionDomain */,
+									nullptr /* methodRemapArray */,
+									J9_CP_INDEX_NONE,
+									LOAD_LOCATION_UNKNOWN,
+									nullptr /* classBeingRedefined */,
+									hostClass);
+	if (nullptr == ramClass || nullptr != currentThread->currentException) {
+		cleanup();
+		return nullptr;
+	}
+
+	jobject result = vmFuncs->j9jni_createLocalRef(env, J9VM_J9CLASS_TO_HEAPCLASS(ramClass));
+	cleanup();
+	return result;
+#undef J9_ROM_ADDRESS_SUFFIX
+#else /* J9VM_OPT_SHARED_CLASSES */
+	return nullptr;
+#endif /* J9VM_OPT_SHARED_CLASSES */
+}
+
 /**
  * [JDK8] static native MemberName resolve(MemberName self, Class<?> caller)
  * 	             throws LinkageError, ClassNotFoundException;

runtime/jcl/exports.cmake

@@ -639,6 +639,7 @@ if(J9VM_OPT_OPENJDK_METHODHANDLE)
 	omr_add_exports(jclse
 		Java_java_lang_invoke_MethodHandleNatives_init
 		Java_java_lang_invoke_MethodHandleNatives_expand
+		Java_java_lang_invoke_MethodHandleNatives_findInSCC
 		Java_java_lang_invoke_MethodHandleNatives_resolve
 		Java_java_lang_invoke_MethodHandleNatives_getMembers
 		Java_java_lang_invoke_MethodHandleNatives_objectFieldOffset

runtime/jcl/uma/java_lang_invoke_MethodHandleNatives_exports.xml

@@ -21,6 +21,7 @@ SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-ex
 <exports group="java_lang_invoke_MethodHandleNatives">
 	<export name="Java_java_lang_invoke_MethodHandleNatives_init" />
 	<export name="Java_java_lang_invoke_MethodHandleNatives_expand" />
+	<export name="Java_java_lang_invoke_MethodHandleNatives_findInSCC" />
 	<export name="Java_java_lang_invoke_MethodHandleNatives_resolve" />
 	<export name="Java_java_lang_invoke_MethodHandleNatives_getMembers" />
 	<export name="Java_java_lang_invoke_MethodHandleNatives_objectFieldOffset" />

runtime/oti/j9consts.h

@@ -448,8 +448,6 @@ extern "C" {
 #define J9_FINDCLASS_FLAG_CLASS_OPTION_NESTMATE 0x40000
 #define J9_FINDCLASS_FLAG_CLASS_OPTION_STRONG 0x80000
 #define J9_FINDCLASS_FLAG_DO_NOT_SHARE 0x100000
-#define J9_FINDCLASS_FLAG_LAMBDA 0x200000
-#define J9_FINDCLASS_FLAG_LAMBDAFORM 0x400000
 
 #define J9_FINDKNOWNCLASS_FLAG_INITIALIZE 0x1
 #define J9_FINDKNOWNCLASS_FLAG_EXISTING_ONLY 0x2

runtime/oti/jclprots.h

@@ -984,6 +984,7 @@ jobject JNICALL Java_java_lang_invoke_MethodType_makeTenured(JNIEnv *env, jclass
 #if defined(J9VM_OPT_OPENJDK_METHODHANDLE)
 void JNICALL Java_java_lang_invoke_MethodHandleNatives_init(JNIEnv *env, jclass clazz, jobject self, jobject ref);
 void JNICALL Java_java_lang_invoke_MethodHandleNatives_expand(JNIEnv *env, jclass clazz, jobject self);
+jobject JNICALL Java_java_lang_invoke_MethodHandleNatives_findInSCC(JNIEnv *env, jclass clazz, jstring classname, jclass lookupClass);
 jobject JNICALL Java_java_lang_invoke_MethodHandleNatives_resolve(
 #if JAVA_SPEC_VERSION == 8
                                                                   JNIEnv *env, jclass clazz, jobject self, jclass caller);