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 sun.invoke.util.VerifyAccess;
29 import sun.invoke.util.VerifyType;
30 import sun.invoke.util.Wrapper;
31
32 import java.lang.classfile.*;
33 import java.lang.classfile.attribute.RuntimeVisibleAnnotationsAttribute;
34 import java.lang.classfile.attribute.SourceFileAttribute;
35 import java.lang.classfile.instruction.SwitchCase;
36 import java.lang.constant.ClassDesc;
37 import java.lang.constant.ConstantDesc;
38 import java.lang.constant.MethodTypeDesc;
39 import java.lang.invoke.LambdaForm.BasicType;
40 import java.lang.invoke.LambdaForm.Name;
41 import java.lang.invoke.LambdaForm.NamedFunction;
42 import java.lang.reflect.Modifier;
43 import java.util.ArrayList;
44 import java.util.Arrays;
45 import java.util.HashMap;
46 import java.util.List;
47 import java.util.Set;
48 import java.util.function.Consumer;
49 import java.util.stream.Stream;
50 import jdk.internal.constant.MethodTypeDescImpl;
51 import jdk.internal.constant.ReferenceClassDescImpl;
52
53 import static java.lang.classfile.ClassFile.*;
54 import static java.lang.constant.ConstantDescs.*;
55 import static java.lang.invoke.LambdaForm.*;
56 import static java.lang.invoke.LambdaForm.BasicType.*;
57 import static java.lang.invoke.MethodHandleNatives.Constants.*;
58 import static java.lang.invoke.MethodHandleStatics.*;
59 import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
60
61 /**
62 * Code generation backend for LambdaForm.
63 * <p>
64 * @author John Rose, JSR 292 EG
65 */
66 class InvokerBytecodeGenerator {
67 /** Define class names for convenience. */
68 private static final ClassDesc CD_CasesHolder = ReferenceClassDescImpl.ofValidated("Ljava/lang/invoke/MethodHandleImpl$CasesHolder;");
69 private static final ClassDesc CD_DirectMethodHandle = ReferenceClassDescImpl.ofValidated("Ljava/lang/invoke/DirectMethodHandle;");
70 private static final ClassDesc CD_MethodHandleImpl = ReferenceClassDescImpl.ofValidated("Ljava/lang/invoke/MethodHandleImpl;");
71 private static final ClassDesc CD_LambdaForm = ReferenceClassDescImpl.ofValidated("Ljava/lang/invoke/LambdaForm;");
72 private static final ClassDesc CD_LambdaForm_Name = ReferenceClassDescImpl.ofValidated("Ljava/lang/invoke/LambdaForm$Name;");
73 private static final ClassDesc CD_LoopClauses = ReferenceClassDescImpl.ofValidated("Ljava/lang/invoke/MethodHandleImpl$LoopClauses;");
74 private static final ClassDesc CD_Object_array = ReferenceClassDescImpl.ofValidated("[Ljava/lang/Object;");
75 private static final ClassDesc CD_MethodHandle_array = ReferenceClassDescImpl.ofValidated("[Ljava/lang/invoke/MethodHandle;");
76 private static final ClassDesc CD_MethodHandle_array2 = ReferenceClassDescImpl.ofValidated("[[Ljava/lang/invoke/MethodHandle;");
77
78 private static final MethodTypeDesc MTD_boolean_Object = MethodTypeDescImpl.ofValidated(CD_boolean, CD_Object);
79 private static final MethodTypeDesc MTD_Object_int = MethodTypeDescImpl.ofValidated(CD_Object, CD_int);
80 private static final MethodTypeDesc MTD_Object_Class = MethodTypeDescImpl.ofValidated(CD_Object, CD_Class);
81 private static final MethodTypeDesc MTD_Object_Object = MethodTypeDescImpl.ofValidated(CD_Object, CD_Object);
82
83 private static final String CLASS_PREFIX = "java/lang/invoke/LambdaForm$";
84 private static final String SOURCE_PREFIX = "LambdaForm$";
85
86 /** Name of its super class*/
87 static final ClassDesc INVOKER_SUPER_DESC = CD_Object;
88
89 /** Name of new class */
90 private final String name;
91 private final String className;
92 private final ClassDesc classDesc;
93
94 private final LambdaForm lambdaForm;
95 private final String invokerName;
96 private final MethodType invokerType;
97
98 /** Info about local variables in compiled lambda form */
99 private int[] localsMap; // index
100 private Class<?>[] localClasses; // type
101
102 private final List<ClassData> classData = new ArrayList<>();
103
104 private static final MemberName.Factory MEMBERNAME_FACTORY = MemberName.getFactory();
105 private static final Class<?> HOST_CLASS = LambdaForm.class;
106 private static final MethodHandles.Lookup LOOKUP = lookup();
107
108 private static MethodHandles.Lookup lookup() {
109 try {
110 return MethodHandles.privateLookupIn(HOST_CLASS, IMPL_LOOKUP);
111 } catch (IllegalAccessException e) {
112 throw newInternalError(e);
113 }
114 }
115
116 /** Main constructor; other constructors delegate to this one. */
117 private InvokerBytecodeGenerator(LambdaForm lambdaForm, int localsMapSize,
118 String name, String invokerName, MethodType invokerType) {
119 int p = invokerName.indexOf('.');
120 if (p > -1) {
121 name = invokerName.substring(0, p);
122 invokerName = invokerName.substring(p + 1);
123 }
124 if (dumper().isEnabled()) {
125 name = makeDumpableClassName(name);
126 }
127 this.name = name;
128 this.className = CLASS_PREFIX + name;
129 this.classDesc = ClassDesc.ofInternalName(className);
130 this.lambdaForm = lambdaForm;
131 this.invokerName = invokerName;
132 this.invokerType = invokerType;
133 this.localsMap = new int[localsMapSize+1]; // last entry of localsMap is count of allocated local slots
134 this.localClasses = new Class<?>[localsMapSize+1];
135 }
136
137 /** For generating LambdaForm interpreter entry points. */
138 private InvokerBytecodeGenerator(String name, String invokerName, MethodType invokerType) {
139 this(null, invokerType.parameterCount(),
140 name, invokerName, invokerType);
141 MethodType mt = invokerType.erase();
142 // Create an array to map name indexes to locals indexes.
143 localsMap[0] = 0; // localsMap has at least one element
144 for (int i = 1, index = 0; i < localsMap.length; i++) {
145 Wrapper w = Wrapper.forBasicType(mt.parameterType(i - 1));
146 index += w.stackSlots();
147 localsMap[i] = index;
148 }
149 }
150
151 /** For generating customized code for a single LambdaForm. */
152 private InvokerBytecodeGenerator(String name, LambdaForm form, MethodType invokerType) {
153 this(name, form.lambdaName(), form, invokerType);
154 }
155
156 /** For generating customized code for a single LambdaForm. */
157 InvokerBytecodeGenerator(String name, String invokerName,
158 LambdaForm form, MethodType invokerType) {
159 this(form, form.names.length,
160 name, invokerName, invokerType);
161 // Create an array to map name indexes to locals indexes.
162 Name[] names = form.names;
163 for (int i = 0, index = 0; i < localsMap.length; i++) {
164 localsMap[i] = index;
165 if (i < names.length) {
166 BasicType type = names[i].type();
167 index += type.basicTypeSlots();
168 }
169 }
170 }
171
172 /** instance counters for dumped classes */
173 private static final HashMap<String,Integer> DUMP_CLASS_FILES_COUNTERS =
174 dumper().isEnabled() ? new HashMap<>(): null;
175
176 private static String makeDumpableClassName(String className) {
177 Integer ctr;
178 synchronized (DUMP_CLASS_FILES_COUNTERS) {
179 ctr = DUMP_CLASS_FILES_COUNTERS.get(className);
180 if (ctr == null) ctr = 0;
181 DUMP_CLASS_FILES_COUNTERS.put(className, ctr+1);
182 }
183 String sfx = ctr.toString();
184 while (sfx.length() < 3)
185 sfx = "0" + sfx;
186 className += sfx;
187 return className;
188 }
189
190 static class ClassData {
191 final String name;
192 final ClassDesc desc;
193 final Object value;
194
195 ClassData(String name, ClassDesc desc, Object value) {
196 this.name = name;
197 this.desc = desc;
198 this.value = value;
199 }
200
201 public String name() { return name; }
202 public String toString() {
203 return name + ",value="+value;
204 }
205 }
206
207 String classData(Object arg) {
208 ClassDesc desc;
209 if (arg instanceof Class) {
210 desc = CD_Class;
211 } else if (arg instanceof MethodHandle) {
212 desc = CD_MethodHandle;
213 } else if (arg instanceof LambdaForm) {
214 desc = CD_LambdaForm;
215 } else {
216 desc = CD_Object;
217 }
218
219 // unique static variable name
220 String name;
221 if (dumper().isEnabled()) {
222 Class<?> c = arg.getClass();
223 while (c.isArray()) {
224 c = c.getComponentType();
225 }
226 name = "_DATA_" + c.getSimpleName() + "_" + classData.size();
227 } else {
228 name = "_D_" + classData.size();
229 }
230 ClassData cd = new ClassData(name, desc, arg);
231 classData.add(cd);
232 return name;
233 }
234
235 /**
236 * Extract the MemberName of a newly-defined method.
237 */
238 private MemberName loadMethod(byte[] classFile) {
239 Class<?> invokerClass = LOOKUP.makeHiddenClassDefiner(className, classFile, Set.of(), dumper())
240 .defineClass(true, classDataValues());
241 return resolveInvokerMember(invokerClass, invokerName, invokerType);
242 }
243
244 private static MemberName resolveInvokerMember(Class<?> invokerClass, String name, MethodType type) {
245 MemberName member = new MemberName(invokerClass, name, type, REF_invokeStatic);
246 try {
247 member = MEMBERNAME_FACTORY.resolveOrFail(REF_invokeStatic, member,
248 HOST_CLASS, LM_TRUSTED,
249 ReflectiveOperationException.class);
250 } catch (ReflectiveOperationException e) {
251 throw newInternalError(e);
252 }
253 return member;
254 }
255
256 /**
257 * Set up class file generation.
258 */
259 private byte[] classFileSetup(Consumer<? super ClassBuilder> config) {
260 try {
261 return ClassFile.of().build(classDesc, new Consumer<>() {
262 @Override
263 public void accept(ClassBuilder clb) {
264 clb.withFlags(ACC_FINAL | ACC_SUPER)
265 .withSuperclass(INVOKER_SUPER_DESC)
266 .with(SourceFileAttribute.of(clb.constantPool().utf8Entry(SOURCE_PREFIX + name)));
267 config.accept(clb);
268 }
269 });
270 } catch (RuntimeException e) {
271 throw new BytecodeGenerationException(e);
272 }
273 }
274
275 private void methodSetup(ClassBuilder clb, Consumer<? super MethodBuilder> config) {
276 var invokerDesc = methodDesc(invokerType);
277 clb.withMethod(invokerName, invokerDesc, ACC_STATIC, config);
278 }
279
280 /**
281 * Returns the class data object that will be passed to `Lookup.defineHiddenClassWithClassData`.
282 * The classData is loaded in the <clinit> method of the generated class.
283 * If the class data contains only one single object, this method returns that single object.
284 * If the class data contains more than one objects, this method returns a List.
285 *
286 * This method returns null if no class data.
287 */
288 private Object classDataValues() {
289 final List<ClassData> cd = classData;
290 return switch (cd.size()) {
291 case 0 -> null; // special case (classData is not used by <clinit>)
292 case 1 -> cd.get(0).value; // special case (single object)
293 case 2 -> List.of(cd.get(0).value, cd.get(1).value);
294 case 3 -> List.of(cd.get(0).value, cd.get(1).value, cd.get(2).value);
295 case 4 -> List.of(cd.get(0).value, cd.get(1).value, cd.get(2).value, cd.get(3).value);
296 default -> {
297 Object[] data = new Object[classData.size()];
298 for (int i = 0; i < classData.size(); i++) {
299 data[i] = classData.get(i).value;
300 }
301 yield List.of(data);
302 }
303 };
304 }
305
306 /*
307 * <clinit> to initialize the static final fields with the live class data
308 * LambdaForms can't use condy due to bootstrapping issue.
309 */
310 static void clinit(ClassBuilder clb, ClassDesc classDesc, List<ClassData> classData) {
311 if (classData.isEmpty())
312 return;
313
314 for (ClassData p : classData) {
315 // add the static field
316 clb.withField(p.name, p.desc, ACC_STATIC | ACC_FINAL);
317 }
318
319 clb.withMethodBody(CLASS_INIT_NAME, MTD_void, ACC_STATIC, new Consumer<>() {
320 @Override
321 public void accept(CodeBuilder cob) {
322 cob.loadConstant(classDesc)
323 .invokestatic(CD_MethodHandles, "classData", MTD_Object_Class);
324 if (classData.size() == 1) {
325 ClassData p = classData.get(0);
326 cob.checkcast(p.desc)
327 .putstatic(classDesc, p.name, p.desc);
328 } else {
329 cob.checkcast(CD_List)
330 .astore(0);
331 int index = 0;
332 var listGet = cob.constantPool().interfaceMethodRefEntry(CD_List, "get", MTD_Object_int);
333 for (ClassData p : classData) {
334 // initialize the static field
335 cob.aload(0)
336 .loadConstant(index++)
337 .invokeinterface(listGet)
338 .checkcast(p.desc)
339 .putstatic(classDesc, p.name, p.desc);
340 }
341 }
342 cob.return_();
343 }
344 });
345 }
346
347 private void emitLoadInsn(CodeBuilder cob, TypeKind type, int index) {
348 cob.loadLocal(type, localsMap[index]);
349 }
350
351 private void emitStoreInsn(CodeBuilder cob, TypeKind type, int index) {
352 cob.storeLocal(type, localsMap[index]);
353 }
354
355 /**
356 * Emit a boxing call.
357 *
358 * @param wrapper primitive type class to box.
359 */
360 private void emitBoxing(CodeBuilder cob, TypeKind tk) {
361 TypeConvertingMethodAdapter.box(cob, tk);
362 }
363
364 /**
365 * Emit an unboxing call (plus preceding checkcast).
366 *
367 * @param wrapper wrapper type class to unbox.
368 */
369 private void emitUnboxing(CodeBuilder cob, TypeKind target) {
370 switch (target) {
371 case BooleanType -> emitReferenceCast(cob, Boolean.class, null);
372 case CharType -> emitReferenceCast(cob, Character.class, null);
373 case ByteType, DoubleType, FloatType, IntType, LongType, ShortType ->
374 emitReferenceCast(cob, Number.class, null);
375 default -> {}
376 }
377 TypeConvertingMethodAdapter.unbox(cob, target);
378 }
379
380 /**
381 * Emit an implicit conversion for an argument which must be of the given pclass.
382 * This is usually a no-op, except when pclass is a subword type or a reference other than Object or an interface.
383 *
384 * @param ptype type of value present on stack
385 * @param pclass type of value required on stack
386 * @param arg compile-time representation of value on stack (Node, constant) or null if none
387 */
388 private void emitImplicitConversion(CodeBuilder cob, BasicType ptype, Class<?> pclass, Object arg) {
389 assert(basicType(pclass) == ptype); // boxing/unboxing handled by caller
390 if (pclass == ptype.basicTypeClass() && ptype != L_TYPE)
391 return; // nothing to do
392 switch (ptype) {
393 case L_TYPE:
394 if (VerifyType.isNullConversion(Object.class, pclass, false)) {
395 if (PROFILE_LEVEL > 0)
396 emitReferenceCast(cob, Object.class, arg);
397 return;
398 }
399 emitReferenceCast(cob, pclass, arg);
400 return;
401 case I_TYPE:
402 if (!VerifyType.isNullConversion(int.class, pclass, false))
403 emitPrimCast(cob, ptype.basicTypeKind(), TypeKind.from(pclass));
404 return;
405 }
406 throw newInternalError("bad implicit conversion: tc="+ptype+": "+pclass);
407 }
408
409 /** Update localClasses type map. Return true if the information is already present. */
410 private boolean assertStaticType(Class<?> cls, Name n) {
411 int local = n.index();
412 Class<?> aclass = localClasses[local];
413 if (aclass != null && (aclass == cls || cls.isAssignableFrom(aclass))) {
414 return true; // type info is already present
415 } else if (aclass == null || aclass.isAssignableFrom(cls)) {
416 localClasses[local] = cls; // type info can be improved
417 }
418 return false;
419 }
420
421 private void emitReferenceCast(CodeBuilder cob, Class<?> cls, Object arg) {
422 Name writeBack = null; // local to write back result
423 if (arg instanceof Name n) {
424 if (lambdaForm.useCount(n) > 1) {
425 // This guy gets used more than once.
426 writeBack = n;
427 if (assertStaticType(cls, n)) {
428 return; // this cast was already performed
429 }
430 }
431 }
432 if (isStaticallyNameable(cls)) {
433 ClassDesc sig = classDesc(cls);
434 cob.checkcast(sig);
435 } else {
436 cob.getstatic(classDesc, classData(cls), CD_Class)
437 .swap()
438 .invokevirtual(CD_Class, "cast", MTD_Object_Object);
439 if (Object[].class.isAssignableFrom(cls))
440 cob.checkcast(CD_Object_array);
441 else if (PROFILE_LEVEL > 0)
442 cob.checkcast(CD_Object);
443 }
444 if (writeBack != null) {
445 cob.dup();
446 emitStoreInsn(cob, TypeKind.ReferenceType, writeBack.index());
447 }
448 }
449
450 private static MemberName resolveFrom(String name, MethodType type, Class<?> holder) {
451 assert(!UNSAFE.shouldBeInitialized(holder)) : holder + "not initialized";
452 MemberName member = new MemberName(holder, name, type, REF_invokeStatic);
453 MemberName resolvedMember = MemberName.getFactory().resolveOrNull(REF_invokeStatic, member, holder, LM_TRUSTED);
454 traceLambdaForm(name, type, holder, resolvedMember);
455 return resolvedMember;
456 }
457
458 private static MemberName lookupPregenerated(LambdaForm form, MethodType invokerType) {
459 if (form.customized != null) {
460 // No pre-generated version for customized LF
461 return null;
462 }
463 String name = form.kind.methodName;
464 switch (form.kind) {
465 case BOUND_REINVOKER: {
466 name = name + "_" + BoundMethodHandle.speciesDataFor(form).key();
467 return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
468 }
469 case DELEGATE: return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
470 case ZERO: // fall-through
471 case IDENTITY: {
472 name = name + "_" + form.returnType().basicTypeChar();
473 return resolveFrom(name, invokerType, LambdaForm.Holder.class);
474 }
475 case EXACT_INVOKER: // fall-through
476 case EXACT_LINKER: // fall-through
477 case LINK_TO_CALL_SITE: // fall-through
478 case LINK_TO_TARGET_METHOD: // fall-through
479 case GENERIC_INVOKER: // fall-through
480 case GENERIC_LINKER: return resolveFrom(name, invokerType, Invokers.Holder.class);
481 case GET_REFERENCE: // fall-through
482 case GET_BOOLEAN: // fall-through
483 case GET_BYTE: // fall-through
484 case GET_CHAR: // fall-through
485 case GET_SHORT: // fall-through
486 case GET_INT: // fall-through
487 case GET_LONG: // fall-through
488 case GET_FLOAT: // fall-through
489 case GET_DOUBLE: // fall-through
490 case PUT_REFERENCE: // fall-through
491 case PUT_BOOLEAN: // fall-through
492 case PUT_BYTE: // fall-through
493 case PUT_CHAR: // fall-through
494 case PUT_SHORT: // fall-through
495 case PUT_INT: // fall-through
496 case PUT_LONG: // fall-through
497 case PUT_FLOAT: // fall-through
498 case PUT_DOUBLE: // fall-through
499 case DIRECT_NEW_INVOKE_SPECIAL: // fall-through
500 case DIRECT_INVOKE_INTERFACE: // fall-through
501 case DIRECT_INVOKE_SPECIAL: // fall-through
502 case DIRECT_INVOKE_SPECIAL_IFC: // fall-through
503 case DIRECT_INVOKE_STATIC: // fall-through
504 case DIRECT_INVOKE_STATIC_INIT: // fall-through
505 case DIRECT_INVOKE_VIRTUAL: return resolveFrom(name, invokerType, DirectMethodHandle.Holder.class);
506 }
507 return null;
508 }
509
510 /**
511 * Generate customized bytecode for a given LambdaForm.
512 */
513 static MemberName generateCustomizedCode(LambdaForm form, MethodType invokerType) {
514 MemberName pregenerated = lookupPregenerated(form, invokerType);
515 if (pregenerated != null) return pregenerated; // pre-generated bytecode
516
517 InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("MH", form, invokerType);
518 return g.loadMethod(g.generateCustomizedCodeBytes());
519 }
520
521 /** Generates code to check that actual receiver and LambdaForm matches */
522 private boolean checkActualReceiver(CodeBuilder cob) {
523 // Expects MethodHandle on the stack and actual receiver MethodHandle in slot #0
524 cob.dup()
525 .aload(0)
526 .invokestatic(CD_MethodHandleImpl, "assertSame", MethodTypeDescImpl.ofValidated(CD_void, CD_Object, CD_Object));
527 return true;
528 }
529
530 static final Annotation DONTINLINE = Annotation.of(ReferenceClassDescImpl.ofValidated("Ljdk/internal/vm/annotation/DontInline;"));
531 static final Annotation FORCEINLINE = Annotation.of(ReferenceClassDescImpl.ofValidated("Ljdk/internal/vm/annotation/ForceInline;"));
532 static final Annotation HIDDEN = Annotation.of(ReferenceClassDescImpl.ofValidated("Ljdk/internal/vm/annotation/Hidden;"));
533 static final Annotation INJECTEDPROFILE = Annotation.of(ReferenceClassDescImpl.ofValidated("Ljava/lang/invoke/InjectedProfile;"));
534 static final Annotation LF_COMPILED = Annotation.of(ReferenceClassDescImpl.ofValidated("Ljava/lang/invoke/LambdaForm$Compiled;"));
535
536 /**
537 * Generate an invoker method for the passed {@link LambdaForm}.
538 */
539 private byte[] generateCustomizedCodeBytes() {
540 final byte[] classFile = classFileSetup(new Consumer<ClassBuilder>() {
541 @Override
542 public void accept(ClassBuilder clb) {
543 addMethod(clb);
544 clinit(clb, classDesc, classData);
545 bogusMethod(clb, lambdaForm);
546 }
547 });
548 return classFile;
549 }
550
551 void addMethod(ClassBuilder clb) {
552 methodSetup(clb, new Consumer<MethodBuilder>() {
553 @Override
554 public void accept(MethodBuilder mb) {
555
556 List<Annotation> annotations = new ArrayList<>(3);
557
558 // Suppress this method in backtraces displayed to the user.
559 annotations.add(HIDDEN);
560
561 // Mark this method as a compiled LambdaForm
562 annotations.add(LF_COMPILED);
563
564 if (lambdaForm.forceInline) {
565 // Force inlining of this invoker method.
566 annotations.add(FORCEINLINE);
567 } else {
568 annotations.add(DONTINLINE);
569 }
570 mb.accept(RuntimeVisibleAnnotationsAttribute.of(annotations));
571
572 classData(lambdaForm); // keep LambdaForm instance & its compiled form lifetime tightly coupled.
573
574 mb.withCode(new Consumer<CodeBuilder>() {
575 @Override
576 public void accept(CodeBuilder cob) {
577 if (lambdaForm.customized != null) {
578 // Since LambdaForm is customized for a particular MethodHandle, it's safe to substitute
579 // receiver MethodHandle (at slot #0) with an embedded constant and use it instead.
580 // It enables more efficient code generation in some situations, since embedded constants
581 // are compile-time constants for JIT compiler.
582 cob.getstatic(classDesc, classData(lambdaForm.customized), CD_MethodHandle)
583 .checkcast(CD_MethodHandle);
584 assert(checkActualReceiver(cob)); // expects MethodHandle on top of the stack
585 cob.astore(0);
586 }
587
588 // iterate over the form's names, generating bytecode instructions for each
589 // start iterating at the first name following the arguments
590 Name onStack = null;
591 for (int i = lambdaForm.arity; i < lambdaForm.names.length; i++) {
592 Name name = lambdaForm.names[i];
593
594 emitStoreResult(cob, onStack);
595 onStack = name; // unless otherwise modified below
596 MethodHandleImpl.Intrinsic intr = name.function.intrinsicName();
597 switch (intr) {
598 case SELECT_ALTERNATIVE:
599 assert lambdaForm.isSelectAlternative(i);
600 if (PROFILE_GWT) {
601 assert(name.arguments[0] instanceof Name n &&
602 n.refersTo(MethodHandleImpl.class, "profileBoolean"));
603 mb.with(RuntimeVisibleAnnotationsAttribute.of(List.of(INJECTEDPROFILE)));
604 }
605 onStack = emitSelectAlternative(cob, name, lambdaForm.names[i+1]);
606 i++; // skip MH.invokeBasic of the selectAlternative result
607 continue;
608 case GUARD_WITH_CATCH:
609 assert lambdaForm.isGuardWithCatch(i);
610 onStack = emitGuardWithCatch(cob, i);
611 i += 2; // jump to the end of GWC idiom
612 continue;
613 case TRY_FINALLY:
614 assert lambdaForm.isTryFinally(i);
615 onStack = emitTryFinally(cob, i);
616 i += 2; // jump to the end of the TF idiom
617 continue;
618 case TABLE_SWITCH:
619 assert lambdaForm.isTableSwitch(i);
620 int numCases = (Integer) name.function.intrinsicData();
621 onStack = emitTableSwitch(cob, i, numCases);
622 i += 2; // jump to the end of the TS idiom
623 continue;
624 case LOOP:
625 assert lambdaForm.isLoop(i);
626 onStack = emitLoop(cob, i);
627 i += 2; // jump to the end of the LOOP idiom
628 continue;
629 case ARRAY_LOAD:
630 emitArrayLoad(cob, name);
631 continue;
632 case ARRAY_STORE:
633 emitArrayStore(cob, name);
634 continue;
635 case ARRAY_LENGTH:
636 emitArrayLength(cob, name);
637 continue;
638 case IDENTITY:
639 assert(name.arguments.length == 1);
640 emitPushArguments(cob, name, 0);
641 continue;
642 case ZERO:
643 assert(name.arguments.length == 0);
644 cob.loadConstant((ConstantDesc)name.type.basicTypeWrapper().zero());
645 continue;
646 case NONE:
647 // no intrinsic associated
648 break;
649 default:
650 throw newInternalError("Unknown intrinsic: "+intr);
651 }
652
653 MemberName member = name.function.member();
654 if (isStaticallyInvocable(member)) {
655 emitStaticInvoke(cob, member, name);
656 } else {
657 emitInvoke(cob, name);
658 }
659 }
660
661 // return statement
662 emitReturn(cob, onStack);
663 }
664 });
665 }
666 });
667 }
668
669 /**
670 * The BytecodeGenerationException.
671 */
672 @SuppressWarnings("serial")
673 static final class BytecodeGenerationException extends RuntimeException {
674 BytecodeGenerationException(Exception cause) {
675 super(cause);
676 }
677 }
678
679 void emitArrayLoad(CodeBuilder cob, Name name) {
680 Class<?> elementType = name.function.methodType().parameterType(0).getComponentType();
681 assert elementType != null;
682 emitPushArguments(cob, name, 0);
683 if (elementType.isPrimitive()) {
684 cob.arrayLoad(TypeKind.from(elementType));
685 } else {
686 cob.aaload();
687 }
688 }
689
690 void emitArrayStore(CodeBuilder cob, Name name) {
691 Class<?> elementType = name.function.methodType().parameterType(0).getComponentType();
692 assert elementType != null;
693 emitPushArguments(cob, name, 0);
694 if (elementType.isPrimitive()) {
695 cob.arrayStore(TypeKind.from(elementType));
696 } else {
697 cob.aastore();
698 }
699 }
700
701 void emitArrayLength(CodeBuilder cob, Name name) {
702 assert name.function.methodType().parameterType(0).isArray();
703 emitPushArguments(cob, name, 0);
704 cob.arraylength();
705 }
706
707 /**
708 * Emit an invoke for the given name.
709 */
710 void emitInvoke(CodeBuilder cob, Name name) {
711 assert(!name.isLinkerMethodInvoke()); // should use the static path for these
712 if (true) {
713 // push receiver
714 MethodHandle target = name.function.resolvedHandle();
715 assert(target != null) : name.exprString();
716 cob.getstatic(classDesc, classData(target), CD_MethodHandle);
717 emitReferenceCast(cob, MethodHandle.class, target);
718 } else {
719 // load receiver
720 cob.aload(0);
721 emitReferenceCast(cob, MethodHandle.class, null);
722 cob.getfield(CD_MethodHandle, "form", CD_LambdaForm)
723 .getfield(CD_LambdaForm, "names", CD_LambdaForm_Name);
724 // TODO more to come
725 }
726
727 // push arguments
728 emitPushArguments(cob, name, 0);
729
730 // invocation
731 MethodType type = name.function.methodType();
732 cob.invokevirtual(CD_MethodHandle, "invokeBasic", methodDesc(type.basicType()));
733 }
734
735 private static final Class<?>[] STATICALLY_INVOCABLE_PACKAGES = {
736 // Sample classes from each package we are willing to bind to statically:
737 java.lang.Object.class,
738 java.util.Arrays.class,
739 jdk.internal.misc.Unsafe.class
740 //MethodHandle.class already covered
741 };
742
743 static boolean isStaticallyInvocable(NamedFunction ... functions) {
744 for (NamedFunction nf : functions) {
745 if (!isStaticallyInvocable(nf.member())) {
746 return false;
747 }
748 }
749 return true;
750 }
751
752 static boolean isStaticallyInvocable(Name name) {
753 return isStaticallyInvocable(name.function.member());
754 }
755
756 static boolean isStaticallyInvocable(MemberName member) {
757 if (member == null) return false;
758 if (member.isConstructor()) return false;
759 Class<?> cls = member.getDeclaringClass();
760 // Fast-path non-private members declared by MethodHandles, which is a common
761 // case
762 if (MethodHandle.class.isAssignableFrom(cls) && !member.isPrivate()) {
763 assert(isStaticallyInvocableType(member.getMethodOrFieldType()));
764 return true;
765 }
766 if (cls.isArray() || cls.isPrimitive())
767 return false; // FIXME
768 if (cls.isAnonymousClass() || cls.isLocalClass())
769 return false; // inner class of some sort
770 if (cls.getClassLoader() != MethodHandle.class.getClassLoader())
771 return false; // not on BCP
772 if (cls.isHidden())
773 return false;
774 if (!isStaticallyInvocableType(member.getMethodOrFieldType()))
775 return false;
776 if (!member.isPrivate() && VerifyAccess.isSamePackage(MethodHandle.class, cls))
777 return true; // in java.lang.invoke package
778 if (member.isPublic() && isStaticallyNameable(cls))
779 return true;
780 return false;
781 }
782
783 private static boolean isStaticallyInvocableType(MethodType mtype) {
784 if (!isStaticallyNameable(mtype.returnType()))
785 return false;
786 for (Class<?> ptype : mtype.ptypes())
787 if (!isStaticallyNameable(ptype))
788 return false;
789 return true;
790 }
791
792 static boolean isStaticallyNameable(Class<?> cls) {
793 if (cls == Object.class)
794 return true;
795 if (MethodHandle.class.isAssignableFrom(cls)) {
796 assert(!cls.isHidden());
797 return true;
798 }
799 while (cls.isArray())
800 cls = cls.getComponentType();
801 if (cls.isPrimitive())
802 return true; // int[].class, for example
803 if (cls.isHidden())
804 return false;
805 // could use VerifyAccess.isClassAccessible but the following is a safe approximation
806 if (cls.getClassLoader() != Object.class.getClassLoader())
807 return false;
808 if (VerifyAccess.isSamePackage(MethodHandle.class, cls))
809 return true;
810 if (!Modifier.isPublic(cls.getModifiers()))
811 return false;
812 for (Class<?> pkgcls : STATICALLY_INVOCABLE_PACKAGES) {
813 if (VerifyAccess.isSamePackage(pkgcls, cls))
814 return true;
815 }
816 return false;
817 }
818
819 void emitStaticInvoke(CodeBuilder cob, Name name) {
820 emitStaticInvoke(cob, name.function.member(), name);
821 }
822
823 /**
824 * Emit an invoke for the given name, using the MemberName directly.
825 */
826 void emitStaticInvoke(CodeBuilder cob, MemberName member, Name name) {
827 assert(member.equals(name.function.member()));
828 Class<?> defc = member.getDeclaringClass();
829 ClassDesc cdesc = classDesc(defc);
830 String mname = member.getName();
831 byte refKind = member.getReferenceKind();
832 if (refKind == REF_invokeSpecial) {
833 // in order to pass the verifier, we need to convert this to invokevirtual in all cases
834 assert(member.canBeStaticallyBound()) : member;
835 refKind = REF_invokeVirtual;
836 }
837
838 assert(!(member.getDeclaringClass().isInterface() && refKind == REF_invokeVirtual));
839
840 // push arguments
841 emitPushArguments(cob, name, 0);
842
843 // invocation
844 if (member.isMethod()) {
845 var methodTypeDesc = methodDesc(member.getMethodType());
846 cob.invoke(refKindOpcode(refKind), cdesc, mname, methodTypeDesc,
847 member.getDeclaringClass().isInterface());
848 } else {
849 var fieldTypeDesc = classDesc(member.getFieldType());
850 cob.fieldAccess(refKindOpcode(refKind), cdesc, mname, fieldTypeDesc);
851 }
852 // Issue a type assertion for the result, so we can avoid casts later.
853 if (name.type == L_TYPE) {
854 Class<?> rtype = member.getInvocationType().returnType();
855 assert(!rtype.isPrimitive());
856 if (rtype != Object.class && !rtype.isInterface()) {
857 assertStaticType(rtype, name);
858 }
859 }
860 }
861
862 Opcode refKindOpcode(byte refKind) {
863 switch (refKind) {
864 case REF_invokeVirtual: return Opcode.INVOKEVIRTUAL;
865 case REF_invokeStatic: return Opcode.INVOKESTATIC;
866 case REF_invokeSpecial: return Opcode.INVOKESPECIAL;
867 case REF_invokeInterface: return Opcode.INVOKEINTERFACE;
868 case REF_getField: return Opcode.GETFIELD;
869 case REF_putField: return Opcode.PUTFIELD;
870 case REF_getStatic: return Opcode.GETSTATIC;
871 case REF_putStatic: return Opcode.PUTSTATIC;
872 }
873 throw new InternalError("refKind="+refKind);
874 }
875
876 /**
877 * Emit bytecode for the selectAlternative idiom.
878 *
879 * The pattern looks like (Cf. MethodHandleImpl.makeGuardWithTest):
880 * <blockquote><pre>{@code
881 * Lambda(a0:L,a1:I)=>{
882 * t2:I=foo.test(a1:I);
883 * t3:L=MethodHandleImpl.selectAlternative(t2:I,(MethodHandle(int)int),(MethodHandle(int)int));
884 * t4:I=MethodHandle.invokeBasic(t3:L,a1:I);t4:I}
885 * }</pre></blockquote>
886 */
887 private Name emitSelectAlternative(CodeBuilder cob, Name selectAlternativeName, Name invokeBasicName) {
888 assert isStaticallyInvocable(invokeBasicName);
889
890 Name receiver = (Name) invokeBasicName.arguments[0];
891
892 Label L_fallback = cob.newLabel();
893 Label L_done = cob.newLabel();
894
895 // load test result
896 emitPushArgument(cob, selectAlternativeName, 0);
897
898 // if_icmpne L_fallback
899 cob.ifeq(L_fallback);
900
901 // invoke selectAlternativeName.arguments[1]
902 Class<?>[] preForkClasses = localClasses.clone();
903 emitPushArgument(cob, selectAlternativeName, 1); // get 2nd argument of selectAlternative
904 emitStoreInsn(cob, TypeKind.ReferenceType, receiver.index()); // store the MH in the receiver slot
905 emitStaticInvoke(cob, invokeBasicName);
906
907 // goto L_done
908 cob.goto_w(L_done);
909
910 // L_fallback:
911 cob.labelBinding(L_fallback);
912
913 // invoke selectAlternativeName.arguments[2]
914 System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
915 emitPushArgument(cob, selectAlternativeName, 2); // get 3rd argument of selectAlternative
916 emitStoreInsn(cob, TypeKind.ReferenceType, receiver.index()); // store the MH in the receiver slot
917 emitStaticInvoke(cob, invokeBasicName);
918
919 // L_done:
920 cob.labelBinding(L_done);
921 // for now do not bother to merge typestate; just reset to the dominator state
922 System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
923
924 return invokeBasicName; // return what's on stack
925 }
926
927 /**
928 * Emit bytecode for the guardWithCatch idiom.
929 *
930 * The pattern looks like (Cf. MethodHandleImpl.makeGuardWithCatch):
931 * <blockquote><pre>{@code
932 * guardWithCatch=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L,a6:L,a7:L)=>{
933 * t8:L=MethodHandle.invokeBasic(a4:L,a6:L,a7:L);
934 * t9:L=MethodHandleImpl.guardWithCatch(a1:L,a2:L,a3:L,t8:L);
935 * t10:I=MethodHandle.invokeBasic(a5:L,t9:L);t10:I}
936 * }</pre></blockquote>
937 *
938 * It is compiled into bytecode equivalent of the following code:
939 * <blockquote><pre>{@code
940 * try {
941 * return a1.invokeBasic(a6, a7);
942 * } catch (Throwable e) {
943 * if (!a2.isInstance(e)) throw e;
944 * return a3.invokeBasic(ex, a6, a7);
945 * }}</pre></blockquote>
946 */
947 private Name emitGuardWithCatch(CodeBuilder cob, int pos) {
948 Name args = lambdaForm.names[pos];
949 Name invoker = lambdaForm.names[pos+1];
950 Name result = lambdaForm.names[pos+2];
951
952 Label L_startBlock = cob.newLabel();
953 Label L_endBlock = cob.newLabel();
954 Label L_handler = cob.newLabel();
955 Label L_done = cob.newLabel();
956
957 Class<?> returnType = result.function.resolvedHandle().type().returnType();
958 MethodType type = args.function.resolvedHandle().type()
959 .dropParameterTypes(0,1)
960 .changeReturnType(returnType);
961
962 cob.exceptionCatch(L_startBlock, L_endBlock, L_handler, CD_Throwable);
963
964 // Normal case
965 cob.labelBinding(L_startBlock);
966 // load target
967 emitPushArgument(cob, invoker, 0);
968 emitPushArguments(cob, args, 1); // skip 1st argument: method handle
969 cob.invokevirtual(CD_MethodHandle, "invokeBasic", methodDesc(type.basicType()));
970 cob.labelBinding(L_endBlock);
971 cob.goto_w(L_done);
972
973 // Exceptional case
974 cob.labelBinding(L_handler);
975
976 // Check exception's type
977 cob.dup();
978 // load exception class
979 emitPushArgument(cob, invoker, 1);
980 cob.swap();
981 cob.invokevirtual(CD_Class, "isInstance", MTD_boolean_Object);
982 Label L_rethrow = cob.newLabel();
983 cob.ifeq(L_rethrow);
984
985 // Invoke catcher
986 // load catcher
987 emitPushArgument(cob, invoker, 2);
988 cob.swap();
989 emitPushArguments(cob, args, 1); // skip 1st argument: method handle
990 MethodType catcherType = type.insertParameterTypes(0, Throwable.class);
991 cob.invokevirtual(CD_MethodHandle, "invokeBasic", methodDesc(catcherType.basicType()));
992 cob.goto_w(L_done);
993
994 cob.labelBinding(L_rethrow);
995 cob.athrow();
996
997 cob.labelBinding(L_done);
998
999 return result;
1000 }
1001
1002 /**
1003 * Emit bytecode for the tryFinally idiom.
1004 * <p>
1005 * The pattern looks like (Cf. MethodHandleImpl.makeTryFinally):
1006 * <blockquote><pre>{@code
1007 * // a0: BMH
1008 * // a1: target, a2: cleanup
1009 * // a3: box, a4: unbox
1010 * // a5 (and following): arguments
1011 * tryFinally=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L)=>{
1012 * t6:L=MethodHandle.invokeBasic(a3:L,a5:L); // box the arguments into an Object[]
1013 * t7:L=MethodHandleImpl.tryFinally(a1:L,a2:L,t6:L); // call the tryFinally executor
1014 * t8:L=MethodHandle.invokeBasic(a4:L,t7:L);t8:L} // unbox the result; return the result
1015 * }</pre></blockquote>
1016 * <p>
1017 * It is compiled into bytecode equivalent to the following code:
1018 * <blockquote><pre>{@code
1019 * Throwable t;
1020 * Object r;
1021 * try {
1022 * r = a1.invokeBasic(a5);
1023 * } catch (Throwable thrown) {
1024 * t = thrown;
1025 * throw t;
1026 * } finally {
1027 * r = a2.invokeBasic(t, r, a5);
1028 * }
1029 * return r;
1030 * }</pre></blockquote>
1031 * <p>
1032 * Specifically, the bytecode will have the following form (the stack effects are given for the beginnings of
1033 * blocks, and for the situations after executing the given instruction - the code will have a slightly different
1034 * shape if the return type is {@code void}):
1035 * <blockquote><pre>{@code
1036 * TRY: (--)
1037 * load target (-- target)
1038 * load args (-- args... target)
1039 * INVOKEVIRTUAL MethodHandle.invokeBasic (depends)
1040 * FINALLY_NORMAL: (-- r_2nd* r)
1041 * store returned value (--)
1042 * load cleanup (-- cleanup)
1043 * ACONST_NULL (-- t cleanup)
1044 * load returned value (-- r_2nd* r t cleanup)
1045 * load args (-- args... r_2nd* r t cleanup)
1046 * INVOKEVIRTUAL MethodHandle.invokeBasic (-- r_2nd* r)
1047 * GOTO DONE
1048 * CATCH: (-- t)
1049 * DUP (-- t t)
1050 * FINALLY_EXCEPTIONAL: (-- t t)
1051 * load cleanup (-- cleanup t t)
1052 * SWAP (-- t cleanup t)
1053 * load default for r (-- r_2nd* r t cleanup t)
1054 * load args (-- args... r_2nd* r t cleanup t)
1055 * INVOKEVIRTUAL MethodHandle.invokeBasic (-- r_2nd* r t)
1056 * POP/POP2* (-- t)
1057 * ATHROW
1058 * DONE: (-- r)
1059 * }</pre></blockquote>
1060 * * = depends on whether the return type takes up 2 stack slots.
1061 */
1062 private Name emitTryFinally(CodeBuilder cob, int pos) {
1063 Name args = lambdaForm.names[pos];
1064 Name invoker = lambdaForm.names[pos+1];
1065 Name result = lambdaForm.names[pos+2];
1066
1067 Label lFrom = cob.newLabel();
1068 Label lTo = cob.newLabel();
1069 Label lCatch = cob.newLabel();
1070 Label lDone = cob.newLabel();
1071
1072 Class<?> returnType = result.function.resolvedHandle().type().returnType();
1073 BasicType basicReturnType = BasicType.basicType(returnType);
1074 boolean isNonVoid = returnType != void.class;
1075
1076 MethodType type = args.function.resolvedHandle().type()
1077 .dropParameterTypes(0,1)
1078 .changeReturnType(returnType);
1079 MethodType cleanupType = type.insertParameterTypes(0, Throwable.class);
1080 if (isNonVoid) {
1081 cleanupType = cleanupType.insertParameterTypes(1, returnType);
1082 }
1083 MethodTypeDesc cleanupDesc = methodDesc(cleanupType.basicType());
1084
1085 // exception handler table
1086 cob.exceptionCatch(lFrom, lTo, lCatch, CD_Throwable);
1087
1088 // TRY:
1089 cob.labelBinding(lFrom);
1090 emitPushArgument(cob, invoker, 0); // load target
1091 emitPushArguments(cob, args, 1); // load args (skip 0: method handle)
1092 cob.invokevirtual(CD_MethodHandle, "invokeBasic", methodDesc(type.basicType()));
1093 cob.labelBinding(lTo);
1094
1095 // FINALLY_NORMAL:
1096 int index = extendLocalsMap(new Class<?>[]{ returnType });
1097 if (isNonVoid) {
1098 emitStoreInsn(cob, basicReturnType.basicTypeKind(), index);
1099 }
1100 emitPushArgument(cob, invoker, 1); // load cleanup
1101 cob.loadConstant(null);
1102 if (isNonVoid) {
1103 emitLoadInsn(cob, basicReturnType.basicTypeKind(), index);
1104 }
1105 emitPushArguments(cob, args, 1); // load args (skip 0: method handle)
1106 cob.invokevirtual(CD_MethodHandle, "invokeBasic", cleanupDesc);
1107 cob.goto_w(lDone);
1108
1109 // CATCH:
1110 cob.labelBinding(lCatch);
1111 cob.dup();
1112
1113 // FINALLY_EXCEPTIONAL:
1114 emitPushArgument(cob, invoker, 1); // load cleanup
1115 cob.swap();
1116 if (isNonVoid) {
1117 emitZero(cob, BasicType.basicType(returnType)); // load default for result
1118 }
1119 emitPushArguments(cob, args, 1); // load args (skip 0: method handle)
1120 cob.invokevirtual(CD_MethodHandle, "invokeBasic", cleanupDesc);
1121 if (isNonVoid) {
1122 emitPopInsn(cob, basicReturnType);
1123 }
1124 cob.athrow();
1125
1126 // DONE:
1127 cob.labelBinding(lDone);
1128
1129 return result;
1130 }
1131
1132 private void emitPopInsn(CodeBuilder cob, BasicType type) {
1133 switch (type) {
1134 case I_TYPE, F_TYPE, L_TYPE -> cob.pop();
1135 case J_TYPE, D_TYPE -> cob.pop2();
1136 default -> throw new InternalError("unknown type: " + type);
1137 }
1138 }
1139
1140 private Name emitTableSwitch(CodeBuilder cob, int pos, int numCases) {
1141 Name args = lambdaForm.names[pos];
1142 Name invoker = lambdaForm.names[pos + 1];
1143 Name result = lambdaForm.names[pos + 2];
1144
1145 Class<?> returnType = result.function.resolvedHandle().type().returnType();
1146 MethodType caseType = args.function.resolvedHandle().type()
1147 .dropParameterTypes(0, 1) // drop collector
1148 .changeReturnType(returnType);
1149 MethodTypeDesc caseDescriptor = methodDesc(caseType.basicType());
1150
1151 emitPushArgument(cob, invoker, 2); // push cases
1152 cob.getfield(CD_CasesHolder, "cases", CD_MethodHandle_array);
1153 int casesLocal = extendLocalsMap(new Class<?>[] { MethodHandle[].class });
1154 emitStoreInsn(cob, TypeKind.ReferenceType, casesLocal);
1155
1156 Label endLabel = cob.newLabel();
1157 Label defaultLabel = cob.newLabel();
1158 List<SwitchCase> cases = new ArrayList<>(numCases);
1159 for (int i = 0; i < numCases; i++) {
1160 cases.add(SwitchCase.of(i, cob.newLabel()));
1161 }
1162
1163 emitPushArgument(cob, invoker, 0); // push switch input
1164 cob.tableswitch(0, numCases - 1, defaultLabel, cases);
1165
1166 cob.labelBinding(defaultLabel);
1167 emitPushArgument(cob, invoker, 1); // push default handle
1168 emitPushArguments(cob, args, 1); // again, skip collector
1169 cob.invokevirtual(CD_MethodHandle, "invokeBasic", caseDescriptor);
1170 cob.goto_(endLabel);
1171
1172 for (int i = 0; i < numCases; i++) {
1173 cob.labelBinding(cases.get(i).target());
1174 // Load the particular case:
1175 emitLoadInsn(cob, TypeKind.ReferenceType, casesLocal);
1176 cob.loadConstant(i);
1177 cob.aaload();
1178
1179 // invoke it:
1180 emitPushArguments(cob, args, 1); // again, skip collector
1181 cob.invokevirtual(CD_MethodHandle, "invokeBasic", caseDescriptor);
1182
1183 cob.goto_(endLabel);
1184 }
1185
1186 cob.labelBinding(endLabel);
1187
1188 return result;
1189 }
1190
1191 /**
1192 * Emit bytecode for the loop idiom.
1193 * <p>
1194 * The pattern looks like (Cf. MethodHandleImpl.loop):
1195 * <blockquote><pre>{@code
1196 * // a0: BMH
1197 * // a1: LoopClauses (containing an array of arrays: inits, steps, preds, finis)
1198 * // a2: box, a3: unbox
1199 * // a4 (and following): arguments
1200 * loop=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L)=>{
1201 * t5:L=MethodHandle.invokeBasic(a2:L,a4:L); // box the arguments into an Object[]
1202 * t6:L=MethodHandleImpl.loop(bt:L,a1:L,t5:L); // call the loop executor (with supplied types in bt)
1203 * t7:L=MethodHandle.invokeBasic(a3:L,t6:L);t7:L} // unbox the result; return the result
1204 * }</pre></blockquote>
1205 * <p>
1206 * It is compiled into bytecode equivalent to the code seen in {@link MethodHandleImpl#loop(BasicType[],
1207 * MethodHandleImpl.LoopClauses, Object...)}, with the difference that no arrays
1208 * will be used for local state storage. Instead, the local state will be mapped to actual stack slots.
1209 * <p>
1210 * Bytecode generation applies an unrolling scheme to enable better bytecode generation regarding local state type
1211 * handling. The generated bytecode will have the following form ({@code void} types are ignored for convenience).
1212 * Assume there are {@code C} clauses in the loop.
1213 * <blockquote><pre>{@code
1214 * PREINIT: ALOAD_1
1215 * CHECKCAST LoopClauses
1216 * GETFIELD LoopClauses.clauses
1217 * ASTORE clauseDataIndex // place the clauses 2-dimensional array on the stack
1218 * INIT: (INIT_SEQ for clause 1)
1219 * ...
1220 * (INIT_SEQ for clause C)
1221 * LOOP: (LOOP_SEQ for clause 1)
1222 * ...
1223 * (LOOP_SEQ for clause C)
1224 * GOTO LOOP
1225 * DONE: ...
1226 * }</pre></blockquote>
1227 * <p>
1228 * The {@code INIT_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
1229 * the following shape. Assume slot {@code vx} is used to hold the state for clause {@code x}.
1230 * <blockquote><pre>{@code
1231 * INIT_SEQ_x: ALOAD clauseDataIndex
1232 * ICONST_0
1233 * AALOAD // load the inits array
1234 * ICONST x
1235 * AALOAD // load the init handle for clause x
1236 * load args
1237 * INVOKEVIRTUAL MethodHandle.invokeBasic
1238 * store vx
1239 * }</pre></blockquote>
1240 * <p>
1241 * The {@code LOOP_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
1242 * the following shape. Again, assume slot {@code vx} is used to hold the state for clause {@code x}.
1243 * <blockquote><pre>{@code
1244 * LOOP_SEQ_x: ALOAD clauseDataIndex
1245 * ICONST_1
1246 * AALOAD // load the steps array
1247 * ICONST x
1248 * AALOAD // load the step handle for clause x
1249 * load locals
1250 * load args
1251 * INVOKEVIRTUAL MethodHandle.invokeBasic
1252 * store vx
1253 * ALOAD clauseDataIndex
1254 * ICONST_2
1255 * AALOAD // load the preds array
1256 * ICONST x
1257 * AALOAD // load the pred handle for clause x
1258 * load locals
1259 * load args
1260 * INVOKEVIRTUAL MethodHandle.invokeBasic
1261 * IFNE LOOP_SEQ_x+1 // predicate returned false -> jump to next clause
1262 * ALOAD clauseDataIndex
1263 * ICONST_3
1264 * AALOAD // load the finis array
1265 * ICONST x
1266 * AALOAD // load the fini handle for clause x
1267 * load locals
1268 * load args
1269 * INVOKEVIRTUAL MethodHandle.invokeBasic
1270 * GOTO DONE // jump beyond end of clauses to return from loop
1271 * }</pre></blockquote>
1272 */
1273 private Name emitLoop(CodeBuilder cob, int pos) {
1274 Name args = lambdaForm.names[pos];
1275 Name invoker = lambdaForm.names[pos+1];
1276 Name result = lambdaForm.names[pos+2];
1277
1278 // extract clause and loop-local state types
1279 // find the type info in the loop invocation
1280 BasicType[] loopClauseTypes = (BasicType[]) invoker.arguments[0];
1281 Class<?>[] loopLocalStateTypes = Stream.of(loopClauseTypes)
1282 .filter(bt -> bt != BasicType.V_TYPE)
1283 .map(BasicType::basicTypeClass).toArray(Class<?>[]::new);
1284 Class<?>[] localTypes = new Class<?>[loopLocalStateTypes.length + 1];
1285 localTypes[0] = MethodHandleImpl.LoopClauses.class;
1286 System.arraycopy(loopLocalStateTypes, 0, localTypes, 1, loopLocalStateTypes.length);
1287
1288 final int clauseDataIndex = extendLocalsMap(localTypes);
1289 final int firstLoopStateIndex = clauseDataIndex + 1;
1290
1291 Class<?> returnType = result.function.resolvedHandle().type().returnType();
1292 MethodType loopType = args.function.resolvedHandle().type()
1293 .dropParameterTypes(0,1)
1294 .changeReturnType(returnType);
1295 MethodType loopHandleType = loopType.insertParameterTypes(0, loopLocalStateTypes);
1296 MethodType predType = loopHandleType.changeReturnType(boolean.class);
1297 MethodType finiType = loopHandleType;
1298
1299 final int nClauses = loopClauseTypes.length;
1300
1301 // indices to invoker arguments to load method handle arrays
1302 final int inits = 1;
1303 final int steps = 2;
1304 final int preds = 3;
1305 final int finis = 4;
1306
1307 Label lLoop = cob.newLabel();
1308 Label lDone = cob.newLabel();
1309 Label lNext;
1310
1311 // PREINIT:
1312 emitPushArgument(cob, MethodHandleImpl.LoopClauses.class, invoker.arguments[1]);
1313 cob.getfield(CD_LoopClauses, "clauses", CD_MethodHandle_array2);
1314 emitStoreInsn(cob, TypeKind.ReferenceType, clauseDataIndex);
1315
1316 // INIT:
1317 for (int c = 0, state = 0; c < nClauses; ++c) {
1318 MethodType cInitType = loopType.changeReturnType(loopClauseTypes[c].basicTypeClass());
1319 emitLoopHandleInvoke(cob, invoker, inits, c, args, false, cInitType, loopLocalStateTypes, clauseDataIndex,
1320 firstLoopStateIndex);
1321 if (cInitType.returnType() != void.class) {
1322 emitStoreInsn(cob, BasicType.basicType(cInitType.returnType()).basicTypeKind(), firstLoopStateIndex + state);
1323 ++state;
1324 }
1325 }
1326
1327 // LOOP:
1328 cob.labelBinding(lLoop);
1329
1330 for (int c = 0, state = 0; c < nClauses; ++c) {
1331 lNext = cob.newLabel();
1332
1333 MethodType stepType = loopHandleType.changeReturnType(loopClauseTypes[c].basicTypeClass());
1334 boolean isVoid = stepType.returnType() == void.class;
1335
1336 // invoke loop step
1337 emitLoopHandleInvoke(cob, invoker, steps, c, args, true, stepType, loopLocalStateTypes, clauseDataIndex,
1338 firstLoopStateIndex);
1339 if (!isVoid) {
1340 emitStoreInsn(cob, BasicType.basicType(stepType.returnType()).basicTypeKind(), firstLoopStateIndex + state);
1341 ++state;
1342 }
1343
1344 // invoke loop predicate
1345 emitLoopHandleInvoke(cob, invoker, preds, c, args, true, predType, loopLocalStateTypes, clauseDataIndex,
1346 firstLoopStateIndex);
1347 cob.ifne(lNext);
1348
1349 // invoke fini
1350 emitLoopHandleInvoke(cob, invoker, finis, c, args, true, finiType, loopLocalStateTypes, clauseDataIndex,
1351 firstLoopStateIndex);
1352 cob.goto_w(lDone);
1353
1354 // this is the beginning of the next loop clause
1355 cob.labelBinding(lNext);
1356 }
1357
1358 cob.goto_w(lLoop);
1359
1360 // DONE:
1361 cob.labelBinding(lDone);
1362
1363 return result;
1364 }
1365
1366 private int extendLocalsMap(Class<?>[] types) {
1367 int firstSlot = localsMap.length - 1;
1368 localsMap = Arrays.copyOf(localsMap, localsMap.length + types.length);
1369 localClasses = Arrays.copyOf(localClasses, localClasses.length + types.length);
1370 System.arraycopy(types, 0, localClasses, firstSlot, types.length);
1371 int index = localsMap[firstSlot - 1] + 1;
1372 int lastSlots = 0;
1373 for (int i = 0; i < types.length; ++i) {
1374 localsMap[firstSlot + i] = index;
1375 lastSlots = BasicType.basicType(localClasses[firstSlot + i]).basicTypeSlots();
1376 index += lastSlots;
1377 }
1378 localsMap[localsMap.length - 1] = index - lastSlots;
1379 return firstSlot;
1380 }
1381
1382 private void emitLoopHandleInvoke(CodeBuilder cob, Name holder, int handles, int clause, Name args, boolean pushLocalState,
1383 MethodType type, Class<?>[] loopLocalStateTypes, int clauseDataSlot,
1384 int firstLoopStateSlot) {
1385 // load handle for clause
1386 emitPushClauseArray(cob, clauseDataSlot, handles);
1387 cob.loadConstant(clause);
1388 cob.aaload();
1389 // load loop state (preceding the other arguments)
1390 if (pushLocalState) {
1391 for (int s = 0; s < loopLocalStateTypes.length; ++s) {
1392 emitLoadInsn(cob, BasicType.basicType(loopLocalStateTypes[s]).basicTypeKind(), firstLoopStateSlot + s);
1393 }
1394 }
1395 // load loop args (skip 0: method handle)
1396 emitPushArguments(cob, args, 1);
1397 cob.invokevirtual(CD_MethodHandle, "invokeBasic", methodDesc(type));
1398 }
1399
1400 private void emitPushClauseArray(CodeBuilder cob, int clauseDataSlot, int which) {
1401 emitLoadInsn(cob, TypeKind.ReferenceType, clauseDataSlot);
1402 cob.loadConstant(which - 1);
1403 cob.aaload();
1404 }
1405
1406 private void emitZero(CodeBuilder cob, BasicType type) {
1407 switch (type) {
1408 case I_TYPE -> cob.iconst_0();
1409 case J_TYPE -> cob.lconst_0();
1410 case F_TYPE -> cob.fconst_0();
1411 case D_TYPE -> cob.dconst_0();
1412 case L_TYPE -> cob.aconst_null();
1413 default -> throw new InternalError("unknown type: " + type);
1414 };
1415 }
1416
1417 private void emitPushArguments(CodeBuilder cob, Name args, int start) {
1418 MethodType type = args.function.methodType();
1419 for (int i = start; i < args.arguments.length; i++) {
1420 emitPushArgument(cob, type.parameterType(i), args.arguments[i]);
1421 }
1422 }
1423
1424 private void emitPushArgument(CodeBuilder cob, Name name, int paramIndex) {
1425 Object arg = name.arguments[paramIndex];
1426 Class<?> ptype = name.function.methodType().parameterType(paramIndex);
1427 emitPushArgument(cob, ptype, arg);
1428 }
1429
1430 private void emitPushArgument(CodeBuilder cob, Class<?> ptype, Object arg) {
1431 BasicType bptype = basicType(ptype);
1432 if (arg instanceof Name n) {
1433 emitLoadInsn(cob, n.type.basicTypeKind(), n.index());
1434 emitImplicitConversion(cob, n.type, ptype, n);
1435 } else if ((arg == null || arg instanceof String) && bptype == L_TYPE) {
1436 cob.loadConstant((ConstantDesc)arg);
1437 } else {
1438 if (Wrapper.isWrapperType(arg.getClass()) && bptype != L_TYPE) {
1439 cob.loadConstant((ConstantDesc)arg);
1440 } else {
1441 cob.getstatic(classDesc, classData(arg), CD_Object);
1442 emitImplicitConversion(cob, L_TYPE, ptype, arg);
1443 }
1444 }
1445 }
1446
1447 /**
1448 * Store the name to its local, if necessary.
1449 */
1450 private void emitStoreResult(CodeBuilder cob, Name name) {
1451 if (name != null && name.type != V_TYPE) {
1452 // non-void: actually assign
1453 emitStoreInsn(cob, name.type.basicTypeKind(), name.index());
1454 }
1455 }
1456
1457 /**
1458 * Emits a return statement from a LF invoker. If required, the result type is cast to the correct return type.
1459 */
1460 private void emitReturn(CodeBuilder cob, Name onStack) {
1461 // return statement
1462 Class<?> rclass = invokerType.returnType();
1463 BasicType rtype = lambdaForm.returnType();
1464 assert(rtype == basicType(rclass)); // must agree
1465 if (rtype == V_TYPE) {
1466 // void
1467 cob.return_();
1468 // it doesn't matter what rclass is; the JVM will discard any value
1469 } else {
1470 LambdaForm.Name rn = lambdaForm.names[lambdaForm.result];
1471
1472 // put return value on the stack if it is not already there
1473 if (rn != onStack) {
1474 emitLoadInsn(cob, rtype.basicTypeKind(), lambdaForm.result);
1475 }
1476
1477 emitImplicitConversion(cob, rtype, rclass, rn);
1478
1479 // generate actual return statement
1480 cob.return_(rtype.basicTypeKind());
1481 }
1482 }
1483
1484 /**
1485 * Emit a type conversion bytecode casting from "from" to "to".
1486 */
1487 private void emitPrimCast(CodeBuilder cob, TypeKind from, TypeKind to) {
1488 // Here's how.
1489 // - indicates forbidden
1490 // <-> indicates implicit
1491 // to ----> boolean byte short char int long float double
1492 // from boolean <-> - - - - - - -
1493 // byte - <-> i2s i2c <-> i2l i2f i2d
1494 // short - i2b <-> i2c <-> i2l i2f i2d
1495 // char - i2b i2s <-> <-> i2l i2f i2d
1496 // int - i2b i2s i2c <-> i2l i2f i2d
1497 // long - l2i,i2b l2i,i2s l2i,i2c l2i <-> l2f l2d
1498 // float - f2i,i2b f2i,i2s f2i,i2c f2i f2l <-> f2d
1499 // double - d2i,i2b d2i,i2s d2i,i2c d2i d2l d2f <->
1500 if (from != to && from != TypeKind.BooleanType) try {
1501 cob.conversion(from, to);
1502 } catch (IllegalArgumentException e) {
1503 throw new IllegalStateException("unhandled prim cast: " + from + "2" + to);
1504 }
1505 }
1506
1507 /**
1508 * Generate bytecode for a LambdaForm.vmentry which calls interpretWithArguments.
1509 */
1510 static MemberName generateLambdaFormInterpreterEntryPoint(MethodType mt) {
1511 assert(isValidSignature(basicTypeSignature(mt)));
1512 String name = "interpret_"+basicTypeChar(mt.returnType());
1513 MethodType type = mt; // includes leading argument
1514 type = type.changeParameterType(0, MethodHandle.class);
1515 InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("LFI", name, type);
1516 return g.loadMethod(g.generateLambdaFormInterpreterEntryPointBytes());
1517 }
1518
1519 private byte[] generateLambdaFormInterpreterEntryPointBytes() {
1520 final byte[] classFile = classFileSetup(new Consumer<ClassBuilder>() {
1521 @Override
1522 public void accept(ClassBuilder clb) {
1523 methodSetup(clb, new Consumer<MethodBuilder>() {
1524 @Override
1525 public void accept(MethodBuilder mb) {
1526
1527 mb.with(RuntimeVisibleAnnotationsAttribute.of(List.of(
1528 HIDDEN, // Suppress this method in backtraces displayed to the user.
1529 DONTINLINE // Don't inline the interpreter entry.
1530 )));
1531
1532 mb.withCode(new Consumer<CodeBuilder>() {
1533 @Override
1534 public void accept(CodeBuilder cob) {
1535 // create parameter array
1536 cob.loadConstant(invokerType.parameterCount());
1537 cob.anewarray(CD_Object);
1538
1539 // fill parameter array
1540 for (int i = 0; i < invokerType.parameterCount(); i++) {
1541 Class<?> ptype = invokerType.parameterType(i);
1542 cob.dup();
1543 cob.loadConstant(i);
1544 emitLoadInsn(cob, basicType(ptype).basicTypeKind(), i);
1545 // box if primitive type
1546 if (ptype.isPrimitive()) {
1547 emitBoxing(cob, TypeKind.from(ptype));
1548 }
1549 cob.aastore();
1550 }
1551 // invoke
1552 cob.aload(0);
1553 cob.getfield(CD_MethodHandle, "form", CD_LambdaForm);
1554 cob.swap(); // swap form and array; avoid local variable
1555 cob.invokevirtual(CD_LambdaForm, "interpretWithArguments", MethodTypeDescImpl.ofValidated(CD_Object, CD_Object_array));
1556
1557 // maybe unbox
1558 Class<?> rtype = invokerType.returnType();
1559 TypeKind rtypeK = TypeKind.from(rtype);
1560 if (rtype.isPrimitive() && rtype != void.class) {
1561 emitUnboxing(cob, rtypeK);
1562 }
1563
1564 // return statement
1565 cob.return_(rtypeK);
1566 }
1567 });
1568 }
1569 });
1570 clinit(clb, classDesc, classData);
1571 bogusMethod(clb, invokerType);
1572 }
1573 });
1574 return classFile;
1575 }
1576
1577 /**
1578 * Generate bytecode for a NamedFunction invoker.
1579 */
1580 static MemberName generateNamedFunctionInvoker(MethodTypeForm typeForm) {
1581 MethodType invokerType = NamedFunction.INVOKER_METHOD_TYPE;
1582 String invokerName = "invoke_" + shortenSignature(basicTypeSignature(typeForm.erasedType()));
1583 InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("NFI", invokerName, invokerType);
1584 return g.loadMethod(g.generateNamedFunctionInvokerImpl(typeForm));
1585 }
1586
1587 private byte[] generateNamedFunctionInvokerImpl(MethodTypeForm typeForm) {
1588 MethodType dstType = typeForm.erasedType();
1589 final byte[] classFile = classFileSetup(new Consumer<ClassBuilder>() {
1590 @Override
1591 public void accept(ClassBuilder clb) {
1592 methodSetup(clb, new Consumer<MethodBuilder>() {
1593 @Override
1594 public void accept(MethodBuilder mb) {
1595
1596 mb.with(RuntimeVisibleAnnotationsAttribute.of(List.of(
1597 HIDDEN, // Suppress this method in backtraces displayed to the user.
1598 FORCEINLINE // Force inlining of this invoker method.
1599 )));
1600
1601 mb.withCode(new Consumer<CodeBuilder>() {
1602 @Override
1603 public void accept(CodeBuilder cob) {
1604 // Load receiver
1605 cob.aload(0);
1606
1607 // Load arguments from array
1608 for (int i = 0; i < dstType.parameterCount(); i++) {
1609 cob.aload(1);
1610 cob.loadConstant(i);
1611 cob.aaload();
1612
1613 // Maybe unbox
1614 Class<?> dptype = dstType.parameterType(i);
1615 if (dptype.isPrimitive()) {
1616 TypeKind dstTK = TypeKind.from(dptype);
1617 TypeKind srcTK = dstTK.asLoadable();
1618 emitUnboxing(cob, srcTK);
1619 emitPrimCast(cob, srcTK, dstTK);
1620 }
1621 }
1622
1623 // Invoke
1624 MethodTypeDesc targetDesc = methodDesc(dstType.basicType());
1625 cob.invokevirtual(CD_MethodHandle, "invokeBasic", targetDesc);
1626
1627 // Box primitive types
1628 Class<?> rtype = dstType.returnType();
1629 if (rtype != void.class && rtype.isPrimitive()) {
1630 TypeKind srcTK = TypeKind.from(rtype);
1631 TypeKind dstTK = srcTK.asLoadable();
1632 // boolean casts not allowed
1633 emitPrimCast(cob, srcTK, dstTK);
1634 emitBoxing(cob, dstTK);
1635 }
1636
1637 // If the return type is void we return a null reference.
1638 if (rtype == void.class) {
1639 cob.aconst_null();
1640 }
1641 cob.areturn(); // NOTE: NamedFunction invokers always return a reference value.
1642 }
1643 });
1644 }
1645 });
1646 clinit(clb, classDesc, classData);
1647 bogusMethod(clb, dstType);
1648 }
1649 });
1650 return classFile;
1651 }
1652
1653 /**
1654 * Emit a bogus method that just loads some string constants. This is to get the constants into the constant pool
1655 * for debugging purposes.
1656 */
1657 private void bogusMethod(ClassBuilder clb, Object os) {
1658 if (dumper().isEnabled()) {
1659 clb.withMethodBody("dummy", MTD_void, ACC_STATIC, new Consumer<>() {
1660 @Override
1661 public void accept(CodeBuilder cob) {
1662 cob.loadConstant(os.toString());
1663 cob.pop();
1664 cob.return_();
1665 }
1666 });
1667 }
1668 }
1669
1670 static ClassDesc classDesc(Class<?> cls) {
1671 // assert(VerifyAccess.isTypeVisible(cls, Object.class)) : cls.getName();
1672 return cls.isPrimitive() ? Wrapper.forPrimitiveType(cls).basicClassDescriptor()
1673 : cls == MethodHandle.class ? CD_MethodHandle
1674 : cls == DirectMethodHandle.class ? CD_DirectMethodHandle
1675 : cls == Object.class ? CD_Object
1676 : ReferenceClassDescImpl.ofValidated(cls.descriptorString());
1677 }
1678
1679 static MethodTypeDesc methodDesc(MethodType mt) {
1680 var params = new ClassDesc[mt.parameterCount()];
1681 for (int i = 0; i < params.length; i++) {
1682 params[i] = classDesc(mt.parameterType(i));
1683 }
1684 return MethodTypeDescImpl.ofValidated(classDesc(mt.returnType()), params);
1685 }
1686 }