1 /*
2 * Copyright (c) 2012, 2016, 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.org.objectweb.asm.ClassWriter;
29 import jdk.internal.org.objectweb.asm.Label;
30 import jdk.internal.org.objectweb.asm.MethodVisitor;
31 import jdk.internal.org.objectweb.asm.Opcodes;
32 import jdk.internal.org.objectweb.asm.Type;
33 import sun.invoke.util.VerifyAccess;
34 import sun.invoke.util.VerifyType;
35 import sun.invoke.util.Wrapper;
36 import sun.reflect.misc.ReflectUtil;
37
38 import java.io.File;
39 import java.io.FileOutputStream;
40 import java.io.IOException;
41 import java.lang.reflect.Modifier;
42 import java.util.Arrays;
43 import java.util.ArrayList;
44 import java.util.HashMap;
45 import java.util.stream.Stream;
46
47 import static java.lang.invoke.LambdaForm.*;
48 import static java.lang.invoke.LambdaForm.BasicType.*;
49 import static java.lang.invoke.LambdaForm.Kind.*;
50 import static java.lang.invoke.MethodHandleNatives.Constants.*;
51 import static java.lang.invoke.MethodHandleStatics.*;
52
53 /**
54 * Code generation backend for LambdaForm.
55 * <p>
56 * @author John Rose, JSR 292 EG
57 */
58 class InvokerBytecodeGenerator {
59 /** Define class names for convenience. */
60 private static final String MH = "java/lang/invoke/MethodHandle";
61 private static final String MHI = "java/lang/invoke/MethodHandleImpl";
62 private static final String LF = "java/lang/invoke/LambdaForm";
63 private static final String LFN = "java/lang/invoke/LambdaForm$Name";
64 private static final String CLS = "java/lang/Class";
65 private static final String OBJ = "java/lang/Object";
66 private static final String OBJARY = "[Ljava/lang/Object;";
67
68 private static final String LF_SIG = "L" + LF + ";";
69 private static final String LFN_SIG = "L" + LFN + ";";
70 private static final String LL_SIG = "(L" + OBJ + ";)L" + OBJ + ";";
71 private static final String LLV_SIG = "(L" + OBJ + ";L" + OBJ + ";)V";
72 private static final String CLASS_PREFIX = LF + "$";
73
74 /** Name of its super class*/
75 static final String INVOKER_SUPER_NAME = OBJ;
76
77 /** Name of new class */
78 private final String className;
79
80 /** Name of the source file (for stack trace printing). */
81 private final String sourceFile;
82
83 private final LambdaForm lambdaForm;
84 private final String invokerName;
85 private final MethodType invokerType;
86
87 /** Info about local variables in compiled lambda form */
88 private int[] localsMap; // index
89 private Class<?>[] localClasses; // type
90
91 /** ASM bytecode generation. */
92 private ClassWriter cw;
93 private MethodVisitor mv;
94
95 private static final MemberName.Factory MEMBERNAME_FACTORY = MemberName.getFactory();
96 private static final Class<?> HOST_CLASS = LambdaForm.class;
97
98 /** Main constructor; other constructors delegate to this one. */
99 private InvokerBytecodeGenerator(LambdaForm lambdaForm, int localsMapSize,
100 String className, String invokerName, MethodType invokerType) {
101 int p = invokerName.indexOf('.');
102 if (p > -1) {
103 className = invokerName.substring(0, p);
104 invokerName = invokerName.substring(p + 1);
105 }
106 if (DUMP_CLASS_FILES) {
107 className = makeDumpableClassName(className);
108 }
109 this.className = CLASS_PREFIX + className;
110 this.sourceFile = "LambdaForm$" + className;
111 this.lambdaForm = lambdaForm;
112 this.invokerName = invokerName;
113 this.invokerType = invokerType;
114 this.localsMap = new int[localsMapSize+1]; // last entry of localsMap is count of allocated local slots
115 this.localClasses = new Class<?>[localsMapSize+1];
116 }
117
118 /** For generating LambdaForm interpreter entry points. */
119 private InvokerBytecodeGenerator(String className, String invokerName, MethodType invokerType) {
120 this(null, invokerType.parameterCount(),
121 className, invokerName, invokerType);
122 // Create an array to map name indexes to locals indexes.
123 for (int i = 0; i < localsMap.length; i++) {
124 localsMap[i] = invokerType.parameterSlotCount() - invokerType.parameterSlotDepth(i);
125 }
126 }
127
128 /** For generating customized code for a single LambdaForm. */
129 private InvokerBytecodeGenerator(String className, LambdaForm form, MethodType invokerType) {
130 this(className, form.debugName, form, invokerType);
131 }
132
133 /** For generating customized code for a single LambdaForm. */
134 InvokerBytecodeGenerator(String className, String invokerName,
135 LambdaForm form, MethodType invokerType) {
136 this(form, form.names.length,
137 className, invokerName, invokerType);
138 // Create an array to map name indexes to locals indexes.
139 Name[] names = form.names;
140 for (int i = 0, index = 0; i < localsMap.length; i++) {
141 localsMap[i] = index;
142 if (i < names.length) {
143 BasicType type = names[i].type();
144 index += type.basicTypeSlots();
145 }
146 }
147 }
148
149 /** instance counters for dumped classes */
150 private static final HashMap<String,Integer> DUMP_CLASS_FILES_COUNTERS;
151 /** debugging flag for saving generated class files */
152 private static final File DUMP_CLASS_FILES_DIR;
153
154 static {
155 if (DUMP_CLASS_FILES) {
156 DUMP_CLASS_FILES_COUNTERS = new HashMap<>();
157 try {
158 File dumpDir = new File("DUMP_CLASS_FILES");
159 if (!dumpDir.exists()) {
160 dumpDir.mkdirs();
161 }
162 DUMP_CLASS_FILES_DIR = dumpDir;
163 System.out.println("Dumping class files to "+DUMP_CLASS_FILES_DIR+"/...");
164 } catch (Exception e) {
165 throw newInternalError(e);
166 }
167 } else {
168 DUMP_CLASS_FILES_COUNTERS = null;
169 DUMP_CLASS_FILES_DIR = null;
170 }
171 }
172
173 static void maybeDump(final String className, final byte[] classFile) {
174 if (DUMP_CLASS_FILES) {
175 java.security.AccessController.doPrivileged(
176 new java.security.PrivilegedAction<>() {
177 public Void run() {
178 try {
179 String dumpName = className;
180 //dumpName = dumpName.replace('/', '-');
181 File dumpFile = new File(DUMP_CLASS_FILES_DIR, dumpName+".class");
182 System.out.println("dump: " + dumpFile);
183 dumpFile.getParentFile().mkdirs();
184 FileOutputStream file = new FileOutputStream(dumpFile);
185 file.write(classFile);
186 file.close();
187 return null;
188 } catch (IOException ex) {
189 throw newInternalError(ex);
190 }
191 }
192 });
193 }
194 }
195
196 private static String makeDumpableClassName(String className) {
197 Integer ctr;
198 synchronized (DUMP_CLASS_FILES_COUNTERS) {
199 ctr = DUMP_CLASS_FILES_COUNTERS.get(className);
200 if (ctr == null) ctr = 0;
201 DUMP_CLASS_FILES_COUNTERS.put(className, ctr+1);
202 }
203 String sfx = ctr.toString();
204 while (sfx.length() < 3)
205 sfx = "0"+sfx;
206 className += sfx;
207 return className;
208 }
209
210 class CpPatch {
211 final int index;
212 final Object value;
213 CpPatch(int index, Object value) {
214 this.index = index;
215 this.value = value;
216 }
217 public String toString() {
218 return "CpPatch/index="+index+",value="+value;
219 }
220 }
221
222 private final ArrayList<CpPatch> cpPatches = new ArrayList<>();
223
224 private int cph = 0; // for counting constant placeholders
225
226 String constantPlaceholder(Object arg) {
227 String cpPlaceholder = "CONSTANT_PLACEHOLDER_" + cph++;
228 if (DUMP_CLASS_FILES) cpPlaceholder += " <<" + debugString(arg) + ">>";
229 // TODO check if arg is already in the constant pool
230 // insert placeholder in CP and remember the patch
231 int index = cw.newConst((Object) cpPlaceholder);
232 cpPatches.add(new CpPatch(index, arg));
233 return cpPlaceholder;
234 }
235
236 Object[] cpPatches(byte[] classFile) {
237 int size = getConstantPoolSize(classFile);
238 Object[] res = new Object[size];
239 for (CpPatch p : cpPatches) {
240 if (p.index >= size)
241 throw new InternalError("in cpool["+size+"]: "+p+"\n"+Arrays.toString(Arrays.copyOf(classFile, 20)));
242 res[p.index] = p.value;
243 }
244 return res;
245 }
246
247 private static String debugString(Object arg) {
248 if (arg instanceof MethodHandle) {
249 MethodHandle mh = (MethodHandle) arg;
250 MemberName member = mh.internalMemberName();
251 if (member != null)
252 return member.toString();
253 return mh.debugString();
254 }
255 return arg.toString();
256 }
257
258 /**
259 * Extract the number of constant pool entries from a given class file.
260 *
261 * @param classFile the bytes of the class file in question.
262 * @return the number of entries in the constant pool.
263 */
264 private static int getConstantPoolSize(byte[] classFile) {
265 // The first few bytes:
266 // u4 magic;
267 // u2 minor_version;
268 // u2 major_version;
269 // u2 constant_pool_count;
270 return ((classFile[8] & 0xFF) << 8) | (classFile[9] & 0xFF);
271 }
272
273 /**
274 * Extract the MemberName of a newly-defined method.
275 */
276 private MemberName loadMethod(byte[] classFile) {
277 Class<?> invokerClass = loadAndInitializeInvokerClass(classFile, cpPatches(classFile));
278 return resolveInvokerMember(invokerClass, invokerName, invokerType);
279 }
280
281 /**
282 * Define a given class as anonymous class in the runtime system.
283 */
284 private static Class<?> loadAndInitializeInvokerClass(byte[] classBytes, Object[] patches) {
285 Class<?> invokerClass = UNSAFE.defineAnonymousClass(HOST_CLASS, classBytes, patches);
286 UNSAFE.ensureClassInitialized(invokerClass); // Make sure the class is initialized; VM might complain.
287 return invokerClass;
288 }
289
290 private static MemberName resolveInvokerMember(Class<?> invokerClass, String name, MethodType type) {
291 MemberName member = new MemberName(invokerClass, name, type, REF_invokeStatic);
292 try {
293 member = MEMBERNAME_FACTORY.resolveOrFail(REF_invokeStatic, member, HOST_CLASS, ReflectiveOperationException.class);
294 } catch (ReflectiveOperationException e) {
295 throw newInternalError(e);
296 }
297 return member;
298 }
299
300 /**
301 * Set up class file generation.
302 */
303 private ClassWriter classFilePrologue() {
304 final int NOT_ACC_PUBLIC = 0; // not ACC_PUBLIC
305 cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);
306 cw.visit(Opcodes.V1_8, NOT_ACC_PUBLIC + Opcodes.ACC_FINAL + Opcodes.ACC_SUPER, className, null, INVOKER_SUPER_NAME, null);
307 cw.visitSource(sourceFile, null);
308 return cw;
309 }
310
311 private void methodPrologue() {
312 String invokerDesc = invokerType.toMethodDescriptorString();
313 mv = cw.visitMethod(Opcodes.ACC_STATIC, invokerName, invokerDesc, null, null);
314 }
315
316 /**
317 * Tear down class file generation.
318 */
319 private void methodEpilogue() {
320 mv.visitMaxs(0, 0);
321 mv.visitEnd();
322 }
323
324 /*
325 * Low-level emit helpers.
326 */
327 private void emitConst(Object con) {
328 if (con == null) {
329 mv.visitInsn(Opcodes.ACONST_NULL);
330 return;
331 }
332 if (con instanceof Integer) {
333 emitIconstInsn((int) con);
334 return;
335 }
336 if (con instanceof Byte) {
337 emitIconstInsn((byte)con);
338 return;
339 }
340 if (con instanceof Short) {
341 emitIconstInsn((short)con);
342 return;
343 }
344 if (con instanceof Character) {
345 emitIconstInsn((char)con);
346 return;
347 }
348 if (con instanceof Long) {
349 long x = (long) con;
350 short sx = (short)x;
351 if (x == sx) {
352 if (sx >= 0 && sx <= 1) {
353 mv.visitInsn(Opcodes.LCONST_0 + (int) sx);
354 } else {
355 emitIconstInsn((int) x);
356 mv.visitInsn(Opcodes.I2L);
357 }
358 return;
359 }
360 }
361 if (con instanceof Float) {
362 float x = (float) con;
363 short sx = (short)x;
364 if (x == sx) {
365 if (sx >= 0 && sx <= 2) {
366 mv.visitInsn(Opcodes.FCONST_0 + (int) sx);
367 } else {
368 emitIconstInsn((int) x);
369 mv.visitInsn(Opcodes.I2F);
370 }
371 return;
372 }
373 }
374 if (con instanceof Double) {
375 double x = (double) con;
376 short sx = (short)x;
377 if (x == sx) {
378 if (sx >= 0 && sx <= 1) {
379 mv.visitInsn(Opcodes.DCONST_0 + (int) sx);
380 } else {
381 emitIconstInsn((int) x);
382 mv.visitInsn(Opcodes.I2D);
383 }
384 return;
385 }
386 }
387 if (con instanceof Boolean) {
388 emitIconstInsn((boolean) con ? 1 : 0);
389 return;
390 }
391 // fall through:
392 mv.visitLdcInsn(con);
393 }
394
395 private void emitIconstInsn(final int cst) {
396 if (cst >= -1 && cst <= 5) {
397 mv.visitInsn(Opcodes.ICONST_0 + cst);
398 } else if (cst >= Byte.MIN_VALUE && cst <= Byte.MAX_VALUE) {
399 mv.visitIntInsn(Opcodes.BIPUSH, cst);
400 } else if (cst >= Short.MIN_VALUE && cst <= Short.MAX_VALUE) {
401 mv.visitIntInsn(Opcodes.SIPUSH, cst);
402 } else {
403 mv.visitLdcInsn(cst);
404 }
405 }
406
407 /*
408 * NOTE: These load/store methods use the localsMap to find the correct index!
409 */
410 private void emitLoadInsn(BasicType type, int index) {
411 int opcode = loadInsnOpcode(type);
412 mv.visitVarInsn(opcode, localsMap[index]);
413 }
414
415 private int loadInsnOpcode(BasicType type) throws InternalError {
416 switch (type) {
417 case I_TYPE: return Opcodes.ILOAD;
418 case J_TYPE: return Opcodes.LLOAD;
419 case F_TYPE: return Opcodes.FLOAD;
420 case D_TYPE: return Opcodes.DLOAD;
421 case L_TYPE: return Opcodes.ALOAD;
422 default:
423 throw new InternalError("unknown type: " + type);
424 }
425 }
426 private void emitAloadInsn(int index) {
427 emitLoadInsn(L_TYPE, index);
428 }
429
430 private void emitStoreInsn(BasicType type, int index) {
431 int opcode = storeInsnOpcode(type);
432 mv.visitVarInsn(opcode, localsMap[index]);
433 }
434
435 private int storeInsnOpcode(BasicType type) throws InternalError {
436 switch (type) {
437 case I_TYPE: return Opcodes.ISTORE;
438 case J_TYPE: return Opcodes.LSTORE;
439 case F_TYPE: return Opcodes.FSTORE;
440 case D_TYPE: return Opcodes.DSTORE;
441 case L_TYPE: return Opcodes.ASTORE;
442 default:
443 throw new InternalError("unknown type: " + type);
444 }
445 }
446 private void emitAstoreInsn(int index) {
447 emitStoreInsn(L_TYPE, index);
448 }
449
450 private byte arrayTypeCode(Wrapper elementType) {
451 switch (elementType) {
452 case BOOLEAN: return Opcodes.T_BOOLEAN;
453 case BYTE: return Opcodes.T_BYTE;
454 case CHAR: return Opcodes.T_CHAR;
455 case SHORT: return Opcodes.T_SHORT;
456 case INT: return Opcodes.T_INT;
457 case LONG: return Opcodes.T_LONG;
458 case FLOAT: return Opcodes.T_FLOAT;
459 case DOUBLE: return Opcodes.T_DOUBLE;
460 case OBJECT: return 0; // in place of Opcodes.T_OBJECT
461 default: throw new InternalError();
462 }
463 }
464
465 private int arrayInsnOpcode(byte tcode, int aaop) throws InternalError {
466 assert(aaop == Opcodes.AASTORE || aaop == Opcodes.AALOAD);
467 int xas;
468 switch (tcode) {
469 case Opcodes.T_BOOLEAN: xas = Opcodes.BASTORE; break;
470 case Opcodes.T_BYTE: xas = Opcodes.BASTORE; break;
471 case Opcodes.T_CHAR: xas = Opcodes.CASTORE; break;
472 case Opcodes.T_SHORT: xas = Opcodes.SASTORE; break;
473 case Opcodes.T_INT: xas = Opcodes.IASTORE; break;
474 case Opcodes.T_LONG: xas = Opcodes.LASTORE; break;
475 case Opcodes.T_FLOAT: xas = Opcodes.FASTORE; break;
476 case Opcodes.T_DOUBLE: xas = Opcodes.DASTORE; break;
477 case 0: xas = Opcodes.AASTORE; break;
478 default: throw new InternalError();
479 }
480 return xas - Opcodes.AASTORE + aaop;
481 }
482
483 /**
484 * Emit a boxing call.
485 *
486 * @param wrapper primitive type class to box.
487 */
488 private void emitBoxing(Wrapper wrapper) {
489 String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();
490 String name = "valueOf";
491 String desc = "(" + wrapper.basicTypeChar() + ")L" + owner + ";";
492 mv.visitMethodInsn(Opcodes.INVOKESTATIC, owner, name, desc, false);
493 }
494
495 /**
496 * Emit an unboxing call (plus preceding checkcast).
497 *
498 * @param wrapper wrapper type class to unbox.
499 */
500 private void emitUnboxing(Wrapper wrapper) {
501 String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();
502 String name = wrapper.primitiveSimpleName() + "Value";
503 String desc = "()" + wrapper.basicTypeChar();
504 emitReferenceCast(wrapper.wrapperType(), null);
505 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, owner, name, desc, false);
506 }
507
508 /**
509 * Emit an implicit conversion for an argument which must be of the given pclass.
510 * This is usually a no-op, except when pclass is a subword type or a reference other than Object or an interface.
511 *
512 * @param ptype type of value present on stack
513 * @param pclass type of value required on stack
514 * @param arg compile-time representation of value on stack (Node, constant) or null if none
515 */
516 private void emitImplicitConversion(BasicType ptype, Class<?> pclass, Object arg) {
517 assert(basicType(pclass) == ptype); // boxing/unboxing handled by caller
518 if (pclass == ptype.basicTypeClass() && ptype != L_TYPE)
519 return; // nothing to do
520 switch (ptype) {
521 case L_TYPE:
522 if (VerifyType.isNullConversion(Object.class, pclass, false)) {
523 if (PROFILE_LEVEL > 0)
524 emitReferenceCast(Object.class, arg);
525 return;
526 }
527 emitReferenceCast(pclass, arg);
528 return;
529 case I_TYPE:
530 if (!VerifyType.isNullConversion(int.class, pclass, false))
531 emitPrimCast(ptype.basicTypeWrapper(), Wrapper.forPrimitiveType(pclass));
532 return;
533 }
534 throw newInternalError("bad implicit conversion: tc="+ptype+": "+pclass);
535 }
536
537 /** Update localClasses type map. Return true if the information is already present. */
538 private boolean assertStaticType(Class<?> cls, Name n) {
539 int local = n.index();
540 Class<?> aclass = localClasses[local];
541 if (aclass != null && (aclass == cls || cls.isAssignableFrom(aclass))) {
542 return true; // type info is already present
543 } else if (aclass == null || aclass.isAssignableFrom(cls)) {
544 localClasses[local] = cls; // type info can be improved
545 }
546 return false;
547 }
548
549 private void emitReferenceCast(Class<?> cls, Object arg) {
550 Name writeBack = null; // local to write back result
551 if (arg instanceof Name) {
552 Name n = (Name) arg;
553 if (lambdaForm.useCount(n) > 1) {
554 // This guy gets used more than once.
555 writeBack = n;
556 if (assertStaticType(cls, n)) {
557 return; // this cast was already performed
558 }
559 }
560 }
561 if (isStaticallyNameable(cls)) {
562 String sig = getInternalName(cls);
563 mv.visitTypeInsn(Opcodes.CHECKCAST, sig);
564 } else {
565 mv.visitLdcInsn(constantPlaceholder(cls));
566 mv.visitTypeInsn(Opcodes.CHECKCAST, CLS);
567 mv.visitInsn(Opcodes.SWAP);
568 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, CLS, "cast", LL_SIG, false);
569 if (Object[].class.isAssignableFrom(cls))
570 mv.visitTypeInsn(Opcodes.CHECKCAST, OBJARY);
571 else if (PROFILE_LEVEL > 0)
572 mv.visitTypeInsn(Opcodes.CHECKCAST, OBJ);
573 }
574 if (writeBack != null) {
575 mv.visitInsn(Opcodes.DUP);
576 emitAstoreInsn(writeBack.index());
577 }
578 }
579
580 /**
581 * Emits an actual return instruction conforming to the given return type.
582 */
583 private void emitReturnInsn(BasicType type) {
584 int opcode;
585 switch (type) {
586 case I_TYPE: opcode = Opcodes.IRETURN; break;
587 case J_TYPE: opcode = Opcodes.LRETURN; break;
588 case F_TYPE: opcode = Opcodes.FRETURN; break;
589 case D_TYPE: opcode = Opcodes.DRETURN; break;
590 case L_TYPE: opcode = Opcodes.ARETURN; break;
591 case V_TYPE: opcode = Opcodes.RETURN; break;
592 default:
593 throw new InternalError("unknown return type: " + type);
594 }
595 mv.visitInsn(opcode);
596 }
597
598 private static String getInternalName(Class<?> c) {
599 if (c == Object.class) return OBJ;
600 else if (c == Object[].class) return OBJARY;
601 else if (c == Class.class) return CLS;
602 else if (c == MethodHandle.class) return MH;
603 assert(VerifyAccess.isTypeVisible(c, Object.class)) : c.getName();
604 return c.getName().replace('.', '/');
605 }
606
607 private static MemberName resolveFrom(String name, MethodType type, Class<?> holder) {
608 MemberName member = new MemberName(holder, name, type, REF_invokeStatic);
609 MemberName resolvedMember = MemberName.getFactory().resolveOrNull(REF_invokeStatic, member, holder);
610
611 return resolvedMember;
612 }
613
614 private static MemberName lookupPregenerated(LambdaForm form) {
615 if (form.customized != null) return null; // No pre-generated version for customized LF
616 MethodType invokerType = form.methodType();
617 String name = form.kind.methodName;
618 switch (form.kind) {
619 case BOUND_REINVOKER: {
620 name = name + "_" + BoundMethodHandle.speciesData(form).fieldSignature();
621 return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
622 }
623 case DELEGATE: return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
624 case DIRECT_INVOKE_INTERFACE: // fall-through
625 case DIRECT_INVOKE_SPECIAL: // fall-through
626 case DIRECT_INVOKE_STATIC: // fall-through
627 case DIRECT_INVOKE_STATIC_INIT: // fall-through
628 case DIRECT_INVOKE_VIRTUAL: return resolveFrom(name, invokerType, DirectMethodHandle.Holder.class);
629 }
630 return null;
631 }
632
633 /**
634 * Generate customized bytecode for a given LambdaForm.
635 */
636 static MemberName generateCustomizedCode(LambdaForm form, MethodType invokerType) {
637 MemberName pregenerated = lookupPregenerated(form);
638 if (pregenerated != null) return pregenerated; // pre-generated bytecode
639
640 InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("MH", form, invokerType);
641 return g.loadMethod(g.generateCustomizedCodeBytes());
642 }
643
644 /** Generates code to check that actual receiver and LambdaForm matches */
645 private boolean checkActualReceiver() {
646 // Expects MethodHandle on the stack and actual receiver MethodHandle in slot #0
647 mv.visitInsn(Opcodes.DUP);
648 mv.visitVarInsn(Opcodes.ALOAD, localsMap[0]);
649 mv.visitMethodInsn(Opcodes.INVOKESTATIC, MHI, "assertSame", LLV_SIG, false);
650 return true;
651 }
652
653 static String className(String cn) {
654 assert checkClassName(cn): "Class not found: " + cn;
655 return cn;
656 }
657
658 static boolean checkClassName(String cn) {
659 Type tp = Type.getType(cn);
660 // additional sanity so only valid "L;" descriptors work
661 if (tp.getSort() != Type.OBJECT) {
662 return false;
663 }
664 try {
665 Class<?> c = Class.forName(tp.getClassName(), false, null);
666 return true;
667 } catch (ClassNotFoundException e) {
668 return false;
669 }
670 }
671
672 static final String LF_HIDDEN_SIG = className("Ljava/lang/invoke/LambdaForm$Hidden;");
673 static final String LF_COMPILED_SIG = className("Ljava/lang/invoke/LambdaForm$Compiled;");
674 static final String FORCEINLINE_SIG = className("Ljdk/internal/vm/annotation/ForceInline;");
675 static final String DONTINLINE_SIG = className("Ljdk/internal/vm/annotation/DontInline;");
676 static final String INJECTEDPROFILE_SIG = className("Ljava/lang/invoke/InjectedProfile;");
677
678 /**
679 * Generate an invoker method for the passed {@link LambdaForm}.
680 */
681 private byte[] generateCustomizedCodeBytes() {
682 classFilePrologue();
683 addMethod();
684 bogusMethod(lambdaForm);
685
686 final byte[] classFile = toByteArray();
687 maybeDump(className, classFile);
688 return classFile;
689 }
690
691 void setClassWriter(ClassWriter cw) {
692 this.cw = cw;
693 }
694
695 void addMethod() {
696 methodPrologue();
697
698 // Suppress this method in backtraces displayed to the user.
699 mv.visitAnnotation(LF_HIDDEN_SIG, true);
700
701 // Mark this method as a compiled LambdaForm
702 mv.visitAnnotation(LF_COMPILED_SIG, true);
703
704 if (lambdaForm.forceInline) {
705 // Force inlining of this invoker method.
706 mv.visitAnnotation(FORCEINLINE_SIG, true);
707 } else {
708 mv.visitAnnotation(DONTINLINE_SIG, true);
709 }
710
711 constantPlaceholder(lambdaForm); // keep LambdaForm instance & its compiled form lifetime tightly coupled.
712
713 if (lambdaForm.customized != null) {
714 // Since LambdaForm is customized for a particular MethodHandle, it's safe to substitute
715 // receiver MethodHandle (at slot #0) with an embedded constant and use it instead.
716 // It enables more efficient code generation in some situations, since embedded constants
717 // are compile-time constants for JIT compiler.
718 mv.visitLdcInsn(constantPlaceholder(lambdaForm.customized));
719 mv.visitTypeInsn(Opcodes.CHECKCAST, MH);
720 assert(checkActualReceiver()); // expects MethodHandle on top of the stack
721 mv.visitVarInsn(Opcodes.ASTORE, localsMap[0]);
722 }
723
724 // iterate over the form's names, generating bytecode instructions for each
725 // start iterating at the first name following the arguments
726 Name onStack = null;
727 for (int i = lambdaForm.arity; i < lambdaForm.names.length; i++) {
728 Name name = lambdaForm.names[i];
729
730 emitStoreResult(onStack);
731 onStack = name; // unless otherwise modified below
732 MethodHandleImpl.Intrinsic intr = name.function.intrinsicName();
733 switch (intr) {
734 case SELECT_ALTERNATIVE:
735 assert lambdaForm.isSelectAlternative(i);
736 if (PROFILE_GWT) {
737 assert(name.arguments[0] instanceof Name &&
738 ((Name)name.arguments[0]).refersTo(MethodHandleImpl.class, "profileBoolean"));
739 mv.visitAnnotation(INJECTEDPROFILE_SIG, true);
740 }
741 onStack = emitSelectAlternative(name, lambdaForm.names[i+1]);
742 i++; // skip MH.invokeBasic of the selectAlternative result
743 continue;
744 case GUARD_WITH_CATCH:
745 assert lambdaForm.isGuardWithCatch(i);
746 onStack = emitGuardWithCatch(i);
747 i += 2; // jump to the end of GWC idiom
748 continue;
749 case TRY_FINALLY:
750 assert lambdaForm.isTryFinally(i);
751 onStack = emitTryFinally(i);
752 i += 2; // jump to the end of the TF idiom
753 continue;
754 case LOOP:
755 assert lambdaForm.isLoop(i);
756 onStack = emitLoop(i);
757 i += 2; // jump to the end of the LOOP idiom
758 continue;
759 case NEW_ARRAY:
760 Class<?> rtype = name.function.methodType().returnType();
761 if (isStaticallyNameable(rtype)) {
762 emitNewArray(name);
763 continue;
764 }
765 break;
766 case ARRAY_LOAD:
767 emitArrayLoad(name);
768 continue;
769 case ARRAY_STORE:
770 emitArrayStore(name);
771 continue;
772 case ARRAY_LENGTH:
773 emitArrayLength(name);
774 continue;
775 case IDENTITY:
776 assert(name.arguments.length == 1);
777 emitPushArguments(name, 0);
778 continue;
779 case ZERO:
780 assert(name.arguments.length == 0);
781 emitConst(name.type.basicTypeWrapper().zero());
782 continue;
783 case NONE:
784 // no intrinsic associated
785 break;
786 default:
787 throw newInternalError("Unknown intrinsic: "+intr);
788 }
789
790 MemberName member = name.function.member();
791 if (isStaticallyInvocable(member)) {
792 emitStaticInvoke(member, name);
793 } else {
794 emitInvoke(name);
795 }
796 }
797
798 // return statement
799 emitReturn(onStack);
800
801 methodEpilogue();
802 }
803
804 /*
805 * @throws BytecodeGenerationException if something goes wrong when
806 * generating the byte code
807 */
808 private byte[] toByteArray() {
809 try {
810 return cw.toByteArray();
811 } catch (RuntimeException e) {
812 throw new BytecodeGenerationException(e);
813 }
814 }
815
816 @SuppressWarnings("serial")
817 static final class BytecodeGenerationException extends RuntimeException {
818 BytecodeGenerationException(Exception cause) {
819 super(cause);
820 }
821 }
822
823 void emitArrayLoad(Name name) { emitArrayOp(name, Opcodes.AALOAD); }
824 void emitArrayStore(Name name) { emitArrayOp(name, Opcodes.AASTORE); }
825 void emitArrayLength(Name name) { emitArrayOp(name, Opcodes.ARRAYLENGTH); }
826
827 void emitArrayOp(Name name, int arrayOpcode) {
828 assert arrayOpcode == Opcodes.AALOAD || arrayOpcode == Opcodes.AASTORE || arrayOpcode == Opcodes.ARRAYLENGTH;
829 Class<?> elementType = name.function.methodType().parameterType(0).getComponentType();
830 assert elementType != null;
831 emitPushArguments(name, 0);
832 if (arrayOpcode != Opcodes.ARRAYLENGTH && elementType.isPrimitive()) {
833 Wrapper w = Wrapper.forPrimitiveType(elementType);
834 arrayOpcode = arrayInsnOpcode(arrayTypeCode(w), arrayOpcode);
835 }
836 mv.visitInsn(arrayOpcode);
837 }
838
839 /**
840 * Emit an invoke for the given name.
841 */
842 void emitInvoke(Name name) {
843 assert(!name.isLinkerMethodInvoke()); // should use the static path for these
844 if (true) {
845 // push receiver
846 MethodHandle target = name.function.resolvedHandle();
847 assert(target != null) : name.exprString();
848 mv.visitLdcInsn(constantPlaceholder(target));
849 emitReferenceCast(MethodHandle.class, target);
850 } else {
851 // load receiver
852 emitAloadInsn(0);
853 emitReferenceCast(MethodHandle.class, null);
854 mv.visitFieldInsn(Opcodes.GETFIELD, MH, "form", LF_SIG);
855 mv.visitFieldInsn(Opcodes.GETFIELD, LF, "names", LFN_SIG);
856 // TODO more to come
857 }
858
859 // push arguments
860 emitPushArguments(name, 0);
861
862 // invocation
863 MethodType type = name.function.methodType();
864 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
865 }
866
867 private static Class<?>[] STATICALLY_INVOCABLE_PACKAGES = {
868 // Sample classes from each package we are willing to bind to statically:
869 java.lang.Object.class,
870 java.util.Arrays.class,
871 jdk.internal.misc.Unsafe.class
872 //MethodHandle.class already covered
873 };
874
875 static boolean isStaticallyInvocable(NamedFunction[] functions) {
876 for (NamedFunction nf : functions) {
877 if (!isStaticallyInvocable(nf.member())) {
878 return false;
879 }
880 }
881 return true;
882 }
883
884 static boolean isStaticallyInvocable(Name name) {
885 return isStaticallyInvocable(name.function.member());
886 }
887
888 static boolean isStaticallyInvocable(MemberName member) {
889 if (member == null) return false;
890 if (member.isConstructor()) return false;
891 Class<?> cls = member.getDeclaringClass();
892 if (cls.isArray() || cls.isPrimitive())
893 return false; // FIXME
894 if (cls.isAnonymousClass() || cls.isLocalClass())
895 return false; // inner class of some sort
896 if (cls.getClassLoader() != MethodHandle.class.getClassLoader())
897 return false; // not on BCP
898 if (ReflectUtil.isVMAnonymousClass(cls)) // FIXME: switch to supported API once it is added
899 return false;
900 MethodType mtype = member.getMethodOrFieldType();
901 if (!isStaticallyNameable(mtype.returnType()))
902 return false;
903 for (Class<?> ptype : mtype.parameterArray())
904 if (!isStaticallyNameable(ptype))
905 return false;
906 if (!member.isPrivate() && VerifyAccess.isSamePackage(MethodHandle.class, cls))
907 return true; // in java.lang.invoke package
908 if (member.isPublic() && isStaticallyNameable(cls))
909 return true;
910 return false;
911 }
912
913 static boolean isStaticallyNameable(Class<?> cls) {
914 if (cls == Object.class)
915 return true;
916 while (cls.isArray())
917 cls = cls.getComponentType();
918 if (cls.isPrimitive())
919 return true; // int[].class, for example
920 if (ReflectUtil.isVMAnonymousClass(cls)) // FIXME: switch to supported API once it is added
921 return false;
922 // could use VerifyAccess.isClassAccessible but the following is a safe approximation
923 if (cls.getClassLoader() != Object.class.getClassLoader())
924 return false;
925 if (VerifyAccess.isSamePackage(MethodHandle.class, cls))
926 return true;
927 if (!Modifier.isPublic(cls.getModifiers()))
928 return false;
929 for (Class<?> pkgcls : STATICALLY_INVOCABLE_PACKAGES) {
930 if (VerifyAccess.isSamePackage(pkgcls, cls))
931 return true;
932 }
933 return false;
934 }
935
936 void emitStaticInvoke(Name name) {
937 emitStaticInvoke(name.function.member(), name);
938 }
939
940 /**
941 * Emit an invoke for the given name, using the MemberName directly.
942 */
943 void emitStaticInvoke(MemberName member, Name name) {
944 assert(member.equals(name.function.member()));
945 Class<?> defc = member.getDeclaringClass();
946 String cname = getInternalName(defc);
947 String mname = member.getName();
948 String mtype;
949 byte refKind = member.getReferenceKind();
950 if (refKind == REF_invokeSpecial) {
951 // in order to pass the verifier, we need to convert this to invokevirtual in all cases
952 assert(member.canBeStaticallyBound()) : member;
953 refKind = REF_invokeVirtual;
954 }
955
956 assert(!(member.getDeclaringClass().isInterface() && refKind == REF_invokeVirtual));
957
958 // push arguments
959 emitPushArguments(name, 0);
960
961 // invocation
962 if (member.isMethod()) {
963 mtype = member.getMethodType().toMethodDescriptorString();
964 mv.visitMethodInsn(refKindOpcode(refKind), cname, mname, mtype,
965 member.getDeclaringClass().isInterface());
966 } else {
967 mtype = MethodType.toFieldDescriptorString(member.getFieldType());
968 mv.visitFieldInsn(refKindOpcode(refKind), cname, mname, mtype);
969 }
970 // Issue a type assertion for the result, so we can avoid casts later.
971 if (name.type == L_TYPE) {
972 Class<?> rtype = member.getInvocationType().returnType();
973 assert(!rtype.isPrimitive());
974 if (rtype != Object.class && !rtype.isInterface()) {
975 assertStaticType(rtype, name);
976 }
977 }
978 }
979
980 void emitNewArray(Name name) throws InternalError {
981 Class<?> rtype = name.function.methodType().returnType();
982 if (name.arguments.length == 0) {
983 // The array will be a constant.
984 Object emptyArray;
985 try {
986 emptyArray = name.function.resolvedHandle().invoke();
987 } catch (Throwable ex) {
988 throw newInternalError(ex);
989 }
990 assert(java.lang.reflect.Array.getLength(emptyArray) == 0);
991 assert(emptyArray.getClass() == rtype); // exact typing
992 mv.visitLdcInsn(constantPlaceholder(emptyArray));
993 emitReferenceCast(rtype, emptyArray);
994 return;
995 }
996 Class<?> arrayElementType = rtype.getComponentType();
997 assert(arrayElementType != null);
998 emitIconstInsn(name.arguments.length);
999 int xas = Opcodes.AASTORE;
1000 if (!arrayElementType.isPrimitive()) {
1001 mv.visitTypeInsn(Opcodes.ANEWARRAY, getInternalName(arrayElementType));
1002 } else {
1003 byte tc = arrayTypeCode(Wrapper.forPrimitiveType(arrayElementType));
1004 xas = arrayInsnOpcode(tc, xas);
1005 mv.visitIntInsn(Opcodes.NEWARRAY, tc);
1006 }
1007 // store arguments
1008 for (int i = 0; i < name.arguments.length; i++) {
1009 mv.visitInsn(Opcodes.DUP);
1010 emitIconstInsn(i);
1011 emitPushArgument(name, i);
1012 mv.visitInsn(xas);
1013 }
1014 // the array is left on the stack
1015 assertStaticType(rtype, name);
1016 }
1017 int refKindOpcode(byte refKind) {
1018 switch (refKind) {
1019 case REF_invokeVirtual: return Opcodes.INVOKEVIRTUAL;
1020 case REF_invokeStatic: return Opcodes.INVOKESTATIC;
1021 case REF_invokeSpecial: return Opcodes.INVOKESPECIAL;
1022 case REF_invokeInterface: return Opcodes.INVOKEINTERFACE;
1023 case REF_getField: return Opcodes.GETFIELD;
1024 case REF_putField: return Opcodes.PUTFIELD;
1025 case REF_getStatic: return Opcodes.GETSTATIC;
1026 case REF_putStatic: return Opcodes.PUTSTATIC;
1027 }
1028 throw new InternalError("refKind="+refKind);
1029 }
1030
1031 /**
1032 * Emit bytecode for the selectAlternative idiom.
1033 *
1034 * The pattern looks like (Cf. MethodHandleImpl.makeGuardWithTest):
1035 * <blockquote><pre>{@code
1036 * Lambda(a0:L,a1:I)=>{
1037 * t2:I=foo.test(a1:I);
1038 * t3:L=MethodHandleImpl.selectAlternative(t2:I,(MethodHandle(int)int),(MethodHandle(int)int));
1039 * t4:I=MethodHandle.invokeBasic(t3:L,a1:I);t4:I}
1040 * }</pre></blockquote>
1041 */
1042 private Name emitSelectAlternative(Name selectAlternativeName, Name invokeBasicName) {
1043 assert isStaticallyInvocable(invokeBasicName);
1044
1045 Name receiver = (Name) invokeBasicName.arguments[0];
1046
1047 Label L_fallback = new Label();
1048 Label L_done = new Label();
1049
1050 // load test result
1051 emitPushArgument(selectAlternativeName, 0);
1052
1053 // if_icmpne L_fallback
1054 mv.visitJumpInsn(Opcodes.IFEQ, L_fallback);
1055
1056 // invoke selectAlternativeName.arguments[1]
1057 Class<?>[] preForkClasses = localClasses.clone();
1058 emitPushArgument(selectAlternativeName, 1); // get 2nd argument of selectAlternative
1059 emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
1060 emitStaticInvoke(invokeBasicName);
1061
1062 // goto L_done
1063 mv.visitJumpInsn(Opcodes.GOTO, L_done);
1064
1065 // L_fallback:
1066 mv.visitLabel(L_fallback);
1067
1068 // invoke selectAlternativeName.arguments[2]
1069 System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
1070 emitPushArgument(selectAlternativeName, 2); // get 3rd argument of selectAlternative
1071 emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
1072 emitStaticInvoke(invokeBasicName);
1073
1074 // L_done:
1075 mv.visitLabel(L_done);
1076 // for now do not bother to merge typestate; just reset to the dominator state
1077 System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
1078
1079 return invokeBasicName; // return what's on stack
1080 }
1081
1082 /**
1083 * Emit bytecode for the guardWithCatch idiom.
1084 *
1085 * The pattern looks like (Cf. MethodHandleImpl.makeGuardWithCatch):
1086 * <blockquote><pre>{@code
1087 * guardWithCatch=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L,a6:L,a7:L)=>{
1088 * t8:L=MethodHandle.invokeBasic(a4:L,a6:L,a7:L);
1089 * t9:L=MethodHandleImpl.guardWithCatch(a1:L,a2:L,a3:L,t8:L);
1090 * t10:I=MethodHandle.invokeBasic(a5:L,t9:L);t10:I}
1091 * }</pre></blockquote>
1092 *
1093 * It is compiled into bytecode equivalent of the following code:
1094 * <blockquote><pre>{@code
1095 * try {
1096 * return a1.invokeBasic(a6, a7);
1097 * } catch (Throwable e) {
1098 * if (!a2.isInstance(e)) throw e;
1099 * return a3.invokeBasic(ex, a6, a7);
1100 * }}
1101 */
1102 private Name emitGuardWithCatch(int pos) {
1103 Name args = lambdaForm.names[pos];
1104 Name invoker = lambdaForm.names[pos+1];
1105 Name result = lambdaForm.names[pos+2];
1106
1107 Label L_startBlock = new Label();
1108 Label L_endBlock = new Label();
1109 Label L_handler = new Label();
1110 Label L_done = new Label();
1111
1112 Class<?> returnType = result.function.resolvedHandle().type().returnType();
1113 MethodType type = args.function.resolvedHandle().type()
1114 .dropParameterTypes(0,1)
1115 .changeReturnType(returnType);
1116
1117 mv.visitTryCatchBlock(L_startBlock, L_endBlock, L_handler, "java/lang/Throwable");
1118
1119 // Normal case
1120 mv.visitLabel(L_startBlock);
1121 // load target
1122 emitPushArgument(invoker, 0);
1123 emitPushArguments(args, 1); // skip 1st argument: method handle
1124 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
1125 mv.visitLabel(L_endBlock);
1126 mv.visitJumpInsn(Opcodes.GOTO, L_done);
1127
1128 // Exceptional case
1129 mv.visitLabel(L_handler);
1130
1131 // Check exception's type
1132 mv.visitInsn(Opcodes.DUP);
1133 // load exception class
1134 emitPushArgument(invoker, 1);
1135 mv.visitInsn(Opcodes.SWAP);
1136 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Class", "isInstance", "(Ljava/lang/Object;)Z", false);
1137 Label L_rethrow = new Label();
1138 mv.visitJumpInsn(Opcodes.IFEQ, L_rethrow);
1139
1140 // Invoke catcher
1141 // load catcher
1142 emitPushArgument(invoker, 2);
1143 mv.visitInsn(Opcodes.SWAP);
1144 emitPushArguments(args, 1); // skip 1st argument: method handle
1145 MethodType catcherType = type.insertParameterTypes(0, Throwable.class);
1146 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", catcherType.basicType().toMethodDescriptorString(), false);
1147 mv.visitJumpInsn(Opcodes.GOTO, L_done);
1148
1149 mv.visitLabel(L_rethrow);
1150 mv.visitInsn(Opcodes.ATHROW);
1151
1152 mv.visitLabel(L_done);
1153
1154 return result;
1155 }
1156
1157 /**
1158 * Emit bytecode for the tryFinally idiom.
1159 * <p>
1160 * The pattern looks like (Cf. MethodHandleImpl.makeTryFinally):
1161 * <blockquote><pre>{@code
1162 * // a0: BMH
1163 * // a1: target, a2: cleanup
1164 * // a3: box, a4: unbox
1165 * // a5 (and following): arguments
1166 * tryFinally=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L)=>{
1167 * t6:L=MethodHandle.invokeBasic(a3:L,a5:L); // box the arguments into an Object[]
1168 * t7:L=MethodHandleImpl.tryFinally(a1:L,a2:L,t6:L); // call the tryFinally executor
1169 * t8:L=MethodHandle.invokeBasic(a4:L,t7:L);t8:L} // unbox the result; return the result
1170 * }</pre></blockquote>
1171 * <p>
1172 * It is compiled into bytecode equivalent to the following code:
1173 * <blockquote><pre>{@code
1174 * Throwable t;
1175 * Object r;
1176 * try {
1177 * r = a1.invokeBasic(a5);
1178 * } catch (Throwable thrown) {
1179 * t = thrown;
1180 * throw t;
1181 * } finally {
1182 * r = a2.invokeBasic(t, r, a5);
1183 * }
1184 * return r;
1185 * }</pre></blockquote>
1186 * <p>
1187 * Specifically, the bytecode will have the following form (the stack effects are given for the beginnings of
1188 * blocks, and for the situations after executing the given instruction - the code will have a slightly different
1189 * shape if the return type is {@code void}):
1190 * <blockquote><pre>{@code
1191 * TRY: (--)
1192 * load target (-- target)
1193 * load args (-- args... target)
1194 * INVOKEVIRTUAL MethodHandle.invokeBasic (depends)
1195 * FINALLY_NORMAL: (-- r)
1196 * load cleanup (-- cleanup r)
1197 * SWAP (-- r cleanup)
1198 * ACONST_NULL (-- t r cleanup)
1199 * SWAP (-- r t cleanup)
1200 * load args (-- args... r t cleanup)
1201 * INVOKEVIRTUAL MethodHandle.invokeBasic (-- r)
1202 * GOTO DONE
1203 * CATCH: (-- t)
1204 * DUP (-- t t)
1205 * FINALLY_EXCEPTIONAL: (-- t t)
1206 * load cleanup (-- cleanup t t)
1207 * SWAP (-- t cleanup t)
1208 * load default for r (-- r t cleanup t)
1209 * load args (-- args... r t cleanup t)
1210 * INVOKEVIRTUAL MethodHandle.invokeBasic (-- r t)
1211 * POP (-- t)
1212 * ATHROW
1213 * DONE: (-- r)
1214 * }</pre></blockquote>
1215 */
1216 private Name emitTryFinally(int pos) {
1217 Name args = lambdaForm.names[pos];
1218 Name invoker = lambdaForm.names[pos+1];
1219 Name result = lambdaForm.names[pos+2];
1220
1221 Label lFrom = new Label();
1222 Label lTo = new Label();
1223 Label lCatch = new Label();
1224 Label lDone = new Label();
1225
1226 Class<?> returnType = result.function.resolvedHandle().type().returnType();
1227 boolean isNonVoid = returnType != void.class;
1228 MethodType type = args.function.resolvedHandle().type()
1229 .dropParameterTypes(0,1)
1230 .changeReturnType(returnType);
1231 MethodType cleanupType = type.insertParameterTypes(0, Throwable.class);
1232 if (isNonVoid) {
1233 cleanupType = cleanupType.insertParameterTypes(1, returnType);
1234 }
1235 String cleanupDesc = cleanupType.basicType().toMethodDescriptorString();
1236
1237 // exception handler table
1238 mv.visitTryCatchBlock(lFrom, lTo, lCatch, "java/lang/Throwable");
1239
1240 // TRY:
1241 mv.visitLabel(lFrom);
1242 emitPushArgument(invoker, 0); // load target
1243 emitPushArguments(args, 1); // load args (skip 0: method handle)
1244 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
1245 mv.visitLabel(lTo);
1246
1247 // FINALLY_NORMAL:
1248 emitPushArgument(invoker, 1); // load cleanup
1249 if (isNonVoid) {
1250 mv.visitInsn(Opcodes.SWAP);
1251 }
1252 mv.visitInsn(Opcodes.ACONST_NULL);
1253 if (isNonVoid) {
1254 mv.visitInsn(Opcodes.SWAP);
1255 }
1256 emitPushArguments(args, 1); // load args (skip 0: method handle)
1257 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", cleanupDesc, false);
1258 mv.visitJumpInsn(Opcodes.GOTO, lDone);
1259
1260 // CATCH:
1261 mv.visitLabel(lCatch);
1262 mv.visitInsn(Opcodes.DUP);
1263
1264 // FINALLY_EXCEPTIONAL:
1265 emitPushArgument(invoker, 1); // load cleanup
1266 mv.visitInsn(Opcodes.SWAP);
1267 if (isNonVoid) {
1268 emitZero(BasicType.basicType(returnType)); // load default for result
1269 }
1270 emitPushArguments(args, 1); // load args (skip 0: method handle)
1271 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", cleanupDesc, false);
1272 if (isNonVoid) {
1273 mv.visitInsn(Opcodes.POP);
1274 }
1275 mv.visitInsn(Opcodes.ATHROW);
1276
1277 // DONE:
1278 mv.visitLabel(lDone);
1279
1280 return result;
1281 }
1282
1283 /**
1284 * Emit bytecode for the loop idiom.
1285 * <p>
1286 * The pattern looks like (Cf. MethodHandleImpl.loop):
1287 * <blockquote><pre>{@code
1288 * // a0: BMH
1289 * // a1: inits, a2: steps, a3: preds, a4: finis
1290 * // a5: box, a6: unbox
1291 * // a7 (and following): arguments
1292 * loop=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L,a6:L,a7:L)=>{
1293 * t8:L=MethodHandle.invokeBasic(a5:L,a7:L); // box the arguments into an Object[]
1294 * t9:L=MethodHandleImpl.loop(bt:L,a1:L,a2:L,a3:L,a4:L,t8:L); // call the loop executor (with supplied types in bt)
1295 * t10:L=MethodHandle.invokeBasic(a6:L,t9:L);t10:L} // unbox the result; return the result
1296 * }</pre></blockquote>
1297 * <p>
1298 * It is compiled into bytecode equivalent to the code seen in {@link MethodHandleImpl#loop(BasicType[],
1299 * MethodHandle[], MethodHandle[], MethodHandle[], MethodHandle[], Object...)}, with the difference that no arrays
1300 * will be used for local state storage. Instead, the local state will be mapped to actual stack slots.
1301 * <p>
1302 * Bytecode generation applies an unrolling scheme to enable better bytecode generation regarding local state type
1303 * handling. The generated bytecode will have the following form ({@code void} types are ignored for convenience).
1304 * Assume there are {@code C} clauses in the loop.
1305 * <blockquote><pre>{@code
1306 * INIT: (INIT_SEQ for clause 1)
1307 * ...
1308 * (INIT_SEQ for clause C)
1309 * LOOP: (LOOP_SEQ for clause 1)
1310 * ...
1311 * (LOOP_SEQ for clause C)
1312 * GOTO LOOP
1313 * DONE: ...
1314 * }</pre></blockquote>
1315 * <p>
1316 * The {@code INIT_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
1317 * the following shape. Assume slot {@code vx} is used to hold the state for clause {@code x}.
1318 * <blockquote><pre>{@code
1319 * INIT_SEQ_x: ALOAD inits
1320 * CHECKCAST MethodHandle[]
1321 * ICONST x
1322 * AALOAD // load the init handle for clause x
1323 * load args
1324 * INVOKEVIRTUAL MethodHandle.invokeBasic
1325 * store vx
1326 * }</pre></blockquote>
1327 * <p>
1328 * The {@code LOOP_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
1329 * the following shape. Again, assume slot {@code vx} is used to hold the state for clause {@code x}.
1330 * <blockquote><pre>{@code
1331 * LOOP_SEQ_x: ALOAD steps
1332 * CHECKCAST MethodHandle[]
1333 * ICONST x
1334 * AALOAD // load the step handle for clause x
1335 * load locals
1336 * load args
1337 * INVOKEVIRTUAL MethodHandle.invokeBasic
1338 * store vx
1339 * ALOAD preds
1340 * CHECKCAST MethodHandle[]
1341 * ICONST x
1342 * AALOAD // load the pred handle for clause x
1343 * load locals
1344 * load args
1345 * INVOKEVIRTUAL MethodHandle.invokeBasic
1346 * IFNE LOOP_SEQ_x+1 // predicate returned false -> jump to next clause
1347 * ALOAD finis
1348 * CHECKCAST MethodHandle[]
1349 * ICONST x
1350 * AALOAD // load the fini handle for clause x
1351 * load locals
1352 * load args
1353 * INVOKEVIRTUAL MethodHandle.invokeBasic
1354 * GOTO DONE // jump beyond end of clauses to return from loop
1355 * }</pre></blockquote>
1356 */
1357 private Name emitLoop(int pos) {
1358 Name args = lambdaForm.names[pos];
1359 Name invoker = lambdaForm.names[pos+1];
1360 Name result = lambdaForm.names[pos+2];
1361
1362 // extract clause and loop-local state types
1363 // find the type info in the loop invocation
1364 BasicType[] loopClauseTypes = (BasicType[]) invoker.arguments[0];
1365 Class<?>[] loopLocalStateTypes = Stream.of(loopClauseTypes).
1366 filter(bt -> bt != BasicType.V_TYPE).map(BasicType::basicTypeClass).toArray(Class<?>[]::new);
1367
1368 final int firstLoopStateIndex = extendLocalsMap(loopLocalStateTypes);
1369
1370 Class<?> returnType = result.function.resolvedHandle().type().returnType();
1371 MethodType loopType = args.function.resolvedHandle().type()
1372 .dropParameterTypes(0,1)
1373 .changeReturnType(returnType);
1374 MethodType loopHandleType = loopType.insertParameterTypes(0, loopLocalStateTypes);
1375 MethodType predType = loopHandleType.changeReturnType(boolean.class);
1376 MethodType finiType = loopHandleType;
1377
1378 final int nClauses = loopClauseTypes.length;
1379
1380 // indices to invoker arguments to load method handle arrays
1381 final int inits = 1;
1382 final int steps = 2;
1383 final int preds = 3;
1384 final int finis = 4;
1385
1386 Label lLoop = new Label();
1387 Label lDone = new Label();
1388 Label lNext;
1389
1390 // INIT:
1391 for (int c = 0, state = 0; c < nClauses; ++c) {
1392 MethodType cInitType = loopType.changeReturnType(loopClauseTypes[c].basicTypeClass());
1393 emitLoopHandleInvoke(invoker, inits, c, args, false, cInitType, loopLocalStateTypes, firstLoopStateIndex);
1394 if (cInitType.returnType() != void.class) {
1395 emitStoreInsn(BasicType.basicType(cInitType.returnType()), firstLoopStateIndex + state);
1396 ++state;
1397 }
1398 }
1399
1400 // LOOP:
1401 mv.visitLabel(lLoop);
1402
1403 for (int c = 0, state = 0; c < nClauses; ++c) {
1404 lNext = new Label();
1405
1406 MethodType stepType = loopHandleType.changeReturnType(loopClauseTypes[c].basicTypeClass());
1407 boolean isVoid = stepType.returnType() == void.class;
1408
1409 // invoke loop step
1410 emitLoopHandleInvoke(invoker, steps, c, args, true, stepType, loopLocalStateTypes, firstLoopStateIndex);
1411 if (!isVoid) {
1412 emitStoreInsn(BasicType.basicType(stepType.returnType()), firstLoopStateIndex + state);
1413 ++state;
1414 }
1415
1416 // invoke loop predicate
1417 emitLoopHandleInvoke(invoker, preds, c, args, true, predType, loopLocalStateTypes, firstLoopStateIndex);
1418 mv.visitJumpInsn(Opcodes.IFNE, lNext);
1419
1420 // invoke fini
1421 emitLoopHandleInvoke(invoker, finis, c, args, true, finiType, loopLocalStateTypes, firstLoopStateIndex);
1422 mv.visitJumpInsn(Opcodes.GOTO, lDone);
1423
1424 // this is the beginning of the next loop clause
1425 mv.visitLabel(lNext);
1426 }
1427
1428 mv.visitJumpInsn(Opcodes.GOTO, lLoop);
1429
1430 // DONE:
1431 mv.visitLabel(lDone);
1432
1433 return result;
1434 }
1435
1436 private int extendLocalsMap(Class<?>[] types) {
1437 int firstSlot = localsMap.length - 1;
1438 localsMap = Arrays.copyOf(localsMap, localsMap.length + types.length);
1439 localClasses = Arrays.copyOf(localClasses, localClasses.length + types.length);
1440 System.arraycopy(types, 0, localClasses, firstSlot, types.length);
1441 int index = localsMap[firstSlot - 1] + 1;
1442 int lastSlots = 0;
1443 for (int i = 0; i < types.length; ++i) {
1444 localsMap[firstSlot + i] = index;
1445 lastSlots = BasicType.basicType(localClasses[firstSlot + i]).basicTypeSlots();
1446 index += lastSlots;
1447 }
1448 localsMap[localsMap.length - 1] = index - lastSlots;
1449 return firstSlot;
1450 }
1451
1452 private void emitLoopHandleInvoke(Name holder, int handles, int clause, Name args, boolean pushLocalState,
1453 MethodType type, Class<?>[] loopLocalStateTypes, int firstLoopStateSlot) {
1454 // load handle for clause
1455 emitPushArgument(holder, handles);
1456 emitIconstInsn(clause);
1457 mv.visitInsn(Opcodes.AALOAD);
1458 // load loop state (preceding the other arguments)
1459 if (pushLocalState) {
1460 for (int s = 0; s < loopLocalStateTypes.length; ++s) {
1461 emitLoadInsn(BasicType.basicType(loopLocalStateTypes[s]), firstLoopStateSlot + s);
1462 }
1463 }
1464 // load loop args (skip 0: method handle)
1465 emitPushArguments(args, 1);
1466 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.toMethodDescriptorString(), false);
1467 }
1468
1469 private void emitZero(BasicType type) {
1470 switch (type) {
1471 case I_TYPE: mv.visitInsn(Opcodes.ICONST_0); break;
1472 case J_TYPE: mv.visitInsn(Opcodes.LCONST_0); break;
1473 case F_TYPE: mv.visitInsn(Opcodes.FCONST_0); break;
1474 case D_TYPE: mv.visitInsn(Opcodes.DCONST_0); break;
1475 case L_TYPE: mv.visitInsn(Opcodes.ACONST_NULL); break;
1476 default: throw new InternalError("unknown type: " + type);
1477 }
1478 }
1479
1480 private void emitPushArguments(Name args, int start) {
1481 MethodType type = args.function.methodType();
1482 for (int i = start; i < args.arguments.length; i++) {
1483 emitPushArgument(type.parameterType(i), args.arguments[i]);
1484 }
1485 }
1486
1487 private void emitPushArgument(Name name, int paramIndex) {
1488 Object arg = name.arguments[paramIndex];
1489 Class<?> ptype = name.function.methodType().parameterType(paramIndex);
1490 emitPushArgument(ptype, arg);
1491 }
1492
1493 private void emitPushArgument(Class<?> ptype, Object arg) {
1494 BasicType bptype = basicType(ptype);
1495 if (arg instanceof Name) {
1496 Name n = (Name) arg;
1497 emitLoadInsn(n.type, n.index());
1498 emitImplicitConversion(n.type, ptype, n);
1499 } else if ((arg == null || arg instanceof String) && bptype == L_TYPE) {
1500 emitConst(arg);
1501 } else {
1502 if (Wrapper.isWrapperType(arg.getClass()) && bptype != L_TYPE) {
1503 emitConst(arg);
1504 } else {
1505 mv.visitLdcInsn(constantPlaceholder(arg));
1506 emitImplicitConversion(L_TYPE, ptype, arg);
1507 }
1508 }
1509 }
1510
1511 /**
1512 * Store the name to its local, if necessary.
1513 */
1514 private void emitStoreResult(Name name) {
1515 if (name != null && name.type != V_TYPE) {
1516 // non-void: actually assign
1517 emitStoreInsn(name.type, name.index());
1518 }
1519 }
1520
1521 /**
1522 * Emits a return statement from a LF invoker. If required, the result type is cast to the correct return type.
1523 */
1524 private void emitReturn(Name onStack) {
1525 // return statement
1526 Class<?> rclass = invokerType.returnType();
1527 BasicType rtype = lambdaForm.returnType();
1528 assert(rtype == basicType(rclass)); // must agree
1529 if (rtype == V_TYPE) {
1530 // void
1531 mv.visitInsn(Opcodes.RETURN);
1532 // it doesn't matter what rclass is; the JVM will discard any value
1533 } else {
1534 LambdaForm.Name rn = lambdaForm.names[lambdaForm.result];
1535
1536 // put return value on the stack if it is not already there
1537 if (rn != onStack) {
1538 emitLoadInsn(rtype, lambdaForm.result);
1539 }
1540
1541 emitImplicitConversion(rtype, rclass, rn);
1542
1543 // generate actual return statement
1544 emitReturnInsn(rtype);
1545 }
1546 }
1547
1548 /**
1549 * Emit a type conversion bytecode casting from "from" to "to".
1550 */
1551 private void emitPrimCast(Wrapper from, Wrapper to) {
1552 // Here's how.
1553 // - indicates forbidden
1554 // <-> indicates implicit
1555 // to ----> boolean byte short char int long float double
1556 // from boolean <-> - - - - - - -
1557 // byte - <-> i2s i2c <-> i2l i2f i2d
1558 // short - i2b <-> i2c <-> i2l i2f i2d
1559 // char - i2b i2s <-> <-> i2l i2f i2d
1560 // int - i2b i2s i2c <-> i2l i2f i2d
1561 // long - l2i,i2b l2i,i2s l2i,i2c l2i <-> l2f l2d
1562 // float - f2i,i2b f2i,i2s f2i,i2c f2i f2l <-> f2d
1563 // double - d2i,i2b d2i,i2s d2i,i2c d2i d2l d2f <->
1564 if (from == to) {
1565 // no cast required, should be dead code anyway
1566 return;
1567 }
1568 if (from.isSubwordOrInt()) {
1569 // cast from {byte,short,char,int} to anything
1570 emitI2X(to);
1571 } else {
1572 // cast from {long,float,double} to anything
1573 if (to.isSubwordOrInt()) {
1574 // cast to {byte,short,char,int}
1575 emitX2I(from);
1576 if (to.bitWidth() < 32) {
1577 // targets other than int require another conversion
1578 emitI2X(to);
1579 }
1580 } else {
1581 // cast to {long,float,double} - this is verbose
1582 boolean error = false;
1583 switch (from) {
1584 case LONG:
1585 switch (to) {
1586 case FLOAT: mv.visitInsn(Opcodes.L2F); break;
1587 case DOUBLE: mv.visitInsn(Opcodes.L2D); break;
1588 default: error = true; break;
1589 }
1590 break;
1591 case FLOAT:
1592 switch (to) {
1593 case LONG : mv.visitInsn(Opcodes.F2L); break;
1594 case DOUBLE: mv.visitInsn(Opcodes.F2D); break;
1595 default: error = true; break;
1596 }
1597 break;
1598 case DOUBLE:
1599 switch (to) {
1600 case LONG : mv.visitInsn(Opcodes.D2L); break;
1601 case FLOAT: mv.visitInsn(Opcodes.D2F); break;
1602 default: error = true; break;
1603 }
1604 break;
1605 default:
1606 error = true;
1607 break;
1608 }
1609 if (error) {
1610 throw new IllegalStateException("unhandled prim cast: " + from + "2" + to);
1611 }
1612 }
1613 }
1614 }
1615
1616 private void emitI2X(Wrapper type) {
1617 switch (type) {
1618 case BYTE: mv.visitInsn(Opcodes.I2B); break;
1619 case SHORT: mv.visitInsn(Opcodes.I2S); break;
1620 case CHAR: mv.visitInsn(Opcodes.I2C); break;
1621 case INT: /* naught */ break;
1622 case LONG: mv.visitInsn(Opcodes.I2L); break;
1623 case FLOAT: mv.visitInsn(Opcodes.I2F); break;
1624 case DOUBLE: mv.visitInsn(Opcodes.I2D); break;
1625 case BOOLEAN:
1626 // For compatibility with ValueConversions and explicitCastArguments:
1627 mv.visitInsn(Opcodes.ICONST_1);
1628 mv.visitInsn(Opcodes.IAND);
1629 break;
1630 default: throw new InternalError("unknown type: " + type);
1631 }
1632 }
1633
1634 private void emitX2I(Wrapper type) {
1635 switch (type) {
1636 case LONG: mv.visitInsn(Opcodes.L2I); break;
1637 case FLOAT: mv.visitInsn(Opcodes.F2I); break;
1638 case DOUBLE: mv.visitInsn(Opcodes.D2I); break;
1639 default: throw new InternalError("unknown type: " + type);
1640 }
1641 }
1642
1643 /**
1644 * Generate bytecode for a LambdaForm.vmentry which calls interpretWithArguments.
1645 */
1646 static MemberName generateLambdaFormInterpreterEntryPoint(MethodType mt) {
1647 assert(isValidSignature(basicTypeSignature(mt)));
1648 String name = "interpret_"+basicTypeChar(mt.returnType());
1649 MethodType type = mt; // includes leading argument
1650 type = type.changeParameterType(0, MethodHandle.class);
1651 InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("LFI", name, type);
1652 return g.loadMethod(g.generateLambdaFormInterpreterEntryPointBytes());
1653 }
1654
1655 private byte[] generateLambdaFormInterpreterEntryPointBytes() {
1656 classFilePrologue();
1657 methodPrologue();
1658
1659 // Suppress this method in backtraces displayed to the user.
1660 mv.visitAnnotation(LF_HIDDEN_SIG, true);
1661
1662 // Don't inline the interpreter entry.
1663 mv.visitAnnotation(DONTINLINE_SIG, true);
1664
1665 // create parameter array
1666 emitIconstInsn(invokerType.parameterCount());
1667 mv.visitTypeInsn(Opcodes.ANEWARRAY, "java/lang/Object");
1668
1669 // fill parameter array
1670 for (int i = 0; i < invokerType.parameterCount(); i++) {
1671 Class<?> ptype = invokerType.parameterType(i);
1672 mv.visitInsn(Opcodes.DUP);
1673 emitIconstInsn(i);
1674 emitLoadInsn(basicType(ptype), i);
1675 // box if primitive type
1676 if (ptype.isPrimitive()) {
1677 emitBoxing(Wrapper.forPrimitiveType(ptype));
1678 }
1679 mv.visitInsn(Opcodes.AASTORE);
1680 }
1681 // invoke
1682 emitAloadInsn(0);
1683 mv.visitFieldInsn(Opcodes.GETFIELD, MH, "form", "Ljava/lang/invoke/LambdaForm;");
1684 mv.visitInsn(Opcodes.SWAP); // swap form and array; avoid local variable
1685 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, LF, "interpretWithArguments", "([Ljava/lang/Object;)Ljava/lang/Object;", false);
1686
1687 // maybe unbox
1688 Class<?> rtype = invokerType.returnType();
1689 if (rtype.isPrimitive() && rtype != void.class) {
1690 emitUnboxing(Wrapper.forPrimitiveType(rtype));
1691 }
1692
1693 // return statement
1694 emitReturnInsn(basicType(rtype));
1695
1696 methodEpilogue();
1697 bogusMethod(invokerType);
1698
1699 final byte[] classFile = cw.toByteArray();
1700 maybeDump(className, classFile);
1701 return classFile;
1702 }
1703
1704 /**
1705 * Generate bytecode for a NamedFunction invoker.
1706 */
1707 static MemberName generateNamedFunctionInvoker(MethodTypeForm typeForm) {
1708 MethodType invokerType = NamedFunction.INVOKER_METHOD_TYPE;
1709 String invokerName = "invoke_" + shortenSignature(basicTypeSignature(typeForm.erasedType()));
1710 InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("NFI", invokerName, invokerType);
1711 return g.loadMethod(g.generateNamedFunctionInvokerImpl(typeForm));
1712 }
1713
1714 private byte[] generateNamedFunctionInvokerImpl(MethodTypeForm typeForm) {
1715 MethodType dstType = typeForm.erasedType();
1716 classFilePrologue();
1717 methodPrologue();
1718
1719 // Suppress this method in backtraces displayed to the user.
1720 mv.visitAnnotation(LF_HIDDEN_SIG, true);
1721
1722 // Force inlining of this invoker method.
1723 mv.visitAnnotation(FORCEINLINE_SIG, true);
1724
1725 // Load receiver
1726 emitAloadInsn(0);
1727
1728 // Load arguments from array
1729 for (int i = 0; i < dstType.parameterCount(); i++) {
1730 emitAloadInsn(1);
1731 emitIconstInsn(i);
1732 mv.visitInsn(Opcodes.AALOAD);
1733
1734 // Maybe unbox
1735 Class<?> dptype = dstType.parameterType(i);
1736 if (dptype.isPrimitive()) {
1737 Wrapper dstWrapper = Wrapper.forBasicType(dptype);
1738 Wrapper srcWrapper = dstWrapper.isSubwordOrInt() ? Wrapper.INT : dstWrapper; // narrow subword from int
1739 emitUnboxing(srcWrapper);
1740 emitPrimCast(srcWrapper, dstWrapper);
1741 }
1742 }
1743
1744 // Invoke
1745 String targetDesc = dstType.basicType().toMethodDescriptorString();
1746 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", targetDesc, false);
1747
1748 // Box primitive types
1749 Class<?> rtype = dstType.returnType();
1750 if (rtype != void.class && rtype.isPrimitive()) {
1751 Wrapper srcWrapper = Wrapper.forBasicType(rtype);
1752 Wrapper dstWrapper = srcWrapper.isSubwordOrInt() ? Wrapper.INT : srcWrapper; // widen subword to int
1753 // boolean casts not allowed
1754 emitPrimCast(srcWrapper, dstWrapper);
1755 emitBoxing(dstWrapper);
1756 }
1757
1758 // If the return type is void we return a null reference.
1759 if (rtype == void.class) {
1760 mv.visitInsn(Opcodes.ACONST_NULL);
1761 }
1762 emitReturnInsn(L_TYPE); // NOTE: NamedFunction invokers always return a reference value.
1763
1764 methodEpilogue();
1765 bogusMethod(dstType);
1766
1767 final byte[] classFile = cw.toByteArray();
1768 maybeDump(className, classFile);
1769 return classFile;
1770 }
1771
1772 /**
1773 * Emit a bogus method that just loads some string constants. This is to get the constants into the constant pool
1774 * for debugging purposes.
1775 */
1776 private void bogusMethod(Object... os) {
1777 if (DUMP_CLASS_FILES) {
1778 mv = cw.visitMethod(Opcodes.ACC_STATIC, "dummy", "()V", null, null);
1779 for (Object o : os) {
1780 mv.visitLdcInsn(o.toString());
1781 mv.visitInsn(Opcodes.POP);
1782 }
1783 mv.visitInsn(Opcodes.RETURN);
1784 mv.visitMaxs(0, 0);
1785 mv.visitEnd();
1786 }
1787 }
1788 }