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) {
616 // No pre-generated version for customized LF
617 return null;
618 }
619 MethodType invokerType = form.methodType();
620 String name = form.kind.methodName;
621 switch (form.kind) {
622 case BOUND_REINVOKER: {
623 name = name + "_" + BoundMethodHandle.speciesData(form).fieldSignature();
624 return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
625 }
626 case DELEGATE: return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
627 case ZERO: // fall-through
628 case IDENTITY: {
629 name = name + "_" + form.returnType().basicTypeChar();
630 return resolveFrom(name, invokerType, LambdaForm.Holder.class);
631 }
632 case DIRECT_INVOKE_INTERFACE: // fall-through
633 case DIRECT_INVOKE_SPECIAL: // fall-through
634 case DIRECT_INVOKE_STATIC: // fall-through
635 case DIRECT_INVOKE_STATIC_INIT: // fall-through
636 case DIRECT_INVOKE_VIRTUAL: return resolveFrom(name, invokerType, DirectMethodHandle.Holder.class);
637 }
638 return null;
639 }
640
641 /**
642 * Generate customized bytecode for a given LambdaForm.
643 */
644 static MemberName generateCustomizedCode(LambdaForm form, MethodType invokerType) {
645 MemberName pregenerated = lookupPregenerated(form);
646 if (pregenerated != null) return pregenerated; // pre-generated bytecode
647
648 InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("MH", form, invokerType);
649 return g.loadMethod(g.generateCustomizedCodeBytes());
650 }
651
652 /** Generates code to check that actual receiver and LambdaForm matches */
653 private boolean checkActualReceiver() {
654 // Expects MethodHandle on the stack and actual receiver MethodHandle in slot #0
655 mv.visitInsn(Opcodes.DUP);
656 mv.visitVarInsn(Opcodes.ALOAD, localsMap[0]);
657 mv.visitMethodInsn(Opcodes.INVOKESTATIC, MHI, "assertSame", LLV_SIG, false);
658 return true;
659 }
660
661 static String className(String cn) {
662 assert checkClassName(cn): "Class not found: " + cn;
663 return cn;
664 }
665
666 static boolean checkClassName(String cn) {
667 Type tp = Type.getType(cn);
668 // additional sanity so only valid "L;" descriptors work
669 if (tp.getSort() != Type.OBJECT) {
670 return false;
671 }
672 try {
673 Class<?> c = Class.forName(tp.getClassName(), false, null);
674 return true;
675 } catch (ClassNotFoundException e) {
676 return false;
677 }
678 }
679
680 static final String LF_HIDDEN_SIG = className("Ljava/lang/invoke/LambdaForm$Hidden;");
681 static final String LF_COMPILED_SIG = className("Ljava/lang/invoke/LambdaForm$Compiled;");
682 static final String FORCEINLINE_SIG = className("Ljdk/internal/vm/annotation/ForceInline;");
683 static final String DONTINLINE_SIG = className("Ljdk/internal/vm/annotation/DontInline;");
684 static final String INJECTEDPROFILE_SIG = className("Ljava/lang/invoke/InjectedProfile;");
685
686 /**
687 * Generate an invoker method for the passed {@link LambdaForm}.
688 */
689 private byte[] generateCustomizedCodeBytes() {
690 classFilePrologue();
691 addMethod();
692 bogusMethod(lambdaForm);
693
694 final byte[] classFile = toByteArray();
695 maybeDump(className, classFile);
696 return classFile;
697 }
698
699 void setClassWriter(ClassWriter cw) {
700 this.cw = cw;
701 }
702
703 void addMethod() {
704 methodPrologue();
705
706 // Suppress this method in backtraces displayed to the user.
707 mv.visitAnnotation(LF_HIDDEN_SIG, true);
708
709 // Mark this method as a compiled LambdaForm
710 mv.visitAnnotation(LF_COMPILED_SIG, true);
711
712 if (lambdaForm.forceInline) {
713 // Force inlining of this invoker method.
714 mv.visitAnnotation(FORCEINLINE_SIG, true);
715 } else {
716 mv.visitAnnotation(DONTINLINE_SIG, true);
717 }
718
719 constantPlaceholder(lambdaForm); // keep LambdaForm instance & its compiled form lifetime tightly coupled.
720
721 if (lambdaForm.customized != null) {
722 // Since LambdaForm is customized for a particular MethodHandle, it's safe to substitute
723 // receiver MethodHandle (at slot #0) with an embedded constant and use it instead.
724 // It enables more efficient code generation in some situations, since embedded constants
725 // are compile-time constants for JIT compiler.
726 mv.visitLdcInsn(constantPlaceholder(lambdaForm.customized));
727 mv.visitTypeInsn(Opcodes.CHECKCAST, MH);
728 assert(checkActualReceiver()); // expects MethodHandle on top of the stack
729 mv.visitVarInsn(Opcodes.ASTORE, localsMap[0]);
730 }
731
732 // iterate over the form's names, generating bytecode instructions for each
733 // start iterating at the first name following the arguments
734 Name onStack = null;
735 for (int i = lambdaForm.arity; i < lambdaForm.names.length; i++) {
736 Name name = lambdaForm.names[i];
737
738 emitStoreResult(onStack);
739 onStack = name; // unless otherwise modified below
740 MethodHandleImpl.Intrinsic intr = name.function.intrinsicName();
741 switch (intr) {
742 case SELECT_ALTERNATIVE:
743 assert lambdaForm.isSelectAlternative(i);
744 if (PROFILE_GWT) {
745 assert(name.arguments[0] instanceof Name &&
746 ((Name)name.arguments[0]).refersTo(MethodHandleImpl.class, "profileBoolean"));
747 mv.visitAnnotation(INJECTEDPROFILE_SIG, true);
748 }
749 onStack = emitSelectAlternative(name, lambdaForm.names[i+1]);
750 i++; // skip MH.invokeBasic of the selectAlternative result
751 continue;
752 case GUARD_WITH_CATCH:
753 assert lambdaForm.isGuardWithCatch(i);
754 onStack = emitGuardWithCatch(i);
755 i += 2; // jump to the end of GWC idiom
756 continue;
757 case TRY_FINALLY:
758 assert lambdaForm.isTryFinally(i);
759 onStack = emitTryFinally(i);
760 i += 2; // jump to the end of the TF idiom
761 continue;
762 case LOOP:
763 assert lambdaForm.isLoop(i);
764 onStack = emitLoop(i);
765 i += 2; // jump to the end of the LOOP idiom
766 continue;
767 case NEW_ARRAY:
768 Class<?> rtype = name.function.methodType().returnType();
769 if (isStaticallyNameable(rtype)) {
770 emitNewArray(name);
771 continue;
772 }
773 break;
774 case ARRAY_LOAD:
775 emitArrayLoad(name);
776 continue;
777 case ARRAY_STORE:
778 emitArrayStore(name);
779 continue;
780 case ARRAY_LENGTH:
781 emitArrayLength(name);
782 continue;
783 case IDENTITY:
784 assert(name.arguments.length == 1);
785 emitPushArguments(name, 0);
786 continue;
787 case ZERO:
788 assert(name.arguments.length == 0);
789 emitConst(name.type.basicTypeWrapper().zero());
790 continue;
791 case NONE:
792 // no intrinsic associated
793 break;
794 default:
795 throw newInternalError("Unknown intrinsic: "+intr);
796 }
797
798 MemberName member = name.function.member();
799 if (isStaticallyInvocable(member)) {
800 emitStaticInvoke(member, name);
801 } else {
802 emitInvoke(name);
803 }
804 }
805
806 // return statement
807 emitReturn(onStack);
808
809 methodEpilogue();
810 }
811
812 /*
813 * @throws BytecodeGenerationException if something goes wrong when
814 * generating the byte code
815 */
816 private byte[] toByteArray() {
817 try {
818 return cw.toByteArray();
819 } catch (RuntimeException e) {
820 throw new BytecodeGenerationException(e);
821 }
822 }
823
824 @SuppressWarnings("serial")
825 static final class BytecodeGenerationException extends RuntimeException {
826 BytecodeGenerationException(Exception cause) {
827 super(cause);
828 }
829 }
830
831 void emitArrayLoad(Name name) { emitArrayOp(name, Opcodes.AALOAD); }
832 void emitArrayStore(Name name) { emitArrayOp(name, Opcodes.AASTORE); }
833 void emitArrayLength(Name name) { emitArrayOp(name, Opcodes.ARRAYLENGTH); }
834
835 void emitArrayOp(Name name, int arrayOpcode) {
836 assert arrayOpcode == Opcodes.AALOAD || arrayOpcode == Opcodes.AASTORE || arrayOpcode == Opcodes.ARRAYLENGTH;
837 Class<?> elementType = name.function.methodType().parameterType(0).getComponentType();
838 assert elementType != null;
839 emitPushArguments(name, 0);
840 if (arrayOpcode != Opcodes.ARRAYLENGTH && elementType.isPrimitive()) {
841 Wrapper w = Wrapper.forPrimitiveType(elementType);
842 arrayOpcode = arrayInsnOpcode(arrayTypeCode(w), arrayOpcode);
843 }
844 mv.visitInsn(arrayOpcode);
845 }
846
847 /**
848 * Emit an invoke for the given name.
849 */
850 void emitInvoke(Name name) {
851 assert(!name.isLinkerMethodInvoke()); // should use the static path for these
852 if (true) {
853 // push receiver
854 MethodHandle target = name.function.resolvedHandle();
855 assert(target != null) : name.exprString();
856 mv.visitLdcInsn(constantPlaceholder(target));
857 emitReferenceCast(MethodHandle.class, target);
858 } else {
859 // load receiver
860 emitAloadInsn(0);
861 emitReferenceCast(MethodHandle.class, null);
862 mv.visitFieldInsn(Opcodes.GETFIELD, MH, "form", LF_SIG);
863 mv.visitFieldInsn(Opcodes.GETFIELD, LF, "names", LFN_SIG);
864 // TODO more to come
865 }
866
867 // push arguments
868 emitPushArguments(name, 0);
869
870 // invocation
871 MethodType type = name.function.methodType();
872 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
873 }
874
875 private static Class<?>[] STATICALLY_INVOCABLE_PACKAGES = {
876 // Sample classes from each package we are willing to bind to statically:
877 java.lang.Object.class,
878 java.util.Arrays.class,
879 jdk.internal.misc.Unsafe.class
880 //MethodHandle.class already covered
881 };
882
883 static boolean isStaticallyInvocable(NamedFunction[] functions) {
884 for (NamedFunction nf : functions) {
885 if (!isStaticallyInvocable(nf.member())) {
886 return false;
887 }
888 }
889 return true;
890 }
891
892 static boolean isStaticallyInvocable(Name name) {
893 return isStaticallyInvocable(name.function.member());
894 }
895
896 static boolean isStaticallyInvocable(MemberName member) {
897 if (member == null) return false;
898 if (member.isConstructor()) return false;
899 Class<?> cls = member.getDeclaringClass();
900 if (cls.isArray() || cls.isPrimitive())
901 return false; // FIXME
902 if (cls.isAnonymousClass() || cls.isLocalClass())
903 return false; // inner class of some sort
904 if (cls.getClassLoader() != MethodHandle.class.getClassLoader())
905 return false; // not on BCP
906 if (ReflectUtil.isVMAnonymousClass(cls)) // FIXME: switch to supported API once it is added
907 return false;
908 MethodType mtype = member.getMethodOrFieldType();
909 if (!isStaticallyNameable(mtype.returnType()))
910 return false;
911 for (Class<?> ptype : mtype.parameterArray())
912 if (!isStaticallyNameable(ptype))
913 return false;
914 if (!member.isPrivate() && VerifyAccess.isSamePackage(MethodHandle.class, cls))
915 return true; // in java.lang.invoke package
916 if (member.isPublic() && isStaticallyNameable(cls))
917 return true;
918 return false;
919 }
920
921 static boolean isStaticallyNameable(Class<?> cls) {
922 if (cls == Object.class)
923 return true;
924 while (cls.isArray())
925 cls = cls.getComponentType();
926 if (cls.isPrimitive())
927 return true; // int[].class, for example
928 if (ReflectUtil.isVMAnonymousClass(cls)) // FIXME: switch to supported API once it is added
929 return false;
930 // could use VerifyAccess.isClassAccessible but the following is a safe approximation
931 if (cls.getClassLoader() != Object.class.getClassLoader())
932 return false;
933 if (VerifyAccess.isSamePackage(MethodHandle.class, cls))
934 return true;
935 if (!Modifier.isPublic(cls.getModifiers()))
936 return false;
937 for (Class<?> pkgcls : STATICALLY_INVOCABLE_PACKAGES) {
938 if (VerifyAccess.isSamePackage(pkgcls, cls))
939 return true;
940 }
941 return false;
942 }
943
944 void emitStaticInvoke(Name name) {
945 emitStaticInvoke(name.function.member(), name);
946 }
947
948 /**
949 * Emit an invoke for the given name, using the MemberName directly.
950 */
951 void emitStaticInvoke(MemberName member, Name name) {
952 assert(member.equals(name.function.member()));
953 Class<?> defc = member.getDeclaringClass();
954 String cname = getInternalName(defc);
955 String mname = member.getName();
956 String mtype;
957 byte refKind = member.getReferenceKind();
958 if (refKind == REF_invokeSpecial) {
959 // in order to pass the verifier, we need to convert this to invokevirtual in all cases
960 assert(member.canBeStaticallyBound()) : member;
961 refKind = REF_invokeVirtual;
962 }
963
964 assert(!(member.getDeclaringClass().isInterface() && refKind == REF_invokeVirtual));
965
966 // push arguments
967 emitPushArguments(name, 0);
968
969 // invocation
970 if (member.isMethod()) {
971 mtype = member.getMethodType().toMethodDescriptorString();
972 mv.visitMethodInsn(refKindOpcode(refKind), cname, mname, mtype,
973 member.getDeclaringClass().isInterface());
974 } else {
975 mtype = MethodType.toFieldDescriptorString(member.getFieldType());
976 mv.visitFieldInsn(refKindOpcode(refKind), cname, mname, mtype);
977 }
978 // Issue a type assertion for the result, so we can avoid casts later.
979 if (name.type == L_TYPE) {
980 Class<?> rtype = member.getInvocationType().returnType();
981 assert(!rtype.isPrimitive());
982 if (rtype != Object.class && !rtype.isInterface()) {
983 assertStaticType(rtype, name);
984 }
985 }
986 }
987
988 void emitNewArray(Name name) throws InternalError {
989 Class<?> rtype = name.function.methodType().returnType();
990 if (name.arguments.length == 0) {
991 // The array will be a constant.
992 Object emptyArray;
993 try {
994 emptyArray = name.function.resolvedHandle().invoke();
995 } catch (Throwable ex) {
996 throw newInternalError(ex);
997 }
998 assert(java.lang.reflect.Array.getLength(emptyArray) == 0);
999 assert(emptyArray.getClass() == rtype); // exact typing
1000 mv.visitLdcInsn(constantPlaceholder(emptyArray));
1001 emitReferenceCast(rtype, emptyArray);
1002 return;
1003 }
1004 Class<?> arrayElementType = rtype.getComponentType();
1005 assert(arrayElementType != null);
1006 emitIconstInsn(name.arguments.length);
1007 int xas = Opcodes.AASTORE;
1008 if (!arrayElementType.isPrimitive()) {
1009 mv.visitTypeInsn(Opcodes.ANEWARRAY, getInternalName(arrayElementType));
1010 } else {
1011 byte tc = arrayTypeCode(Wrapper.forPrimitiveType(arrayElementType));
1012 xas = arrayInsnOpcode(tc, xas);
1013 mv.visitIntInsn(Opcodes.NEWARRAY, tc);
1014 }
1015 // store arguments
1016 for (int i = 0; i < name.arguments.length; i++) {
1017 mv.visitInsn(Opcodes.DUP);
1018 emitIconstInsn(i);
1019 emitPushArgument(name, i);
1020 mv.visitInsn(xas);
1021 }
1022 // the array is left on the stack
1023 assertStaticType(rtype, name);
1024 }
1025 int refKindOpcode(byte refKind) {
1026 switch (refKind) {
1027 case REF_invokeVirtual: return Opcodes.INVOKEVIRTUAL;
1028 case REF_invokeStatic: return Opcodes.INVOKESTATIC;
1029 case REF_invokeSpecial: return Opcodes.INVOKESPECIAL;
1030 case REF_invokeInterface: return Opcodes.INVOKEINTERFACE;
1031 case REF_getField: return Opcodes.GETFIELD;
1032 case REF_putField: return Opcodes.PUTFIELD;
1033 case REF_getStatic: return Opcodes.GETSTATIC;
1034 case REF_putStatic: return Opcodes.PUTSTATIC;
1035 }
1036 throw new InternalError("refKind="+refKind);
1037 }
1038
1039 /**
1040 * Emit bytecode for the selectAlternative idiom.
1041 *
1042 * The pattern looks like (Cf. MethodHandleImpl.makeGuardWithTest):
1043 * <blockquote><pre>{@code
1044 * Lambda(a0:L,a1:I)=>{
1045 * t2:I=foo.test(a1:I);
1046 * t3:L=MethodHandleImpl.selectAlternative(t2:I,(MethodHandle(int)int),(MethodHandle(int)int));
1047 * t4:I=MethodHandle.invokeBasic(t3:L,a1:I);t4:I}
1048 * }</pre></blockquote>
1049 */
1050 private Name emitSelectAlternative(Name selectAlternativeName, Name invokeBasicName) {
1051 assert isStaticallyInvocable(invokeBasicName);
1052
1053 Name receiver = (Name) invokeBasicName.arguments[0];
1054
1055 Label L_fallback = new Label();
1056 Label L_done = new Label();
1057
1058 // load test result
1059 emitPushArgument(selectAlternativeName, 0);
1060
1061 // if_icmpne L_fallback
1062 mv.visitJumpInsn(Opcodes.IFEQ, L_fallback);
1063
1064 // invoke selectAlternativeName.arguments[1]
1065 Class<?>[] preForkClasses = localClasses.clone();
1066 emitPushArgument(selectAlternativeName, 1); // get 2nd argument of selectAlternative
1067 emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
1068 emitStaticInvoke(invokeBasicName);
1069
1070 // goto L_done
1071 mv.visitJumpInsn(Opcodes.GOTO, L_done);
1072
1073 // L_fallback:
1074 mv.visitLabel(L_fallback);
1075
1076 // invoke selectAlternativeName.arguments[2]
1077 System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
1078 emitPushArgument(selectAlternativeName, 2); // get 3rd argument of selectAlternative
1079 emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
1080 emitStaticInvoke(invokeBasicName);
1081
1082 // L_done:
1083 mv.visitLabel(L_done);
1084 // for now do not bother to merge typestate; just reset to the dominator state
1085 System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
1086
1087 return invokeBasicName; // return what's on stack
1088 }
1089
1090 /**
1091 * Emit bytecode for the guardWithCatch idiom.
1092 *
1093 * The pattern looks like (Cf. MethodHandleImpl.makeGuardWithCatch):
1094 * <blockquote><pre>{@code
1095 * guardWithCatch=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L,a6:L,a7:L)=>{
1096 * t8:L=MethodHandle.invokeBasic(a4:L,a6:L,a7:L);
1097 * t9:L=MethodHandleImpl.guardWithCatch(a1:L,a2:L,a3:L,t8:L);
1098 * t10:I=MethodHandle.invokeBasic(a5:L,t9:L);t10:I}
1099 * }</pre></blockquote>
1100 *
1101 * It is compiled into bytecode equivalent of the following code:
1102 * <blockquote><pre>{@code
1103 * try {
1104 * return a1.invokeBasic(a6, a7);
1105 * } catch (Throwable e) {
1106 * if (!a2.isInstance(e)) throw e;
1107 * return a3.invokeBasic(ex, a6, a7);
1108 * }}
1109 */
1110 private Name emitGuardWithCatch(int pos) {
1111 Name args = lambdaForm.names[pos];
1112 Name invoker = lambdaForm.names[pos+1];
1113 Name result = lambdaForm.names[pos+2];
1114
1115 Label L_startBlock = new Label();
1116 Label L_endBlock = new Label();
1117 Label L_handler = new Label();
1118 Label L_done = new Label();
1119
1120 Class<?> returnType = result.function.resolvedHandle().type().returnType();
1121 MethodType type = args.function.resolvedHandle().type()
1122 .dropParameterTypes(0,1)
1123 .changeReturnType(returnType);
1124
1125 mv.visitTryCatchBlock(L_startBlock, L_endBlock, L_handler, "java/lang/Throwable");
1126
1127 // Normal case
1128 mv.visitLabel(L_startBlock);
1129 // load target
1130 emitPushArgument(invoker, 0);
1131 emitPushArguments(args, 1); // skip 1st argument: method handle
1132 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
1133 mv.visitLabel(L_endBlock);
1134 mv.visitJumpInsn(Opcodes.GOTO, L_done);
1135
1136 // Exceptional case
1137 mv.visitLabel(L_handler);
1138
1139 // Check exception's type
1140 mv.visitInsn(Opcodes.DUP);
1141 // load exception class
1142 emitPushArgument(invoker, 1);
1143 mv.visitInsn(Opcodes.SWAP);
1144 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Class", "isInstance", "(Ljava/lang/Object;)Z", false);
1145 Label L_rethrow = new Label();
1146 mv.visitJumpInsn(Opcodes.IFEQ, L_rethrow);
1147
1148 // Invoke catcher
1149 // load catcher
1150 emitPushArgument(invoker, 2);
1151 mv.visitInsn(Opcodes.SWAP);
1152 emitPushArguments(args, 1); // skip 1st argument: method handle
1153 MethodType catcherType = type.insertParameterTypes(0, Throwable.class);
1154 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", catcherType.basicType().toMethodDescriptorString(), false);
1155 mv.visitJumpInsn(Opcodes.GOTO, L_done);
1156
1157 mv.visitLabel(L_rethrow);
1158 mv.visitInsn(Opcodes.ATHROW);
1159
1160 mv.visitLabel(L_done);
1161
1162 return result;
1163 }
1164
1165 /**
1166 * Emit bytecode for the tryFinally idiom.
1167 * <p>
1168 * The pattern looks like (Cf. MethodHandleImpl.makeTryFinally):
1169 * <blockquote><pre>{@code
1170 * // a0: BMH
1171 * // a1: target, a2: cleanup
1172 * // a3: box, a4: unbox
1173 * // a5 (and following): arguments
1174 * tryFinally=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L)=>{
1175 * t6:L=MethodHandle.invokeBasic(a3:L,a5:L); // box the arguments into an Object[]
1176 * t7:L=MethodHandleImpl.tryFinally(a1:L,a2:L,t6:L); // call the tryFinally executor
1177 * t8:L=MethodHandle.invokeBasic(a4:L,t7:L);t8:L} // unbox the result; return the result
1178 * }</pre></blockquote>
1179 * <p>
1180 * It is compiled into bytecode equivalent to the following code:
1181 * <blockquote><pre>{@code
1182 * Throwable t;
1183 * Object r;
1184 * try {
1185 * r = a1.invokeBasic(a5);
1186 * } catch (Throwable thrown) {
1187 * t = thrown;
1188 * throw t;
1189 * } finally {
1190 * r = a2.invokeBasic(t, r, a5);
1191 * }
1192 * return r;
1193 * }</pre></blockquote>
1194 * <p>
1195 * Specifically, the bytecode will have the following form (the stack effects are given for the beginnings of
1196 * blocks, and for the situations after executing the given instruction - the code will have a slightly different
1197 * shape if the return type is {@code void}):
1198 * <blockquote><pre>{@code
1199 * TRY: (--)
1200 * load target (-- target)
1201 * load args (-- args... target)
1202 * INVOKEVIRTUAL MethodHandle.invokeBasic (depends)
1203 * FINALLY_NORMAL: (-- r)
1204 * load cleanup (-- cleanup r)
1205 * SWAP (-- r cleanup)
1206 * ACONST_NULL (-- t r cleanup)
1207 * SWAP (-- r t cleanup)
1208 * load args (-- args... r t cleanup)
1209 * INVOKEVIRTUAL MethodHandle.invokeBasic (-- r)
1210 * GOTO DONE
1211 * CATCH: (-- t)
1212 * DUP (-- t t)
1213 * FINALLY_EXCEPTIONAL: (-- t t)
1214 * load cleanup (-- cleanup t t)
1215 * SWAP (-- t cleanup t)
1216 * load default for r (-- r t cleanup t)
1217 * load args (-- args... r t cleanup t)
1218 * INVOKEVIRTUAL MethodHandle.invokeBasic (-- r t)
1219 * POP (-- t)
1220 * ATHROW
1221 * DONE: (-- r)
1222 * }</pre></blockquote>
1223 */
1224 private Name emitTryFinally(int pos) {
1225 Name args = lambdaForm.names[pos];
1226 Name invoker = lambdaForm.names[pos+1];
1227 Name result = lambdaForm.names[pos+2];
1228
1229 Label lFrom = new Label();
1230 Label lTo = new Label();
1231 Label lCatch = new Label();
1232 Label lDone = new Label();
1233
1234 Class<?> returnType = result.function.resolvedHandle().type().returnType();
1235 boolean isNonVoid = returnType != void.class;
1236 MethodType type = args.function.resolvedHandle().type()
1237 .dropParameterTypes(0,1)
1238 .changeReturnType(returnType);
1239 MethodType cleanupType = type.insertParameterTypes(0, Throwable.class);
1240 if (isNonVoid) {
1241 cleanupType = cleanupType.insertParameterTypes(1, returnType);
1242 }
1243 String cleanupDesc = cleanupType.basicType().toMethodDescriptorString();
1244
1245 // exception handler table
1246 mv.visitTryCatchBlock(lFrom, lTo, lCatch, "java/lang/Throwable");
1247
1248 // TRY:
1249 mv.visitLabel(lFrom);
1250 emitPushArgument(invoker, 0); // load target
1251 emitPushArguments(args, 1); // load args (skip 0: method handle)
1252 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
1253 mv.visitLabel(lTo);
1254
1255 // FINALLY_NORMAL:
1256 emitPushArgument(invoker, 1); // load cleanup
1257 if (isNonVoid) {
1258 mv.visitInsn(Opcodes.SWAP);
1259 }
1260 mv.visitInsn(Opcodes.ACONST_NULL);
1261 if (isNonVoid) {
1262 mv.visitInsn(Opcodes.SWAP);
1263 }
1264 emitPushArguments(args, 1); // load args (skip 0: method handle)
1265 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", cleanupDesc, false);
1266 mv.visitJumpInsn(Opcodes.GOTO, lDone);
1267
1268 // CATCH:
1269 mv.visitLabel(lCatch);
1270 mv.visitInsn(Opcodes.DUP);
1271
1272 // FINALLY_EXCEPTIONAL:
1273 emitPushArgument(invoker, 1); // load cleanup
1274 mv.visitInsn(Opcodes.SWAP);
1275 if (isNonVoid) {
1276 emitZero(BasicType.basicType(returnType)); // load default for result
1277 }
1278 emitPushArguments(args, 1); // load args (skip 0: method handle)
1279 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", cleanupDesc, false);
1280 if (isNonVoid) {
1281 mv.visitInsn(Opcodes.POP);
1282 }
1283 mv.visitInsn(Opcodes.ATHROW);
1284
1285 // DONE:
1286 mv.visitLabel(lDone);
1287
1288 return result;
1289 }
1290
1291 /**
1292 * Emit bytecode for the loop idiom.
1293 * <p>
1294 * The pattern looks like (Cf. MethodHandleImpl.loop):
1295 * <blockquote><pre>{@code
1296 * // a0: BMH
1297 * // a1: inits, a2: steps, a3: preds, a4: finis
1298 * // a5: box, a6: unbox
1299 * // a7 (and following): arguments
1300 * loop=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L,a6:L,a7:L)=>{
1301 * t8:L=MethodHandle.invokeBasic(a5:L,a7:L); // box the arguments into an Object[]
1302 * 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)
1303 * t10:L=MethodHandle.invokeBasic(a6:L,t9:L);t10:L} // unbox the result; return the result
1304 * }</pre></blockquote>
1305 * <p>
1306 * It is compiled into bytecode equivalent to the code seen in {@link MethodHandleImpl#loop(BasicType[],
1307 * MethodHandle[], MethodHandle[], MethodHandle[], MethodHandle[], Object...)}, with the difference that no arrays
1308 * will be used for local state storage. Instead, the local state will be mapped to actual stack slots.
1309 * <p>
1310 * Bytecode generation applies an unrolling scheme to enable better bytecode generation regarding local state type
1311 * handling. The generated bytecode will have the following form ({@code void} types are ignored for convenience).
1312 * Assume there are {@code C} clauses in the loop.
1313 * <blockquote><pre>{@code
1314 * INIT: (INIT_SEQ for clause 1)
1315 * ...
1316 * (INIT_SEQ for clause C)
1317 * LOOP: (LOOP_SEQ for clause 1)
1318 * ...
1319 * (LOOP_SEQ for clause C)
1320 * GOTO LOOP
1321 * DONE: ...
1322 * }</pre></blockquote>
1323 * <p>
1324 * The {@code INIT_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
1325 * the following shape. Assume slot {@code vx} is used to hold the state for clause {@code x}.
1326 * <blockquote><pre>{@code
1327 * INIT_SEQ_x: ALOAD inits
1328 * CHECKCAST MethodHandle[]
1329 * ICONST x
1330 * AALOAD // load the init handle for clause x
1331 * load args
1332 * INVOKEVIRTUAL MethodHandle.invokeBasic
1333 * store vx
1334 * }</pre></blockquote>
1335 * <p>
1336 * The {@code LOOP_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
1337 * the following shape. Again, assume slot {@code vx} is used to hold the state for clause {@code x}.
1338 * <blockquote><pre>{@code
1339 * LOOP_SEQ_x: ALOAD steps
1340 * CHECKCAST MethodHandle[]
1341 * ICONST x
1342 * AALOAD // load the step handle for clause x
1343 * load locals
1344 * load args
1345 * INVOKEVIRTUAL MethodHandle.invokeBasic
1346 * store vx
1347 * ALOAD preds
1348 * CHECKCAST MethodHandle[]
1349 * ICONST x
1350 * AALOAD // load the pred handle for clause x
1351 * load locals
1352 * load args
1353 * INVOKEVIRTUAL MethodHandle.invokeBasic
1354 * IFNE LOOP_SEQ_x+1 // predicate returned false -> jump to next clause
1355 * ALOAD finis
1356 * CHECKCAST MethodHandle[]
1357 * ICONST x
1358 * AALOAD // load the fini handle for clause x
1359 * load locals
1360 * load args
1361 * INVOKEVIRTUAL MethodHandle.invokeBasic
1362 * GOTO DONE // jump beyond end of clauses to return from loop
1363 * }</pre></blockquote>
1364 */
1365 private Name emitLoop(int pos) {
1366 Name args = lambdaForm.names[pos];
1367 Name invoker = lambdaForm.names[pos+1];
1368 Name result = lambdaForm.names[pos+2];
1369
1370 // extract clause and loop-local state types
1371 // find the type info in the loop invocation
1372 BasicType[] loopClauseTypes = (BasicType[]) invoker.arguments[0];
1373 Class<?>[] loopLocalStateTypes = Stream.of(loopClauseTypes).
1374 filter(bt -> bt != BasicType.V_TYPE).map(BasicType::basicTypeClass).toArray(Class<?>[]::new);
1375
1376 final int firstLoopStateIndex = extendLocalsMap(loopLocalStateTypes);
1377
1378 Class<?> returnType = result.function.resolvedHandle().type().returnType();
1379 MethodType loopType = args.function.resolvedHandle().type()
1380 .dropParameterTypes(0,1)
1381 .changeReturnType(returnType);
1382 MethodType loopHandleType = loopType.insertParameterTypes(0, loopLocalStateTypes);
1383 MethodType predType = loopHandleType.changeReturnType(boolean.class);
1384 MethodType finiType = loopHandleType;
1385
1386 final int nClauses = loopClauseTypes.length;
1387
1388 // indices to invoker arguments to load method handle arrays
1389 final int inits = 1;
1390 final int steps = 2;
1391 final int preds = 3;
1392 final int finis = 4;
1393
1394 Label lLoop = new Label();
1395 Label lDone = new Label();
1396 Label lNext;
1397
1398 // INIT:
1399 for (int c = 0, state = 0; c < nClauses; ++c) {
1400 MethodType cInitType = loopType.changeReturnType(loopClauseTypes[c].basicTypeClass());
1401 emitLoopHandleInvoke(invoker, inits, c, args, false, cInitType, loopLocalStateTypes, firstLoopStateIndex);
1402 if (cInitType.returnType() != void.class) {
1403 emitStoreInsn(BasicType.basicType(cInitType.returnType()), firstLoopStateIndex + state);
1404 ++state;
1405 }
1406 }
1407
1408 // LOOP:
1409 mv.visitLabel(lLoop);
1410
1411 for (int c = 0, state = 0; c < nClauses; ++c) {
1412 lNext = new Label();
1413
1414 MethodType stepType = loopHandleType.changeReturnType(loopClauseTypes[c].basicTypeClass());
1415 boolean isVoid = stepType.returnType() == void.class;
1416
1417 // invoke loop step
1418 emitLoopHandleInvoke(invoker, steps, c, args, true, stepType, loopLocalStateTypes, firstLoopStateIndex);
1419 if (!isVoid) {
1420 emitStoreInsn(BasicType.basicType(stepType.returnType()), firstLoopStateIndex + state);
1421 ++state;
1422 }
1423
1424 // invoke loop predicate
1425 emitLoopHandleInvoke(invoker, preds, c, args, true, predType, loopLocalStateTypes, firstLoopStateIndex);
1426 mv.visitJumpInsn(Opcodes.IFNE, lNext);
1427
1428 // invoke fini
1429 emitLoopHandleInvoke(invoker, finis, c, args, true, finiType, loopLocalStateTypes, firstLoopStateIndex);
1430 mv.visitJumpInsn(Opcodes.GOTO, lDone);
1431
1432 // this is the beginning of the next loop clause
1433 mv.visitLabel(lNext);
1434 }
1435
1436 mv.visitJumpInsn(Opcodes.GOTO, lLoop);
1437
1438 // DONE:
1439 mv.visitLabel(lDone);
1440
1441 return result;
1442 }
1443
1444 private int extendLocalsMap(Class<?>[] types) {
1445 int firstSlot = localsMap.length - 1;
1446 localsMap = Arrays.copyOf(localsMap, localsMap.length + types.length);
1447 localClasses = Arrays.copyOf(localClasses, localClasses.length + types.length);
1448 System.arraycopy(types, 0, localClasses, firstSlot, types.length);
1449 int index = localsMap[firstSlot - 1] + 1;
1450 int lastSlots = 0;
1451 for (int i = 0; i < types.length; ++i) {
1452 localsMap[firstSlot + i] = index;
1453 lastSlots = BasicType.basicType(localClasses[firstSlot + i]).basicTypeSlots();
1454 index += lastSlots;
1455 }
1456 localsMap[localsMap.length - 1] = index - lastSlots;
1457 return firstSlot;
1458 }
1459
1460 private void emitLoopHandleInvoke(Name holder, int handles, int clause, Name args, boolean pushLocalState,
1461 MethodType type, Class<?>[] loopLocalStateTypes, int firstLoopStateSlot) {
1462 // load handle for clause
1463 emitPushArgument(holder, handles);
1464 emitIconstInsn(clause);
1465 mv.visitInsn(Opcodes.AALOAD);
1466 // load loop state (preceding the other arguments)
1467 if (pushLocalState) {
1468 for (int s = 0; s < loopLocalStateTypes.length; ++s) {
1469 emitLoadInsn(BasicType.basicType(loopLocalStateTypes[s]), firstLoopStateSlot + s);
1470 }
1471 }
1472 // load loop args (skip 0: method handle)
1473 emitPushArguments(args, 1);
1474 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.toMethodDescriptorString(), false);
1475 }
1476
1477 private void emitZero(BasicType type) {
1478 switch (type) {
1479 case I_TYPE: mv.visitInsn(Opcodes.ICONST_0); break;
1480 case J_TYPE: mv.visitInsn(Opcodes.LCONST_0); break;
1481 case F_TYPE: mv.visitInsn(Opcodes.FCONST_0); break;
1482 case D_TYPE: mv.visitInsn(Opcodes.DCONST_0); break;
1483 case L_TYPE: mv.visitInsn(Opcodes.ACONST_NULL); break;
1484 default: throw new InternalError("unknown type: " + type);
1485 }
1486 }
1487
1488 private void emitPushArguments(Name args, int start) {
1489 MethodType type = args.function.methodType();
1490 for (int i = start; i < args.arguments.length; i++) {
1491 emitPushArgument(type.parameterType(i), args.arguments[i]);
1492 }
1493 }
1494
1495 private void emitPushArgument(Name name, int paramIndex) {
1496 Object arg = name.arguments[paramIndex];
1497 Class<?> ptype = name.function.methodType().parameterType(paramIndex);
1498 emitPushArgument(ptype, arg);
1499 }
1500
1501 private void emitPushArgument(Class<?> ptype, Object arg) {
1502 BasicType bptype = basicType(ptype);
1503 if (arg instanceof Name) {
1504 Name n = (Name) arg;
1505 emitLoadInsn(n.type, n.index());
1506 emitImplicitConversion(n.type, ptype, n);
1507 } else if ((arg == null || arg instanceof String) && bptype == L_TYPE) {
1508 emitConst(arg);
1509 } else {
1510 if (Wrapper.isWrapperType(arg.getClass()) && bptype != L_TYPE) {
1511 emitConst(arg);
1512 } else {
1513 mv.visitLdcInsn(constantPlaceholder(arg));
1514 emitImplicitConversion(L_TYPE, ptype, arg);
1515 }
1516 }
1517 }
1518
1519 /**
1520 * Store the name to its local, if necessary.
1521 */
1522 private void emitStoreResult(Name name) {
1523 if (name != null && name.type != V_TYPE) {
1524 // non-void: actually assign
1525 emitStoreInsn(name.type, name.index());
1526 }
1527 }
1528
1529 /**
1530 * Emits a return statement from a LF invoker. If required, the result type is cast to the correct return type.
1531 */
1532 private void emitReturn(Name onStack) {
1533 // return statement
1534 Class<?> rclass = invokerType.returnType();
1535 BasicType rtype = lambdaForm.returnType();
1536 assert(rtype == basicType(rclass)); // must agree
1537 if (rtype == V_TYPE) {
1538 // void
1539 mv.visitInsn(Opcodes.RETURN);
1540 // it doesn't matter what rclass is; the JVM will discard any value
1541 } else {
1542 LambdaForm.Name rn = lambdaForm.names[lambdaForm.result];
1543
1544 // put return value on the stack if it is not already there
1545 if (rn != onStack) {
1546 emitLoadInsn(rtype, lambdaForm.result);
1547 }
1548
1549 emitImplicitConversion(rtype, rclass, rn);
1550
1551 // generate actual return statement
1552 emitReturnInsn(rtype);
1553 }
1554 }
1555
1556 /**
1557 * Emit a type conversion bytecode casting from "from" to "to".
1558 */
1559 private void emitPrimCast(Wrapper from, Wrapper to) {
1560 // Here's how.
1561 // - indicates forbidden
1562 // <-> indicates implicit
1563 // to ----> boolean byte short char int long float double
1564 // from boolean <-> - - - - - - -
1565 // byte - <-> i2s i2c <-> i2l i2f i2d
1566 // short - i2b <-> i2c <-> i2l i2f i2d
1567 // char - i2b i2s <-> <-> i2l i2f i2d
1568 // int - i2b i2s i2c <-> i2l i2f i2d
1569 // long - l2i,i2b l2i,i2s l2i,i2c l2i <-> l2f l2d
1570 // float - f2i,i2b f2i,i2s f2i,i2c f2i f2l <-> f2d
1571 // double - d2i,i2b d2i,i2s d2i,i2c d2i d2l d2f <->
1572 if (from == to) {
1573 // no cast required, should be dead code anyway
1574 return;
1575 }
1576 if (from.isSubwordOrInt()) {
1577 // cast from {byte,short,char,int} to anything
1578 emitI2X(to);
1579 } else {
1580 // cast from {long,float,double} to anything
1581 if (to.isSubwordOrInt()) {
1582 // cast to {byte,short,char,int}
1583 emitX2I(from);
1584 if (to.bitWidth() < 32) {
1585 // targets other than int require another conversion
1586 emitI2X(to);
1587 }
1588 } else {
1589 // cast to {long,float,double} - this is verbose
1590 boolean error = false;
1591 switch (from) {
1592 case LONG:
1593 switch (to) {
1594 case FLOAT: mv.visitInsn(Opcodes.L2F); break;
1595 case DOUBLE: mv.visitInsn(Opcodes.L2D); break;
1596 default: error = true; break;
1597 }
1598 break;
1599 case FLOAT:
1600 switch (to) {
1601 case LONG : mv.visitInsn(Opcodes.F2L); break;
1602 case DOUBLE: mv.visitInsn(Opcodes.F2D); break;
1603 default: error = true; break;
1604 }
1605 break;
1606 case DOUBLE:
1607 switch (to) {
1608 case LONG : mv.visitInsn(Opcodes.D2L); break;
1609 case FLOAT: mv.visitInsn(Opcodes.D2F); break;
1610 default: error = true; break;
1611 }
1612 break;
1613 default:
1614 error = true;
1615 break;
1616 }
1617 if (error) {
1618 throw new IllegalStateException("unhandled prim cast: " + from + "2" + to);
1619 }
1620 }
1621 }
1622 }
1623
1624 private void emitI2X(Wrapper type) {
1625 switch (type) {
1626 case BYTE: mv.visitInsn(Opcodes.I2B); break;
1627 case SHORT: mv.visitInsn(Opcodes.I2S); break;
1628 case CHAR: mv.visitInsn(Opcodes.I2C); break;
1629 case INT: /* naught */ break;
1630 case LONG: mv.visitInsn(Opcodes.I2L); break;
1631 case FLOAT: mv.visitInsn(Opcodes.I2F); break;
1632 case DOUBLE: mv.visitInsn(Opcodes.I2D); break;
1633 case BOOLEAN:
1634 // For compatibility with ValueConversions and explicitCastArguments:
1635 mv.visitInsn(Opcodes.ICONST_1);
1636 mv.visitInsn(Opcodes.IAND);
1637 break;
1638 default: throw new InternalError("unknown type: " + type);
1639 }
1640 }
1641
1642 private void emitX2I(Wrapper type) {
1643 switch (type) {
1644 case LONG: mv.visitInsn(Opcodes.L2I); break;
1645 case FLOAT: mv.visitInsn(Opcodes.F2I); break;
1646 case DOUBLE: mv.visitInsn(Opcodes.D2I); break;
1647 default: throw new InternalError("unknown type: " + type);
1648 }
1649 }
1650
1651 /**
1652 * Generate bytecode for a LambdaForm.vmentry which calls interpretWithArguments.
1653 */
1654 static MemberName generateLambdaFormInterpreterEntryPoint(MethodType mt) {
1655 assert(isValidSignature(basicTypeSignature(mt)));
1656 String name = "interpret_"+basicTypeChar(mt.returnType());
1657 MethodType type = mt; // includes leading argument
1658 type = type.changeParameterType(0, MethodHandle.class);
1659 InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("LFI", name, type);
1660 return g.loadMethod(g.generateLambdaFormInterpreterEntryPointBytes());
1661 }
1662
1663 private byte[] generateLambdaFormInterpreterEntryPointBytes() {
1664 classFilePrologue();
1665 methodPrologue();
1666
1667 // Suppress this method in backtraces displayed to the user.
1668 mv.visitAnnotation(LF_HIDDEN_SIG, true);
1669
1670 // Don't inline the interpreter entry.
1671 mv.visitAnnotation(DONTINLINE_SIG, true);
1672
1673 // create parameter array
1674 emitIconstInsn(invokerType.parameterCount());
1675 mv.visitTypeInsn(Opcodes.ANEWARRAY, "java/lang/Object");
1676
1677 // fill parameter array
1678 for (int i = 0; i < invokerType.parameterCount(); i++) {
1679 Class<?> ptype = invokerType.parameterType(i);
1680 mv.visitInsn(Opcodes.DUP);
1681 emitIconstInsn(i);
1682 emitLoadInsn(basicType(ptype), i);
1683 // box if primitive type
1684 if (ptype.isPrimitive()) {
1685 emitBoxing(Wrapper.forPrimitiveType(ptype));
1686 }
1687 mv.visitInsn(Opcodes.AASTORE);
1688 }
1689 // invoke
1690 emitAloadInsn(0);
1691 mv.visitFieldInsn(Opcodes.GETFIELD, MH, "form", "Ljava/lang/invoke/LambdaForm;");
1692 mv.visitInsn(Opcodes.SWAP); // swap form and array; avoid local variable
1693 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, LF, "interpretWithArguments", "([Ljava/lang/Object;)Ljava/lang/Object;", false);
1694
1695 // maybe unbox
1696 Class<?> rtype = invokerType.returnType();
1697 if (rtype.isPrimitive() && rtype != void.class) {
1698 emitUnboxing(Wrapper.forPrimitiveType(rtype));
1699 }
1700
1701 // return statement
1702 emitReturnInsn(basicType(rtype));
1703
1704 methodEpilogue();
1705 bogusMethod(invokerType);
1706
1707 final byte[] classFile = cw.toByteArray();
1708 maybeDump(className, classFile);
1709 return classFile;
1710 }
1711
1712 /**
1713 * Generate bytecode for a NamedFunction invoker.
1714 */
1715 static MemberName generateNamedFunctionInvoker(MethodTypeForm typeForm) {
1716 MethodType invokerType = NamedFunction.INVOKER_METHOD_TYPE;
1717 String invokerName = "invoke_" + shortenSignature(basicTypeSignature(typeForm.erasedType()));
1718 InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("NFI", invokerName, invokerType);
1719 return g.loadMethod(g.generateNamedFunctionInvokerImpl(typeForm));
1720 }
1721
1722 private byte[] generateNamedFunctionInvokerImpl(MethodTypeForm typeForm) {
1723 MethodType dstType = typeForm.erasedType();
1724 classFilePrologue();
1725 methodPrologue();
1726
1727 // Suppress this method in backtraces displayed to the user.
1728 mv.visitAnnotation(LF_HIDDEN_SIG, true);
1729
1730 // Force inlining of this invoker method.
1731 mv.visitAnnotation(FORCEINLINE_SIG, true);
1732
1733 // Load receiver
1734 emitAloadInsn(0);
1735
1736 // Load arguments from array
1737 for (int i = 0; i < dstType.parameterCount(); i++) {
1738 emitAloadInsn(1);
1739 emitIconstInsn(i);
1740 mv.visitInsn(Opcodes.AALOAD);
1741
1742 // Maybe unbox
1743 Class<?> dptype = dstType.parameterType(i);
1744 if (dptype.isPrimitive()) {
1745 Wrapper dstWrapper = Wrapper.forBasicType(dptype);
1746 Wrapper srcWrapper = dstWrapper.isSubwordOrInt() ? Wrapper.INT : dstWrapper; // narrow subword from int
1747 emitUnboxing(srcWrapper);
1748 emitPrimCast(srcWrapper, dstWrapper);
1749 }
1750 }
1751
1752 // Invoke
1753 String targetDesc = dstType.basicType().toMethodDescriptorString();
1754 mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", targetDesc, false);
1755
1756 // Box primitive types
1757 Class<?> rtype = dstType.returnType();
1758 if (rtype != void.class && rtype.isPrimitive()) {
1759 Wrapper srcWrapper = Wrapper.forBasicType(rtype);
1760 Wrapper dstWrapper = srcWrapper.isSubwordOrInt() ? Wrapper.INT : srcWrapper; // widen subword to int
1761 // boolean casts not allowed
1762 emitPrimCast(srcWrapper, dstWrapper);
1763 emitBoxing(dstWrapper);
1764 }
1765
1766 // If the return type is void we return a null reference.
1767 if (rtype == void.class) {
1768 mv.visitInsn(Opcodes.ACONST_NULL);
1769 }
1770 emitReturnInsn(L_TYPE); // NOTE: NamedFunction invokers always return a reference value.
1771
1772 methodEpilogue();
1773 bogusMethod(dstType);
1774
1775 final byte[] classFile = cw.toByteArray();
1776 maybeDump(className, classFile);
1777 return classFile;
1778 }
1779
1780 /**
1781 * Emit a bogus method that just loads some string constants. This is to get the constants into the constant pool
1782 * for debugging purposes.
1783 */
1784 private void bogusMethod(Object... os) {
1785 if (DUMP_CLASS_FILES) {
1786 mv = cw.visitMethod(Opcodes.ACC_STATIC, "dummy", "()V", null, null);
1787 for (Object o : os) {
1788 mv.visitLdcInsn(o.toString());
1789 mv.visitInsn(Opcodes.POP);
1790 }
1791 mv.visitInsn(Opcodes.RETURN);
1792 mv.visitMaxs(0, 0);
1793 mv.visitEnd();
1794 }
1795 }
1796 }