rev 17771 : 8184777: species logic for BoundMethodHandle doesn't scale, needs refactor

   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.ArrayList;
  43 import java.util.Arrays;
  44 import java.util.HashMap;
  45 import java.util.stream.Stream;
  46 
  47 import static java.lang.invoke.LambdaForm.BasicType;
  48 import static java.lang.invoke.LambdaForm.BasicType.*;
  49 import static java.lang.invoke.LambdaForm.*;
  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$Name";
  64     private static final String CLS     = "java/lang/Class";
  65     private static final String OBJ     = "java/lang/Object";
  66     private static final String OBJARY  = "[Ljava/lang/Object;";
  67 
  68     private static final String LOOP_CLAUSES = MHI + "$LoopClauses";
  69     private static final String MHARY2       = "[[L" + MH + ";";
  70 
  71     private static final String LF_SIG  = "L" + LF + ";";
  72     private static final String LFN_SIG = "L" + LFN + ";";
  73     private static final String LL_SIG  = "(L" + OBJ + ";)L" + OBJ + ";";
  74     private static final String LLV_SIG = "(L" + OBJ + ";L" + OBJ + ";)V";
  75     private static final String CLASS_PREFIX = LF + "$";
  76     private static final String SOURCE_PREFIX = "LambdaForm$";
  77 
  78     /** Name of its super class*/
  79     static final String INVOKER_SUPER_NAME = OBJ;
  80 
  81     /** Name of new class */
  82     private final String className;
  83 
  84     private final LambdaForm lambdaForm;
  85     private final String     invokerName;
  86     private final MethodType invokerType;
  87 
  88     /** Info about local variables in compiled lambda form */
  89     private int[]       localsMap;    // index
  90     private Class<?>[]  localClasses; // type
  91 
  92     /** ASM bytecode generation. */
  93     private ClassWriter cw;
  94     private MethodVisitor mv;
  95 
  96     private static final MemberName.Factory MEMBERNAME_FACTORY = MemberName.getFactory();
  97     private static final Class<?> HOST_CLASS = LambdaForm.class;
  98 
  99     /** Main constructor; other constructors delegate to this one. */
 100     private InvokerBytecodeGenerator(LambdaForm lambdaForm, int localsMapSize,
 101                                      String className, String invokerName, MethodType invokerType) {
 102         int p = invokerName.indexOf('.');
 103         if (p > -1) {
 104             className = invokerName.substring(0, p);
 105             invokerName = invokerName.substring(p + 1);
 106         }
 107         if (DUMP_CLASS_FILES) {
 108             className = makeDumpableClassName(className);
 109         }
 110         this.className  = 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.lambdaName(), 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     private void maybeDump(final byte[] classFile) {
 174         if (DUMP_CLASS_FILES) {
 175             maybeDump(CLASS_PREFIX + className, classFile);
 176         }
 177     }
 178 
 179     // Also used from BoundMethodHandle
 180     static void maybeDump(final String className, final byte[] classFile) {
 181         if (DUMP_CLASS_FILES) {
 182             java.security.AccessController.doPrivileged(
 183             new java.security.PrivilegedAction<>() {
 184                 public Void run() {
 185                     try {
 186                         String dumpName = className;
 187                         //dumpName = dumpName.replace('/', '-');
 188                         File dumpFile = new File(DUMP_CLASS_FILES_DIR, dumpName+".class");
 189                         System.out.println("dump: " + dumpFile);
 190                         dumpFile.getParentFile().mkdirs();
 191                         FileOutputStream file = new FileOutputStream(dumpFile);
 192                         file.write(classFile);
 193                         file.close();
 194                         return null;
 195                     } catch (IOException ex) {
 196                         throw newInternalError(ex);
 197                     }
 198                 }
 199             });
 200         }
 201     }
 202 
 203     private static String makeDumpableClassName(String className) {
 204         Integer ctr;
 205         synchronized (DUMP_CLASS_FILES_COUNTERS) {
 206             ctr = DUMP_CLASS_FILES_COUNTERS.get(className);
 207             if (ctr == null)  ctr = 0;
 208             DUMP_CLASS_FILES_COUNTERS.put(className, ctr+1);
 209         }
 210         String sfx = ctr.toString();
 211         while (sfx.length() < 3)
 212             sfx = "0"+sfx;
 213         className += sfx;
 214         return className;
 215     }
 216 
 217     class CpPatch {
 218         final int index;
 219         final Object value;
 220         CpPatch(int index, Object value) {
 221             this.index = index;
 222             this.value = value;
 223         }
 224         public String toString() {
 225             return "CpPatch/index="+index+",value="+value;
 226         }
 227     }
 228 
 229     private final ArrayList<CpPatch> cpPatches = new ArrayList<>();
 230 
 231     private int cph = 0;  // for counting constant placeholders
 232 
 233     String constantPlaceholder(Object arg) {
 234         String cpPlaceholder = "CONSTANT_PLACEHOLDER_" + cph++;
 235         if (DUMP_CLASS_FILES) cpPlaceholder += " <<" + debugString(arg) + ">>";
 236         // TODO check if arg is already in the constant pool
 237         // insert placeholder in CP and remember the patch
 238         int index = cw.newConst((Object) cpPlaceholder);
 239         cpPatches.add(new CpPatch(index, arg));
 240         return cpPlaceholder;
 241     }
 242 
 243     Object[] cpPatches(byte[] classFile) {
 244         int size = getConstantPoolSize(classFile);
 245         Object[] res = new Object[size];
 246         for (CpPatch p : cpPatches) {
 247             if (p.index >= size)
 248                 throw new InternalError("in cpool["+size+"]: "+p+"\n"+Arrays.toString(Arrays.copyOf(classFile, 20)));
 249             res[p.index] = p.value;
 250         }
 251         return res;
 252     }
 253 
 254     private static String debugString(Object arg) {
 255         if (arg instanceof MethodHandle) {
 256             MethodHandle mh = (MethodHandle) arg;
 257             MemberName member = mh.internalMemberName();
 258             if (member != null)
 259                 return member.toString();
 260             return mh.debugString();
 261         }
 262         return arg.toString();
 263     }
 264 
 265     /**
 266      * Extract the number of constant pool entries from a given class file.
 267      *
 268      * @param classFile the bytes of the class file in question.
 269      * @return the number of entries in the constant pool.
 270      */
 271     private static int getConstantPoolSize(byte[] classFile) {
 272         // The first few bytes:
 273         // u4 magic;
 274         // u2 minor_version;
 275         // u2 major_version;
 276         // u2 constant_pool_count;
 277         return ((classFile[8] & 0xFF) << 8) | (classFile[9] & 0xFF);
 278     }
 279 
 280     /**
 281      * Extract the MemberName of a newly-defined method.
 282      */
 283     private MemberName loadMethod(byte[] classFile) {
 284         Class<?> invokerClass = loadAndInitializeInvokerClass(classFile, cpPatches(classFile));
 285         return resolveInvokerMember(invokerClass, invokerName, invokerType);
 286     }
 287 
 288     /**
 289      * Define a given class as anonymous class in the runtime system.
 290      */
 291     private static Class<?> loadAndInitializeInvokerClass(byte[] classBytes, Object[] patches) {
 292         Class<?> invokerClass = UNSAFE.defineAnonymousClass(HOST_CLASS, classBytes, patches);
 293         UNSAFE.ensureClassInitialized(invokerClass);  // Make sure the class is initialized; VM might complain.
 294         return invokerClass;
 295     }
 296 
 297     private static MemberName resolveInvokerMember(Class<?> invokerClass, String name, MethodType type) {
 298         MemberName member = new MemberName(invokerClass, name, type, REF_invokeStatic);
 299         try {
 300             member = MEMBERNAME_FACTORY.resolveOrFail(REF_invokeStatic, member, HOST_CLASS, ReflectiveOperationException.class);
 301         } catch (ReflectiveOperationException e) {
 302             throw newInternalError(e);
 303         }
 304         return member;
 305     }
 306 
 307     /**
 308      * Set up class file generation.
 309      */
 310     private ClassWriter classFilePrologue() {
 311         final int NOT_ACC_PUBLIC = 0;  // not ACC_PUBLIC
 312         cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);
 313         cw.visit(Opcodes.V1_8, NOT_ACC_PUBLIC + Opcodes.ACC_FINAL + Opcodes.ACC_SUPER,
 314                 CLASS_PREFIX + className, null, INVOKER_SUPER_NAME, null);
 315         cw.visitSource(SOURCE_PREFIX + className, null);
 316         return cw;
 317     }
 318 
 319     private void methodPrologue() {
 320         String invokerDesc = invokerType.toMethodDescriptorString();
 321         mv = cw.visitMethod(Opcodes.ACC_STATIC, invokerName, invokerDesc, null, null);
 322     }
 323 
 324     /**
 325      * Tear down class file generation.
 326      */
 327     private void methodEpilogue() {
 328         mv.visitMaxs(0, 0);
 329         mv.visitEnd();
 330     }
 331 
 332     /*
 333      * Low-level emit helpers.
 334      */
 335     private void emitConst(Object con) {
 336         if (con == null) {
 337             mv.visitInsn(Opcodes.ACONST_NULL);
 338             return;
 339         }
 340         if (con instanceof Integer) {
 341             emitIconstInsn((int) con);
 342             return;
 343         }
 344         if (con instanceof Byte) {
 345             emitIconstInsn((byte)con);
 346             return;
 347         }
 348         if (con instanceof Short) {
 349             emitIconstInsn((short)con);
 350             return;
 351         }
 352         if (con instanceof Character) {
 353             emitIconstInsn((char)con);
 354             return;
 355         }
 356         if (con instanceof Long) {
 357             long x = (long) con;
 358             short sx = (short)x;
 359             if (x == sx) {
 360                 if (sx >= 0 && sx <= 1) {
 361                     mv.visitInsn(Opcodes.LCONST_0 + (int) sx);
 362                 } else {
 363                     emitIconstInsn((int) x);
 364                     mv.visitInsn(Opcodes.I2L);
 365                 }
 366                 return;
 367             }
 368         }
 369         if (con instanceof Float) {
 370             float x = (float) con;
 371             short sx = (short)x;
 372             if (x == sx) {
 373                 if (sx >= 0 && sx <= 2) {
 374                     mv.visitInsn(Opcodes.FCONST_0 + (int) sx);
 375                 } else {
 376                     emitIconstInsn((int) x);
 377                     mv.visitInsn(Opcodes.I2F);
 378                 }
 379                 return;
 380             }
 381         }
 382         if (con instanceof Double) {
 383             double x = (double) con;
 384             short sx = (short)x;
 385             if (x == sx) {
 386                 if (sx >= 0 && sx <= 1) {
 387                     mv.visitInsn(Opcodes.DCONST_0 + (int) sx);
 388                 } else {
 389                     emitIconstInsn((int) x);
 390                     mv.visitInsn(Opcodes.I2D);
 391                 }
 392                 return;
 393             }
 394         }
 395         if (con instanceof Boolean) {
 396             emitIconstInsn((boolean) con ? 1 : 0);
 397             return;
 398         }
 399         // fall through:
 400         mv.visitLdcInsn(con);
 401     }
 402 
 403     private void emitIconstInsn(final int cst) {
 404         if (cst >= -1 && cst <= 5) {
 405             mv.visitInsn(Opcodes.ICONST_0 + cst);
 406         } else if (cst >= Byte.MIN_VALUE && cst <= Byte.MAX_VALUE) {
 407             mv.visitIntInsn(Opcodes.BIPUSH, cst);
 408         } else if (cst >= Short.MIN_VALUE && cst <= Short.MAX_VALUE) {
 409             mv.visitIntInsn(Opcodes.SIPUSH, cst);
 410         } else {
 411             mv.visitLdcInsn(cst);
 412         }
 413     }
 414 
 415     /*
 416      * NOTE: These load/store methods use the localsMap to find the correct index!
 417      */
 418     private void emitLoadInsn(BasicType type, int index) {
 419         int opcode = loadInsnOpcode(type);
 420         mv.visitVarInsn(opcode, localsMap[index]);
 421     }
 422 
 423     private int loadInsnOpcode(BasicType type) throws InternalError {
 424         switch (type) {
 425             case I_TYPE: return Opcodes.ILOAD;
 426             case J_TYPE: return Opcodes.LLOAD;
 427             case F_TYPE: return Opcodes.FLOAD;
 428             case D_TYPE: return Opcodes.DLOAD;
 429             case L_TYPE: return Opcodes.ALOAD;
 430             default:
 431                 throw new InternalError("unknown type: " + type);
 432         }
 433     }
 434     private void emitAloadInsn(int index) {
 435         emitLoadInsn(L_TYPE, index);
 436     }
 437 
 438     private void emitStoreInsn(BasicType type, int index) {
 439         int opcode = storeInsnOpcode(type);
 440         mv.visitVarInsn(opcode, localsMap[index]);
 441     }
 442 
 443     private int storeInsnOpcode(BasicType type) throws InternalError {
 444         switch (type) {
 445             case I_TYPE: return Opcodes.ISTORE;
 446             case J_TYPE: return Opcodes.LSTORE;
 447             case F_TYPE: return Opcodes.FSTORE;
 448             case D_TYPE: return Opcodes.DSTORE;
 449             case L_TYPE: return Opcodes.ASTORE;
 450             default:
 451                 throw new InternalError("unknown type: " + type);
 452         }
 453     }
 454     private void emitAstoreInsn(int index) {
 455         emitStoreInsn(L_TYPE, index);
 456     }
 457 
 458     private byte arrayTypeCode(Wrapper elementType) {
 459         switch (elementType) {
 460             case BOOLEAN: return Opcodes.T_BOOLEAN;
 461             case BYTE:    return Opcodes.T_BYTE;
 462             case CHAR:    return Opcodes.T_CHAR;
 463             case SHORT:   return Opcodes.T_SHORT;
 464             case INT:     return Opcodes.T_INT;
 465             case LONG:    return Opcodes.T_LONG;
 466             case FLOAT:   return Opcodes.T_FLOAT;
 467             case DOUBLE:  return Opcodes.T_DOUBLE;
 468             case OBJECT:  return 0; // in place of Opcodes.T_OBJECT
 469             default:      throw new InternalError();
 470         }
 471     }
 472 
 473     private int arrayInsnOpcode(byte tcode, int aaop) throws InternalError {
 474         assert(aaop == Opcodes.AASTORE || aaop == Opcodes.AALOAD);
 475         int xas;
 476         switch (tcode) {
 477             case Opcodes.T_BOOLEAN: xas = Opcodes.BASTORE; break;
 478             case Opcodes.T_BYTE:    xas = Opcodes.BASTORE; break;
 479             case Opcodes.T_CHAR:    xas = Opcodes.CASTORE; break;
 480             case Opcodes.T_SHORT:   xas = Opcodes.SASTORE; break;
 481             case Opcodes.T_INT:     xas = Opcodes.IASTORE; break;
 482             case Opcodes.T_LONG:    xas = Opcodes.LASTORE; break;
 483             case Opcodes.T_FLOAT:   xas = Opcodes.FASTORE; break;
 484             case Opcodes.T_DOUBLE:  xas = Opcodes.DASTORE; break;
 485             case 0:                 xas = Opcodes.AASTORE; break;
 486             default:      throw new InternalError();
 487         }
 488         return xas - Opcodes.AASTORE + aaop;
 489     }
 490 
 491     /**
 492      * Emit a boxing call.
 493      *
 494      * @param wrapper primitive type class to box.
 495      */
 496     private void emitBoxing(Wrapper wrapper) {
 497         String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();
 498         String name  = "valueOf";
 499         String desc  = "(" + wrapper.basicTypeChar() + ")L" + owner + ";";
 500         mv.visitMethodInsn(Opcodes.INVOKESTATIC, owner, name, desc, false);
 501     }
 502 
 503     /**
 504      * Emit an unboxing call (plus preceding checkcast).
 505      *
 506      * @param wrapper wrapper type class to unbox.
 507      */
 508     private void emitUnboxing(Wrapper wrapper) {
 509         String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();
 510         String name  = wrapper.primitiveSimpleName() + "Value";
 511         String desc  = "()" + wrapper.basicTypeChar();
 512         emitReferenceCast(wrapper.wrapperType(), null);
 513         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, owner, name, desc, false);
 514     }
 515 
 516     /**
 517      * Emit an implicit conversion for an argument which must be of the given pclass.
 518      * This is usually a no-op, except when pclass is a subword type or a reference other than Object or an interface.
 519      *
 520      * @param ptype type of value present on stack
 521      * @param pclass type of value required on stack
 522      * @param arg compile-time representation of value on stack (Node, constant) or null if none
 523      */
 524     private void emitImplicitConversion(BasicType ptype, Class<?> pclass, Object arg) {
 525         assert(basicType(pclass) == ptype);  // boxing/unboxing handled by caller
 526         if (pclass == ptype.basicTypeClass() && ptype != L_TYPE)
 527             return;   // nothing to do
 528         switch (ptype) {
 529             case L_TYPE:
 530                 if (VerifyType.isNullConversion(Object.class, pclass, false)) {
 531                     if (PROFILE_LEVEL > 0)
 532                         emitReferenceCast(Object.class, arg);
 533                     return;
 534                 }
 535                 emitReferenceCast(pclass, arg);
 536                 return;
 537             case I_TYPE:
 538                 if (!VerifyType.isNullConversion(int.class, pclass, false))
 539                     emitPrimCast(ptype.basicTypeWrapper(), Wrapper.forPrimitiveType(pclass));
 540                 return;
 541         }
 542         throw newInternalError("bad implicit conversion: tc="+ptype+": "+pclass);
 543     }
 544 
 545     /** Update localClasses type map.  Return true if the information is already present. */
 546     private boolean assertStaticType(Class<?> cls, Name n) {
 547         int local = n.index();
 548         Class<?> aclass = localClasses[local];
 549         if (aclass != null && (aclass == cls || cls.isAssignableFrom(aclass))) {
 550             return true;  // type info is already present
 551         } else if (aclass == null || aclass.isAssignableFrom(cls)) {
 552             localClasses[local] = cls;  // type info can be improved
 553         }
 554         return false;
 555     }
 556 
 557     private void emitReferenceCast(Class<?> cls, Object arg) {
 558         Name writeBack = null;  // local to write back result
 559         if (arg instanceof Name) {
 560             Name n = (Name) arg;
 561             if (lambdaForm.useCount(n) > 1) {
 562                 // This guy gets used more than once.
 563                 writeBack = n;
 564                 if (assertStaticType(cls, n)) {
 565                     return; // this cast was already performed
 566                 }
 567             }
 568         }
 569         if (isStaticallyNameable(cls)) {
 570             String sig = getInternalName(cls);
 571             mv.visitTypeInsn(Opcodes.CHECKCAST, sig);
 572         } else {
 573             mv.visitLdcInsn(constantPlaceholder(cls));
 574             mv.visitTypeInsn(Opcodes.CHECKCAST, CLS);
 575             mv.visitInsn(Opcodes.SWAP);
 576             mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, CLS, "cast", LL_SIG, false);
 577             if (Object[].class.isAssignableFrom(cls))
 578                 mv.visitTypeInsn(Opcodes.CHECKCAST, OBJARY);
 579             else if (PROFILE_LEVEL > 0)
 580                 mv.visitTypeInsn(Opcodes.CHECKCAST, OBJ);
 581         }
 582         if (writeBack != null) {
 583             mv.visitInsn(Opcodes.DUP);
 584             emitAstoreInsn(writeBack.index());
 585         }
 586     }
 587 
 588     /**
 589      * Emits an actual return instruction conforming to the given return type.
 590      */
 591     private void emitReturnInsn(BasicType type) {
 592         int opcode;
 593         switch (type) {
 594         case I_TYPE:  opcode = Opcodes.IRETURN;  break;
 595         case J_TYPE:  opcode = Opcodes.LRETURN;  break;
 596         case F_TYPE:  opcode = Opcodes.FRETURN;  break;
 597         case D_TYPE:  opcode = Opcodes.DRETURN;  break;
 598         case L_TYPE:  opcode = Opcodes.ARETURN;  break;
 599         case V_TYPE:  opcode = Opcodes.RETURN;   break;
 600         default:
 601             throw new InternalError("unknown return type: " + type);
 602         }
 603         mv.visitInsn(opcode);
 604     }
 605 
 606     private static String getInternalName(Class<?> c) {
 607         if (c == Object.class)             return OBJ;
 608         else if (c == Object[].class)      return OBJARY;
 609         else if (c == Class.class)         return CLS;
 610         else if (c == MethodHandle.class)  return MH;
 611         assert(VerifyAccess.isTypeVisible(c, Object.class)) : c.getName();
 612         return c.getName().replace('.', '/');
 613     }
 614 
 615     private static MemberName resolveFrom(String name, MethodType type, Class<?> holder) {
 616         MemberName member = new MemberName(holder, name, type, REF_invokeStatic);
 617         MemberName resolvedMember = MemberName.getFactory().resolveOrNull(REF_invokeStatic, member, holder);
 618         if (TRACE_RESOLVE) {
 619             System.out.println("[LF_RESOLVE] " + holder.getName() + " " + name + " " +
 620                     shortenSignature(basicTypeSignature(type)) + (resolvedMember != null ? " (success)" : " (fail)") );
 621         }
 622         return resolvedMember;
 623     }
 624 
 625     private static MemberName lookupPregenerated(LambdaForm form, MethodType invokerType) {
 626         if (form.customized != null) {
 627             // No pre-generated version for customized LF
 628             return null;
 629         }
 630         String name = form.kind.methodName;
 631         switch (form.kind) {
 632             case BOUND_REINVOKER: {
 633                 name = name + "_" + BoundMethodHandle.speciesData(form).fieldSignature();
 634                 return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
 635             }
 636             case DELEGATE:                  return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
 637             case ZERO:                      // fall-through
 638             case IDENTITY: {
 639                 name = name + "_" + form.returnType().basicTypeChar();
 640                 return resolveFrom(name, invokerType, LambdaForm.Holder.class);
 641             }
 642             case EXACT_INVOKER:             // fall-through
 643             case EXACT_LINKER:              // fall-through
 644             case GENERIC_INVOKER:           // fall-through
 645             case GENERIC_LINKER:            return resolveFrom(name, invokerType.basicType(), Invokers.Holder.class);
 646             case GET_OBJECT:                // fall-through
 647             case GET_BOOLEAN:               // fall-through
 648             case GET_BYTE:                  // fall-through
 649             case GET_CHAR:                  // fall-through
 650             case GET_SHORT:                 // fall-through
 651             case GET_INT:                   // fall-through
 652             case GET_LONG:                  // fall-through
 653             case GET_FLOAT:                 // fall-through
 654             case GET_DOUBLE:                // fall-through
 655             case PUT_OBJECT:                // fall-through
 656             case PUT_BOOLEAN:               // fall-through
 657             case PUT_BYTE:                  // fall-through
 658             case PUT_CHAR:                  // fall-through
 659             case PUT_SHORT:                 // fall-through
 660             case PUT_INT:                   // fall-through
 661             case PUT_LONG:                  // fall-through
 662             case PUT_FLOAT:                 // fall-through
 663             case PUT_DOUBLE:                // fall-through
 664             case DIRECT_INVOKE_INTERFACE:   // fall-through
 665             case DIRECT_INVOKE_SPECIAL:     // fall-through
 666             case DIRECT_INVOKE_STATIC:      // fall-through
 667             case DIRECT_INVOKE_STATIC_INIT: // fall-through
 668             case DIRECT_INVOKE_VIRTUAL:     return resolveFrom(name, invokerType, DirectMethodHandle.Holder.class);
 669         }
 670         return null;
 671     }
 672 
 673     /**
 674      * Generate customized bytecode for a given LambdaForm.
 675      */
 676     static MemberName generateCustomizedCode(LambdaForm form, MethodType invokerType) {
 677         MemberName pregenerated = lookupPregenerated(form, invokerType);
 678         if (pregenerated != null)  return pregenerated; // pre-generated bytecode
 679 
 680         InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("MH", form, invokerType);
 681         return g.loadMethod(g.generateCustomizedCodeBytes());
 682     }
 683 
 684     /** Generates code to check that actual receiver and LambdaForm matches */
 685     private boolean checkActualReceiver() {
 686         // Expects MethodHandle on the stack and actual receiver MethodHandle in slot #0
 687         mv.visitInsn(Opcodes.DUP);
 688         mv.visitVarInsn(Opcodes.ALOAD, localsMap[0]);
 689         mv.visitMethodInsn(Opcodes.INVOKESTATIC, MHI, "assertSame", LLV_SIG, false);
 690         return true;
 691     }
 692 
 693     static String className(String cn) {
 694         assert checkClassName(cn): "Class not found: " + cn;
 695         return cn;
 696     }
 697 
 698     static boolean checkClassName(String cn) {
 699         Type tp = Type.getType(cn);
 700         // additional sanity so only valid "L;" descriptors work
 701         if (tp.getSort() != Type.OBJECT) {
 702             return false;
 703         }
 704         try {
 705             Class<?> c = Class.forName(tp.getClassName(), false, null);
 706             return true;
 707         } catch (ClassNotFoundException e) {
 708             return false;
 709         }
 710     }
 711 
 712     static final String  LF_HIDDEN_SIG = className("Ljava/lang/invoke/LambdaForm$Hidden;");
 713     static final String  LF_COMPILED_SIG = className("Ljava/lang/invoke/LambdaForm$Compiled;");
 714     static final String  FORCEINLINE_SIG = className("Ljdk/internal/vm/annotation/ForceInline;");
 715     static final String  DONTINLINE_SIG = className("Ljdk/internal/vm/annotation/DontInline;");
 716     static final String  INJECTEDPROFILE_SIG = className("Ljava/lang/invoke/InjectedProfile;");
 717 
 718     /**
 719      * Generate an invoker method for the passed {@link LambdaForm}.
 720      */
 721     private byte[] generateCustomizedCodeBytes() {
 722         classFilePrologue();
 723         addMethod();
 724         bogusMethod(lambdaForm);
 725 
 726         final byte[] classFile = toByteArray();
 727         maybeDump(classFile);
 728         return classFile;
 729     }
 730 
 731     void setClassWriter(ClassWriter cw) {
 732         this.cw = cw;
 733     }
 734 
 735     void addMethod() {
 736         methodPrologue();
 737 
 738         // Suppress this method in backtraces displayed to the user.
 739         mv.visitAnnotation(LF_HIDDEN_SIG, true);
 740 
 741         // Mark this method as a compiled LambdaForm
 742         mv.visitAnnotation(LF_COMPILED_SIG, true);
 743 
 744         if (lambdaForm.forceInline) {
 745             // Force inlining of this invoker method.
 746             mv.visitAnnotation(FORCEINLINE_SIG, true);
 747         } else {
 748             mv.visitAnnotation(DONTINLINE_SIG, true);
 749         }
 750 
 751         constantPlaceholder(lambdaForm); // keep LambdaForm instance & its compiled form lifetime tightly coupled.
 752 
 753         if (lambdaForm.customized != null) {
 754             // Since LambdaForm is customized for a particular MethodHandle, it's safe to substitute
 755             // receiver MethodHandle (at slot #0) with an embedded constant and use it instead.
 756             // It enables more efficient code generation in some situations, since embedded constants
 757             // are compile-time constants for JIT compiler.
 758             mv.visitLdcInsn(constantPlaceholder(lambdaForm.customized));
 759             mv.visitTypeInsn(Opcodes.CHECKCAST, MH);
 760             assert(checkActualReceiver()); // expects MethodHandle on top of the stack
 761             mv.visitVarInsn(Opcodes.ASTORE, localsMap[0]);
 762         }
 763 
 764         // iterate over the form's names, generating bytecode instructions for each
 765         // start iterating at the first name following the arguments
 766         Name onStack = null;
 767         for (int i = lambdaForm.arity; i < lambdaForm.names.length; i++) {
 768             Name name = lambdaForm.names[i];
 769 
 770             emitStoreResult(onStack);
 771             onStack = name;  // unless otherwise modified below
 772             MethodHandleImpl.Intrinsic intr = name.function.intrinsicName();
 773             switch (intr) {
 774                 case SELECT_ALTERNATIVE:
 775                     assert lambdaForm.isSelectAlternative(i);
 776                     if (PROFILE_GWT) {
 777                         assert(name.arguments[0] instanceof Name &&
 778                                 ((Name)name.arguments[0]).refersTo(MethodHandleImpl.class, "profileBoolean"));
 779                         mv.visitAnnotation(INJECTEDPROFILE_SIG, true);
 780                     }
 781                     onStack = emitSelectAlternative(name, lambdaForm.names[i+1]);
 782                     i++;  // skip MH.invokeBasic of the selectAlternative result
 783                     continue;
 784                 case GUARD_WITH_CATCH:
 785                     assert lambdaForm.isGuardWithCatch(i);
 786                     onStack = emitGuardWithCatch(i);
 787                     i += 2; // jump to the end of GWC idiom
 788                     continue;
 789                 case TRY_FINALLY:
 790                     assert lambdaForm.isTryFinally(i);
 791                     onStack = emitTryFinally(i);
 792                     i += 2; // jump to the end of the TF idiom
 793                     continue;
 794                 case LOOP:
 795                     assert lambdaForm.isLoop(i);
 796                     onStack = emitLoop(i);
 797                     i += 2; // jump to the end of the LOOP idiom
 798                     continue;
 799                 case NEW_ARRAY:
 800                     Class<?> rtype = name.function.methodType().returnType();
 801                     if (isStaticallyNameable(rtype)) {
 802                         emitNewArray(name);
 803                         continue;
 804                     }
 805                     break;
 806                 case ARRAY_LOAD:
 807                     emitArrayLoad(name);
 808                     continue;
 809                 case ARRAY_STORE:
 810                     emitArrayStore(name);
 811                     continue;
 812                 case ARRAY_LENGTH:
 813                     emitArrayLength(name);
 814                     continue;
 815                 case IDENTITY:
 816                     assert(name.arguments.length == 1);
 817                     emitPushArguments(name, 0);
 818                     continue;
 819                 case ZERO:
 820                     assert(name.arguments.length == 0);
 821                     emitConst(name.type.basicTypeWrapper().zero());
 822                     continue;
 823                 case NONE:
 824                     // no intrinsic associated
 825                     break;
 826                 default:
 827                     throw newInternalError("Unknown intrinsic: "+intr);
 828             }
 829 
 830             MemberName member = name.function.member();
 831             if (isStaticallyInvocable(member)) {
 832                 emitStaticInvoke(member, name);
 833             } else {
 834                 emitInvoke(name);
 835             }
 836         }
 837 
 838         // return statement
 839         emitReturn(onStack);
 840 
 841         methodEpilogue();
 842     }
 843 
 844     /*
 845      * @throws BytecodeGenerationException if something goes wrong when
 846      *         generating the byte code
 847      */
 848     private byte[] toByteArray() {
 849         try {
 850             return cw.toByteArray();
 851         } catch (RuntimeException e) {
 852             throw new BytecodeGenerationException(e);
 853         }
 854     }
 855 
 856     @SuppressWarnings("serial")
 857     static final class BytecodeGenerationException extends RuntimeException {
 858         BytecodeGenerationException(Exception cause) {
 859             super(cause);
 860         }
 861     }
 862 
 863     void emitArrayLoad(Name name)   { emitArrayOp(name, Opcodes.AALOAD);      }
 864     void emitArrayStore(Name name)  { emitArrayOp(name, Opcodes.AASTORE);     }
 865     void emitArrayLength(Name name) { emitArrayOp(name, Opcodes.ARRAYLENGTH); }
 866 
 867     void emitArrayOp(Name name, int arrayOpcode) {
 868         assert arrayOpcode == Opcodes.AALOAD || arrayOpcode == Opcodes.AASTORE || arrayOpcode == Opcodes.ARRAYLENGTH;
 869         Class<?> elementType = name.function.methodType().parameterType(0).getComponentType();
 870         assert elementType != null;
 871         emitPushArguments(name, 0);
 872         if (arrayOpcode != Opcodes.ARRAYLENGTH && elementType.isPrimitive()) {
 873             Wrapper w = Wrapper.forPrimitiveType(elementType);
 874             arrayOpcode = arrayInsnOpcode(arrayTypeCode(w), arrayOpcode);
 875         }
 876         mv.visitInsn(arrayOpcode);
 877     }
 878 
 879     /**
 880      * Emit an invoke for the given name.
 881      */
 882     void emitInvoke(Name name) {
 883         assert(!name.isLinkerMethodInvoke());  // should use the static path for these
 884         if (true) {
 885             // push receiver
 886             MethodHandle target = name.function.resolvedHandle();
 887             assert(target != null) : name.exprString();
 888             mv.visitLdcInsn(constantPlaceholder(target));
 889             emitReferenceCast(MethodHandle.class, target);
 890         } else {
 891             // load receiver
 892             emitAloadInsn(0);
 893             emitReferenceCast(MethodHandle.class, null);
 894             mv.visitFieldInsn(Opcodes.GETFIELD, MH, "form", LF_SIG);
 895             mv.visitFieldInsn(Opcodes.GETFIELD, LF, "names", LFN_SIG);
 896             // TODO more to come
 897         }
 898 
 899         // push arguments
 900         emitPushArguments(name, 0);
 901 
 902         // invocation
 903         MethodType type = name.function.methodType();
 904         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
 905     }
 906 
 907     private static Class<?>[] STATICALLY_INVOCABLE_PACKAGES = {
 908         // Sample classes from each package we are willing to bind to statically:
 909         java.lang.Object.class,
 910         java.util.Arrays.class,
 911         jdk.internal.misc.Unsafe.class
 912         //MethodHandle.class already covered
 913     };
 914 
 915     static boolean isStaticallyInvocable(NamedFunction ... functions) {
 916         for (NamedFunction nf : functions) {
 917             if (!isStaticallyInvocable(nf.member())) {
 918                 return false;
 919             }
 920         }
 921         return true;
 922     }
 923 
 924     static boolean isStaticallyInvocable(Name name) {
 925         return isStaticallyInvocable(name.function.member());
 926     }
 927 
 928     static boolean isStaticallyInvocable(MemberName member) {
 929         if (member == null)  return false;
 930         if (member.isConstructor())  return false;
 931         Class<?> cls = member.getDeclaringClass();
 932         if (cls.isArray() || cls.isPrimitive())
 933             return false;  // FIXME
 934         if (cls.isAnonymousClass() || cls.isLocalClass())
 935             return false;  // inner class of some sort
 936         if (cls.getClassLoader() != MethodHandle.class.getClassLoader())
 937             return false;  // not on BCP
 938         if (ReflectUtil.isVMAnonymousClass(cls)) // FIXME: switch to supported API once it is added
 939             return false;
 940         MethodType mtype = member.getMethodOrFieldType();
 941         if (!isStaticallyNameable(mtype.returnType()))
 942             return false;
 943         for (Class<?> ptype : mtype.parameterArray())
 944             if (!isStaticallyNameable(ptype))
 945                 return false;
 946         if (!member.isPrivate() && VerifyAccess.isSamePackage(MethodHandle.class, cls))
 947             return true;   // in java.lang.invoke package
 948         if (member.isPublic() && isStaticallyNameable(cls))
 949             return true;
 950         return false;
 951     }
 952 
 953     static boolean isStaticallyNameable(Class<?> cls) {
 954         if (cls == Object.class)
 955             return true;
 956         while (cls.isArray())
 957             cls = cls.getComponentType();
 958         if (cls.isPrimitive())
 959             return true;  // int[].class, for example
 960         if (ReflectUtil.isVMAnonymousClass(cls)) // FIXME: switch to supported API once it is added
 961             return false;
 962         // could use VerifyAccess.isClassAccessible but the following is a safe approximation
 963         if (cls.getClassLoader() != Object.class.getClassLoader())
 964             return false;
 965         if (VerifyAccess.isSamePackage(MethodHandle.class, cls))
 966             return true;
 967         if (!Modifier.isPublic(cls.getModifiers()))
 968             return false;
 969         for (Class<?> pkgcls : STATICALLY_INVOCABLE_PACKAGES) {
 970             if (VerifyAccess.isSamePackage(pkgcls, cls))
 971                 return true;
 972         }
 973         return false;
 974     }
 975 
 976     void emitStaticInvoke(Name name) {
 977         emitStaticInvoke(name.function.member(), name);
 978     }
 979 
 980     /**
 981      * Emit an invoke for the given name, using the MemberName directly.
 982      */
 983     void emitStaticInvoke(MemberName member, Name name) {
 984         assert(member.equals(name.function.member()));
 985         Class<?> defc = member.getDeclaringClass();
 986         String cname = getInternalName(defc);
 987         String mname = member.getName();
 988         String mtype;
 989         byte refKind = member.getReferenceKind();
 990         if (refKind == REF_invokeSpecial) {
 991             // in order to pass the verifier, we need to convert this to invokevirtual in all cases
 992             assert(member.canBeStaticallyBound()) : member;
 993             refKind = REF_invokeVirtual;
 994         }
 995 
 996         assert(!(member.getDeclaringClass().isInterface() && refKind == REF_invokeVirtual));
 997 
 998         // push arguments
 999         emitPushArguments(name, 0);
1000 
1001         // invocation
1002         if (member.isMethod()) {
1003             mtype = member.getMethodType().toMethodDescriptorString();
1004             mv.visitMethodInsn(refKindOpcode(refKind), cname, mname, mtype,
1005                                member.getDeclaringClass().isInterface());
1006         } else {
1007             mtype = MethodType.toFieldDescriptorString(member.getFieldType());
1008             mv.visitFieldInsn(refKindOpcode(refKind), cname, mname, mtype);
1009         }
1010         // Issue a type assertion for the result, so we can avoid casts later.
1011         if (name.type == L_TYPE) {
1012             Class<?> rtype = member.getInvocationType().returnType();
1013             assert(!rtype.isPrimitive());
1014             if (rtype != Object.class && !rtype.isInterface()) {
1015                 assertStaticType(rtype, name);
1016             }
1017         }
1018     }
1019 
1020     void emitNewArray(Name name) throws InternalError {
1021         Class<?> rtype = name.function.methodType().returnType();
1022         if (name.arguments.length == 0) {
1023             // The array will be a constant.
1024             Object emptyArray;
1025             try {
1026                 emptyArray = name.function.resolvedHandle().invoke();
1027             } catch (Throwable ex) {
1028                 throw uncaughtException(ex);
1029             }
1030             assert(java.lang.reflect.Array.getLength(emptyArray) == 0);
1031             assert(emptyArray.getClass() == rtype);  // exact typing
1032             mv.visitLdcInsn(constantPlaceholder(emptyArray));
1033             emitReferenceCast(rtype, emptyArray);
1034             return;
1035         }
1036         Class<?> arrayElementType = rtype.getComponentType();
1037         assert(arrayElementType != null);
1038         emitIconstInsn(name.arguments.length);
1039         int xas = Opcodes.AASTORE;
1040         if (!arrayElementType.isPrimitive()) {
1041             mv.visitTypeInsn(Opcodes.ANEWARRAY, getInternalName(arrayElementType));
1042         } else {
1043             byte tc = arrayTypeCode(Wrapper.forPrimitiveType(arrayElementType));
1044             xas = arrayInsnOpcode(tc, xas);
1045             mv.visitIntInsn(Opcodes.NEWARRAY, tc);
1046         }
1047         // store arguments
1048         for (int i = 0; i < name.arguments.length; i++) {
1049             mv.visitInsn(Opcodes.DUP);
1050             emitIconstInsn(i);
1051             emitPushArgument(name, i);
1052             mv.visitInsn(xas);
1053         }
1054         // the array is left on the stack
1055         assertStaticType(rtype, name);
1056     }
1057     int refKindOpcode(byte refKind) {
1058         switch (refKind) {
1059         case REF_invokeVirtual:      return Opcodes.INVOKEVIRTUAL;
1060         case REF_invokeStatic:       return Opcodes.INVOKESTATIC;
1061         case REF_invokeSpecial:      return Opcodes.INVOKESPECIAL;
1062         case REF_invokeInterface:    return Opcodes.INVOKEINTERFACE;
1063         case REF_getField:           return Opcodes.GETFIELD;
1064         case REF_putField:           return Opcodes.PUTFIELD;
1065         case REF_getStatic:          return Opcodes.GETSTATIC;
1066         case REF_putStatic:          return Opcodes.PUTSTATIC;
1067         }
1068         throw new InternalError("refKind="+refKind);
1069     }
1070 
1071     /**
1072      * Emit bytecode for the selectAlternative idiom.
1073      *
1074      * The pattern looks like (Cf. MethodHandleImpl.makeGuardWithTest):
1075      * <blockquote><pre>{@code
1076      *   Lambda(a0:L,a1:I)=>{
1077      *     t2:I=foo.test(a1:I);
1078      *     t3:L=MethodHandleImpl.selectAlternative(t2:I,(MethodHandle(int)int),(MethodHandle(int)int));
1079      *     t4:I=MethodHandle.invokeBasic(t3:L,a1:I);t4:I}
1080      * }</pre></blockquote>
1081      */
1082     private Name emitSelectAlternative(Name selectAlternativeName, Name invokeBasicName) {
1083         assert isStaticallyInvocable(invokeBasicName);
1084 
1085         Name receiver = (Name) invokeBasicName.arguments[0];
1086 
1087         Label L_fallback = new Label();
1088         Label L_done     = new Label();
1089 
1090         // load test result
1091         emitPushArgument(selectAlternativeName, 0);
1092 
1093         // if_icmpne L_fallback
1094         mv.visitJumpInsn(Opcodes.IFEQ, L_fallback);
1095 
1096         // invoke selectAlternativeName.arguments[1]
1097         Class<?>[] preForkClasses = localClasses.clone();
1098         emitPushArgument(selectAlternativeName, 1);  // get 2nd argument of selectAlternative
1099         emitAstoreInsn(receiver.index());  // store the MH in the receiver slot
1100         emitStaticInvoke(invokeBasicName);
1101 
1102         // goto L_done
1103         mv.visitJumpInsn(Opcodes.GOTO, L_done);
1104 
1105         // L_fallback:
1106         mv.visitLabel(L_fallback);
1107 
1108         // invoke selectAlternativeName.arguments[2]
1109         System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
1110         emitPushArgument(selectAlternativeName, 2);  // get 3rd argument of selectAlternative
1111         emitAstoreInsn(receiver.index());  // store the MH in the receiver slot
1112         emitStaticInvoke(invokeBasicName);
1113 
1114         // L_done:
1115         mv.visitLabel(L_done);
1116         // for now do not bother to merge typestate; just reset to the dominator state
1117         System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
1118 
1119         return invokeBasicName;  // return what's on stack
1120     }
1121 
1122     /**
1123       * Emit bytecode for the guardWithCatch idiom.
1124       *
1125       * The pattern looks like (Cf. MethodHandleImpl.makeGuardWithCatch):
1126       * <blockquote><pre>{@code
1127       *  guardWithCatch=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L,a6:L,a7:L)=>{
1128       *    t8:L=MethodHandle.invokeBasic(a4:L,a6:L,a7:L);
1129       *    t9:L=MethodHandleImpl.guardWithCatch(a1:L,a2:L,a3:L,t8:L);
1130       *   t10:I=MethodHandle.invokeBasic(a5:L,t9:L);t10:I}
1131       * }</pre></blockquote>
1132       *
1133       * It is compiled into bytecode equivalent of the following code:
1134       * <blockquote><pre>{@code
1135       *  try {
1136       *      return a1.invokeBasic(a6, a7);
1137       *  } catch (Throwable e) {
1138       *      if (!a2.isInstance(e)) throw e;
1139       *      return a3.invokeBasic(ex, a6, a7);
1140       *  }}
1141       */
1142     private Name emitGuardWithCatch(int pos) {
1143         Name args    = lambdaForm.names[pos];
1144         Name invoker = lambdaForm.names[pos+1];
1145         Name result  = lambdaForm.names[pos+2];
1146 
1147         Label L_startBlock = new Label();
1148         Label L_endBlock = new Label();
1149         Label L_handler = new Label();
1150         Label L_done = new Label();
1151 
1152         Class<?> returnType = result.function.resolvedHandle().type().returnType();
1153         MethodType type = args.function.resolvedHandle().type()
1154                               .dropParameterTypes(0,1)
1155                               .changeReturnType(returnType);
1156 
1157         mv.visitTryCatchBlock(L_startBlock, L_endBlock, L_handler, "java/lang/Throwable");
1158 
1159         // Normal case
1160         mv.visitLabel(L_startBlock);
1161         // load target
1162         emitPushArgument(invoker, 0);
1163         emitPushArguments(args, 1); // skip 1st argument: method handle
1164         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
1165         mv.visitLabel(L_endBlock);
1166         mv.visitJumpInsn(Opcodes.GOTO, L_done);
1167 
1168         // Exceptional case
1169         mv.visitLabel(L_handler);
1170 
1171         // Check exception's type
1172         mv.visitInsn(Opcodes.DUP);
1173         // load exception class
1174         emitPushArgument(invoker, 1);
1175         mv.visitInsn(Opcodes.SWAP);
1176         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Class", "isInstance", "(Ljava/lang/Object;)Z", false);
1177         Label L_rethrow = new Label();
1178         mv.visitJumpInsn(Opcodes.IFEQ, L_rethrow);
1179 
1180         // Invoke catcher
1181         // load catcher
1182         emitPushArgument(invoker, 2);
1183         mv.visitInsn(Opcodes.SWAP);
1184         emitPushArguments(args, 1); // skip 1st argument: method handle
1185         MethodType catcherType = type.insertParameterTypes(0, Throwable.class);
1186         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", catcherType.basicType().toMethodDescriptorString(), false);
1187         mv.visitJumpInsn(Opcodes.GOTO, L_done);
1188 
1189         mv.visitLabel(L_rethrow);
1190         mv.visitInsn(Opcodes.ATHROW);
1191 
1192         mv.visitLabel(L_done);
1193 
1194         return result;
1195     }
1196 
1197     /**
1198      * Emit bytecode for the tryFinally idiom.
1199      * <p>
1200      * The pattern looks like (Cf. MethodHandleImpl.makeTryFinally):
1201      * <blockquote><pre>{@code
1202      * // a0: BMH
1203      * // a1: target, a2: cleanup
1204      * // a3: box, a4: unbox
1205      * // a5 (and following): arguments
1206      * tryFinally=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L)=>{
1207      *   t6:L=MethodHandle.invokeBasic(a3:L,a5:L);         // box the arguments into an Object[]
1208      *   t7:L=MethodHandleImpl.tryFinally(a1:L,a2:L,t6:L); // call the tryFinally executor
1209      *   t8:L=MethodHandle.invokeBasic(a4:L,t7:L);t8:L}    // unbox the result; return the result
1210      * }</pre></blockquote>
1211      * <p>
1212      * It is compiled into bytecode equivalent to the following code:
1213      * <blockquote><pre>{@code
1214      * Throwable t;
1215      * Object r;
1216      * try {
1217      *     r = a1.invokeBasic(a5);
1218      * } catch (Throwable thrown) {
1219      *     t = thrown;
1220      *     throw t;
1221      * } finally {
1222      *     r = a2.invokeBasic(t, r, a5);
1223      * }
1224      * return r;
1225      * }</pre></blockquote>
1226      * <p>
1227      * Specifically, the bytecode will have the following form (the stack effects are given for the beginnings of
1228      * blocks, and for the situations after executing the given instruction - the code will have a slightly different
1229      * shape if the return type is {@code void}):
1230      * <blockquote><pre>{@code
1231      * TRY:                 (--)
1232      *                      load target                             (-- target)
1233      *                      load args                               (-- args... target)
1234      *                      INVOKEVIRTUAL MethodHandle.invokeBasic  (depends)
1235      * FINALLY_NORMAL:      (-- r)
1236      *                      load cleanup                            (-- cleanup r)
1237      *                      SWAP                                    (-- r cleanup)
1238      *                      ACONST_NULL                             (-- t r cleanup)
1239      *                      SWAP                                    (-- r t cleanup)
1240      *                      load args                               (-- args... r t cleanup)
1241      *                      INVOKEVIRTUAL MethodHandle.invokeBasic  (-- r)
1242      *                      GOTO DONE
1243      * CATCH:               (-- t)
1244      *                      DUP                                     (-- t t)
1245      * FINALLY_EXCEPTIONAL: (-- t t)
1246      *                      load cleanup                            (-- cleanup t t)
1247      *                      SWAP                                    (-- t cleanup t)
1248      *                      load default for r                      (-- r t cleanup t)
1249      *                      load args                               (-- args... r t cleanup t)
1250      *                      INVOKEVIRTUAL MethodHandle.invokeBasic  (-- r t)
1251      *                      POP                                     (-- t)
1252      *                      ATHROW
1253      * DONE:                (-- r)
1254      * }</pre></blockquote>
1255      */
1256     private Name emitTryFinally(int pos) {
1257         Name args    = lambdaForm.names[pos];
1258         Name invoker = lambdaForm.names[pos+1];
1259         Name result  = lambdaForm.names[pos+2];
1260 
1261         Label lFrom = new Label();
1262         Label lTo = new Label();
1263         Label lCatch = new Label();
1264         Label lDone = new Label();
1265 
1266         Class<?> returnType = result.function.resolvedHandle().type().returnType();
1267         boolean isNonVoid = returnType != void.class;
1268         MethodType type = args.function.resolvedHandle().type()
1269                 .dropParameterTypes(0,1)
1270                 .changeReturnType(returnType);
1271         MethodType cleanupType = type.insertParameterTypes(0, Throwable.class);
1272         if (isNonVoid) {
1273             cleanupType = cleanupType.insertParameterTypes(1, returnType);
1274         }
1275         String cleanupDesc = cleanupType.basicType().toMethodDescriptorString();
1276 
1277         // exception handler table
1278         mv.visitTryCatchBlock(lFrom, lTo, lCatch, "java/lang/Throwable");
1279 
1280         // TRY:
1281         mv.visitLabel(lFrom);
1282         emitPushArgument(invoker, 0); // load target
1283         emitPushArguments(args, 1); // load args (skip 0: method handle)
1284         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
1285         mv.visitLabel(lTo);
1286 
1287         // FINALLY_NORMAL:
1288         emitPushArgument(invoker, 1); // load cleanup
1289         if (isNonVoid) {
1290             mv.visitInsn(Opcodes.SWAP);
1291         }
1292         mv.visitInsn(Opcodes.ACONST_NULL);
1293         if (isNonVoid) {
1294             mv.visitInsn(Opcodes.SWAP);
1295         }
1296         emitPushArguments(args, 1); // load args (skip 0: method handle)
1297         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", cleanupDesc, false);
1298         mv.visitJumpInsn(Opcodes.GOTO, lDone);
1299 
1300         // CATCH:
1301         mv.visitLabel(lCatch);
1302         mv.visitInsn(Opcodes.DUP);
1303 
1304         // FINALLY_EXCEPTIONAL:
1305         emitPushArgument(invoker, 1); // load cleanup
1306         mv.visitInsn(Opcodes.SWAP);
1307         if (isNonVoid) {
1308             emitZero(BasicType.basicType(returnType)); // load default for result
1309         }
1310         emitPushArguments(args, 1); // load args (skip 0: method handle)
1311         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", cleanupDesc, false);
1312         if (isNonVoid) {
1313             mv.visitInsn(Opcodes.POP);
1314         }
1315         mv.visitInsn(Opcodes.ATHROW);
1316 
1317         // DONE:
1318         mv.visitLabel(lDone);
1319 
1320         return result;
1321     }
1322 
1323     /**
1324      * Emit bytecode for the loop idiom.
1325      * <p>
1326      * The pattern looks like (Cf. MethodHandleImpl.loop):
1327      * <blockquote><pre>{@code
1328      * // a0: BMH
1329      * // a1: LoopClauses (containing an array of arrays: inits, steps, preds, finis)
1330      * // a2: box, a3: unbox
1331      * // a4 (and following): arguments
1332      * loop=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L)=>{
1333      *   t5:L=MethodHandle.invokeBasic(a2:L,a4:L);          // box the arguments into an Object[]
1334      *   t6:L=MethodHandleImpl.loop(bt:L,a1:L,t5:L);        // call the loop executor (with supplied types in bt)
1335      *   t7:L=MethodHandle.invokeBasic(a3:L,t6:L);t7:L}     // unbox the result; return the result
1336      * }</pre></blockquote>
1337      * <p>
1338      * It is compiled into bytecode equivalent to the code seen in {@link MethodHandleImpl#loop(BasicType[],
1339      * MethodHandleImpl.LoopClauses, Object...)}, with the difference that no arrays
1340      * will be used for local state storage. Instead, the local state will be mapped to actual stack slots.
1341      * <p>
1342      * Bytecode generation applies an unrolling scheme to enable better bytecode generation regarding local state type
1343      * handling. The generated bytecode will have the following form ({@code void} types are ignored for convenience).
1344      * Assume there are {@code C} clauses in the loop.
1345      * <blockquote><pre>{@code
1346      * PREINIT: ALOAD_1
1347      *          CHECKCAST LoopClauses
1348      *          GETFIELD LoopClauses.clauses
1349      *          ASTORE clauseDataIndex          // place the clauses 2-dimensional array on the stack
1350      * INIT:    (INIT_SEQ for clause 1)
1351      *          ...
1352      *          (INIT_SEQ for clause C)
1353      * LOOP:    (LOOP_SEQ for clause 1)
1354      *          ...
1355      *          (LOOP_SEQ for clause C)
1356      *          GOTO LOOP
1357      * DONE:    ...
1358      * }</pre></blockquote>
1359      * <p>
1360      * The {@code INIT_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
1361      * the following shape. Assume slot {@code vx} is used to hold the state for clause {@code x}.
1362      * <blockquote><pre>{@code
1363      * INIT_SEQ_x:  ALOAD clauseDataIndex
1364      *              ICONST_0
1365      *              AALOAD      // load the inits array
1366      *              ICONST x
1367      *              AALOAD      // load the init handle for clause x
1368      *              load args
1369      *              INVOKEVIRTUAL MethodHandle.invokeBasic
1370      *              store vx
1371      * }</pre></blockquote>
1372      * <p>
1373      * The {@code LOOP_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
1374      * the following shape. Again, assume slot {@code vx} is used to hold the state for clause {@code x}.
1375      * <blockquote><pre>{@code
1376      * LOOP_SEQ_x:  ALOAD clauseDataIndex
1377      *              ICONST_1
1378      *              AALOAD              // load the steps array
1379      *              ICONST x
1380      *              AALOAD              // load the step handle for clause x
1381      *              load locals
1382      *              load args
1383      *              INVOKEVIRTUAL MethodHandle.invokeBasic
1384      *              store vx
1385      *              ALOAD clauseDataIndex
1386      *              ICONST_2
1387      *              AALOAD              // load the preds array
1388      *              ICONST x
1389      *              AALOAD              // load the pred handle for clause x
1390      *              load locals
1391      *              load args
1392      *              INVOKEVIRTUAL MethodHandle.invokeBasic
1393      *              IFNE LOOP_SEQ_x+1   // predicate returned false -> jump to next clause
1394      *              ALOAD clauseDataIndex
1395      *              ICONST_3
1396      *              AALOAD              // load the finis array
1397      *              ICONST x
1398      *              AALOAD              // load the fini handle for clause x
1399      *              load locals
1400      *              load args
1401      *              INVOKEVIRTUAL MethodHandle.invokeBasic
1402      *              GOTO DONE           // jump beyond end of clauses to return from loop
1403      * }</pre></blockquote>
1404      */
1405     private Name emitLoop(int pos) {
1406         Name args    = lambdaForm.names[pos];
1407         Name invoker = lambdaForm.names[pos+1];
1408         Name result  = lambdaForm.names[pos+2];
1409 
1410         // extract clause and loop-local state types
1411         // find the type info in the loop invocation
1412         BasicType[] loopClauseTypes = (BasicType[]) invoker.arguments[0];
1413         Class<?>[] loopLocalStateTypes = Stream.of(loopClauseTypes).
1414                 filter(bt -> bt != BasicType.V_TYPE).map(BasicType::basicTypeClass).toArray(Class<?>[]::new);
1415         Class<?>[] localTypes = new Class<?>[loopLocalStateTypes.length + 1];
1416         localTypes[0] = MethodHandleImpl.LoopClauses.class;
1417         System.arraycopy(loopLocalStateTypes, 0, localTypes, 1, loopLocalStateTypes.length);
1418 
1419         final int clauseDataIndex = extendLocalsMap(localTypes);
1420         final int firstLoopStateIndex = clauseDataIndex + 1;
1421 
1422         Class<?> returnType = result.function.resolvedHandle().type().returnType();
1423         MethodType loopType = args.function.resolvedHandle().type()
1424                 .dropParameterTypes(0,1)
1425                 .changeReturnType(returnType);
1426         MethodType loopHandleType = loopType.insertParameterTypes(0, loopLocalStateTypes);
1427         MethodType predType = loopHandleType.changeReturnType(boolean.class);
1428         MethodType finiType = loopHandleType;
1429 
1430         final int nClauses = loopClauseTypes.length;
1431 
1432         // indices to invoker arguments to load method handle arrays
1433         final int inits = 1;
1434         final int steps = 2;
1435         final int preds = 3;
1436         final int finis = 4;
1437 
1438         Label lLoop = new Label();
1439         Label lDone = new Label();
1440         Label lNext;
1441 
1442         // PREINIT:
1443         emitPushArgument(MethodHandleImpl.LoopClauses.class, invoker.arguments[1]);
1444         mv.visitFieldInsn(Opcodes.GETFIELD, LOOP_CLAUSES, "clauses", MHARY2);
1445         emitAstoreInsn(clauseDataIndex);
1446 
1447         // INIT:
1448         for (int c = 0, state = 0; c < nClauses; ++c) {
1449             MethodType cInitType = loopType.changeReturnType(loopClauseTypes[c].basicTypeClass());
1450             emitLoopHandleInvoke(invoker, inits, c, args, false, cInitType, loopLocalStateTypes, clauseDataIndex,
1451                     firstLoopStateIndex);
1452             if (cInitType.returnType() != void.class) {
1453                 emitStoreInsn(BasicType.basicType(cInitType.returnType()), firstLoopStateIndex + state);
1454                 ++state;
1455             }
1456         }
1457 
1458         // LOOP:
1459         mv.visitLabel(lLoop);
1460 
1461         for (int c = 0, state = 0; c < nClauses; ++c) {
1462             lNext = new Label();
1463 
1464             MethodType stepType = loopHandleType.changeReturnType(loopClauseTypes[c].basicTypeClass());
1465             boolean isVoid = stepType.returnType() == void.class;
1466 
1467             // invoke loop step
1468             emitLoopHandleInvoke(invoker, steps, c, args, true, stepType, loopLocalStateTypes, clauseDataIndex,
1469                     firstLoopStateIndex);
1470             if (!isVoid) {
1471                 emitStoreInsn(BasicType.basicType(stepType.returnType()), firstLoopStateIndex + state);
1472                 ++state;
1473             }
1474 
1475             // invoke loop predicate
1476             emitLoopHandleInvoke(invoker, preds, c, args, true, predType, loopLocalStateTypes, clauseDataIndex,
1477                     firstLoopStateIndex);
1478             mv.visitJumpInsn(Opcodes.IFNE, lNext);
1479 
1480             // invoke fini
1481             emitLoopHandleInvoke(invoker, finis, c, args, true, finiType, loopLocalStateTypes, clauseDataIndex,
1482                     firstLoopStateIndex);
1483             mv.visitJumpInsn(Opcodes.GOTO, lDone);
1484 
1485             // this is the beginning of the next loop clause
1486             mv.visitLabel(lNext);
1487         }
1488 
1489         mv.visitJumpInsn(Opcodes.GOTO, lLoop);
1490 
1491         // DONE:
1492         mv.visitLabel(lDone);
1493 
1494         return result;
1495     }
1496 
1497     private int extendLocalsMap(Class<?>[] types) {
1498         int firstSlot = localsMap.length - 1;
1499         localsMap = Arrays.copyOf(localsMap, localsMap.length + types.length);
1500         localClasses = Arrays.copyOf(localClasses, localClasses.length + types.length);
1501         System.arraycopy(types, 0, localClasses, firstSlot, types.length);
1502         int index = localsMap[firstSlot - 1] + 1;
1503         int lastSlots = 0;
1504         for (int i = 0; i < types.length; ++i) {
1505             localsMap[firstSlot + i] = index;
1506             lastSlots = BasicType.basicType(localClasses[firstSlot + i]).basicTypeSlots();
1507             index += lastSlots;
1508         }
1509         localsMap[localsMap.length - 1] = index - lastSlots;
1510         return firstSlot;
1511     }
1512 
1513     private void emitLoopHandleInvoke(Name holder, int handles, int clause, Name args, boolean pushLocalState,
1514                                       MethodType type, Class<?>[] loopLocalStateTypes, int clauseDataSlot,
1515                                       int firstLoopStateSlot) {
1516         // load handle for clause
1517         emitPushClauseArray(clauseDataSlot, handles);
1518         emitIconstInsn(clause);
1519         mv.visitInsn(Opcodes.AALOAD);
1520         // load loop state (preceding the other arguments)
1521         if (pushLocalState) {
1522             for (int s = 0; s < loopLocalStateTypes.length; ++s) {
1523                 emitLoadInsn(BasicType.basicType(loopLocalStateTypes[s]), firstLoopStateSlot + s);
1524             }
1525         }
1526         // load loop args (skip 0: method handle)
1527         emitPushArguments(args, 1);
1528         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.toMethodDescriptorString(), false);
1529     }
1530 
1531     private void emitPushClauseArray(int clauseDataSlot, int which) {
1532         emitAloadInsn(clauseDataSlot);
1533         emitIconstInsn(which - 1);
1534         mv.visitInsn(Opcodes.AALOAD);
1535     }
1536 
1537     private void emitZero(BasicType type) {
1538         switch (type) {
1539             case I_TYPE: mv.visitInsn(Opcodes.ICONST_0); break;
1540             case J_TYPE: mv.visitInsn(Opcodes.LCONST_0); break;
1541             case F_TYPE: mv.visitInsn(Opcodes.FCONST_0); break;
1542             case D_TYPE: mv.visitInsn(Opcodes.DCONST_0); break;
1543             case L_TYPE: mv.visitInsn(Opcodes.ACONST_NULL); break;
1544             default: throw new InternalError("unknown type: " + type);
1545         }
1546     }
1547 
1548     private void emitPushArguments(Name args, int start) {
1549         MethodType type = args.function.methodType();
1550         for (int i = start; i < args.arguments.length; i++) {
1551             emitPushArgument(type.parameterType(i), args.arguments[i]);
1552         }
1553     }
1554 
1555     private void emitPushArgument(Name name, int paramIndex) {
1556         Object arg = name.arguments[paramIndex];
1557         Class<?> ptype = name.function.methodType().parameterType(paramIndex);
1558         emitPushArgument(ptype, arg);
1559     }
1560 
1561     private void emitPushArgument(Class<?> ptype, Object arg) {
1562         BasicType bptype = basicType(ptype);
1563         if (arg instanceof Name) {
1564             Name n = (Name) arg;
1565             emitLoadInsn(n.type, n.index());
1566             emitImplicitConversion(n.type, ptype, n);
1567         } else if ((arg == null || arg instanceof String) && bptype == L_TYPE) {
1568             emitConst(arg);
1569         } else {
1570             if (Wrapper.isWrapperType(arg.getClass()) && bptype != L_TYPE) {
1571                 emitConst(arg);
1572             } else {
1573                 mv.visitLdcInsn(constantPlaceholder(arg));
1574                 emitImplicitConversion(L_TYPE, ptype, arg);
1575             }
1576         }
1577     }
1578 
1579     /**
1580      * Store the name to its local, if necessary.
1581      */
1582     private void emitStoreResult(Name name) {
1583         if (name != null && name.type != V_TYPE) {
1584             // non-void: actually assign
1585             emitStoreInsn(name.type, name.index());
1586         }
1587     }
1588 
1589     /**
1590      * Emits a return statement from a LF invoker. If required, the result type is cast to the correct return type.
1591      */
1592     private void emitReturn(Name onStack) {
1593         // return statement
1594         Class<?> rclass = invokerType.returnType();
1595         BasicType rtype = lambdaForm.returnType();
1596         assert(rtype == basicType(rclass));  // must agree
1597         if (rtype == V_TYPE) {
1598             // void
1599             mv.visitInsn(Opcodes.RETURN);
1600             // it doesn't matter what rclass is; the JVM will discard any value
1601         } else {
1602             LambdaForm.Name rn = lambdaForm.names[lambdaForm.result];
1603 
1604             // put return value on the stack if it is not already there
1605             if (rn != onStack) {
1606                 emitLoadInsn(rtype, lambdaForm.result);
1607             }
1608 
1609             emitImplicitConversion(rtype, rclass, rn);
1610 
1611             // generate actual return statement
1612             emitReturnInsn(rtype);
1613         }
1614     }
1615 
1616     /**
1617      * Emit a type conversion bytecode casting from "from" to "to".
1618      */
1619     private void emitPrimCast(Wrapper from, Wrapper to) {
1620         // Here's how.
1621         // -   indicates forbidden
1622         // <-> indicates implicit
1623         //      to ----> boolean  byte     short    char     int      long     float    double
1624         // from boolean    <->        -        -        -        -        -        -        -
1625         //      byte        -       <->       i2s      i2c      <->      i2l      i2f      i2d
1626         //      short       -       i2b       <->      i2c      <->      i2l      i2f      i2d
1627         //      char        -       i2b       i2s      <->      <->      i2l      i2f      i2d
1628         //      int         -       i2b       i2s      i2c      <->      i2l      i2f      i2d
1629         //      long        -     l2i,i2b   l2i,i2s  l2i,i2c    l2i      <->      l2f      l2d
1630         //      float       -     f2i,i2b   f2i,i2s  f2i,i2c    f2i      f2l      <->      f2d
1631         //      double      -     d2i,i2b   d2i,i2s  d2i,i2c    d2i      d2l      d2f      <->
1632         if (from == to) {
1633             // no cast required, should be dead code anyway
1634             return;
1635         }
1636         if (from.isSubwordOrInt()) {
1637             // cast from {byte,short,char,int} to anything
1638             emitI2X(to);
1639         } else {
1640             // cast from {long,float,double} to anything
1641             if (to.isSubwordOrInt()) {
1642                 // cast to {byte,short,char,int}
1643                 emitX2I(from);
1644                 if (to.bitWidth() < 32) {
1645                     // targets other than int require another conversion
1646                     emitI2X(to);
1647                 }
1648             } else {
1649                 // cast to {long,float,double} - this is verbose
1650                 boolean error = false;
1651                 switch (from) {
1652                 case LONG:
1653                     switch (to) {
1654                     case FLOAT:   mv.visitInsn(Opcodes.L2F);  break;
1655                     case DOUBLE:  mv.visitInsn(Opcodes.L2D);  break;
1656                     default:      error = true;               break;
1657                     }
1658                     break;
1659                 case FLOAT:
1660                     switch (to) {
1661                     case LONG :   mv.visitInsn(Opcodes.F2L);  break;
1662                     case DOUBLE:  mv.visitInsn(Opcodes.F2D);  break;
1663                     default:      error = true;               break;
1664                     }
1665                     break;
1666                 case DOUBLE:
1667                     switch (to) {
1668                     case LONG :   mv.visitInsn(Opcodes.D2L);  break;
1669                     case FLOAT:   mv.visitInsn(Opcodes.D2F);  break;
1670                     default:      error = true;               break;
1671                     }
1672                     break;
1673                 default:
1674                     error = true;
1675                     break;
1676                 }
1677                 if (error) {
1678                     throw new IllegalStateException("unhandled prim cast: " + from + "2" + to);
1679                 }
1680             }
1681         }
1682     }
1683 
1684     private void emitI2X(Wrapper type) {
1685         switch (type) {
1686         case BYTE:    mv.visitInsn(Opcodes.I2B);  break;
1687         case SHORT:   mv.visitInsn(Opcodes.I2S);  break;
1688         case CHAR:    mv.visitInsn(Opcodes.I2C);  break;
1689         case INT:     /* naught */                break;
1690         case LONG:    mv.visitInsn(Opcodes.I2L);  break;
1691         case FLOAT:   mv.visitInsn(Opcodes.I2F);  break;
1692         case DOUBLE:  mv.visitInsn(Opcodes.I2D);  break;
1693         case BOOLEAN:
1694             // For compatibility with ValueConversions and explicitCastArguments:
1695             mv.visitInsn(Opcodes.ICONST_1);
1696             mv.visitInsn(Opcodes.IAND);
1697             break;
1698         default:   throw new InternalError("unknown type: " + type);
1699         }
1700     }
1701 
1702     private void emitX2I(Wrapper type) {
1703         switch (type) {
1704         case LONG:    mv.visitInsn(Opcodes.L2I);  break;
1705         case FLOAT:   mv.visitInsn(Opcodes.F2I);  break;
1706         case DOUBLE:  mv.visitInsn(Opcodes.D2I);  break;
1707         default:      throw new InternalError("unknown type: " + type);
1708         }
1709     }
1710 
1711     /**
1712      * Generate bytecode for a LambdaForm.vmentry which calls interpretWithArguments.
1713      */
1714     static MemberName generateLambdaFormInterpreterEntryPoint(MethodType mt) {
1715         assert(isValidSignature(basicTypeSignature(mt)));
1716         String name = "interpret_"+basicTypeChar(mt.returnType());
1717         MethodType type = mt;  // includes leading argument
1718         type = type.changeParameterType(0, MethodHandle.class);
1719         InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("LFI", name, type);
1720         return g.loadMethod(g.generateLambdaFormInterpreterEntryPointBytes());
1721     }
1722 
1723     private byte[] generateLambdaFormInterpreterEntryPointBytes() {
1724         classFilePrologue();
1725         methodPrologue();
1726 
1727         // Suppress this method in backtraces displayed to the user.
1728         mv.visitAnnotation(LF_HIDDEN_SIG, true);
1729 
1730         // Don't inline the interpreter entry.
1731         mv.visitAnnotation(DONTINLINE_SIG, true);
1732 
1733         // create parameter array
1734         emitIconstInsn(invokerType.parameterCount());
1735         mv.visitTypeInsn(Opcodes.ANEWARRAY, "java/lang/Object");
1736 
1737         // fill parameter array
1738         for (int i = 0; i < invokerType.parameterCount(); i++) {
1739             Class<?> ptype = invokerType.parameterType(i);
1740             mv.visitInsn(Opcodes.DUP);
1741             emitIconstInsn(i);
1742             emitLoadInsn(basicType(ptype), i);
1743             // box if primitive type
1744             if (ptype.isPrimitive()) {
1745                 emitBoxing(Wrapper.forPrimitiveType(ptype));
1746             }
1747             mv.visitInsn(Opcodes.AASTORE);
1748         }
1749         // invoke
1750         emitAloadInsn(0);
1751         mv.visitFieldInsn(Opcodes.GETFIELD, MH, "form", "Ljava/lang/invoke/LambdaForm;");
1752         mv.visitInsn(Opcodes.SWAP);  // swap form and array; avoid local variable
1753         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, LF, "interpretWithArguments", "([Ljava/lang/Object;)Ljava/lang/Object;", false);
1754 
1755         // maybe unbox
1756         Class<?> rtype = invokerType.returnType();
1757         if (rtype.isPrimitive() && rtype != void.class) {
1758             emitUnboxing(Wrapper.forPrimitiveType(rtype));
1759         }
1760 
1761         // return statement
1762         emitReturnInsn(basicType(rtype));
1763 
1764         methodEpilogue();
1765         bogusMethod(invokerType);
1766 
1767         final byte[] classFile = cw.toByteArray();
1768         maybeDump(classFile);
1769         return classFile;
1770     }
1771 
1772     /**
1773      * Generate bytecode for a NamedFunction invoker.
1774      */
1775     static MemberName generateNamedFunctionInvoker(MethodTypeForm typeForm) {
1776         MethodType invokerType = NamedFunction.INVOKER_METHOD_TYPE;
1777         String invokerName = "invoke_" + shortenSignature(basicTypeSignature(typeForm.erasedType()));
1778         InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("NFI", invokerName, invokerType);
1779         return g.loadMethod(g.generateNamedFunctionInvokerImpl(typeForm));
1780     }
1781 
1782     private byte[] generateNamedFunctionInvokerImpl(MethodTypeForm typeForm) {
1783         MethodType dstType = typeForm.erasedType();
1784         classFilePrologue();
1785         methodPrologue();
1786 
1787         // Suppress this method in backtraces displayed to the user.
1788         mv.visitAnnotation(LF_HIDDEN_SIG, true);
1789 
1790         // Force inlining of this invoker method.
1791         mv.visitAnnotation(FORCEINLINE_SIG, true);
1792 
1793         // Load receiver
1794         emitAloadInsn(0);
1795 
1796         // Load arguments from array
1797         for (int i = 0; i < dstType.parameterCount(); i++) {
1798             emitAloadInsn(1);
1799             emitIconstInsn(i);
1800             mv.visitInsn(Opcodes.AALOAD);
1801 
1802             // Maybe unbox
1803             Class<?> dptype = dstType.parameterType(i);
1804             if (dptype.isPrimitive()) {
1805                 Wrapper dstWrapper = Wrapper.forBasicType(dptype);
1806                 Wrapper srcWrapper = dstWrapper.isSubwordOrInt() ? Wrapper.INT : dstWrapper;  // narrow subword from int
1807                 emitUnboxing(srcWrapper);
1808                 emitPrimCast(srcWrapper, dstWrapper);
1809             }
1810         }
1811 
1812         // Invoke
1813         String targetDesc = dstType.basicType().toMethodDescriptorString();
1814         mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", targetDesc, false);
1815 
1816         // Box primitive types
1817         Class<?> rtype = dstType.returnType();
1818         if (rtype != void.class && rtype.isPrimitive()) {
1819             Wrapper srcWrapper = Wrapper.forBasicType(rtype);
1820             Wrapper dstWrapper = srcWrapper.isSubwordOrInt() ? Wrapper.INT : srcWrapper;  // widen subword to int
1821             // boolean casts not allowed
1822             emitPrimCast(srcWrapper, dstWrapper);
1823             emitBoxing(dstWrapper);
1824         }
1825 
1826         // If the return type is void we return a null reference.
1827         if (rtype == void.class) {
1828             mv.visitInsn(Opcodes.ACONST_NULL);
1829         }
1830         emitReturnInsn(L_TYPE);  // NOTE: NamedFunction invokers always return a reference value.
1831 
1832         methodEpilogue();
1833         bogusMethod(dstType);
1834 
1835         final byte[] classFile = cw.toByteArray();
1836         maybeDump(classFile);
1837         return classFile;
1838     }
1839 
1840     /**
1841      * Emit a bogus method that just loads some string constants. This is to get the constants into the constant pool
1842      * for debugging purposes.
1843      */
1844     private void bogusMethod(Object... os) {
1845         if (DUMP_CLASS_FILES) {
1846             mv = cw.visitMethod(Opcodes.ACC_STATIC, "dummy", "()V", null, null);
1847             for (Object o : os) {
1848                 mv.visitLdcInsn(o.toString());
1849                 mv.visitInsn(Opcodes.POP);
1850             }
1851             mv.visitInsn(Opcodes.RETURN);
1852             mv.visitMaxs(0, 0);
1853             mv.visitEnd();
1854         }
1855     }
1856 }
--- EOF ---