1 /*
   2  * Copyright (c) 1999, 2023, 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 com.sun.tools.javac.jvm;
  27 
  28 import java.io.*;
  29 import java.util.LinkedHashMap;
  30 import java.util.Map;
  31 import java.util.Set;
  32 import java.util.LinkedHashSet;
  33 import java.util.function.ToIntFunction;
  34 
  35 import javax.tools.JavaFileManager;
  36 import javax.tools.FileObject;
  37 import javax.tools.JavaFileManager.Location;
  38 import javax.tools.JavaFileObject;
  39 
  40 import com.sun.tools.javac.code.*;
  41 import com.sun.tools.javac.code.Attribute.RetentionPolicy;
  42 import com.sun.tools.javac.code.Directive.*;
  43 import com.sun.tools.javac.code.Scope.WriteableScope;
  44 import com.sun.tools.javac.code.Source.Feature;
  45 import com.sun.tools.javac.code.Symbol.*;
  46 import com.sun.tools.javac.code.Type.*;
  47 import com.sun.tools.javac.code.Types.SignatureGenerator.InvalidSignatureException;
  48 import com.sun.tools.javac.comp.Check;
  49 import com.sun.tools.javac.file.PathFileObject;
  50 import com.sun.tools.javac.jvm.PoolConstant.LoadableConstant;
  51 import com.sun.tools.javac.jvm.PoolConstant.Dynamic.BsmKey;
  52 import com.sun.tools.javac.resources.CompilerProperties.Errors;
  53 import com.sun.tools.javac.resources.CompilerProperties.Fragments;
  54 import com.sun.tools.javac.util.*;
  55 import com.sun.tools.javac.util.List;
  56 
  57 import static com.sun.tools.javac.code.Flags.*;
  58 import static com.sun.tools.javac.code.Kinds.Kind.*;
  59 import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;
  60 import static com.sun.tools.javac.code.TypeTag.*;
  61 import static com.sun.tools.javac.main.Option.*;
  62 
  63 import static javax.tools.StandardLocation.CLASS_OUTPUT;
  64 
  65 /** This class provides operations to map an internal symbol table graph
  66  *  rooted in a ClassSymbol into a classfile.
  67  *
  68  *  <p><b>This is NOT part of any supported API.
  69  *  If you write code that depends on this, you do so at your own risk.
  70  *  This code and its internal interfaces are subject to change or
  71  *  deletion without notice.</b>
  72  */
  73 public class ClassWriter extends ClassFile {
  74     protected static final Context.Key<ClassWriter> classWriterKey = new Context.Key<>();
  75 
  76     private final Options options;
  77 
  78     /** Switch: verbose output.
  79      */
  80     private boolean verbose;
  81 
  82     /** Switch: emit source file attribute.
  83      */
  84     private boolean emitSourceFile;
  85 
  86     /** Switch: generate CharacterRangeTable attribute.
  87      */
  88     private boolean genCrt;
  89 
  90     /** Switch: describe the generated stackmap.
  91      */
  92     private boolean debugstackmap;
  93 
  94     /** Preview language level.
  95      */
  96     private Preview preview;
  97 
  98     /**
  99      * Target class version.
 100      */
 101     private Target target;
 102 
 103     /**
 104      * Source language version.
 105      */
 106     private Source source;
 107 
 108     /** Type utilities. */
 109     private Types types;
 110 
 111     private Check check;
 112 
 113     private boolean allowPrimitiveClasses;
 114 
 115     /**
 116      * If true, class files will be written in module-specific subdirectories
 117      * of the CLASS_OUTPUT location.
 118      */
 119     public boolean multiModuleMode;
 120 
 121     private List<ToIntFunction<Symbol>> extraAttributeHooks = List.nil();
 122 
 123     /** The initial sizes of the data and constant pool buffers.
 124      *  Sizes are increased when buffers get full.
 125      */
 126     static final int DATA_BUF_SIZE = 0x0fff0;
 127     static final int CLASS_BUF_SIZE = 0x1fff0;
 128 
 129     /** An output buffer for member info.
 130      */
 131     public ByteBuffer databuf = new ByteBuffer(DATA_BUF_SIZE);
 132 
 133     /** An output buffer for the constant pool.
 134      */
 135     ByteBuffer poolbuf = new ByteBuffer(CLASS_BUF_SIZE);
 136 
 137     /** The constant pool writer.
 138      */
 139     final PoolWriter poolWriter;
 140 
 141     /** The log to use for verbose output.
 142      */
 143     private final Log log;
 144 
 145     /** The name table. */
 146     private final Names names;
 147 
 148     private final Symtab syms;
 149 
 150     /** Access to files. */
 151     private final JavaFileManager fileManager;
 152 
 153     /** The tags and constants used in compressed stackmap. */
 154     static final int SAME_FRAME_SIZE = 64;
 155     static final int SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247;
 156     static final int SAME_FRAME_EXTENDED = 251;
 157     static final int FULL_FRAME = 255;
 158     static final int MAX_LOCAL_LENGTH_DIFF = 4;
 159 
 160     /** Get the ClassWriter instance for this context. */
 161     public static ClassWriter instance(Context context) {
 162         ClassWriter instance = context.get(classWriterKey);
 163         if (instance == null)
 164             instance = new ClassWriter(context);
 165         return instance;
 166     }
 167 
 168     /** Construct a class writer, given an options table.
 169      */
 170     @SuppressWarnings("this-escape")
 171     protected ClassWriter(Context context) {
 172         context.put(classWriterKey, this);
 173 
 174         log = Log.instance(context);
 175         names = Names.instance(context);
 176         options = Options.instance(context);
 177         preview = Preview.instance(context);
 178         target = Target.instance(context);
 179         source = Source.instance(context);
 180         types = Types.instance(context);
 181         check = Check.instance(context);
 182         fileManager = context.get(JavaFileManager.class);
 183         poolWriter = Gen.instance(context).poolWriter;
 184         syms = Symtab.instance(context);
 185 
 186         verbose        = options.isSet(VERBOSE);
 187         genCrt         = options.isSet(XJCOV);
 188         debugstackmap = options.isSet("debug.stackmap");
 189 
 190         emitSourceFile = options.isUnset(G_CUSTOM) ||
 191                             options.isSet(G_CUSTOM, "source");
 192 
 193         String modifierFlags = options.get("debug.dumpmodifiers");
 194         if (modifierFlags != null) {
 195             dumpClassModifiers = modifierFlags.indexOf('c') != -1;
 196             dumpFieldModifiers = modifierFlags.indexOf('f') != -1;
 197             dumpInnerClassModifiers = modifierFlags.indexOf('i') != -1;
 198             dumpMethodModifiers = modifierFlags.indexOf('m') != -1;
 199         }
 200         Source source = Source.instance(context);
 201         allowPrimitiveClasses = Feature.PRIMITIVE_CLASSES.allowedInSource(source) && options.isSet("enablePrimitiveClasses");
 202     }
 203 
 204     public void addExtraAttributes(ToIntFunction<Symbol> addExtraAttributes) {
 205         extraAttributeHooks = extraAttributeHooks.prepend(addExtraAttributes);
 206     }
 207 
 208 /******************************************************************
 209  * Diagnostics: dump generated class names and modifiers
 210  ******************************************************************/
 211 
 212     /** Value of option 'dumpmodifiers' is a string
 213      *  indicating which modifiers should be dumped for debugging:
 214      *    'c' -- classes
 215      *    'f' -- fields
 216      *    'i' -- innerclass attributes
 217      *    'm' -- methods
 218      *  For example, to dump everything:
 219      *    javac -XDdumpmodifiers=cifm MyProg.java
 220      */
 221     private boolean dumpClassModifiers; // -XDdumpmodifiers=c
 222     private boolean dumpFieldModifiers; // -XDdumpmodifiers=f
 223     private boolean dumpInnerClassModifiers; // -XDdumpmodifiers=i
 224     private boolean dumpMethodModifiers; // -XDdumpmodifiers=m
 225 
 226 
 227     /** Return flags as a string, separated by " ".
 228      */
 229     public static String flagNames(long flags) {
 230         StringBuilder sbuf = new StringBuilder();
 231         int i = 0;
 232         long f = flags & StandardFlags;
 233         while (f != 0) {
 234             if ((f & 1) != 0) {
 235                 sbuf.append(" ");
 236                 sbuf.append(flagName[i]);
 237             }
 238             f = f >> 1;
 239             i++;
 240         }
 241         return sbuf.toString();
 242     }
 243     //where
 244         private static final String[] flagName = {
 245             "PUBLIC", "PRIVATE", "PROTECTED", "STATIC", "FINAL",
 246             "IDENTITY", "VOLATILE", "TRANSIENT", "NATIVE", "INTERFACE",
 247             "ABSTRACT", "STRICTFP"};
 248 
 249 /******************************************************************
 250  * Output routines
 251  ******************************************************************/
 252 
 253     /** Write a character into given byte buffer;
 254      *  byte buffer will not be grown.
 255      */
 256     void putChar(ByteBuffer buf, int op, int x) {
 257         buf.elems[op  ] = (byte)((x >>  8) & 0xFF);
 258         buf.elems[op+1] = (byte)((x      ) & 0xFF);
 259     }
 260 
 261     /** Write an integer into given byte buffer;
 262      *  byte buffer will not be grown.
 263      */
 264     void putInt(ByteBuffer buf, int adr, int x) {
 265         buf.elems[adr  ] = (byte)((x >> 24) & 0xFF);
 266         buf.elems[adr+1] = (byte)((x >> 16) & 0xFF);
 267         buf.elems[adr+2] = (byte)((x >>  8) & 0xFF);
 268         buf.elems[adr+3] = (byte)((x      ) & 0xFF);
 269     }
 270 
 271 /******************************************************************
 272  * Writing the Constant Pool
 273  ******************************************************************/
 274 
 275     /** Thrown when the constant pool is over full.
 276      */
 277     public static class PoolOverflow extends RuntimeException {
 278         private static final long serialVersionUID = 0;
 279         public PoolOverflow() {}
 280     }
 281     public static class StringOverflow extends RuntimeException {
 282         private static final long serialVersionUID = 0;
 283         public final String value;
 284         public StringOverflow(String s) {
 285             value = s;
 286         }
 287     }
 288 
 289 /******************************************************************
 290  * Writing Attributes
 291  ******************************************************************/
 292 
 293     /** Write header for an attribute to data buffer and return
 294      *  position past attribute length index.
 295      */
 296     public int writeAttr(Name attrName) {
 297         int index = poolWriter.putName(attrName);
 298         databuf.appendChar(index);
 299         databuf.appendInt(0);
 300         return databuf.length;
 301     }
 302 
 303     /** Fill in attribute length.
 304      */
 305     public void endAttr(int index) {
 306         putInt(databuf, index - 4, databuf.length - index);
 307     }
 308 
 309     /** Leave space for attribute count and return index for
 310      *  number of attributes field.
 311      */
 312     int beginAttrs() {
 313         databuf.appendChar(0);
 314         return databuf.length;
 315     }
 316 
 317     /** Fill in number of attributes.
 318      */
 319     void endAttrs(int index, int count) {
 320         putChar(databuf, index - 2, count);
 321     }
 322 
 323     /** Write the EnclosingMethod attribute if needed.
 324      *  Returns the number of attributes written (0 or 1).
 325      */
 326     int writeEnclosingMethodAttribute(ClassSymbol c) {
 327         return writeEnclosingMethodAttribute(names.EnclosingMethod, c);
 328     }
 329 
 330     /** Write the EnclosingMethod attribute with a specified name.
 331      *  Returns the number of attributes written (0 or 1).
 332      */
 333     protected int writeEnclosingMethodAttribute(Name attributeName, ClassSymbol c) {
 334         if (c.owner.kind != MTH && // neither a local class
 335             c.name != names.empty) // nor anonymous
 336             return 0;
 337 
 338         int alenIdx = writeAttr(attributeName);
 339         ClassSymbol enclClass = c.owner.enclClass();
 340         MethodSymbol enclMethod =
 341             (c.owner.type == null // local to init block
 342              || c.owner.kind != MTH) // or member init
 343             ? null
 344             : ((MethodSymbol)c.owner).originalEnclosingMethod();
 345         databuf.appendChar(poolWriter.putClass(enclClass));
 346         databuf.appendChar(enclMethod == null ? 0 : poolWriter.putNameAndType(enclMethod));
 347         endAttr(alenIdx);
 348         return 1;
 349     }
 350 
 351     /** Write flag attributes; return number of attributes written.
 352      */
 353     int writeFlagAttrs(long flags) {
 354         int acount = 0;
 355         if ((flags & DEPRECATED) != 0) {
 356             int alenIdx = writeAttr(names.Deprecated);
 357             endAttr(alenIdx);
 358             acount++;
 359         }
 360         return acount;
 361     }
 362 
 363     /** Write member (field or method) attributes;
 364      *  return number of attributes written.
 365      */
 366     int writeMemberAttrs(Symbol sym, boolean isRecordComponent) {
 367         int acount = 0;
 368         if (!isRecordComponent) {
 369             acount = writeFlagAttrs(sym.flags());
 370         }
 371         long flags = sym.flags();
 372         if ((flags & (SYNTHETIC | BRIDGE)) != SYNTHETIC &&
 373             (flags & ANONCONSTR) == 0 &&
 374             (!types.isSameType(sym.type, sym.erasure(types)) ||
 375              poolWriter.signatureGen.hasTypeVar(sym.type.getThrownTypes()))) {
 376             // note that a local class with captured variables
 377             // will get a signature attribute
 378             int alenIdx = writeAttr(names.Signature);
 379             databuf.appendChar(poolWriter.putSignature(sym));
 380             endAttr(alenIdx);
 381             acount++;
 382         }
 383         acount += writeJavaAnnotations(sym.getRawAttributes());
 384         acount += writeTypeAnnotations(sym.getRawTypeAttributes(), false);
 385         return acount;
 386     }
 387 
 388     /**
 389      * Write method parameter names attribute.
 390      */
 391     int writeMethodParametersAttr(MethodSymbol m, boolean writeParamNames) {
 392         MethodType ty = m.externalType(types).asMethodType();
 393         final int allparams = ty.argtypes.size();
 394         if (m.params != null && allparams != 0) {
 395             final int attrIndex = writeAttr(names.MethodParameters);
 396             databuf.appendByte(allparams);
 397             // Write extra parameters first
 398             for (VarSymbol s : m.extraParams) {
 399                 final int flags =
 400                     ((int) s.flags() & (FINAL | SYNTHETIC | MANDATED)) |
 401                     ((int) m.flags() & SYNTHETIC);
 402                 if (writeParamNames)
 403                     databuf.appendChar(poolWriter.putName(s.name));
 404                 else
 405                     databuf.appendChar(0);
 406                 databuf.appendChar(flags);
 407             }
 408             // Now write the real parameters
 409             for (VarSymbol s : m.params) {
 410                 final int flags =
 411                     ((int) s.flags() & (FINAL | SYNTHETIC | MANDATED)) |
 412                     ((int) m.flags() & SYNTHETIC);
 413                 if (writeParamNames)
 414                     databuf.appendChar(poolWriter.putName(s.name));
 415                 else
 416                     databuf.appendChar(0);
 417                 databuf.appendChar(flags);
 418             }
 419             // Now write the captured locals
 420             for (VarSymbol s : m.capturedLocals) {
 421                 final int flags =
 422                     ((int) s.flags() & (FINAL | SYNTHETIC | MANDATED)) |
 423                     ((int) m.flags() & SYNTHETIC);
 424                 if (writeParamNames)
 425                     databuf.appendChar(poolWriter.putName(s.name));
 426                 else
 427                     databuf.appendChar(0);
 428                 databuf.appendChar(flags);
 429             }
 430             endAttr(attrIndex);
 431             return 1;
 432         } else
 433             return 0;
 434     }
 435 
 436     private void writeParamAnnotations(List<VarSymbol> params,
 437                                        RetentionPolicy retention) {
 438         databuf.appendByte(params.length());
 439         for (VarSymbol s : params) {
 440             ListBuffer<Attribute.Compound> buf = new ListBuffer<>();
 441             for (Attribute.Compound a : s.getRawAttributes())
 442                 if (types.getRetention(a) == retention)
 443                     buf.append(a);
 444             databuf.appendChar(buf.length());
 445             for (Attribute.Compound a : buf)
 446                 writeCompoundAttribute(a);
 447         }
 448 
 449     }
 450 
 451     private void writeParamAnnotations(MethodSymbol m,
 452                                        RetentionPolicy retention) {
 453         databuf.appendByte(m.params.length());
 454         writeParamAnnotations(m.params, retention);
 455     }
 456 
 457     /** Write method parameter annotations;
 458      *  return number of attributes written.
 459      */
 460     int writeParameterAttrs(List<VarSymbol> vars) {
 461         boolean hasVisible = false;
 462         boolean hasInvisible = false;
 463         if (vars != null) {
 464             for (VarSymbol s : vars) {
 465                 for (Attribute.Compound a : s.getRawAttributes()) {
 466                     switch (types.getRetention(a)) {
 467                     case SOURCE: break;
 468                     case CLASS: hasInvisible = true; break;
 469                     case RUNTIME: hasVisible = true; break;
 470                     default: // /* fail soft */ throw new AssertionError(vis);
 471                     }
 472                 }
 473             }
 474         }
 475 
 476         int attrCount = 0;
 477         if (hasVisible) {
 478             int attrIndex = writeAttr(names.RuntimeVisibleParameterAnnotations);
 479             writeParamAnnotations(vars, RetentionPolicy.RUNTIME);
 480             endAttr(attrIndex);
 481             attrCount++;
 482         }
 483         if (hasInvisible) {
 484             int attrIndex = writeAttr(names.RuntimeInvisibleParameterAnnotations);
 485             writeParamAnnotations(vars, RetentionPolicy.CLASS);
 486             endAttr(attrIndex);
 487             attrCount++;
 488         }
 489         return attrCount;
 490     }
 491 
 492 /**********************************************************************
 493  * Writing Java-language annotations (aka metadata, attributes)
 494  **********************************************************************/
 495 
 496     /** Write Java-language annotations; return number of JVM
 497      *  attributes written (zero or one).
 498      */
 499     int writeJavaAnnotations(List<Attribute.Compound> attrs) {
 500         if (attrs.isEmpty()) return 0;
 501         ListBuffer<Attribute.Compound> visibles = new ListBuffer<>();
 502         ListBuffer<Attribute.Compound> invisibles = new ListBuffer<>();
 503         for (Attribute.Compound a : attrs) {
 504             switch (types.getRetention(a)) {
 505             case SOURCE: break;
 506             case CLASS: invisibles.append(a); break;
 507             case RUNTIME: visibles.append(a); break;
 508             default: // /* fail soft */ throw new AssertionError(vis);
 509             }
 510         }
 511 
 512         int attrCount = 0;
 513         if (visibles.length() != 0) {
 514             int attrIndex = writeAttr(names.RuntimeVisibleAnnotations);
 515             databuf.appendChar(visibles.length());
 516             for (Attribute.Compound a : visibles)
 517                 writeCompoundAttribute(a);
 518             endAttr(attrIndex);
 519             attrCount++;
 520         }
 521         if (invisibles.length() != 0) {
 522             int attrIndex = writeAttr(names.RuntimeInvisibleAnnotations);
 523             databuf.appendChar(invisibles.length());
 524             for (Attribute.Compound a : invisibles)
 525                 writeCompoundAttribute(a);
 526             endAttr(attrIndex);
 527             attrCount++;
 528         }
 529         return attrCount;
 530     }
 531 
 532     int writeTypeAnnotations(List<Attribute.TypeCompound> typeAnnos, boolean inCode) {
 533         if (typeAnnos.isEmpty()) return 0;
 534 
 535         ListBuffer<Attribute.TypeCompound> visibles = new ListBuffer<>();
 536         ListBuffer<Attribute.TypeCompound> invisibles = new ListBuffer<>();
 537 
 538         for (Attribute.TypeCompound tc : typeAnnos) {
 539             if (tc.hasUnknownPosition()) {
 540                 boolean fixed = tc.tryFixPosition();
 541 
 542                 // Could we fix it?
 543                 if (!fixed) {
 544                     // This happens for nested types like @A Outer. @B Inner.
 545                     // For method parameters we get the annotation twice! Once with
 546                     // a valid position, once unknown.
 547                     // TODO: find a cleaner solution.
 548                     PrintWriter pw = log.getWriter(Log.WriterKind.ERROR);
 549                     pw.println("ClassWriter: Position UNKNOWN in type annotation: " + tc);
 550                     continue;
 551                 }
 552             }
 553 
 554             if (tc.position.type.isLocal() != inCode)
 555                 continue;
 556             if (!tc.position.emitToClassfile())
 557                 continue;
 558             switch (types.getRetention(tc)) {
 559             case SOURCE: break;
 560             case CLASS: invisibles.append(tc); break;
 561             case RUNTIME: visibles.append(tc); break;
 562             default: // /* fail soft */ throw new AssertionError(vis);
 563             }
 564         }
 565 
 566         int attrCount = 0;
 567         if (visibles.length() != 0) {
 568             int attrIndex = writeAttr(names.RuntimeVisibleTypeAnnotations);
 569             databuf.appendChar(visibles.length());
 570             for (Attribute.TypeCompound p : visibles)
 571                 writeTypeAnnotation(p);
 572             endAttr(attrIndex);
 573             attrCount++;
 574         }
 575 
 576         if (invisibles.length() != 0) {
 577             int attrIndex = writeAttr(names.RuntimeInvisibleTypeAnnotations);
 578             databuf.appendChar(invisibles.length());
 579             for (Attribute.TypeCompound p : invisibles)
 580                 writeTypeAnnotation(p);
 581             endAttr(attrIndex);
 582             attrCount++;
 583         }
 584 
 585         return attrCount;
 586     }
 587 
 588     /** A visitor to write an attribute including its leading
 589      *  single-character marker.
 590      */
 591     class AttributeWriter implements Attribute.Visitor {
 592         public void visitConstant(Attribute.Constant _value) {
 593             if (_value.type.getTag() == CLASS) {
 594                 Assert.check(_value.value instanceof String);
 595                 String s = (String)_value.value;
 596                 databuf.appendByte('s');
 597                 databuf.appendChar(poolWriter.putName(names.fromString(s)));
 598             } else {
 599                 switch (_value.type.getTag()) {
 600                     case BYTE:
 601                         databuf.appendByte('B');
 602                         break;
 603                     case CHAR:
 604                         databuf.appendByte('C');
 605                         break;
 606                     case SHORT:
 607                         databuf.appendByte('S');
 608                         break;
 609                     case INT:
 610                         databuf.appendByte('I');
 611                         break;
 612                     case LONG:
 613                         databuf.appendByte('J');
 614                         break;
 615                     case FLOAT:
 616                         databuf.appendByte('F');
 617                         break;
 618                     case DOUBLE:
 619                         databuf.appendByte('D');
 620                         break;
 621                     case BOOLEAN:
 622                         databuf.appendByte('Z');
 623                         break;
 624                     default:
 625                         throw new AssertionError(_value.type);
 626                 }
 627                 databuf.appendChar(poolWriter.putConstant(_value.value));
 628             }
 629         }
 630         public void visitEnum(Attribute.Enum e) {
 631             databuf.appendByte('e');
 632             databuf.appendChar(poolWriter.putDescriptor(e.value.type));
 633             databuf.appendChar(poolWriter.putName(e.value.name));
 634         }
 635         public void visitClass(Attribute.Class clazz) {
 636             databuf.appendByte('c');
 637             databuf.appendChar(poolWriter.putDescriptor(clazz.classType));
 638         }
 639         public void visitCompound(Attribute.Compound compound) {
 640             databuf.appendByte('@');
 641             writeCompoundAttribute(compound);
 642         }
 643         public void visitError(Attribute.Error x) {
 644             throw new AssertionError(x);
 645         }
 646         public void visitArray(Attribute.Array array) {
 647             databuf.appendByte('[');
 648             databuf.appendChar(array.values.length);
 649             for (Attribute a : array.values) {
 650                 a.accept(this);
 651             }
 652         }
 653     }
 654     AttributeWriter awriter = new AttributeWriter();
 655 
 656     /** Write a compound attribute excluding the '@' marker. */
 657     void writeCompoundAttribute(Attribute.Compound c) {
 658         databuf.appendChar(poolWriter.putDescriptor(c.type));
 659         databuf.appendChar(c.values.length());
 660         for (Pair<Symbol.MethodSymbol,Attribute> p : c.values) {
 661             databuf.appendChar(poolWriter.putName(p.fst.name));
 662             p.snd.accept(awriter);
 663         }
 664     }
 665 
 666     void writeTypeAnnotation(Attribute.TypeCompound c) {
 667         writePosition(c.position);
 668         writeCompoundAttribute(c);
 669     }
 670 
 671     void writePosition(TypeAnnotationPosition p) {
 672         databuf.appendByte(p.type.targetTypeValue()); // TargetType tag is a byte
 673         switch (p.type) {
 674         // instanceof
 675         case INSTANCEOF:
 676         // new expression
 677         case NEW:
 678         // constructor/method reference receiver
 679         case CONSTRUCTOR_REFERENCE:
 680         case METHOD_REFERENCE:
 681             databuf.appendChar(p.offset);
 682             break;
 683         // local variable
 684         case LOCAL_VARIABLE:
 685         // resource variable
 686         case RESOURCE_VARIABLE:
 687             databuf.appendChar(p.lvarOffset.length);  // for table length
 688             for (int i = 0; i < p.lvarOffset.length; ++i) {
 689                 databuf.appendChar(p.lvarOffset[i]);
 690                 databuf.appendChar(p.lvarLength[i]);
 691                 databuf.appendChar(p.lvarIndex[i]);
 692             }
 693             break;
 694         // exception parameter
 695         case EXCEPTION_PARAMETER:
 696             databuf.appendChar(p.getExceptionIndex());
 697             break;
 698         // method receiver
 699         case METHOD_RECEIVER:
 700             // Do nothing
 701             break;
 702         // type parameter
 703         case CLASS_TYPE_PARAMETER:
 704         case METHOD_TYPE_PARAMETER:
 705             databuf.appendByte(p.parameter_index);
 706             break;
 707         // type parameter bound
 708         case CLASS_TYPE_PARAMETER_BOUND:
 709         case METHOD_TYPE_PARAMETER_BOUND:
 710             databuf.appendByte(p.parameter_index);
 711             databuf.appendByte(p.bound_index);
 712             break;
 713         // class extends or implements clause
 714         case CLASS_EXTENDS:
 715             databuf.appendChar(p.type_index);
 716             break;
 717         // throws
 718         case THROWS:
 719             databuf.appendChar(p.type_index);
 720             break;
 721         // method parameter
 722         case METHOD_FORMAL_PARAMETER:
 723             databuf.appendByte(p.parameter_index);
 724             break;
 725         // type cast
 726         case CAST:
 727         // method/constructor/reference type argument
 728         case CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT:
 729         case METHOD_INVOCATION_TYPE_ARGUMENT:
 730         case CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT:
 731         case METHOD_REFERENCE_TYPE_ARGUMENT:
 732             databuf.appendChar(p.offset);
 733             databuf.appendByte(p.type_index);
 734             break;
 735         // We don't need to worry about these
 736         case METHOD_RETURN:
 737         case FIELD:
 738             break;
 739         case UNKNOWN:
 740             throw new AssertionError("jvm.ClassWriter: UNKNOWN target type should never occur!");
 741         default:
 742             throw new AssertionError("jvm.ClassWriter: Unknown target type for position: " + p);
 743         }
 744 
 745         { // Append location data for generics/arrays.
 746             databuf.appendByte(p.location.size());
 747             java.util.List<Integer> loc = TypeAnnotationPosition.getBinaryFromTypePath(p.location);
 748             for (int i : loc)
 749                 databuf.appendByte((byte)i);
 750         }
 751     }
 752 
 753 /**********************************************************************
 754  * Writing module attributes
 755  **********************************************************************/
 756 
 757     /** Write the Module attribute if needed.
 758      *  Returns the number of attributes written (0 or 1).
 759      */
 760     int writeModuleAttribute(ClassSymbol c) {
 761         ModuleSymbol m = (ModuleSymbol) c.owner;
 762 
 763         int alenIdx = writeAttr(names.Module);
 764 
 765         databuf.appendChar(poolWriter.putModule(m));
 766         databuf.appendChar(ModuleFlags.value(m.flags)); // module_flags
 767         databuf.appendChar(m.version != null ? poolWriter.putName(m.version) : 0);
 768 
 769         ListBuffer<RequiresDirective> requires = new ListBuffer<>();
 770         for (RequiresDirective r: m.requires) {
 771             if (!r.flags.contains(RequiresFlag.EXTRA))
 772                 requires.add(r);
 773         }
 774         databuf.appendChar(requires.size());
 775         for (RequiresDirective r: requires) {
 776             databuf.appendChar(poolWriter.putModule(r.module));
 777             databuf.appendChar(RequiresFlag.value(r.flags));
 778             databuf.appendChar(r.module.version != null ? poolWriter.putName(r.module.version) : 0);
 779         }
 780 
 781         List<ExportsDirective> exports = m.exports;
 782         databuf.appendChar(exports.size());
 783         for (ExportsDirective e: exports) {
 784             databuf.appendChar(poolWriter.putPackage(e.packge));
 785             databuf.appendChar(ExportsFlag.value(e.flags));
 786             if (e.modules == null) {
 787                 databuf.appendChar(0);
 788             } else {
 789                 databuf.appendChar(e.modules.size());
 790                 for (ModuleSymbol msym: e.modules) {
 791                     databuf.appendChar(poolWriter.putModule(msym));
 792                 }
 793             }
 794         }
 795 
 796         List<OpensDirective> opens = m.opens;
 797         databuf.appendChar(opens.size());
 798         for (OpensDirective o: opens) {
 799             databuf.appendChar(poolWriter.putPackage(o.packge));
 800             databuf.appendChar(OpensFlag.value(o.flags));
 801             if (o.modules == null) {
 802                 databuf.appendChar(0);
 803             } else {
 804                 databuf.appendChar(o.modules.size());
 805                 for (ModuleSymbol msym: o.modules) {
 806                     databuf.appendChar(poolWriter.putModule(msym));
 807                 }
 808             }
 809         }
 810 
 811         List<UsesDirective> uses = m.uses;
 812         databuf.appendChar(uses.size());
 813         for (UsesDirective s: uses) {
 814             databuf.appendChar(poolWriter.putClass(s.service));
 815         }
 816 
 817         // temporary fix to merge repeated provides clause for same service;
 818         // eventually this should be disallowed when analyzing the module,
 819         // so that each service type only appears once.
 820         Map<ClassSymbol, Set<ClassSymbol>> mergedProvides = new LinkedHashMap<>();
 821         for (ProvidesDirective p : m.provides) {
 822             mergedProvides.computeIfAbsent(p.service, s -> new LinkedHashSet<>()).addAll(p.impls);
 823         }
 824         databuf.appendChar(mergedProvides.size());
 825         mergedProvides.forEach((srvc, impls) -> {
 826             databuf.appendChar(poolWriter.putClass(srvc));
 827             databuf.appendChar(impls.size());
 828             impls.forEach(impl -> databuf.appendChar(poolWriter.putClass(impl)));
 829         });
 830 
 831         endAttr(alenIdx);
 832         return 1;
 833     }
 834 
 835 /**********************************************************************
 836  * Writing Objects
 837  **********************************************************************/
 838 
 839     /** Write "inner classes" attribute.
 840      */
 841     void writeInnerClasses() {
 842         int alenIdx = writeAttr(names.InnerClasses);
 843         databuf.appendChar(poolWriter.innerClasses.size());
 844         for (ClassSymbol inner : poolWriter.innerClasses) {
 845             inner.markAbstractIfNeeded(types);
 846             int flags = adjustFlags(inner.flags_field);
 847             if ((flags & INTERFACE) != 0) flags |= ABSTRACT; // Interfaces are always ABSTRACT
 848             if (dumpInnerClassModifiers) {
 849                 PrintWriter pw = log.getWriter(Log.WriterKind.ERROR);
 850                 pw.println("INNERCLASS  " + inner.name);
 851                 pw.println("---" + flagNames(flags));
 852             }
 853             databuf.appendChar(poolWriter.putClass(inner));
 854             databuf.appendChar(
 855                 inner.owner.kind == TYP && !inner.name.isEmpty() ? poolWriter.putClass((ClassSymbol)inner.owner) : 0);
 856             databuf.appendChar(
 857                 !inner.name.isEmpty() ? poolWriter.putName(inner.name) : 0);
 858             databuf.appendChar(flags);
 859         }
 860         endAttr(alenIdx);
 861     }
 862 
 863      /** Write out "Preload" attribute by enumerating the value classes encountered in field/method descriptors during this compilation.
 864       */
 865      void writePreloadAttribute() {
 866         int alenIdx = writeAttr(names.Preload);
 867         databuf.appendChar(poolWriter.preloadClasses.size());
 868         for (ClassSymbol c : poolWriter.preloadClasses) {
 869             databuf.appendChar(poolWriter.putClass(c));
 870         }
 871         endAttr(alenIdx);
 872      }
 873 
 874     int writeRecordAttribute(ClassSymbol csym) {
 875         int alenIdx = writeAttr(names.Record);
 876         Scope s = csym.members();
 877         databuf.appendChar(csym.getRecordComponents().size());
 878         for (VarSymbol v: csym.getRecordComponents()) {
 879             //databuf.appendChar(poolWriter.putMember(v.accessor.head.snd));
 880             databuf.appendChar(poolWriter.putName(v.name));
 881             databuf.appendChar(poolWriter.putDescriptor(v));
 882             int acountIdx = beginAttrs();
 883             int acount = 0;
 884             acount += writeMemberAttrs(v, true);
 885             endAttrs(acountIdx, acount);
 886         }
 887         endAttr(alenIdx);
 888         return 1;
 889     }
 890 
 891     /**
 892      * Write NestMembers attribute (if needed)
 893      */
 894     int writeNestMembersIfNeeded(ClassSymbol csym) {
 895         ListBuffer<ClassSymbol> nested = new ListBuffer<>();
 896         listNested(csym, nested);
 897         Set<ClassSymbol> nestedUnique = new LinkedHashSet<>(nested);
 898         if (csym.owner.kind == PCK && !nestedUnique.isEmpty()) {
 899             int alenIdx = writeAttr(names.NestMembers);
 900             databuf.appendChar(nestedUnique.size());
 901             for (ClassSymbol s : nestedUnique) {
 902                 databuf.appendChar(poolWriter.putClass(s));
 903             }
 904             endAttr(alenIdx);
 905             return 1;
 906         }
 907         return 0;
 908     }
 909 
 910     /**
 911      * Write NestHost attribute (if needed)
 912      */
 913     int writeNestHostIfNeeded(ClassSymbol csym) {
 914         if (csym.owner.kind != PCK) {
 915             int alenIdx = writeAttr(names.NestHost);
 916             databuf.appendChar(poolWriter.putClass(csym.outermostClass()));
 917             endAttr(alenIdx);
 918             return 1;
 919         }
 920         return 0;
 921     }
 922 
 923     private void listNested(Symbol sym, ListBuffer<ClassSymbol> seen) {
 924         if (sym.kind != TYP) return;
 925         ClassSymbol csym = (ClassSymbol)sym;
 926         if (csym.owner.kind != PCK) {
 927             seen.add(csym);
 928         }
 929         if (csym.members() != null) {
 930             for (Symbol s : sym.members().getSymbols()) {
 931                 listNested(s, seen);
 932             }
 933         }
 934         if (csym.trans_local != null) {
 935             for (Symbol s : csym.trans_local) {
 936                 listNested(s, seen);
 937             }
 938         }
 939     }
 940 
 941     /** Write "PermittedSubclasses" attribute.
 942      */
 943     int writePermittedSubclassesIfNeeded(ClassSymbol csym) {
 944         if (csym.permitted.nonEmpty()) {
 945             int alenIdx = writeAttr(names.PermittedSubclasses);
 946             databuf.appendChar(csym.permitted.size());
 947             for (Symbol c : csym.permitted) {
 948                 databuf.appendChar(poolWriter.putClass((ClassSymbol) c));
 949             }
 950             endAttr(alenIdx);
 951             return 1;
 952         }
 953         return 0;
 954     }
 955 
 956     /** Write "bootstrapMethods" attribute.
 957      */
 958     void writeBootstrapMethods() {
 959         int alenIdx = writeAttr(names.BootstrapMethods);
 960         int lastBootstrapMethods;
 961         do {
 962             lastBootstrapMethods = poolWriter.bootstrapMethods.size();
 963             for (BsmKey bsmKey : java.util.List.copyOf(poolWriter.bootstrapMethods.keySet())) {
 964                 for (LoadableConstant arg : bsmKey.staticArgs) {
 965                     poolWriter.putConstant(arg);
 966                 }
 967             }
 968         } while (lastBootstrapMethods < poolWriter.bootstrapMethods.size());
 969         databuf.appendChar(poolWriter.bootstrapMethods.size());
 970         for (BsmKey bsmKey : poolWriter.bootstrapMethods.keySet()) {
 971             //write BSM handle
 972             databuf.appendChar(poolWriter.putConstant(bsmKey.bsm));
 973             LoadableConstant[] uniqueArgs = bsmKey.staticArgs;
 974             //write static args length
 975             databuf.appendChar(uniqueArgs.length);
 976             //write static args array
 977             for (LoadableConstant arg : uniqueArgs) {
 978                 databuf.appendChar(poolWriter.putConstant(arg));
 979             }
 980         }
 981         endAttr(alenIdx);
 982     }
 983 
 984     /** Write field symbol, entering all references into constant pool.
 985      */
 986     void writeField(VarSymbol v) {
 987         int flags = adjustFlags(v.flags());
 988         databuf.appendChar(flags);
 989         if (dumpFieldModifiers) {
 990             PrintWriter pw = log.getWriter(Log.WriterKind.ERROR);
 991             pw.println("FIELD  " + v.name);
 992             pw.println("---" + flagNames(v.flags()));
 993         }
 994         databuf.appendChar(poolWriter.putName(v.name));
 995         databuf.appendChar(poolWriter.putDescriptor(v));
 996         Type fldType = v.erasure(types);
 997         if (fldType.requiresPreload(v.owner)) {
 998             poolWriter.enterPreloadClass((ClassSymbol) fldType.tsym);
 999         }
1000         int acountIdx = beginAttrs();
1001         int acount = 0;
1002         if (v.getConstValue() != null) {
1003             int alenIdx = writeAttr(names.ConstantValue);
1004             databuf.appendChar(poolWriter.putConstant(v.getConstValue()));
1005             endAttr(alenIdx);
1006             acount++;
1007         }
1008         acount += writeMemberAttrs(v, false);
1009         acount += writeExtraAttributes(v);
1010         endAttrs(acountIdx, acount);
1011     }
1012 
1013     /** Write method symbol, entering all references into constant pool.
1014      */
1015     void writeMethod(MethodSymbol m) {
1016         int flags = adjustFlags(m.flags());
1017         databuf.appendChar(flags);
1018         if (dumpMethodModifiers) {
1019             PrintWriter pw = log.getWriter(Log.WriterKind.ERROR);
1020             pw.println("METHOD  " + m.name);
1021             pw.println("---" + flagNames(m.flags()));
1022         }
1023         databuf.appendChar(poolWriter.putName(m.name));
1024         databuf.appendChar(poolWriter.putDescriptor(m));
1025         MethodType mtype = (MethodType) m.externalType(types);
1026         for (Type t : mtype.getParameterTypes()) {
1027             if (t.requiresPreload(m.owner)) {
1028                 poolWriter.enterPreloadClass((ClassSymbol) t.tsym);
1029             }
1030         }
1031         Type returnType = mtype.getReturnType();
1032         if (returnType.requiresPreload(m.owner)) {
1033             poolWriter.enterPreloadClass((ClassSymbol) returnType.tsym);
1034         }
1035         int acountIdx = beginAttrs();
1036         int acount = 0;
1037         if (m.code != null) {
1038             int alenIdx = writeAttr(names.Code);
1039             writeCode(m.code);
1040             m.code = null; // to conserve space
1041             endAttr(alenIdx);
1042             acount++;
1043         }
1044         List<Type> thrown = m.erasure(types).getThrownTypes();
1045         if (thrown.nonEmpty()) {
1046             int alenIdx = writeAttr(names.Exceptions);
1047             databuf.appendChar(thrown.length());
1048             for (List<Type> l = thrown; l.nonEmpty(); l = l.tail)
1049                 databuf.appendChar(poolWriter.putClass(l.head));
1050             endAttr(alenIdx);
1051             acount++;
1052         }
1053         if (m.defaultValue != null) {
1054             int alenIdx = writeAttr(names.AnnotationDefault);
1055             m.defaultValue.accept(awriter);
1056             endAttr(alenIdx);
1057             acount++;
1058         }
1059         if (target.hasMethodParameters()) {
1060             if (!m.isLambdaMethod()) { // Per JDK-8138729, do not emit parameters table for lambda bodies.
1061                 boolean requiresParamNames = requiresParamNames(m);
1062                 if (requiresParamNames || requiresParamFlags(m))
1063                     acount += writeMethodParametersAttr(m, requiresParamNames);
1064             }
1065         }
1066         acount += writeMemberAttrs(m, false);
1067         if (!m.isLambdaMethod())
1068             acount += writeParameterAttrs(m.params);
1069         acount += writeExtraAttributes(m);
1070         endAttrs(acountIdx, acount);
1071     }
1072 
1073     private boolean requiresParamNames(MethodSymbol m) {
1074         if (options.isSet(PARAMETERS))
1075             return true;
1076         if ((m.isInitOrVNew() || m.isValueObjectFactory()) && (m.flags_field & RECORD) != 0)
1077             return true;
1078         return false;
1079     }
1080 
1081     private boolean requiresParamFlags(MethodSymbol m) {
1082         if (!m.extraParams.isEmpty()) {
1083             return m.extraParams.stream().anyMatch(p -> (p.flags_field & (SYNTHETIC | MANDATED)) != 0);
1084         }
1085         if (m.params != null) {
1086             // parameter is stored in params for Enum#valueOf(name)
1087             return m.params.stream().anyMatch(p -> (p.flags_field & (SYNTHETIC | MANDATED)) != 0);
1088         }
1089         return false;
1090     }
1091 
1092     /** Write code attribute of method.
1093      */
1094     void writeCode(Code code) {
1095         databuf.appendChar(code.max_stack);
1096         databuf.appendChar(code.max_locals);
1097         databuf.appendInt(code.cp);
1098         databuf.appendBytes(code.code, 0, code.cp);
1099         databuf.appendChar(code.catchInfo.length());
1100         for (List<char[]> l = code.catchInfo.toList();
1101              l.nonEmpty();
1102              l = l.tail) {
1103             for (int i = 0; i < l.head.length; i++)
1104                 databuf.appendChar(l.head[i]);
1105         }
1106         int acountIdx = beginAttrs();
1107         int acount = 0;
1108 
1109         if (code.lineInfo.nonEmpty()) {
1110             int alenIdx = writeAttr(names.LineNumberTable);
1111             databuf.appendChar(code.lineInfo.length());
1112             for (List<char[]> l = code.lineInfo.reverse();
1113                  l.nonEmpty();
1114                  l = l.tail)
1115                 for (int i = 0; i < l.head.length; i++)
1116                     databuf.appendChar(l.head[i]);
1117             endAttr(alenIdx);
1118             acount++;
1119         }
1120 
1121         if (genCrt && (code.crt != null)) {
1122             CRTable crt = code.crt;
1123             int alenIdx = writeAttr(names.CharacterRangeTable);
1124             int crtIdx = beginAttrs();
1125             int crtEntries = crt.writeCRT(databuf, code.lineMap, log);
1126             endAttrs(crtIdx, crtEntries);
1127             endAttr(alenIdx);
1128             acount++;
1129         }
1130 
1131         // counter for number of generic local variables
1132         if (code.varDebugInfo && code.varBufferSize > 0) {
1133             int nGenericVars = 0;
1134             int alenIdx = writeAttr(names.LocalVariableTable);
1135             databuf.appendChar(code.getLVTSize());
1136             for (int i=0; i<code.varBufferSize; i++) {
1137                 Code.LocalVar var = code.varBuffer[i];
1138 
1139                 for (Code.LocalVar.Range r: var.aliveRanges) {
1140                     // write variable info
1141                     Assert.check(r.start_pc >= 0
1142                             && r.start_pc <= code.cp);
1143                     databuf.appendChar(r.start_pc);
1144                     Assert.check(r.length > 0
1145                             && (r.start_pc + r.length) <= code.cp);
1146                     databuf.appendChar(r.length);
1147                     VarSymbol sym = var.sym;
1148                     databuf.appendChar(poolWriter.putName(sym.name));
1149                     databuf.appendChar(poolWriter.putDescriptor(sym));
1150                     databuf.appendChar(var.reg);
1151                     if (needsLocalVariableTypeEntry(var.sym.type)) {
1152                         nGenericVars++;
1153                     }
1154                 }
1155             }
1156             endAttr(alenIdx);
1157             acount++;
1158 
1159             if (nGenericVars > 0) {
1160                 alenIdx = writeAttr(names.LocalVariableTypeTable);
1161                 databuf.appendChar(nGenericVars);
1162                 int count = 0;
1163 
1164                 for (int i=0; i<code.varBufferSize; i++) {
1165                     Code.LocalVar var = code.varBuffer[i];
1166                     VarSymbol sym = var.sym;
1167                     if (!needsLocalVariableTypeEntry(sym.type))
1168                         continue;
1169                     for (Code.LocalVar.Range r : var.aliveRanges) {
1170                         // write variable info
1171                         databuf.appendChar(r.start_pc);
1172                         databuf.appendChar(r.length);
1173                         databuf.appendChar(poolWriter.putName(sym.name));
1174                         databuf.appendChar(poolWriter.putSignature(sym));
1175                         databuf.appendChar(var.reg);
1176                         count++;
1177                     }
1178                 }
1179                 Assert.check(count == nGenericVars);
1180                 endAttr(alenIdx);
1181                 acount++;
1182             }
1183         }
1184 
1185         if (code.stackMapBufferSize > 0) {
1186             if (debugstackmap) System.out.println("Stack map for " + code.meth);
1187             int alenIdx = writeAttr(code.stackMap.getAttributeName(names));
1188             writeStackMap(code);
1189             endAttr(alenIdx);
1190             acount++;
1191         }
1192 
1193         acount += writeTypeAnnotations(code.meth.getRawTypeAttributes(), true);
1194 
1195         endAttrs(acountIdx, acount);
1196     }
1197     //where
1198     private boolean needsLocalVariableTypeEntry(Type t) {
1199         //a local variable needs a type-entry if its type T is generic
1200         //(i.e. |T| != T) and if it's not an non-denotable type (non-denotable
1201         // types are not supported in signature attribute grammar!)
1202         return !types.isSameType(t, types.erasure(t)) &&
1203                 check.checkDenotable(t);
1204     }
1205 
1206     void writeStackMap(Code code) {
1207         int nframes = code.stackMapBufferSize;
1208         if (debugstackmap) System.out.println(" nframes = " + nframes);
1209         databuf.appendChar(nframes);
1210 
1211         switch (code.stackMap) {
1212         case CLDC:
1213             for (int i=0; i<nframes; i++) {
1214                 if (debugstackmap) System.out.print("  " + i + ":");
1215                 Code.StackMapFrame frame = code.stackMapBuffer[i];
1216 
1217                 // output PC
1218                 if (debugstackmap) System.out.print(" pc=" + frame.pc);
1219                 databuf.appendChar(frame.pc);
1220 
1221                 // output locals
1222                 int localCount = 0;
1223                 for (int j=0; j<frame.locals.length;
1224                      j += Code.width(frame.locals[j])) {
1225                     localCount++;
1226                 }
1227                 if (debugstackmap) System.out.print(" nlocals=" +
1228                                                     localCount);
1229                 databuf.appendChar(localCount);
1230                 for (int j=0; j<frame.locals.length;
1231                      j += Code.width(frame.locals[j])) {
1232                     if (debugstackmap) System.out.print(" local[" + j + "]=");
1233                     writeStackMapType(frame.locals[j]);
1234                 }
1235 
1236                 // output stack
1237                 int stackCount = 0;
1238                 for (int j=0; j<frame.stack.length;
1239                      j += Code.width(frame.stack[j])) {
1240                     stackCount++;
1241                 }
1242                 if (debugstackmap) System.out.print(" nstack=" +
1243                                                     stackCount);
1244                 databuf.appendChar(stackCount);
1245                 for (int j=0; j<frame.stack.length;
1246                      j += Code.width(frame.stack[j])) {
1247                     if (debugstackmap) System.out.print(" stack[" + j + "]=");
1248                     writeStackMapType(frame.stack[j]);
1249                 }
1250                 if (debugstackmap) System.out.println();
1251             }
1252             break;
1253         case JSR202: {
1254             Assert.checkNull(code.stackMapBuffer);
1255             for (int i=0; i<nframes; i++) {
1256                 if (debugstackmap) System.out.print("  " + i + ":");
1257                 StackMapTableFrame frame = code.stackMapTableBuffer[i];
1258                 frame.write(this);
1259                 if (debugstackmap) System.out.println();
1260             }
1261             break;
1262         }
1263         default:
1264             throw new AssertionError("Unexpected stackmap format value");
1265         }
1266     }
1267 
1268         //where
1269         void writeStackMapType(Type t) {
1270             if (t == null) {
1271                 if (debugstackmap) System.out.print("empty");
1272                 databuf.appendByte(0);
1273             }
1274             else switch(t.getTag()) {
1275             case BYTE:
1276             case CHAR:
1277             case SHORT:
1278             case INT:
1279             case BOOLEAN:
1280                 if (debugstackmap) System.out.print("int");
1281                 databuf.appendByte(1);
1282                 break;
1283             case FLOAT:
1284                 if (debugstackmap) System.out.print("float");
1285                 databuf.appendByte(2);
1286                 break;
1287             case DOUBLE:
1288                 if (debugstackmap) System.out.print("double");
1289                 databuf.appendByte(3);
1290                 break;
1291             case LONG:
1292                 if (debugstackmap) System.out.print("long");
1293                 databuf.appendByte(4);
1294                 break;
1295             case BOT: // null
1296                 if (debugstackmap) System.out.print("null");
1297                 databuf.appendByte(5);
1298                 break;
1299             case CLASS:
1300             case ARRAY:
1301                 if (debugstackmap) System.out.print("object(" + types.erasure(t).tsym + ")");
1302                 databuf.appendByte(7);
1303                 databuf.appendChar(allowPrimitiveClasses && t.isPrimitiveClass() ? poolWriter.putClass(new ConstantPoolQType(types.erasure(t), types)) : poolWriter.putClass(types.erasure(t)));
1304                 break;
1305             case TYPEVAR:
1306                 if (debugstackmap) System.out.print("object(" + types.erasure(t).tsym + ")");
1307                 databuf.appendByte(7);
1308                 databuf.appendChar(poolWriter.putClass(types.erasure(t)));
1309                 break;
1310             case UNINITIALIZED_THIS:
1311                 if (debugstackmap) System.out.print("uninit_this");
1312                 databuf.appendByte(6);
1313                 break;
1314             case UNINITIALIZED_OBJECT:
1315                 { UninitializedType uninitType = (UninitializedType)t;
1316                 databuf.appendByte(8);
1317                 if (debugstackmap) System.out.print("uninit_object@" + uninitType.offset);
1318                 databuf.appendChar(uninitType.offset);
1319                 }
1320                 break;
1321             default:
1322                 throw new AssertionError();
1323             }
1324         }
1325 
1326     /** An entry in the JSR202 StackMapTable */
1327     abstract static class StackMapTableFrame {
1328         abstract int getFrameType();
1329 
1330         void write(ClassWriter writer) {
1331             int frameType = getFrameType();
1332             writer.databuf.appendByte(frameType);
1333             if (writer.debugstackmap) System.out.print(" frame_type=" + frameType);
1334         }
1335 
1336         static class SameFrame extends StackMapTableFrame {
1337             final int offsetDelta;
1338             SameFrame(int offsetDelta) {
1339                 this.offsetDelta = offsetDelta;
1340             }
1341             int getFrameType() {
1342                 return (offsetDelta < SAME_FRAME_SIZE) ? offsetDelta : SAME_FRAME_EXTENDED;
1343             }
1344             @Override
1345             void write(ClassWriter writer) {
1346                 super.write(writer);
1347                 if (getFrameType() == SAME_FRAME_EXTENDED) {
1348                     writer.databuf.appendChar(offsetDelta);
1349                     if (writer.debugstackmap){
1350                         System.out.print(" offset_delta=" + offsetDelta);
1351                     }
1352                 }
1353             }
1354         }
1355 
1356         static class SameLocals1StackItemFrame extends StackMapTableFrame {
1357             final int offsetDelta;
1358             final Type stack;
1359             SameLocals1StackItemFrame(int offsetDelta, Type stack) {
1360                 this.offsetDelta = offsetDelta;
1361                 this.stack = stack;
1362             }
1363             int getFrameType() {
1364                 return (offsetDelta < SAME_FRAME_SIZE) ?
1365                        (SAME_FRAME_SIZE + offsetDelta) :
1366                        SAME_LOCALS_1_STACK_ITEM_EXTENDED;
1367             }
1368             @Override
1369             void write(ClassWriter writer) {
1370                 super.write(writer);
1371                 if (getFrameType() == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
1372                     writer.databuf.appendChar(offsetDelta);
1373                     if (writer.debugstackmap) {
1374                         System.out.print(" offset_delta=" + offsetDelta);
1375                     }
1376                 }
1377                 if (writer.debugstackmap) {
1378                     System.out.print(" stack[" + 0 + "]=");
1379                 }
1380                 writer.writeStackMapType(stack);
1381             }
1382         }
1383 
1384         static class ChopFrame extends StackMapTableFrame {
1385             final int frameType;
1386             final int offsetDelta;
1387             ChopFrame(int frameType, int offsetDelta) {
1388                 this.frameType = frameType;
1389                 this.offsetDelta = offsetDelta;
1390             }
1391             int getFrameType() { return frameType; }
1392             @Override
1393             void write(ClassWriter writer) {
1394                 super.write(writer);
1395                 writer.databuf.appendChar(offsetDelta);
1396                 if (writer.debugstackmap) {
1397                     System.out.print(" offset_delta=" + offsetDelta);
1398                 }
1399             }
1400         }
1401 
1402         static class AppendFrame extends StackMapTableFrame {
1403             final int frameType;
1404             final int offsetDelta;
1405             final Type[] locals;
1406             AppendFrame(int frameType, int offsetDelta, Type[] locals) {
1407                 this.frameType = frameType;
1408                 this.offsetDelta = offsetDelta;
1409                 this.locals = locals;
1410             }
1411             int getFrameType() { return frameType; }
1412             @Override
1413             void write(ClassWriter writer) {
1414                 super.write(writer);
1415                 writer.databuf.appendChar(offsetDelta);
1416                 if (writer.debugstackmap) {
1417                     System.out.print(" offset_delta=" + offsetDelta);
1418                 }
1419                 for (int i=0; i<locals.length; i++) {
1420                      if (writer.debugstackmap) System.out.print(" locals[" + i + "]=");
1421                      writer.writeStackMapType(locals[i]);
1422                 }
1423             }
1424         }
1425 
1426         static class FullFrame extends StackMapTableFrame {
1427             final int offsetDelta;
1428             final Type[] locals;
1429             final Type[] stack;
1430             FullFrame(int offsetDelta, Type[] locals, Type[] stack) {
1431                 this.offsetDelta = offsetDelta;
1432                 this.locals = locals;
1433                 this.stack = stack;
1434             }
1435             int getFrameType() { return FULL_FRAME; }
1436             @Override
1437             void write(ClassWriter writer) {
1438                 super.write(writer);
1439                 writer.databuf.appendChar(offsetDelta);
1440                 writer.databuf.appendChar(locals.length);
1441                 if (writer.debugstackmap) {
1442                     System.out.print(" offset_delta=" + offsetDelta);
1443                     System.out.print(" nlocals=" + locals.length);
1444                 }
1445                 for (int i=0; i<locals.length; i++) {
1446                     if (writer.debugstackmap) System.out.print(" locals[" + i + "]=");
1447                     writer.writeStackMapType(locals[i]);
1448                 }
1449 
1450                 writer.databuf.appendChar(stack.length);
1451                 if (writer.debugstackmap) { System.out.print(" nstack=" + stack.length); }
1452                 for (int i=0; i<stack.length; i++) {
1453                     if (writer.debugstackmap) System.out.print(" stack[" + i + "]=");
1454                     writer.writeStackMapType(stack[i]);
1455                 }
1456             }
1457         }
1458 
1459        /** Compare this frame with the previous frame and produce
1460         *  an entry of compressed stack map frame. */
1461         static StackMapTableFrame getInstance(Code.StackMapFrame this_frame,
1462                                               int prev_pc,
1463                                               Type[] prev_locals,
1464                                               Types types) {
1465             Type[] locals = this_frame.locals;
1466             Type[] stack = this_frame.stack;
1467             int offset_delta = this_frame.pc - prev_pc - 1;
1468             if (stack.length == 1) {
1469                 if (locals.length == prev_locals.length
1470                     && compare(prev_locals, locals, types) == 0) {
1471                     return new SameLocals1StackItemFrame(offset_delta, stack[0]);
1472                 }
1473             } else if (stack.length == 0) {
1474                 int diff_length = compare(prev_locals, locals, types);
1475                 if (diff_length == 0) {
1476                     return new SameFrame(offset_delta);
1477                 } else if (-MAX_LOCAL_LENGTH_DIFF < diff_length && diff_length < 0) {
1478                     // APPEND
1479                     Type[] local_diff = new Type[-diff_length];
1480                     for (int i=prev_locals.length, j=0; i<locals.length; i++,j++) {
1481                         local_diff[j] = locals[i];
1482                     }
1483                     return new AppendFrame(SAME_FRAME_EXTENDED - diff_length,
1484                                            offset_delta,
1485                                            local_diff);
1486                 } else if (0 < diff_length && diff_length < MAX_LOCAL_LENGTH_DIFF) {
1487                     // CHOP
1488                     return new ChopFrame(SAME_FRAME_EXTENDED - diff_length,
1489                                          offset_delta);
1490                 }
1491             }
1492             // FULL_FRAME
1493             return new FullFrame(offset_delta, locals, stack);
1494         }
1495 
1496         static boolean isInt(Type t) {
1497             return (t.getTag().isStrictSubRangeOf(INT)  || t.hasTag(BOOLEAN));
1498         }
1499 
1500         static boolean isSameType(Type t1, Type t2, Types types) {
1501             if (t1 == null) { return t2 == null; }
1502             if (t2 == null) { return false; }
1503 
1504             if (isInt(t1) && isInt(t2)) { return true; }
1505 
1506             if (t1.hasTag(UNINITIALIZED_THIS)) {
1507                 return t2.hasTag(UNINITIALIZED_THIS);
1508             } else if (t1.hasTag(UNINITIALIZED_OBJECT)) {
1509                 if (t2.hasTag(UNINITIALIZED_OBJECT)) {
1510                     return ((UninitializedType)t1).offset == ((UninitializedType)t2).offset;
1511                 } else {
1512                     return false;
1513                 }
1514             } else if (t2.hasTag(UNINITIALIZED_THIS) || t2.hasTag(UNINITIALIZED_OBJECT)) {
1515                 return false;
1516             }
1517 
1518             return types.isSameType(t1, t2);
1519         }
1520 
1521         static int compare(Type[] arr1, Type[] arr2, Types types) {
1522             int diff_length = arr1.length - arr2.length;
1523             if (diff_length > MAX_LOCAL_LENGTH_DIFF || diff_length < -MAX_LOCAL_LENGTH_DIFF) {
1524                 return Integer.MAX_VALUE;
1525             }
1526             int len = (diff_length > 0) ? arr2.length : arr1.length;
1527             for (int i=0; i<len; i++) {
1528                 if (!isSameType(arr1[i], arr2[i], types)) {
1529                     return Integer.MAX_VALUE;
1530                 }
1531             }
1532             return diff_length;
1533         }
1534     }
1535 
1536     void writeFields(Scope s) {
1537         // process them in reverse sibling order;
1538         // i.e., process them in declaration order.
1539         List<VarSymbol> vars = List.nil();
1540         for (Symbol sym : s.getSymbols(NON_RECURSIVE)) {
1541             if (sym.kind == VAR) vars = vars.prepend((VarSymbol)sym);
1542         }
1543         while (vars.nonEmpty()) {
1544             writeField(vars.head);
1545             vars = vars.tail;
1546         }
1547     }
1548 
1549     void writeMethods(Scope s) {
1550         List<MethodSymbol> methods = List.nil();
1551         for (Symbol sym : s.getSymbols(NON_RECURSIVE)) {
1552             if (sym.kind == MTH && (sym.flags() & HYPOTHETICAL) == 0)
1553                 methods = methods.prepend((MethodSymbol)sym);
1554         }
1555         while (methods.nonEmpty()) {
1556             writeMethod(methods.head);
1557             methods = methods.tail;
1558         }
1559     }
1560 
1561     /** Emit a class file for a given class.
1562      *  @param c      The class from which a class file is generated.
1563      */
1564     public JavaFileObject writeClass(ClassSymbol c)
1565         throws IOException, PoolOverflow, StringOverflow
1566     {
1567         String name = (c.owner.kind == MDL ? c.name : c.flatname).toString();
1568         Location outLocn;
1569         if (multiModuleMode) {
1570             ModuleSymbol msym = c.owner.kind == MDL ? (ModuleSymbol) c.owner : c.packge().modle;
1571             outLocn = fileManager.getLocationForModule(CLASS_OUTPUT, msym.name.toString());
1572         } else {
1573             outLocn = CLASS_OUTPUT;
1574         }
1575         JavaFileObject outFile
1576             = fileManager.getJavaFileForOutput(outLocn,
1577                                                name,
1578                                                JavaFileObject.Kind.CLASS,
1579                                                c.sourcefile);
1580         OutputStream out = outFile.openOutputStream();
1581         try {
1582             writeClassFile(out, c);
1583             if (verbose)
1584                 log.printVerbose("wrote.file", outFile.getName());
1585             out.close();
1586             out = null;
1587         } catch (InvalidSignatureException ex) {
1588             log.error(Errors.CannotGenerateClass(c, Fragments.IllegalSignature(c, ex.type())));
1589         } finally {
1590             if (out != null) {
1591                 // if we are propagating an exception, delete the file
1592                 out.close();
1593                 outFile.delete();
1594                 outFile = null;
1595             }
1596         }
1597         return outFile; // may be null if write failed
1598     }
1599 
1600     /** Write class `c' to outstream `out'.
1601      */
1602     public void writeClassFile(OutputStream out, ClassSymbol c)
1603         throws IOException, PoolOverflow, StringOverflow {
1604         Assert.check((c.flags() & COMPOUND) == 0);
1605         databuf.reset();
1606         poolbuf.reset();
1607 
1608         Type supertype = types.supertype(c.type);
1609         List<Type> interfaces = types.interfaces(c.type);
1610         List<Type> typarams = c.type.getTypeArguments();
1611 
1612         int flags;
1613         if (c.owner.kind == MDL) {
1614             flags = ACC_MODULE;
1615         } else {
1616             flags = adjustFlags(c.flags() & ~(DEFAULT | STRICTFP));
1617             if ((flags & PROTECTED) != 0) flags |= PUBLIC;
1618             flags = flags & AdjustedClassFlags;
1619         }
1620 
1621         if (dumpClassModifiers) {
1622             PrintWriter pw = log.getWriter(Log.WriterKind.ERROR);
1623             pw.println();
1624             pw.println("CLASSFILE  " + c.getQualifiedName());
1625             pw.println("---" + flagNames(flags));
1626         }
1627         databuf.appendChar(flags);
1628 
1629         if (c.owner.kind == MDL) {
1630             PackageSymbol unnamed = ((ModuleSymbol) c.owner).unnamedPackage;
1631             databuf.appendChar(poolWriter.putClass(new ClassSymbol(0, names.module_info, unnamed)));
1632         } else {
1633             databuf.appendChar(poolWriter.putClass(c));
1634         }
1635         databuf.appendChar(supertype.hasTag(CLASS) ? poolWriter.putClass((ClassSymbol)supertype.tsym) : 0);
1636         databuf.appendChar(interfaces.length());
1637         for (List<Type> l = interfaces; l.nonEmpty(); l = l.tail)
1638             databuf.appendChar(poolWriter.putClass((ClassSymbol)l.head.tsym));
1639         int fieldsCount = 0;
1640         int methodsCount = 0;
1641         for (Symbol sym : c.members().getSymbols(NON_RECURSIVE)) {
1642             switch (sym.kind) {
1643             case VAR: fieldsCount++; break;
1644             case MTH: if ((sym.flags() & HYPOTHETICAL) == 0) methodsCount++;
1645                       break;
1646             case TYP: poolWriter.enterInnerClass((ClassSymbol)sym); break;
1647             default : Assert.error();
1648             }
1649         }
1650 
1651         if (c.trans_local != null) {
1652             for (ClassSymbol local : c.trans_local) {
1653                 poolWriter.enterInnerClass(local);
1654             }
1655         }
1656 
1657         databuf.appendChar(fieldsCount);
1658         writeFields(c.members());
1659         databuf.appendChar(methodsCount);
1660         writeMethods(c.members());
1661 
1662         int acountIdx = beginAttrs();
1663         int acount = 0;
1664 
1665         boolean sigReq =
1666             typarams.length() != 0 || supertype.allparams().length() != 0;
1667         for (List<Type> l = interfaces; !sigReq && l.nonEmpty(); l = l.tail)
1668             sigReq = l.head.allparams().length() != 0;
1669         if (sigReq) {
1670             int alenIdx = writeAttr(names.Signature);
1671             databuf.appendChar(poolWriter.putSignature(c));
1672             endAttr(alenIdx);
1673             acount++;
1674         }
1675 
1676         if (c.sourcefile != null && emitSourceFile) {
1677             int alenIdx = writeAttr(names.SourceFile);
1678             // WHM 6/29/1999: Strip file path prefix.  We do it here at
1679             // the last possible moment because the sourcefile may be used
1680             // elsewhere in error diagnostics. Fixes 4241573.
1681             String simpleName = PathFileObject.getSimpleName(c.sourcefile);
1682             databuf.appendChar(poolWriter.putName(names.fromString(simpleName)));
1683             endAttr(alenIdx);
1684             acount++;
1685         }
1686 
1687         if (genCrt) {
1688             // Append SourceID attribute
1689             int alenIdx = writeAttr(names.SourceID);
1690             databuf.appendChar(poolWriter.putName(names.fromString(Long.toString(getLastModified(c.sourcefile)))));
1691             endAttr(alenIdx);
1692             acount++;
1693             // Append CompilationID attribute
1694             alenIdx = writeAttr(names.CompilationID);
1695             databuf.appendChar(poolWriter.putName(names.fromString(Long.toString(System.currentTimeMillis()))));
1696             endAttr(alenIdx);
1697             acount++;
1698         }
1699 
1700         acount += writeFlagAttrs(c.flags());
1701         acount += writeJavaAnnotations(c.getRawAttributes());
1702         acount += writeTypeAnnotations(c.getRawTypeAttributes(), false);
1703         acount += writeEnclosingMethodAttribute(c);
1704         if (c.owner.kind == MDL) {
1705             acount += writeModuleAttribute(c);
1706             acount += writeFlagAttrs(c.owner.flags() & ~DEPRECATED);
1707         }
1708         acount += writeExtraClassAttributes(c);
1709         acount += writeExtraAttributes(c);
1710 
1711         poolbuf.appendInt(JAVA_MAGIC);
1712         if (preview.isEnabled() && preview.usesPreview(c.sourcefile)) {
1713             poolbuf.appendChar(ClassFile.PREVIEW_MINOR_VERSION);
1714         } else {
1715             poolbuf.appendChar(target.minorVersion);
1716         }
1717         poolbuf.appendChar(target.majorVersion);
1718 
1719         if (c.owner.kind != MDL) {
1720             if (target.hasNestmateAccess()) {
1721                 acount += writeNestMembersIfNeeded(c);
1722                 acount += writeNestHostIfNeeded(c);
1723             }
1724         }
1725 
1726         if (c.isRecord()) {
1727             acount += writeRecordAttribute(c);
1728         }
1729 
1730         if (target.hasSealedClasses()) {
1731             acount += writePermittedSubclassesIfNeeded(c);
1732         }
1733 
1734         if (!poolWriter.bootstrapMethods.isEmpty()) {
1735             writeBootstrapMethods();
1736             acount++;
1737         }
1738 
1739         if (!poolWriter.innerClasses.isEmpty()) {
1740             writeInnerClasses();
1741             acount++;
1742         }
1743 
1744         if (!poolWriter.preloadClasses.isEmpty()) {
1745             writePreloadAttribute();
1746             acount++;
1747         }
1748 
1749         endAttrs(acountIdx, acount);
1750 
1751         out.write(poolbuf.elems, 0, poolbuf.length);
1752 
1753         poolWriter.writePool(out);
1754         poolWriter.reset(); // to save space
1755 
1756         out.write(databuf.elems, 0, databuf.length);
1757     }
1758 
1759      /**Allows subclasses to write additional class attributes
1760       *
1761       * @return the number of attributes written
1762       */
1763     protected int writeExtraClassAttributes(ClassSymbol c) {
1764         return 0;
1765     }
1766 
1767     /**Allows friends to write additional attributes
1768      *
1769      * @return the number of attributes written
1770      */
1771     protected int writeExtraAttributes(Symbol sym) {
1772         int i = 0;
1773         for (ToIntFunction<Symbol> hook : extraAttributeHooks) {
1774             i += hook.applyAsInt(sym);
1775         }
1776         return i;
1777     }
1778 
1779     int adjustFlags(final long flags) {
1780         int result = (int)flags;
1781 
1782         // Elide strictfp bit in class files
1783         if (target.obsoleteAccStrict())
1784             result &= ~STRICTFP;
1785 
1786         if ((flags & BRIDGE) != 0)
1787             result |= ACC_BRIDGE;
1788         if ((flags & VARARGS) != 0)
1789             result |= ACC_VARARGS;
1790         if ((flags & DEFAULT) != 0)
1791             result &= ~ABSTRACT;
1792         if ((flags & PRIMITIVE_CLASS) != 0)
1793             result |= ACC_PRIMITIVE;
1794         if ((flags & VALUE_CLASS) != 0)
1795             result |= ACC_VALUE;
1796         if ((flags & IDENTITY_TYPE) != 0)
1797             result |= ACC_IDENTITY;
1798         return result;
1799     }
1800 
1801     long getLastModified(FileObject filename) {
1802         long mod = 0;
1803         try {
1804             mod = filename.getLastModified();
1805         } catch (SecurityException e) {
1806             throw new AssertionError("CRT: couldn't get source file modification date: " + e.getMessage());
1807         }
1808         return mod;
1809     }
1810 }