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