1 /*
   2  * Copyright (c) 1999, 2013, 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 import java.util.*;
  28 
  29 import com.sun.tools.javac.util.*;
  30 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
  31 import com.sun.tools.javac.util.List;
  32 import com.sun.tools.javac.code.*;
  33 import com.sun.tools.javac.code.Attribute.TypeCompound;
  34 import com.sun.tools.javac.code.Symbol.VarSymbol;
  35 import com.sun.tools.javac.comp.*;
  36 import com.sun.tools.javac.tree.*;
  37 
  38 import com.sun.tools.javac.code.Symbol.*;
  39 import com.sun.tools.javac.code.Type.*;
  40 import com.sun.tools.javac.jvm.Code.*;
  41 import com.sun.tools.javac.jvm.Items.*;
  42 import com.sun.tools.javac.tree.EndPosTable;
  43 import com.sun.tools.javac.tree.JCTree.*;
  44 
  45 import static com.sun.tools.javac.code.Flags.*;
  46 import static com.sun.tools.javac.code.Kinds.*;
  47 import static com.sun.tools.javac.code.TypeTag.*;
  48 import static com.sun.tools.javac.jvm.ByteCodes.*;
  49 import static com.sun.tools.javac.jvm.CRTFlags.*;
  50 import static com.sun.tools.javac.main.Option.*;
  51 import static com.sun.tools.javac.tree.JCTree.Tag.*;
  52 
  53 /** This pass maps flat Java (i.e. without inner classes) to bytecodes.
  54  *
  55  *  <p><b>This is NOT part of any supported API.
  56  *  If you write code that depends on this, you do so at your own risk.
  57  *  This code and its internal interfaces are subject to change or
  58  *  deletion without notice.</b>
  59  */
  60 public class Gen extends JCTree.Visitor {
  61     protected static final Context.Key<Gen> genKey =
  62         new Context.Key<Gen>();
  63 
  64     private final Log log;
  65     private final Symtab syms;
  66     private final Check chk;
  67     private final Resolve rs;
  68     private final TreeMaker make;
  69     private final Names names;
  70     private final Target target;
  71     private final Type stringBufferType;
  72     private final Map<Type,Symbol> stringBufferAppend;
  73     private Name accessDollar;
  74     private final Types types;
  75     private final Lower lower;
  76 
  77     /** Switch: GJ mode?
  78      */
  79     private final boolean allowGenerics;
  80 
  81     /** Set when Miranda method stubs are to be generated. */
  82     private final boolean generateIproxies;
  83 
  84     /** Format of stackmap tables to be generated. */
  85     private final Code.StackMapFormat stackMap;
  86 
  87     /** A type that serves as the expected type for all method expressions.
  88      */
  89     private final Type methodType;
  90 
  91     public static Gen instance(Context context) {
  92         Gen instance = context.get(genKey);
  93         if (instance == null)
  94             instance = new Gen(context);
  95         return instance;
  96     }
  97 
  98     /* Constant pool, reset by genClass.
  99      */
 100     private Pool pool;
 101 
 102     protected Gen(Context context) {
 103         context.put(genKey, this);
 104 
 105         names = Names.instance(context);
 106         log = Log.instance(context);
 107         syms = Symtab.instance(context);
 108         chk = Check.instance(context);
 109         rs = Resolve.instance(context);
 110         make = TreeMaker.instance(context);
 111         target = Target.instance(context);
 112         types = Types.instance(context);
 113         methodType = new MethodType(null, null, null, syms.methodClass);
 114         allowGenerics = Source.instance(context).allowGenerics();
 115         stringBufferType = target.useStringBuilder()
 116             ? syms.stringBuilderType
 117             : syms.stringBufferType;
 118         stringBufferAppend = new HashMap<Type,Symbol>();
 119         accessDollar = names.
 120             fromString("access" + target.syntheticNameChar());
 121         lower = Lower.instance(context);
 122 
 123         Options options = Options.instance(context);
 124         lineDebugInfo =
 125             options.isUnset(G_CUSTOM) ||
 126             options.isSet(G_CUSTOM, "lines");
 127         varDebugInfo =
 128             options.isUnset(G_CUSTOM)
 129             ? options.isSet(G)
 130             : options.isSet(G_CUSTOM, "vars");
 131         genCrt = options.isSet(XJCOV);
 132         debugCode = options.isSet("debugcode");
 133         allowInvokedynamic = target.hasInvokedynamic() || options.isSet("invokedynamic");
 134         pool = new Pool(types);
 135 
 136         generateIproxies =
 137             target.requiresIproxy() ||
 138             options.isSet("miranda");
 139 
 140         if (target.generateStackMapTable()) {
 141             // ignore cldc because we cannot have both stackmap formats
 142             this.stackMap = StackMapFormat.JSR202;
 143         } else {
 144             if (target.generateCLDCStackmap()) {
 145                 this.stackMap = StackMapFormat.CLDC;
 146             } else {
 147                 this.stackMap = StackMapFormat.NONE;
 148             }
 149         }
 150 
 151         // by default, avoid jsr's for simple finalizers
 152         int setjsrlimit = 50;
 153         String jsrlimitString = options.get("jsrlimit");
 154         if (jsrlimitString != null) {
 155             try {
 156                 setjsrlimit = Integer.parseInt(jsrlimitString);
 157             } catch (NumberFormatException ex) {
 158                 // ignore ill-formed numbers for jsrlimit
 159             }
 160         }
 161         this.jsrlimit = setjsrlimit;
 162         this.useJsrLocally = false; // reset in visitTry
 163     }
 164 
 165     /** Switches
 166      */
 167     private final boolean lineDebugInfo;
 168     private final boolean varDebugInfo;
 169     private final boolean genCrt;
 170     private final boolean debugCode;
 171     private final boolean allowInvokedynamic;
 172 
 173     /** Default limit of (approximate) size of finalizer to inline.
 174      *  Zero means always use jsr.  100 or greater means never use
 175      *  jsr.
 176      */
 177     private final int jsrlimit;
 178 
 179     /** True if jsr is used.
 180      */
 181     private boolean useJsrLocally;
 182 
 183     /** Code buffer, set by genMethod.
 184      */
 185     private Code code;
 186 
 187     /** Items structure, set by genMethod.
 188      */
 189     private Items items;
 190 
 191     /** Environment for symbol lookup, set by genClass
 192      */
 193     private Env<AttrContext> attrEnv;
 194 
 195     /** The top level tree.
 196      */
 197     private JCCompilationUnit toplevel;
 198 
 199     /** The number of code-gen errors in this class.
 200      */
 201     private int nerrs = 0;
 202 
 203     /** An object containing mappings of syntax trees to their
 204      *  ending source positions.
 205      */
 206     EndPosTable endPosTable;
 207 
 208     /** Generate code to load an integer constant.
 209      *  @param n     The integer to be loaded.
 210      */
 211     void loadIntConst(int n) {
 212         items.makeImmediateItem(syms.intType, n).load();
 213     }
 214 
 215     /** The opcode that loads a zero constant of a given type code.
 216      *  @param tc   The given type code (@see ByteCode).
 217      */
 218     public static int zero(int tc) {
 219         switch(tc) {
 220         case INTcode: case BYTEcode: case SHORTcode: case CHARcode:
 221             return iconst_0;
 222         case LONGcode:
 223             return lconst_0;
 224         case FLOATcode:
 225             return fconst_0;
 226         case DOUBLEcode:
 227             return dconst_0;
 228         default:
 229             throw new AssertionError("zero");
 230         }
 231     }
 232 
 233     /** The opcode that loads a one constant of a given type code.
 234      *  @param tc   The given type code (@see ByteCode).
 235      */
 236     public static int one(int tc) {
 237         return zero(tc) + 1;
 238     }
 239 
 240     /** Generate code to load -1 of the given type code (either int or long).
 241      *  @param tc   The given type code (@see ByteCode).
 242      */
 243     void emitMinusOne(int tc) {
 244         if (tc == LONGcode) {
 245             items.makeImmediateItem(syms.longType, new Long(-1)).load();
 246         } else {
 247             code.emitop0(iconst_m1);
 248         }
 249     }
 250 
 251     /** Construct a symbol to reflect the qualifying type that should
 252      *  appear in the byte code as per JLS 13.1.
 253      *
 254      *  For {@literal target >= 1.2}: Clone a method with the qualifier as owner (except
 255      *  for those cases where we need to work around VM bugs).
 256      *
 257      *  For {@literal target <= 1.1}: If qualified variable or method is defined in a
 258      *  non-accessible class, clone it with the qualifier class as owner.
 259      *
 260      *  @param sym    The accessed symbol
 261      *  @param site   The qualifier's type.
 262      */
 263     Symbol binaryQualifier(Symbol sym, Type site) {
 264 
 265         if (site.hasTag(ARRAY)) {
 266             if (sym == syms.lengthVar ||
 267                 sym.owner != syms.arrayClass)
 268                 return sym;
 269             // array clone can be qualified by the array type in later targets
 270             Symbol qualifier = target.arrayBinaryCompatibility()
 271                 ? new ClassSymbol(Flags.PUBLIC, site.tsym.name,
 272                                   site, syms.noSymbol)
 273                 : syms.objectType.tsym;
 274             return sym.clone(qualifier);
 275         }
 276 
 277         if (sym.owner == site.tsym ||
 278             (sym.flags() & (STATIC | SYNTHETIC)) == (STATIC | SYNTHETIC)) {
 279             return sym;
 280         }
 281         if (!target.obeyBinaryCompatibility())
 282             return rs.isAccessible(attrEnv, (TypeSymbol)sym.owner)
 283                 ? sym
 284                 : sym.clone(site.tsym);
 285 
 286         if (!target.interfaceFieldsBinaryCompatibility()) {
 287             if ((sym.owner.flags() & INTERFACE) != 0 && sym.kind == VAR)
 288                 return sym;
 289         }
 290 
 291         // leave alone methods inherited from Object
 292         // JLS 13.1.
 293         if (sym.owner == syms.objectType.tsym)
 294             return sym;
 295 
 296         if (!target.interfaceObjectOverridesBinaryCompatibility()) {
 297             if ((sym.owner.flags() & INTERFACE) != 0 &&
 298                 syms.objectType.tsym.members().lookup(sym.name).scope != null)
 299                 return sym;
 300         }
 301 
 302         return sym.clone(site.tsym);
 303     }
 304 
 305     /** Insert a reference to given type in the constant pool,
 306      *  checking for an array with too many dimensions;
 307      *  return the reference's index.
 308      *  @param type   The type for which a reference is inserted.
 309      */
 310     int makeRef(DiagnosticPosition pos, Type type) {
 311         checkDimension(pos, type);
 312         if (type.isAnnotated()) {
 313             // Treat annotated types separately - we don't want
 314             // to collapse all of them - at least for annotated
 315             // exceptions.
 316             // TODO: review this.
 317             return pool.put((Object)type);
 318         } else {
 319             return pool.put(type.hasTag(CLASS) ? (Object)type.tsym : (Object)type);
 320         }
 321     }
 322 
 323     /** Check if the given type is an array with too many dimensions.
 324      */
 325     private void checkDimension(DiagnosticPosition pos, Type t) {
 326         switch (t.getTag()) {
 327         case METHOD:
 328             checkDimension(pos, t.getReturnType());
 329             for (List<Type> args = t.getParameterTypes(); args.nonEmpty(); args = args.tail)
 330                 checkDimension(pos, args.head);
 331             break;
 332         case ARRAY:
 333             if (types.dimensions(t) > ClassFile.MAX_DIMENSIONS) {
 334                 log.error(pos, "limit.dimensions");
 335                 nerrs++;
 336             }
 337             break;
 338         default:
 339             break;
 340         }
 341     }
 342 
 343     /** Create a tempory variable.
 344      *  @param type   The variable's type.
 345      */
 346     LocalItem makeTemp(Type type) {
 347         VarSymbol v = new VarSymbol(Flags.SYNTHETIC,
 348                                     names.empty,
 349                                     type,
 350                                     env.enclMethod.sym);
 351         code.newLocal(v);
 352         return items.makeLocalItem(v);
 353     }
 354 
 355     /** Generate code to call a non-private method or constructor.
 356      *  @param pos         Position to be used for error reporting.
 357      *  @param site        The type of which the method is a member.
 358      *  @param name        The method's name.
 359      *  @param argtypes    The method's argument types.
 360      *  @param isStatic    A flag that indicates whether we call a
 361      *                     static or instance method.
 362      */
 363     void callMethod(DiagnosticPosition pos,
 364                     Type site, Name name, List<Type> argtypes,
 365                     boolean isStatic) {
 366         Symbol msym = rs.
 367             resolveInternalMethod(pos, attrEnv, site, name, argtypes, null);
 368         if (isStatic) items.makeStaticItem(msym).invoke();
 369         else items.makeMemberItem(msym, name == names.init).invoke();
 370     }
 371 
 372     /** Is the given method definition an access method
 373      *  resulting from a qualified super? This is signified by an odd
 374      *  access code.
 375      */
 376     private boolean isAccessSuper(JCMethodDecl enclMethod) {
 377         return
 378             (enclMethod.mods.flags & SYNTHETIC) != 0 &&
 379             isOddAccessName(enclMethod.name);
 380     }
 381 
 382     /** Does given name start with "access$" and end in an odd digit?
 383      */
 384     private boolean isOddAccessName(Name name) {
 385         return
 386             name.startsWith(accessDollar) &&
 387             (name.getByteAt(name.getByteLength() - 1) & 1) == 1;
 388     }
 389 
 390 /* ************************************************************************
 391  * Non-local exits
 392  *************************************************************************/
 393 
 394     /** Generate code to invoke the finalizer associated with given
 395      *  environment.
 396      *  Any calls to finalizers are appended to the environments `cont' chain.
 397      *  Mark beginning of gap in catch all range for finalizer.
 398      */
 399     void genFinalizer(Env<GenContext> env) {
 400         if (code.isAlive() && env.info.finalize != null)
 401             env.info.finalize.gen();
 402     }
 403 
 404     /** Generate code to call all finalizers of structures aborted by
 405      *  a non-local
 406      *  exit.  Return target environment of the non-local exit.
 407      *  @param target      The tree representing the structure that's aborted
 408      *  @param env         The environment current at the non-local exit.
 409      */
 410     Env<GenContext> unwind(JCTree target, Env<GenContext> env) {
 411         Env<GenContext> env1 = env;
 412         while (true) {
 413             genFinalizer(env1);
 414             if (env1.tree == target) break;
 415             env1 = env1.next;
 416         }
 417         return env1;
 418     }
 419 
 420     /** Mark end of gap in catch-all range for finalizer.
 421      *  @param env   the environment which might contain the finalizer
 422      *               (if it does, env.info.gaps != null).
 423      */
 424     void endFinalizerGap(Env<GenContext> env) {
 425         if (env.info.gaps != null && env.info.gaps.length() % 2 == 1)
 426             env.info.gaps.append(code.curPc());
 427     }
 428 
 429     /** Mark end of all gaps in catch-all ranges for finalizers of environments
 430      *  lying between, and including to two environments.
 431      *  @param from    the most deeply nested environment to mark
 432      *  @param to      the least deeply nested environment to mark
 433      */
 434     void endFinalizerGaps(Env<GenContext> from, Env<GenContext> to) {
 435         Env<GenContext> last = null;
 436         while (last != to) {
 437             endFinalizerGap(from);
 438             last = from;
 439             from = from.next;
 440         }
 441     }
 442 
 443     /** Do any of the structures aborted by a non-local exit have
 444      *  finalizers that require an empty stack?
 445      *  @param target      The tree representing the structure that's aborted
 446      *  @param env         The environment current at the non-local exit.
 447      */
 448     boolean hasFinally(JCTree target, Env<GenContext> env) {
 449         while (env.tree != target) {
 450             if (env.tree.hasTag(TRY) && env.info.finalize.hasFinalizer())
 451                 return true;
 452             env = env.next;
 453         }
 454         return false;
 455     }
 456 
 457 /* ************************************************************************
 458  * Normalizing class-members.
 459  *************************************************************************/
 460 
 461     /** Distribute member initializer code into constructors and {@code <clinit>}
 462      *  method.
 463      *  @param defs         The list of class member declarations.
 464      *  @param c            The enclosing class.
 465      */
 466     List<JCTree> normalizeDefs(List<JCTree> defs, ClassSymbol c) {
 467         ListBuffer<JCStatement> initCode = new ListBuffer<JCStatement>();
 468         ListBuffer<Attribute.TypeCompound> initTAs = new ListBuffer<Attribute.TypeCompound>();
 469         ListBuffer<JCStatement> clinitCode = new ListBuffer<JCStatement>();
 470         ListBuffer<Attribute.TypeCompound> clinitTAs = new ListBuffer<Attribute.TypeCompound>();
 471         ListBuffer<JCTree> methodDefs = new ListBuffer<JCTree>();
 472         // Sort definitions into three listbuffers:
 473         //  - initCode for instance initializers
 474         //  - clinitCode for class initializers
 475         //  - methodDefs for method definitions
 476         for (List<JCTree> l = defs; l.nonEmpty(); l = l.tail) {
 477             JCTree def = l.head;
 478             switch (def.getTag()) {
 479             case BLOCK:
 480                 JCBlock block = (JCBlock)def;
 481                 if ((block.flags & STATIC) != 0)
 482                     clinitCode.append(block);
 483                 else
 484                     initCode.append(block);
 485                 break;
 486             case METHODDEF:
 487                 methodDefs.append(def);
 488                 break;
 489             case VARDEF:
 490                 JCVariableDecl vdef = (JCVariableDecl) def;
 491                 VarSymbol sym = vdef.sym;
 492                 checkDimension(vdef.pos(), sym.type);
 493                 if (vdef.init != null) {
 494                     if ((sym.flags() & STATIC) == 0) {
 495                         // Always initialize instance variables.
 496                         JCStatement init = make.at(vdef.pos()).
 497                             Assignment(sym, vdef.init);
 498                         initCode.append(init);
 499                         endPosTable.replaceTree(vdef, init);
 500                         initTAs.addAll(getAndRemoveNonFieldTAs(sym));
 501                     } else if (sym.getConstValue() == null) {
 502                         // Initialize class (static) variables only if
 503                         // they are not compile-time constants.
 504                         JCStatement init = make.at(vdef.pos).
 505                             Assignment(sym, vdef.init);
 506                         clinitCode.append(init);
 507                         endPosTable.replaceTree(vdef, init);
 508                         clinitTAs.addAll(getAndRemoveNonFieldTAs(sym));
 509                     } else {
 510                         checkStringConstant(vdef.init.pos(), sym.getConstValue());
 511                     }
 512                 }
 513                 break;
 514             default:
 515                 Assert.error();
 516             }
 517         }
 518         // Insert any instance initializers into all constructors.
 519         if (initCode.length() != 0) {
 520             List<JCStatement> inits = initCode.toList();
 521             initTAs.addAll(c.getInitTypeAttributes());
 522             List<Attribute.TypeCompound> initTAlist = initTAs.toList();
 523             for (JCTree t : methodDefs) {
 524                 normalizeMethod((JCMethodDecl)t, inits, initTAlist);
 525             }
 526         }
 527         // If there are class initializers, create a <clinit> method
 528         // that contains them as its body.
 529         if (clinitCode.length() != 0) {
 530             MethodSymbol clinit = new MethodSymbol(
 531                 STATIC | (c.flags() & STRICTFP),
 532                 names.clinit,
 533                 new MethodType(
 534                     List.<Type>nil(), syms.voidType,
 535                     List.<Type>nil(), syms.methodClass),
 536                 c);
 537             c.members().enter(clinit);
 538             List<JCStatement> clinitStats = clinitCode.toList();
 539             JCBlock block = make.at(clinitStats.head.pos()).Block(0, clinitStats);
 540             block.endpos = TreeInfo.endPos(clinitStats.last());
 541             methodDefs.append(make.MethodDef(clinit, block));
 542 
 543             if (!clinitTAs.isEmpty())
 544                 clinit.appendUniqueTypeAttributes(clinitTAs.toList());
 545             if (!c.getClassInitTypeAttributes().isEmpty())
 546                 clinit.appendUniqueTypeAttributes(c.getClassInitTypeAttributes());
 547         }
 548         // Return all method definitions.
 549         return methodDefs.toList();
 550     }
 551 
 552     private List<Attribute.TypeCompound> getAndRemoveNonFieldTAs(VarSymbol sym) {
 553         List<TypeCompound> tas = sym.getRawTypeAttributes();
 554         ListBuffer<Attribute.TypeCompound> fieldTAs = new ListBuffer<Attribute.TypeCompound>();
 555         ListBuffer<Attribute.TypeCompound> nonfieldTAs = new ListBuffer<Attribute.TypeCompound>();
 556         for (TypeCompound ta : tas) {
 557             if (ta.position.type == TargetType.FIELD) {
 558                 fieldTAs.add(ta);
 559             } else {
 560                 nonfieldTAs.add(ta);
 561             }
 562         }
 563         sym.setTypeAttributes(fieldTAs.toList());
 564         return nonfieldTAs.toList();
 565     }
 566 
 567     /** Check a constant value and report if it is a string that is
 568      *  too large.
 569      */
 570     private void checkStringConstant(DiagnosticPosition pos, Object constValue) {
 571         if (nerrs != 0 || // only complain about a long string once
 572             constValue == null ||
 573             !(constValue instanceof String) ||
 574             ((String)constValue).length() < Pool.MAX_STRING_LENGTH)
 575             return;
 576         log.error(pos, "limit.string");
 577         nerrs++;
 578     }
 579 
 580     /** Insert instance initializer code into initial constructor.
 581      *  @param md        The tree potentially representing a
 582      *                   constructor's definition.
 583      *  @param initCode  The list of instance initializer statements.
 584      *  @param initTAs  Type annotations from the initializer expression.
 585      */
 586     void normalizeMethod(JCMethodDecl md, List<JCStatement> initCode, List<TypeCompound> initTAs) {
 587         if (md.name == names.init && TreeInfo.isInitialConstructor(md)) {
 588             // We are seeing a constructor that does not call another
 589             // constructor of the same class.
 590             List<JCStatement> stats = md.body.stats;
 591             ListBuffer<JCStatement> newstats = new ListBuffer<JCStatement>();
 592 
 593             if (stats.nonEmpty()) {
 594                 // Copy initializers of synthetic variables generated in
 595                 // the translation of inner classes.
 596                 while (TreeInfo.isSyntheticInit(stats.head)) {
 597                     newstats.append(stats.head);
 598                     stats = stats.tail;
 599                 }
 600                 // Copy superclass constructor call
 601                 newstats.append(stats.head);
 602                 stats = stats.tail;
 603                 // Copy remaining synthetic initializers.
 604                 while (stats.nonEmpty() &&
 605                        TreeInfo.isSyntheticInit(stats.head)) {
 606                     newstats.append(stats.head);
 607                     stats = stats.tail;
 608                 }
 609                 // Now insert the initializer code.
 610                 newstats.appendList(initCode);
 611                 // And copy all remaining statements.
 612                 while (stats.nonEmpty()) {
 613                     newstats.append(stats.head);
 614                     stats = stats.tail;
 615                 }
 616             }
 617             md.body.stats = newstats.toList();
 618             if (md.body.endpos == Position.NOPOS)
 619                 md.body.endpos = TreeInfo.endPos(md.body.stats.last());
 620 
 621             md.sym.appendUniqueTypeAttributes(initTAs);
 622         }
 623     }
 624 
 625 /* ********************************************************************
 626  * Adding miranda methods
 627  *********************************************************************/
 628 
 629     /** Add abstract methods for all methods defined in one of
 630      *  the interfaces of a given class,
 631      *  provided they are not already implemented in the class.
 632      *
 633      *  @param c      The class whose interfaces are searched for methods
 634      *                for which Miranda methods should be added.
 635      */
 636     void implementInterfaceMethods(ClassSymbol c) {
 637         implementInterfaceMethods(c, c);
 638     }
 639 
 640     /** Add abstract methods for all methods defined in one of
 641      *  the interfaces of a given class,
 642      *  provided they are not already implemented in the class.
 643      *
 644      *  @param c      The class whose interfaces are searched for methods
 645      *                for which Miranda methods should be added.
 646      *  @param site   The class in which a definition may be needed.
 647      */
 648     void implementInterfaceMethods(ClassSymbol c, ClassSymbol site) {
 649         for (List<Type> l = types.interfaces(c.type); l.nonEmpty(); l = l.tail) {
 650             ClassSymbol i = (ClassSymbol)l.head.tsym;
 651             for (Scope.Entry e = i.members().elems;
 652                  e != null;
 653                  e = e.sibling)
 654             {
 655                 if (e.sym.kind == MTH && (e.sym.flags() & STATIC) == 0)
 656                 {
 657                     MethodSymbol absMeth = (MethodSymbol)e.sym;
 658                     MethodSymbol implMeth = absMeth.binaryImplementation(site, types);
 659                     if (implMeth == null)
 660                         addAbstractMethod(site, absMeth);
 661                     else if ((implMeth.flags() & IPROXY) != 0)
 662                         adjustAbstractMethod(site, implMeth, absMeth);
 663                 }
 664             }
 665             implementInterfaceMethods(i, site);
 666         }
 667     }
 668 
 669     /** Add an abstract methods to a class
 670      *  which implicitly implements a method defined in some interface
 671      *  implemented by the class. These methods are called "Miranda methods".
 672      *  Enter the newly created method into its enclosing class scope.
 673      *  Note that it is not entered into the class tree, as the emitter
 674      *  doesn't need to see it there to emit an abstract method.
 675      *
 676      *  @param c      The class to which the Miranda method is added.
 677      *  @param m      The interface method symbol for which a Miranda method
 678      *                is added.
 679      */
 680     private void addAbstractMethod(ClassSymbol c,
 681                                    MethodSymbol m) {
 682         MethodSymbol absMeth = new MethodSymbol(
 683             m.flags() | IPROXY | SYNTHETIC, m.name,
 684             m.type, // was c.type.memberType(m), but now only !generics supported
 685             c);
 686         c.members().enter(absMeth); // add to symbol table
 687     }
 688 
 689     private void adjustAbstractMethod(ClassSymbol c,
 690                                       MethodSymbol pm,
 691                                       MethodSymbol im) {
 692         MethodType pmt = (MethodType)pm.type;
 693         Type imt = types.memberType(c.type, im);
 694         pmt.thrown = chk.intersect(pmt.getThrownTypes(), imt.getThrownTypes());
 695     }
 696 
 697 /* ************************************************************************
 698  * Traversal methods
 699  *************************************************************************/
 700 
 701     /** Visitor argument: The current environment.
 702      */
 703     Env<GenContext> env;
 704 
 705     /** Visitor argument: The expected type (prototype).
 706      */
 707     Type pt;
 708 
 709     /** Visitor result: The item representing the computed value.
 710      */
 711     Item result;
 712 
 713     /** Visitor method: generate code for a definition, catching and reporting
 714      *  any completion failures.
 715      *  @param tree    The definition to be visited.
 716      *  @param env     The environment current at the definition.
 717      */
 718     public void genDef(JCTree tree, Env<GenContext> env) {
 719         Env<GenContext> prevEnv = this.env;
 720         try {
 721             this.env = env;
 722             tree.accept(this);
 723         } catch (CompletionFailure ex) {
 724             chk.completionError(tree.pos(), ex);
 725         } finally {
 726             this.env = prevEnv;
 727         }
 728     }
 729 
 730     /** Derived visitor method: check whether CharacterRangeTable
 731      *  should be emitted, if so, put a new entry into CRTable
 732      *  and call method to generate bytecode.
 733      *  If not, just call method to generate bytecode.
 734      *  @see    #genStat(JCTree, Env)
 735      *
 736      *  @param  tree     The tree to be visited.
 737      *  @param  env      The environment to use.
 738      *  @param  crtFlags The CharacterRangeTable flags
 739      *                   indicating type of the entry.
 740      */
 741     public void genStat(JCTree tree, Env<GenContext> env, int crtFlags) {
 742         if (!genCrt) {
 743             genStat(tree, env);
 744             return;
 745         }
 746         int startpc = code.curPc();
 747         genStat(tree, env);
 748         if (tree.hasTag(Tag.BLOCK)) crtFlags |= CRT_BLOCK;
 749         code.crt.put(tree, crtFlags, startpc, code.curPc());
 750     }
 751 
 752     /** Derived visitor method: generate code for a statement.
 753      */
 754     public void genStat(JCTree tree, Env<GenContext> env) {
 755         if (code.isAlive()) {
 756             code.statBegin(tree.pos);
 757             genDef(tree, env);
 758         } else if (env.info.isSwitch && tree.hasTag(VARDEF)) {
 759             // variables whose declarations are in a switch
 760             // can be used even if the decl is unreachable.
 761             code.newLocal(((JCVariableDecl) tree).sym);
 762         }
 763     }
 764 
 765     /** Derived visitor method: check whether CharacterRangeTable
 766      *  should be emitted, if so, put a new entry into CRTable
 767      *  and call method to generate bytecode.
 768      *  If not, just call method to generate bytecode.
 769      *  @see    #genStats(List, Env)
 770      *
 771      *  @param  trees    The list of trees to be visited.
 772      *  @param  env      The environment to use.
 773      *  @param  crtFlags The CharacterRangeTable flags
 774      *                   indicating type of the entry.
 775      */
 776     public void genStats(List<JCStatement> trees, Env<GenContext> env, int crtFlags) {
 777         if (!genCrt) {
 778             genStats(trees, env);
 779             return;
 780         }
 781         if (trees.length() == 1) {        // mark one statement with the flags
 782             genStat(trees.head, env, crtFlags | CRT_STATEMENT);
 783         } else {
 784             int startpc = code.curPc();
 785             genStats(trees, env);
 786             code.crt.put(trees, crtFlags, startpc, code.curPc());
 787         }
 788     }
 789 
 790     /** Derived visitor method: generate code for a list of statements.
 791      */
 792     public void genStats(List<? extends JCTree> trees, Env<GenContext> env) {
 793         for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
 794             genStat(l.head, env, CRT_STATEMENT);
 795     }
 796 
 797     /** Derived visitor method: check whether CharacterRangeTable
 798      *  should be emitted, if so, put a new entry into CRTable
 799      *  and call method to generate bytecode.
 800      *  If not, just call method to generate bytecode.
 801      *  @see    #genCond(JCTree,boolean)
 802      *
 803      *  @param  tree     The tree to be visited.
 804      *  @param  crtFlags The CharacterRangeTable flags
 805      *                   indicating type of the entry.
 806      */
 807     public CondItem genCond(JCTree tree, int crtFlags) {
 808         if (!genCrt) return genCond(tree, false);
 809         int startpc = code.curPc();
 810         CondItem item = genCond(tree, (crtFlags & CRT_FLOW_CONTROLLER) != 0);
 811         code.crt.put(tree, crtFlags, startpc, code.curPc());
 812         return item;
 813     }
 814 
 815     /** Derived visitor method: generate code for a boolean
 816      *  expression in a control-flow context.
 817      *  @param _tree         The expression to be visited.
 818      *  @param markBranches The flag to indicate that the condition is
 819      *                      a flow controller so produced conditions
 820      *                      should contain a proper tree to generate
 821      *                      CharacterRangeTable branches for them.
 822      */
 823     public CondItem genCond(JCTree _tree, boolean markBranches) {
 824         JCTree inner_tree = TreeInfo.skipParens(_tree);
 825         if (inner_tree.hasTag(CONDEXPR)) {
 826             JCConditional tree = (JCConditional)inner_tree;
 827             CondItem cond = genCond(tree.cond, CRT_FLOW_CONTROLLER);
 828             if (cond.isTrue()) {
 829                 code.resolve(cond.trueJumps);
 830                 CondItem result = genCond(tree.truepart, CRT_FLOW_TARGET);
 831                 if (markBranches) result.tree = tree.truepart;
 832                 return result;
 833             }
 834             if (cond.isFalse()) {
 835                 code.resolve(cond.falseJumps);
 836                 CondItem result = genCond(tree.falsepart, CRT_FLOW_TARGET);
 837                 if (markBranches) result.tree = tree.falsepart;
 838                 return result;
 839             }
 840             Chain secondJumps = cond.jumpFalse();
 841             code.resolve(cond.trueJumps);
 842             CondItem first = genCond(tree.truepart, CRT_FLOW_TARGET);
 843             if (markBranches) first.tree = tree.truepart;
 844             Chain falseJumps = first.jumpFalse();
 845             code.resolve(first.trueJumps);
 846             Chain trueJumps = code.branch(goto_);
 847             code.resolve(secondJumps);
 848             CondItem second = genCond(tree.falsepart, CRT_FLOW_TARGET);
 849             CondItem result = items.makeCondItem(second.opcode,
 850                                       Code.mergeChains(trueJumps, second.trueJumps),
 851                                       Code.mergeChains(falseJumps, second.falseJumps));
 852             if (markBranches) result.tree = tree.falsepart;
 853             return result;
 854         } else {
 855             CondItem result = genExpr(_tree, syms.booleanType).mkCond();
 856             if (markBranches) result.tree = _tree;
 857             return result;
 858         }
 859     }
 860 
 861     /** Visitor class for expressions which might be constant expressions.
 862      *  This class is a subset of TreeScanner. Intended to visit trees pruned by
 863      *  Lower as long as constant expressions looking for references to any
 864      *  ClassSymbol. Any such reference will be added to the constant pool so
 865      *  automated tools can detect class dependencies better.
 866      */
 867     class ClassReferenceVisitor extends JCTree.Visitor {
 868 
 869         @Override
 870         public void visitTree(JCTree tree) {}
 871 
 872         @Override
 873         public void visitBinary(JCBinary tree) {
 874             tree.lhs.accept(this);
 875             tree.rhs.accept(this);
 876         }
 877 
 878         @Override
 879         public void visitSelect(JCFieldAccess tree) {
 880             if (tree.selected.type.hasTag(CLASS)) {
 881                 makeRef(tree.selected.pos(), tree.selected.type);
 882             }
 883         }
 884 
 885         @Override
 886         public void visitIdent(JCIdent tree) {
 887             if (tree.sym.owner instanceof ClassSymbol) {
 888                 pool.put(tree.sym.owner);
 889             }
 890         }
 891 
 892         @Override
 893         public void visitConditional(JCConditional tree) {
 894             tree.cond.accept(this);
 895             tree.truepart.accept(this);
 896             tree.falsepart.accept(this);
 897         }
 898 
 899         @Override
 900         public void visitUnary(JCUnary tree) {
 901             tree.arg.accept(this);
 902         }
 903 
 904         @Override
 905         public void visitParens(JCParens tree) {
 906             tree.expr.accept(this);
 907         }
 908 
 909         @Override
 910         public void visitTypeCast(JCTypeCast tree) {
 911             tree.expr.accept(this);
 912         }
 913     }
 914 
 915     private ClassReferenceVisitor classReferenceVisitor = new ClassReferenceVisitor();
 916 
 917     /** Visitor method: generate code for an expression, catching and reporting
 918      *  any completion failures.
 919      *  @param tree    The expression to be visited.
 920      *  @param pt      The expression's expected type (proto-type).
 921      */
 922     public Item genExpr(JCTree tree, Type pt) {
 923         Type prevPt = this.pt;
 924         try {
 925             if (tree.type.constValue() != null) {
 926                 // Short circuit any expressions which are constants
 927                 tree.accept(classReferenceVisitor);
 928                 checkStringConstant(tree.pos(), tree.type.constValue());
 929                 result = items.makeImmediateItem(tree.type, tree.type.constValue());
 930             } else {
 931                 this.pt = pt;
 932                 tree.accept(this);
 933             }
 934             return result.coerce(pt);
 935         } catch (CompletionFailure ex) {
 936             chk.completionError(tree.pos(), ex);
 937             code.state.stacksize = 1;
 938             return items.makeStackItem(pt);
 939         } finally {
 940             this.pt = prevPt;
 941         }
 942     }
 943 
 944     /** Derived visitor method: generate code for a list of method arguments.
 945      *  @param trees    The argument expressions to be visited.
 946      *  @param pts      The expression's expected types (i.e. the formal parameter
 947      *                  types of the invoked method).
 948      */
 949     public void genArgs(List<JCExpression> trees, List<Type> pts) {
 950         for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail) {
 951             genExpr(l.head, pts.head).load();
 952             pts = pts.tail;
 953         }
 954         // require lists be of same length
 955         Assert.check(pts.isEmpty());
 956     }
 957 
 958 /* ************************************************************************
 959  * Visitor methods for statements and definitions
 960  *************************************************************************/
 961 
 962     /** Thrown when the byte code size exceeds limit.
 963      */
 964     public static class CodeSizeOverflow extends RuntimeException {
 965         private static final long serialVersionUID = 0;
 966         public CodeSizeOverflow() {}
 967     }
 968 
 969     public void visitMethodDef(JCMethodDecl tree) {
 970         // Create a new local environment that points pack at method
 971         // definition.
 972         Env<GenContext> localEnv = env.dup(tree);
 973         localEnv.enclMethod = tree;
 974 
 975         // The expected type of every return statement in this method
 976         // is the method's return type.
 977         this.pt = tree.sym.erasure(types).getReturnType();
 978 
 979         checkDimension(tree.pos(), tree.sym.erasure(types));
 980         genMethod(tree, localEnv, false);
 981     }
 982 //where
 983         /** Generate code for a method.
 984          *  @param tree     The tree representing the method definition.
 985          *  @param env      The environment current for the method body.
 986          *  @param fatcode  A flag that indicates whether all jumps are
 987          *                  within 32K.  We first invoke this method under
 988          *                  the assumption that fatcode == false, i.e. all
 989          *                  jumps are within 32K.  If this fails, fatcode
 990          *                  is set to true and we try again.
 991          */
 992         void genMethod(JCMethodDecl tree, Env<GenContext> env, boolean fatcode) {
 993             MethodSymbol meth = tree.sym;
 994 //      System.err.println("Generating " + meth + " in " + meth.owner); //DEBUG
 995             if (Code.width(types.erasure(env.enclMethod.sym.type).getParameterTypes())  +
 996                 (((tree.mods.flags & STATIC) == 0 || meth.isConstructor()) ? 1 : 0) >
 997                 ClassFile.MAX_PARAMETERS) {
 998                 log.error(tree.pos(), "limit.parameters");
 999                 nerrs++;
1000             }
1001 
1002             else if (tree.body != null) {
1003                 // Create a new code structure and initialize it.
1004                 int startpcCrt = initCode(tree, env, fatcode);
1005 
1006                 try {
1007                     genStat(tree.body, env);
1008                 } catch (CodeSizeOverflow e) {
1009                     // Failed due to code limit, try again with jsr/ret
1010                     startpcCrt = initCode(tree, env, fatcode);
1011                     genStat(tree.body, env);
1012                 }
1013 
1014                 if (code.state.stacksize != 0) {
1015                     log.error(tree.body.pos(), "stack.sim.error", tree);
1016                     throw new AssertionError();
1017                 }
1018 
1019                 // If last statement could complete normally, insert a
1020                 // return at the end.
1021                 if (code.isAlive()) {
1022                     code.statBegin(TreeInfo.endPos(tree.body));
1023                     if (env.enclMethod == null ||
1024                         env.enclMethod.sym.type.getReturnType().hasTag(VOID)) {
1025                         code.emitop0(return_);
1026                     } else {
1027                         // sometime dead code seems alive (4415991);
1028                         // generate a small loop instead
1029                         int startpc = code.entryPoint();
1030                         CondItem c = items.makeCondItem(goto_);
1031                         code.resolve(c.jumpTrue(), startpc);
1032                     }
1033                 }
1034                 if (genCrt)
1035                     code.crt.put(tree.body,
1036                                  CRT_BLOCK,
1037                                  startpcCrt,
1038                                  code.curPc());
1039 
1040                 code.endScopes(0);
1041 
1042                 // If we exceeded limits, panic
1043                 if (code.checkLimits(tree.pos(), log)) {
1044                     nerrs++;
1045                     return;
1046                 }
1047 
1048                 // If we generated short code but got a long jump, do it again
1049                 // with fatCode = true.
1050                 if (!fatcode && code.fatcode) genMethod(tree, env, true);
1051 
1052                 // Clean up
1053                 if(stackMap == StackMapFormat.JSR202) {
1054                     code.lastFrame = null;
1055                     code.frameBeforeLast = null;
1056                 }
1057 
1058                 // Compress exception table
1059                 code.compressCatchTable();
1060 
1061                 // Fill in type annotation positions for exception parameters
1062                 code.fillExceptionParameterPositions();
1063             }
1064         }
1065 
1066         private int initCode(JCMethodDecl tree, Env<GenContext> env, boolean fatcode) {
1067             MethodSymbol meth = tree.sym;
1068 
1069             // Create a new code structure.
1070             meth.code = code = new Code(meth,
1071                                         fatcode,
1072                                         lineDebugInfo ? toplevel.lineMap : null,
1073                                         varDebugInfo,
1074                                         stackMap,
1075                                         debugCode,
1076                                         genCrt ? new CRTable(tree, env.toplevel.endPositions)
1077                                                : null,
1078                                         syms,
1079                                         types,
1080                                         pool);
1081             items = new Items(pool, code, syms, types);
1082             if (code.debugCode)
1083                 System.err.println(meth + " for body " + tree);
1084 
1085             // If method is not static, create a new local variable address
1086             // for `this'.
1087             if ((tree.mods.flags & STATIC) == 0) {
1088                 Type selfType = meth.owner.type;
1089                 if (meth.isConstructor() && selfType != syms.objectType)
1090                     selfType = UninitializedType.uninitializedThis(selfType);
1091                 code.setDefined(
1092                         code.newLocal(
1093                             new VarSymbol(FINAL, names._this, selfType, meth.owner)));
1094             }
1095 
1096             // Mark all parameters as defined from the beginning of
1097             // the method.
1098             for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
1099                 checkDimension(l.head.pos(), l.head.sym.type);
1100                 code.setDefined(code.newLocal(l.head.sym));
1101             }
1102 
1103             // Get ready to generate code for method body.
1104             int startpcCrt = genCrt ? code.curPc() : 0;
1105             code.entryPoint();
1106 
1107             // Suppress initial stackmap
1108             code.pendingStackMap = false;
1109 
1110             return startpcCrt;
1111         }
1112 
1113     public void visitVarDef(JCVariableDecl tree) {
1114         VarSymbol v = tree.sym;
1115         code.newLocal(v);
1116         if (tree.init != null) {
1117             checkStringConstant(tree.init.pos(), v.getConstValue());
1118             if (v.getConstValue() == null || varDebugInfo) {
1119                 genExpr(tree.init, v.erasure(types)).load();
1120                 items.makeLocalItem(v).store();
1121             }
1122         }
1123         checkDimension(tree.pos(), v.type);
1124     }
1125 
1126     public void visitSkip(JCSkip tree) {
1127     }
1128 
1129     public void visitBlock(JCBlock tree) {
1130         int limit = code.nextreg;
1131         Env<GenContext> localEnv = env.dup(tree, new GenContext());
1132         genStats(tree.stats, localEnv);
1133         // End the scope of all block-local variables in variable info.
1134         if (!env.tree.hasTag(METHODDEF)) {
1135             code.statBegin(tree.endpos);
1136             code.endScopes(limit);
1137             code.pendingStatPos = Position.NOPOS;
1138         }
1139     }
1140 
1141     public void visitDoLoop(JCDoWhileLoop tree) {
1142         genLoop(tree, tree.body, tree.cond, List.<JCExpressionStatement>nil(), false);
1143     }
1144 
1145     public void visitWhileLoop(JCWhileLoop tree) {
1146         genLoop(tree, tree.body, tree.cond, List.<JCExpressionStatement>nil(), true);
1147     }
1148 
1149     public void visitForLoop(JCForLoop tree) {
1150         int limit = code.nextreg;
1151         genStats(tree.init, env);
1152         genLoop(tree, tree.body, tree.cond, tree.step, true);
1153         code.endScopes(limit);
1154     }
1155     //where
1156         /** Generate code for a loop.
1157          *  @param loop       The tree representing the loop.
1158          *  @param body       The loop's body.
1159          *  @param cond       The loop's controling condition.
1160          *  @param step       "Step" statements to be inserted at end of
1161          *                    each iteration.
1162          *  @param testFirst  True if the loop test belongs before the body.
1163          */
1164         private void genLoop(JCStatement loop,
1165                              JCStatement body,
1166                              JCExpression cond,
1167                              List<JCExpressionStatement> step,
1168                              boolean testFirst) {
1169             Env<GenContext> loopEnv = env.dup(loop, new GenContext());
1170             int startpc = code.entryPoint();
1171             if (testFirst) {
1172                 CondItem c;
1173                 if (cond != null) {
1174                     code.statBegin(cond.pos);
1175                     c = genCond(TreeInfo.skipParens(cond), CRT_FLOW_CONTROLLER);
1176                 } else {
1177                     c = items.makeCondItem(goto_);
1178                 }
1179                 Chain loopDone = c.jumpFalse();
1180                 code.resolve(c.trueJumps);
1181                 genStat(body, loopEnv, CRT_STATEMENT | CRT_FLOW_TARGET);
1182                 code.resolve(loopEnv.info.cont);
1183                 genStats(step, loopEnv);
1184                 code.resolve(code.branch(goto_), startpc);
1185                 code.resolve(loopDone);
1186             } else {
1187                 genStat(body, loopEnv, CRT_STATEMENT | CRT_FLOW_TARGET);
1188                 code.resolve(loopEnv.info.cont);
1189                 genStats(step, loopEnv);
1190                 CondItem c;
1191                 if (cond != null) {
1192                     code.statBegin(cond.pos);
1193                     c = genCond(TreeInfo.skipParens(cond), CRT_FLOW_CONTROLLER);
1194                 } else {
1195                     c = items.makeCondItem(goto_);
1196                 }
1197                 code.resolve(c.jumpTrue(), startpc);
1198                 code.resolve(c.falseJumps);
1199             }
1200             code.resolve(loopEnv.info.exit);
1201         }
1202 
1203     public void visitForeachLoop(JCEnhancedForLoop tree) {
1204         throw new AssertionError(); // should have been removed by Lower.
1205     }
1206 
1207     public void visitLabelled(JCLabeledStatement tree) {
1208         Env<GenContext> localEnv = env.dup(tree, new GenContext());
1209         genStat(tree.body, localEnv, CRT_STATEMENT);
1210         code.resolve(localEnv.info.exit);
1211     }
1212 
1213     public void visitSwitch(JCSwitch tree) {
1214         int limit = code.nextreg;
1215         Assert.check(!tree.selector.type.hasTag(CLASS));
1216         int startpcCrt = genCrt ? code.curPc() : 0;
1217         Item sel = genExpr(tree.selector, syms.intType);
1218         List<JCCase> cases = tree.cases;
1219         if (cases.isEmpty()) {
1220             // We are seeing:  switch <sel> {}
1221             sel.load().drop();
1222             if (genCrt)
1223                 code.crt.put(TreeInfo.skipParens(tree.selector),
1224                              CRT_FLOW_CONTROLLER, startpcCrt, code.curPc());
1225         } else {
1226             // We are seeing a nonempty switch.
1227             sel.load();
1228             if (genCrt)
1229                 code.crt.put(TreeInfo.skipParens(tree.selector),
1230                              CRT_FLOW_CONTROLLER, startpcCrt, code.curPc());
1231             Env<GenContext> switchEnv = env.dup(tree, new GenContext());
1232             switchEnv.info.isSwitch = true;
1233 
1234             // Compute number of labels and minimum and maximum label values.
1235             // For each case, store its label in an array.
1236             int lo = Integer.MAX_VALUE;  // minimum label.
1237             int hi = Integer.MIN_VALUE;  // maximum label.
1238             int nlabels = 0;               // number of labels.
1239 
1240             int[] labels = new int[cases.length()];  // the label array.
1241             int defaultIndex = -1;     // the index of the default clause.
1242 
1243             List<JCCase> l = cases;
1244             for (int i = 0; i < labels.length; i++) {
1245                 if (l.head.pat != null) {
1246                     int val = ((Number)l.head.pat.type.constValue()).intValue();
1247                     labels[i] = val;
1248                     if (val < lo) lo = val;
1249                     if (hi < val) hi = val;
1250                     nlabels++;
1251                 } else {
1252                     Assert.check(defaultIndex == -1);
1253                     defaultIndex = i;
1254                 }
1255                 l = l.tail;
1256             }
1257 
1258             // Determine whether to issue a tableswitch or a lookupswitch
1259             // instruction.
1260             long table_space_cost = 4 + ((long) hi - lo + 1); // words
1261             long table_time_cost = 3; // comparisons
1262             long lookup_space_cost = 3 + 2 * (long) nlabels;
1263             long lookup_time_cost = nlabels;
1264             int opcode =
1265                 nlabels > 0 &&
1266                 table_space_cost + 3 * table_time_cost <=
1267                 lookup_space_cost + 3 * lookup_time_cost
1268                 ?
1269                 tableswitch : lookupswitch;
1270 
1271             int startpc = code.curPc();    // the position of the selector operation
1272             code.emitop0(opcode);
1273             code.align(4);
1274             int tableBase = code.curPc();  // the start of the jump table
1275             int[] offsets = null;          // a table of offsets for a lookupswitch
1276             code.emit4(-1);                // leave space for default offset
1277             if (opcode == tableswitch) {
1278                 code.emit4(lo);            // minimum label
1279                 code.emit4(hi);            // maximum label
1280                 for (long i = lo; i <= hi; i++) {  // leave space for jump table
1281                     code.emit4(-1);
1282                 }
1283             } else {
1284                 code.emit4(nlabels);    // number of labels
1285                 for (int i = 0; i < nlabels; i++) {
1286                     code.emit4(-1); code.emit4(-1); // leave space for lookup table
1287                 }
1288                 offsets = new int[labels.length];
1289             }
1290             Code.State stateSwitch = code.state.dup();
1291             code.markDead();
1292 
1293             // For each case do:
1294             l = cases;
1295             for (int i = 0; i < labels.length; i++) {
1296                 JCCase c = l.head;
1297                 l = l.tail;
1298 
1299                 int pc = code.entryPoint(stateSwitch);
1300                 // Insert offset directly into code or else into the
1301                 // offsets table.
1302                 if (i != defaultIndex) {
1303                     if (opcode == tableswitch) {
1304                         code.put4(
1305                             tableBase + 4 * (labels[i] - lo + 3),
1306                             pc - startpc);
1307                     } else {
1308                         offsets[i] = pc - startpc;
1309                     }
1310                 } else {
1311                     code.put4(tableBase, pc - startpc);
1312                 }
1313 
1314                 // Generate code for the statements in this case.
1315                 genStats(c.stats, switchEnv, CRT_FLOW_TARGET);
1316             }
1317 
1318             // Resolve all breaks.
1319             code.resolve(switchEnv.info.exit);
1320 
1321             // If we have not set the default offset, we do so now.
1322             if (code.get4(tableBase) == -1) {
1323                 code.put4(tableBase, code.entryPoint(stateSwitch) - startpc);
1324             }
1325 
1326             if (opcode == tableswitch) {
1327                 // Let any unfilled slots point to the default case.
1328                 int defaultOffset = code.get4(tableBase);
1329                 for (long i = lo; i <= hi; i++) {
1330                     int t = (int)(tableBase + 4 * (i - lo + 3));
1331                     if (code.get4(t) == -1)
1332                         code.put4(t, defaultOffset);
1333                 }
1334             } else {
1335                 // Sort non-default offsets and copy into lookup table.
1336                 if (defaultIndex >= 0)
1337                     for (int i = defaultIndex; i < labels.length - 1; i++) {
1338                         labels[i] = labels[i+1];
1339                         offsets[i] = offsets[i+1];
1340                     }
1341                 if (nlabels > 0)
1342                     qsort2(labels, offsets, 0, nlabels - 1);
1343                 for (int i = 0; i < nlabels; i++) {
1344                     int caseidx = tableBase + 8 * (i + 1);
1345                     code.put4(caseidx, labels[i]);
1346                     code.put4(caseidx + 4, offsets[i]);
1347                 }
1348             }
1349         }
1350         code.endScopes(limit);
1351     }
1352 //where
1353         /** Sort (int) arrays of keys and values
1354          */
1355        static void qsort2(int[] keys, int[] values, int lo, int hi) {
1356             int i = lo;
1357             int j = hi;
1358             int pivot = keys[(i+j)/2];
1359             do {
1360                 while (keys[i] < pivot) i++;
1361                 while (pivot < keys[j]) j--;
1362                 if (i <= j) {
1363                     int temp1 = keys[i];
1364                     keys[i] = keys[j];
1365                     keys[j] = temp1;
1366                     int temp2 = values[i];
1367                     values[i] = values[j];
1368                     values[j] = temp2;
1369                     i++;
1370                     j--;
1371                 }
1372             } while (i <= j);
1373             if (lo < j) qsort2(keys, values, lo, j);
1374             if (i < hi) qsort2(keys, values, i, hi);
1375         }
1376 
1377     public void visitSynchronized(JCSynchronized tree) {
1378         int limit = code.nextreg;
1379         // Generate code to evaluate lock and save in temporary variable.
1380         final LocalItem lockVar = makeTemp(syms.objectType);
1381         genExpr(tree.lock, tree.lock.type).load().duplicate();
1382         lockVar.store();
1383 
1384         // Generate code to enter monitor.
1385         code.emitop0(monitorenter);
1386         code.state.lock(lockVar.reg);
1387 
1388         // Generate code for a try statement with given body, no catch clauses
1389         // in a new environment with the "exit-monitor" operation as finalizer.
1390         final Env<GenContext> syncEnv = env.dup(tree, new GenContext());
1391         syncEnv.info.finalize = new GenFinalizer() {
1392             void gen() {
1393                 genLast();
1394                 Assert.check(syncEnv.info.gaps.length() % 2 == 0);
1395                 syncEnv.info.gaps.append(code.curPc());
1396             }
1397             void genLast() {
1398                 if (code.isAlive()) {
1399                     lockVar.load();
1400                     code.emitop0(monitorexit);
1401                     code.state.unlock(lockVar.reg);
1402                 }
1403             }
1404         };
1405         syncEnv.info.gaps = new ListBuffer<Integer>();
1406         genTry(tree.body, List.<JCCatch>nil(), syncEnv);
1407         code.endScopes(limit);
1408     }
1409 
1410     public void visitTry(final JCTry tree) {
1411         // Generate code for a try statement with given body and catch clauses,
1412         // in a new environment which calls the finally block if there is one.
1413         final Env<GenContext> tryEnv = env.dup(tree, new GenContext());
1414         final Env<GenContext> oldEnv = env;
1415         if (!useJsrLocally) {
1416             useJsrLocally =
1417                 (stackMap == StackMapFormat.NONE) &&
1418                 (jsrlimit <= 0 ||
1419                 jsrlimit < 100 &&
1420                 estimateCodeComplexity(tree.finalizer)>jsrlimit);
1421         }
1422         tryEnv.info.finalize = new GenFinalizer() {
1423             void gen() {
1424                 if (useJsrLocally) {
1425                     if (tree.finalizer != null) {
1426                         Code.State jsrState = code.state.dup();
1427                         jsrState.push(Code.jsrReturnValue);
1428                         tryEnv.info.cont =
1429                             new Chain(code.emitJump(jsr),
1430                                       tryEnv.info.cont,
1431                                       jsrState);
1432                     }
1433                     Assert.check(tryEnv.info.gaps.length() % 2 == 0);
1434                     tryEnv.info.gaps.append(code.curPc());
1435                 } else {
1436                     Assert.check(tryEnv.info.gaps.length() % 2 == 0);
1437                     tryEnv.info.gaps.append(code.curPc());
1438                     genLast();
1439                 }
1440             }
1441             void genLast() {
1442                 if (tree.finalizer != null)
1443                     genStat(tree.finalizer, oldEnv, CRT_BLOCK);
1444             }
1445             boolean hasFinalizer() {
1446                 return tree.finalizer != null;
1447             }
1448         };
1449         tryEnv.info.gaps = new ListBuffer<Integer>();
1450         genTry(tree.body, tree.catchers, tryEnv);
1451     }
1452     //where
1453         /** Generate code for a try or synchronized statement
1454          *  @param body      The body of the try or synchronized statement.
1455          *  @param catchers  The lis of catch clauses.
1456          *  @param env       the environment current for the body.
1457          */
1458         void genTry(JCTree body, List<JCCatch> catchers, Env<GenContext> env) {
1459             int limit = code.nextreg;
1460             int startpc = code.curPc();
1461             Code.State stateTry = code.state.dup();
1462             genStat(body, env, CRT_BLOCK);
1463             int endpc = code.curPc();
1464             boolean hasFinalizer =
1465                 env.info.finalize != null &&
1466                 env.info.finalize.hasFinalizer();
1467             List<Integer> gaps = env.info.gaps.toList();
1468             code.statBegin(TreeInfo.endPos(body));
1469             genFinalizer(env);
1470             code.statBegin(TreeInfo.endPos(env.tree));
1471             Chain exitChain = code.branch(goto_);
1472             endFinalizerGap(env);
1473             if (startpc != endpc) for (List<JCCatch> l = catchers; l.nonEmpty(); l = l.tail) {
1474                 // start off with exception on stack
1475                 code.entryPoint(stateTry, l.head.param.sym.type);
1476                 genCatch(l.head, env, startpc, endpc, gaps);
1477                 genFinalizer(env);
1478                 if (hasFinalizer || l.tail.nonEmpty()) {
1479                     code.statBegin(TreeInfo.endPos(env.tree));
1480                     exitChain = Code.mergeChains(exitChain,
1481                                                  code.branch(goto_));
1482                 }
1483                 endFinalizerGap(env);
1484             }
1485             if (hasFinalizer) {
1486                 // Create a new register segement to avoid allocating
1487                 // the same variables in finalizers and other statements.
1488                 code.newRegSegment();
1489 
1490                 // Add a catch-all clause.
1491 
1492                 // start off with exception on stack
1493                 int catchallpc = code.entryPoint(stateTry, syms.throwableType);
1494 
1495                 // Register all exception ranges for catch all clause.
1496                 // The range of the catch all clause is from the beginning
1497                 // of the try or synchronized block until the present
1498                 // code pointer excluding all gaps in the current
1499                 // environment's GenContext.
1500                 int startseg = startpc;
1501                 while (env.info.gaps.nonEmpty()) {
1502                     int endseg = env.info.gaps.next().intValue();
1503                     registerCatch(body.pos(), startseg, endseg,
1504                                   catchallpc, 0);
1505                     startseg = env.info.gaps.next().intValue();
1506                 }
1507                 code.statBegin(TreeInfo.finalizerPos(env.tree));
1508                 code.markStatBegin();
1509 
1510                 Item excVar = makeTemp(syms.throwableType);
1511                 excVar.store();
1512                 genFinalizer(env);
1513                 excVar.load();
1514                 registerCatch(body.pos(), startseg,
1515                               env.info.gaps.next().intValue(),
1516                               catchallpc, 0);
1517                 code.emitop0(athrow);
1518                 code.markDead();
1519 
1520                 // If there are jsr's to this finalizer, ...
1521                 if (env.info.cont != null) {
1522                     // Resolve all jsr's.
1523                     code.resolve(env.info.cont);
1524 
1525                     // Mark statement line number
1526                     code.statBegin(TreeInfo.finalizerPos(env.tree));
1527                     code.markStatBegin();
1528 
1529                     // Save return address.
1530                     LocalItem retVar = makeTemp(syms.throwableType);
1531                     retVar.store();
1532 
1533                     // Generate finalizer code.
1534                     env.info.finalize.genLast();
1535 
1536                     // Return.
1537                     code.emitop1w(ret, retVar.reg);
1538                     code.markDead();
1539                 }
1540             }
1541             // Resolve all breaks.
1542             code.resolve(exitChain);
1543 
1544             code.endScopes(limit);
1545         }
1546 
1547         /** Generate code for a catch clause.
1548          *  @param tree     The catch clause.
1549          *  @param env      The environment current in the enclosing try.
1550          *  @param startpc  Start pc of try-block.
1551          *  @param endpc    End pc of try-block.
1552          */
1553         void genCatch(JCCatch tree,
1554                       Env<GenContext> env,
1555                       int startpc, int endpc,
1556                       List<Integer> gaps) {
1557             if (startpc != endpc) {
1558                 List<JCExpression> subClauses = TreeInfo.isMultiCatch(tree) ?
1559                         ((JCTypeUnion)tree.param.vartype).alternatives :
1560                         List.of(tree.param.vartype);
1561                 while (gaps.nonEmpty()) {
1562                     for (JCExpression subCatch : subClauses) {
1563                         int catchType = makeRef(tree.pos(), subCatch.type);
1564                         int end = gaps.head.intValue();
1565                         registerCatch(tree.pos(),
1566                                       startpc,  end, code.curPc(),
1567                                       catchType);
1568                         if (subCatch.type.isAnnotated()) {
1569                             // All compounds share the same position, simply update the
1570                             // first one.
1571                             subCatch.type.getAnnotationMirrors().head.position.type_index = catchType;
1572                         }
1573                     }
1574                     gaps = gaps.tail;
1575                     startpc = gaps.head.intValue();
1576                     gaps = gaps.tail;
1577                 }
1578                 if (startpc < endpc) {
1579                     for (JCExpression subCatch : subClauses) {
1580                         int catchType = makeRef(tree.pos(), subCatch.type);
1581                         registerCatch(tree.pos(),
1582                                       startpc, endpc, code.curPc(),
1583                                       catchType);
1584                         if (subCatch.type.isAnnotated()) {
1585                             // All compounds share the same position, simply update the
1586                             // first one.
1587                             subCatch.type.getAnnotationMirrors().head.position.type_index = catchType;
1588                         }
1589                     }
1590                 }
1591                 VarSymbol exparam = tree.param.sym;
1592                 code.statBegin(tree.pos);
1593                 code.markStatBegin();
1594                 int limit = code.nextreg;
1595                 int exlocal = code.newLocal(exparam);
1596                 items.makeLocalItem(exparam).store();
1597                 code.statBegin(TreeInfo.firstStatPos(tree.body));
1598                 genStat(tree.body, env, CRT_BLOCK);
1599                 code.endScopes(limit);
1600                 code.statBegin(TreeInfo.endPos(tree.body));
1601             }
1602         }
1603 
1604         /** Register a catch clause in the "Exceptions" code-attribute.
1605          */
1606         void registerCatch(DiagnosticPosition pos,
1607                            int startpc, int endpc,
1608                            int handler_pc, int catch_type) {
1609             char startpc1 = (char)startpc;
1610             char endpc1 = (char)endpc;
1611             char handler_pc1 = (char)handler_pc;
1612             if (startpc1 == startpc &&
1613                 endpc1 == endpc &&
1614                 handler_pc1 == handler_pc) {
1615                 code.addCatch(startpc1, endpc1, handler_pc1,
1616                               (char)catch_type);
1617             } else {
1618                 if (!useJsrLocally && !target.generateStackMapTable()) {
1619                     useJsrLocally = true;
1620                     throw new CodeSizeOverflow();
1621                 } else {
1622                     log.error(pos, "limit.code.too.large.for.try.stmt");
1623                     nerrs++;
1624                 }
1625             }
1626         }
1627 
1628     /** Very roughly estimate the number of instructions needed for
1629      *  the given tree.
1630      */
1631     int estimateCodeComplexity(JCTree tree) {
1632         if (tree == null) return 0;
1633         class ComplexityScanner extends TreeScanner {
1634             int complexity = 0;
1635             public void scan(JCTree tree) {
1636                 if (complexity > jsrlimit) return;
1637                 super.scan(tree);
1638             }
1639             public void visitClassDef(JCClassDecl tree) {}
1640             public void visitDoLoop(JCDoWhileLoop tree)
1641                 { super.visitDoLoop(tree); complexity++; }
1642             public void visitWhileLoop(JCWhileLoop tree)
1643                 { super.visitWhileLoop(tree); complexity++; }
1644             public void visitForLoop(JCForLoop tree)
1645                 { super.visitForLoop(tree); complexity++; }
1646             public void visitSwitch(JCSwitch tree)
1647                 { super.visitSwitch(tree); complexity+=5; }
1648             public void visitCase(JCCase tree)
1649                 { super.visitCase(tree); complexity++; }
1650             public void visitSynchronized(JCSynchronized tree)
1651                 { super.visitSynchronized(tree); complexity+=6; }
1652             public void visitTry(JCTry tree)
1653                 { super.visitTry(tree);
1654                   if (tree.finalizer != null) complexity+=6; }
1655             public void visitCatch(JCCatch tree)
1656                 { super.visitCatch(tree); complexity+=2; }
1657             public void visitConditional(JCConditional tree)
1658                 { super.visitConditional(tree); complexity+=2; }
1659             public void visitIf(JCIf tree)
1660                 { super.visitIf(tree); complexity+=2; }
1661             // note: for break, continue, and return we don't take unwind() into account.
1662             public void visitBreak(JCBreak tree)
1663                 { super.visitBreak(tree); complexity+=1; }
1664             public void visitContinue(JCContinue tree)
1665                 { super.visitContinue(tree); complexity+=1; }
1666             public void visitReturn(JCReturn tree)
1667                 { super.visitReturn(tree); complexity+=1; }
1668             public void visitThrow(JCThrow tree)
1669                 { super.visitThrow(tree); complexity+=1; }
1670             public void visitAssert(JCAssert tree)
1671                 { super.visitAssert(tree); complexity+=5; }
1672             public void visitApply(JCMethodInvocation tree)
1673                 { super.visitApply(tree); complexity+=2; }
1674             public void visitNewClass(JCNewClass tree)
1675                 { scan(tree.encl); scan(tree.args); complexity+=2; }
1676             public void visitNewArray(JCNewArray tree)
1677                 { super.visitNewArray(tree); complexity+=5; }
1678             public void visitAssign(JCAssign tree)
1679                 { super.visitAssign(tree); complexity+=1; }
1680             public void visitAssignop(JCAssignOp tree)
1681                 { super.visitAssignop(tree); complexity+=2; }
1682             public void visitUnary(JCUnary tree)
1683                 { complexity+=1;
1684                   if (tree.type.constValue() == null) super.visitUnary(tree); }
1685             public void visitBinary(JCBinary tree)
1686                 { complexity+=1;
1687                   if (tree.type.constValue() == null) super.visitBinary(tree); }
1688             public void visitTypeTest(JCInstanceOf tree)
1689                 { super.visitTypeTest(tree); complexity+=1; }
1690             public void visitIndexed(JCArrayAccess tree)
1691                 { super.visitIndexed(tree); complexity+=1; }
1692             public void visitSelect(JCFieldAccess tree)
1693                 { super.visitSelect(tree);
1694                   if (tree.sym.kind == VAR) complexity+=1; }
1695             public void visitIdent(JCIdent tree) {
1696                 if (tree.sym.kind == VAR) {
1697                     complexity+=1;
1698                     if (tree.type.constValue() == null &&
1699                         tree.sym.owner.kind == TYP)
1700                         complexity+=1;
1701                 }
1702             }
1703             public void visitLiteral(JCLiteral tree)
1704                 { complexity+=1; }
1705             public void visitTree(JCTree tree) {}
1706             public void visitWildcard(JCWildcard tree) {
1707                 throw new AssertionError(this.getClass().getName());
1708             }
1709         }
1710         ComplexityScanner scanner = new ComplexityScanner();
1711         tree.accept(scanner);
1712         return scanner.complexity;
1713     }
1714 
1715     public void visitIf(JCIf tree) {
1716         int limit = code.nextreg;
1717         Chain thenExit = null;
1718         CondItem c = genCond(TreeInfo.skipParens(tree.cond),
1719                              CRT_FLOW_CONTROLLER);
1720         Chain elseChain = c.jumpFalse();
1721         if (!c.isFalse()) {
1722             code.resolve(c.trueJumps);
1723             genStat(tree.thenpart, env, CRT_STATEMENT | CRT_FLOW_TARGET);
1724             thenExit = code.branch(goto_);
1725         }
1726         if (elseChain != null) {
1727             code.resolve(elseChain);
1728             if (tree.elsepart != null)
1729                 genStat(tree.elsepart, env,CRT_STATEMENT | CRT_FLOW_TARGET);
1730         }
1731         code.resolve(thenExit);
1732         code.endScopes(limit);
1733     }
1734 
1735     public void visitExec(JCExpressionStatement tree) {
1736         // Optimize x++ to ++x and x-- to --x.
1737         JCExpression e = tree.expr;
1738         switch (e.getTag()) {
1739             case POSTINC:
1740                 ((JCUnary) e).setTag(PREINC);
1741                 break;
1742             case POSTDEC:
1743                 ((JCUnary) e).setTag(PREDEC);
1744                 break;
1745         }
1746         genExpr(tree.expr, tree.expr.type).drop();
1747     }
1748 
1749     public void visitBreak(JCBreak tree) {
1750         Env<GenContext> targetEnv = unwind(tree.target, env);
1751         Assert.check(code.state.stacksize == 0);
1752         targetEnv.info.addExit(code.branch(goto_));
1753         endFinalizerGaps(env, targetEnv);
1754     }
1755 
1756     public void visitContinue(JCContinue tree) {
1757         Env<GenContext> targetEnv = unwind(tree.target, env);
1758         Assert.check(code.state.stacksize == 0);
1759         targetEnv.info.addCont(code.branch(goto_));
1760         endFinalizerGaps(env, targetEnv);
1761     }
1762 
1763     public void visitReturn(JCReturn tree) {
1764         int limit = code.nextreg;
1765         final Env<GenContext> targetEnv;
1766         if (tree.expr != null) {
1767             Item r = genExpr(tree.expr, pt).load();
1768             if (hasFinally(env.enclMethod, env)) {
1769                 r = makeTemp(pt);
1770                 r.store();
1771             }
1772             targetEnv = unwind(env.enclMethod, env);
1773             r.load();
1774             code.emitop0(ireturn + Code.truncate(Code.typecode(pt)));
1775         } else {
1776             targetEnv = unwind(env.enclMethod, env);
1777             code.emitop0(return_);
1778         }
1779         endFinalizerGaps(env, targetEnv);
1780         code.endScopes(limit);
1781     }
1782 
1783     public void visitThrow(JCThrow tree) {
1784         genExpr(tree.expr, tree.expr.type).load();
1785         code.emitop0(athrow);
1786     }
1787 
1788 /* ************************************************************************
1789  * Visitor methods for expressions
1790  *************************************************************************/
1791 
1792     public void visitApply(JCMethodInvocation tree) {
1793         setTypeAnnotationPositions(tree.pos);
1794         // Generate code for method.
1795         Item m = genExpr(tree.meth, methodType);
1796         // Generate code for all arguments, where the expected types are
1797         // the parameters of the method's external type (that is, any implicit
1798         // outer instance of a super(...) call appears as first parameter).
1799         MethodSymbol msym = (MethodSymbol)TreeInfo.symbol(tree.meth);
1800         genArgs(tree.args,
1801                 msym.externalType(types).getParameterTypes());
1802         if (!msym.isDynamic()) {
1803             code.statBegin(tree.pos);
1804             code.markStatBegin();
1805         }
1806         result = m.invoke();
1807     }
1808 
1809     public void visitConditional(JCConditional tree) {
1810         Chain thenExit = null;
1811         CondItem c = genCond(tree.cond, CRT_FLOW_CONTROLLER);
1812         Chain elseChain = c.jumpFalse();
1813         if (!c.isFalse()) {
1814             code.resolve(c.trueJumps);
1815             int startpc = genCrt ? code.curPc() : 0;
1816             genExpr(tree.truepart, pt).load();
1817             code.state.forceStackTop(tree.type);
1818             if (genCrt) code.crt.put(tree.truepart, CRT_FLOW_TARGET,
1819                                      startpc, code.curPc());
1820             thenExit = code.branch(goto_);
1821         }
1822         if (elseChain != null) {
1823             code.resolve(elseChain);
1824             int startpc = genCrt ? code.curPc() : 0;
1825             genExpr(tree.falsepart, pt).load();
1826             code.state.forceStackTop(tree.type);
1827             if (genCrt) code.crt.put(tree.falsepart, CRT_FLOW_TARGET,
1828                                      startpc, code.curPc());
1829         }
1830         code.resolve(thenExit);
1831         result = items.makeStackItem(pt);
1832     }
1833 
1834     private void setTypeAnnotationPositions(int treePos) {
1835         MethodSymbol meth = code.meth;
1836         boolean initOrClinit = code.meth.getKind() == javax.lang.model.element.ElementKind.CONSTRUCTOR
1837                 || code.meth.getKind() == javax.lang.model.element.ElementKind.STATIC_INIT;
1838 
1839         for (Attribute.TypeCompound ta : meth.getRawTypeAttributes()) {
1840             if (ta.hasUnknownPosition())
1841                 ta.tryFixPosition();
1842 
1843             if (ta.position.matchesPos(treePos))
1844                 ta.position.updatePosOffset(code.cp);
1845         }
1846 
1847         if (!initOrClinit)
1848             return;
1849 
1850         for (Attribute.TypeCompound ta : meth.owner.getRawTypeAttributes()) {
1851             if (ta.hasUnknownPosition())
1852                 ta.tryFixPosition();
1853 
1854             if (ta.position.matchesPos(treePos))
1855                 ta.position.updatePosOffset(code.cp);
1856         }
1857 
1858         ClassSymbol clazz = meth.enclClass();
1859         for (Symbol s : new com.sun.tools.javac.model.FilteredMemberList(clazz.members())) {
1860             if (!s.getKind().isField())
1861                 continue;
1862 
1863             for (Attribute.TypeCompound ta : s.getRawTypeAttributes()) {
1864                 if (ta.hasUnknownPosition())
1865                     ta.tryFixPosition();
1866 
1867                 if (ta.position.matchesPos(treePos))
1868                     ta.position.updatePosOffset(code.cp);
1869             }
1870         }
1871     }
1872 
1873     public void visitNewClass(JCNewClass tree) {
1874         // Enclosing instances or anonymous classes should have been eliminated
1875         // by now.
1876         Assert.check(tree.encl == null && tree.def == null);
1877         setTypeAnnotationPositions(tree.pos);
1878 
1879         code.emitop2(new_, makeRef(tree.pos(), tree.type));
1880         code.emitop0(dup);
1881 
1882         // Generate code for all arguments, where the expected types are
1883         // the parameters of the constructor's external type (that is,
1884         // any implicit outer instance appears as first parameter).
1885         genArgs(tree.args, tree.constructor.externalType(types).getParameterTypes());
1886 
1887         items.makeMemberItem(tree.constructor, true).invoke();
1888         result = items.makeStackItem(tree.type);
1889     }
1890 
1891     public void visitNewArray(JCNewArray tree) {
1892         setTypeAnnotationPositions(tree.pos);
1893 
1894         if (tree.elems != null) {
1895             Type elemtype = types.elemtype(tree.type);
1896             loadIntConst(tree.elems.length());
1897             Item arr = makeNewArray(tree.pos(), tree.type, 1);
1898             int i = 0;
1899             for (List<JCExpression> l = tree.elems; l.nonEmpty(); l = l.tail) {
1900                 arr.duplicate();
1901                 loadIntConst(i);
1902                 i++;
1903                 genExpr(l.head, elemtype).load();
1904                 items.makeIndexedItem(elemtype).store();
1905             }
1906             result = arr;
1907         } else {
1908             for (List<JCExpression> l = tree.dims; l.nonEmpty(); l = l.tail) {
1909                 genExpr(l.head, syms.intType).load();
1910             }
1911             result = makeNewArray(tree.pos(), tree.type, tree.dims.length());
1912         }
1913     }
1914 //where
1915         /** Generate code to create an array with given element type and number
1916          *  of dimensions.
1917          */
1918         Item makeNewArray(DiagnosticPosition pos, Type type, int ndims) {
1919             Type elemtype = types.elemtype(type);
1920             if (types.dimensions(type) > ClassFile.MAX_DIMENSIONS) {
1921                 log.error(pos, "limit.dimensions");
1922                 nerrs++;
1923             }
1924             int elemcode = Code.arraycode(elemtype);
1925             if (elemcode == 0 || (elemcode == 1 && ndims == 1)) {
1926                 code.emitAnewarray(makeRef(pos, elemtype), type);
1927             } else if (elemcode == 1) {
1928                 code.emitMultianewarray(ndims, makeRef(pos, type), type);
1929             } else {
1930                 code.emitNewarray(elemcode, type);
1931             }
1932             return items.makeStackItem(type);
1933         }
1934 
1935     public void visitParens(JCParens tree) {
1936         result = genExpr(tree.expr, tree.expr.type);
1937     }
1938 
1939     public void visitAssign(JCAssign tree) {
1940         Item l = genExpr(tree.lhs, tree.lhs.type);
1941         genExpr(tree.rhs, tree.lhs.type).load();
1942         result = items.makeAssignItem(l);
1943     }
1944 
1945     public void visitAssignop(JCAssignOp tree) {
1946         OperatorSymbol operator = (OperatorSymbol) tree.operator;
1947         Item l;
1948         if (operator.opcode == string_add) {
1949             // Generate code to make a string buffer
1950             makeStringBuffer(tree.pos());
1951 
1952             // Generate code for first string, possibly save one
1953             // copy under buffer
1954             l = genExpr(tree.lhs, tree.lhs.type);
1955             if (l.width() > 0) {
1956                 code.emitop0(dup_x1 + 3 * (l.width() - 1));
1957             }
1958 
1959             // Load first string and append to buffer.
1960             l.load();
1961             appendString(tree.lhs);
1962 
1963             // Append all other strings to buffer.
1964             appendStrings(tree.rhs);
1965 
1966             // Convert buffer to string.
1967             bufferToString(tree.pos());
1968         } else {
1969             // Generate code for first expression
1970             l = genExpr(tree.lhs, tree.lhs.type);
1971 
1972             // If we have an increment of -32768 to +32767 of a local
1973             // int variable we can use an incr instruction instead of
1974             // proceeding further.
1975             if ((tree.hasTag(PLUS_ASG) || tree.hasTag(MINUS_ASG)) &&
1976                 l instanceof LocalItem &&
1977                 tree.lhs.type.getTag().isSubRangeOf(INT) &&
1978                 tree.rhs.type.getTag().isSubRangeOf(INT) &&
1979                 tree.rhs.type.constValue() != null) {
1980                 int ival = ((Number) tree.rhs.type.constValue()).intValue();
1981                 if (tree.hasTag(MINUS_ASG)) ival = -ival;
1982                 ((LocalItem)l).incr(ival);
1983                 result = l;
1984                 return;
1985             }
1986             // Otherwise, duplicate expression, load one copy
1987             // and complete binary operation.
1988             l.duplicate();
1989             l.coerce(operator.type.getParameterTypes().head).load();
1990             completeBinop(tree.lhs, tree.rhs, operator).coerce(tree.lhs.type);
1991         }
1992         result = items.makeAssignItem(l);
1993     }
1994 
1995     public void visitUnary(JCUnary tree) {
1996         OperatorSymbol operator = (OperatorSymbol)tree.operator;
1997         if (tree.hasTag(NOT)) {
1998             CondItem od = genCond(tree.arg, false);
1999             result = od.negate();
2000         } else {
2001             Item od = genExpr(tree.arg, operator.type.getParameterTypes().head);
2002             switch (tree.getTag()) {
2003             case POS:
2004                 result = od.load();
2005                 break;
2006             case NEG:
2007                 result = od.load();
2008                 code.emitop0(operator.opcode);
2009                 break;
2010             case COMPL:
2011                 result = od.load();
2012                 emitMinusOne(od.typecode);
2013                 code.emitop0(operator.opcode);
2014                 break;
2015             case PREINC: case PREDEC:
2016                 od.duplicate();
2017                 if (od instanceof LocalItem &&
2018                     (operator.opcode == iadd || operator.opcode == isub)) {
2019                     ((LocalItem)od).incr(tree.hasTag(PREINC) ? 1 : -1);
2020                     result = od;
2021                 } else {
2022                     od.load();
2023                     code.emitop0(one(od.typecode));
2024                     code.emitop0(operator.opcode);
2025                     // Perform narrowing primitive conversion if byte,
2026                     // char, or short.  Fix for 4304655.
2027                     if (od.typecode != INTcode &&
2028                         Code.truncate(od.typecode) == INTcode)
2029                       code.emitop0(int2byte + od.typecode - BYTEcode);
2030                     result = items.makeAssignItem(od);
2031                 }
2032                 break;
2033             case POSTINC: case POSTDEC:
2034                 od.duplicate();
2035                 if (od instanceof LocalItem &&
2036                     (operator.opcode == iadd || operator.opcode == isub)) {
2037                     Item res = od.load();
2038                     ((LocalItem)od).incr(tree.hasTag(POSTINC) ? 1 : -1);
2039                     result = res;
2040                 } else {
2041                     Item res = od.load();
2042                     od.stash(od.typecode);
2043                     code.emitop0(one(od.typecode));
2044                     code.emitop0(operator.opcode);
2045                     // Perform narrowing primitive conversion if byte,
2046                     // char, or short.  Fix for 4304655.
2047                     if (od.typecode != INTcode &&
2048                         Code.truncate(od.typecode) == INTcode)
2049                       code.emitop0(int2byte + od.typecode - BYTEcode);
2050                     od.store();
2051                     result = res;
2052                 }
2053                 break;
2054             case NULLCHK:
2055                 result = od.load();
2056                 code.emitop0(dup);
2057                 genNullCheck(tree.pos());
2058                 break;
2059             default:
2060                 Assert.error();
2061             }
2062         }
2063     }
2064 
2065     /** Generate a null check from the object value at stack top. */
2066     private void genNullCheck(DiagnosticPosition pos) {
2067         callMethod(pos, syms.objectType, names.getClass,
2068                    List.<Type>nil(), false);
2069         code.emitop0(pop);
2070     }
2071 
2072     public void visitBinary(JCBinary tree) {
2073         OperatorSymbol operator = (OperatorSymbol)tree.operator;
2074         if (operator.opcode == string_add) {
2075             // Create a string buffer.
2076             makeStringBuffer(tree.pos());
2077             // Append all strings to buffer.
2078             appendStrings(tree);
2079             // Convert buffer to string.
2080             bufferToString(tree.pos());
2081             result = items.makeStackItem(syms.stringType);
2082         } else if (tree.hasTag(AND)) {
2083             CondItem lcond = genCond(tree.lhs, CRT_FLOW_CONTROLLER);
2084             if (!lcond.isFalse()) {
2085                 Chain falseJumps = lcond.jumpFalse();
2086                 code.resolve(lcond.trueJumps);
2087                 CondItem rcond = genCond(tree.rhs, CRT_FLOW_TARGET);
2088                 result = items.
2089                     makeCondItem(rcond.opcode,
2090                                  rcond.trueJumps,
2091                                  Code.mergeChains(falseJumps,
2092                                                   rcond.falseJumps));
2093             } else {
2094                 result = lcond;
2095             }
2096         } else if (tree.hasTag(OR)) {
2097             CondItem lcond = genCond(tree.lhs, CRT_FLOW_CONTROLLER);
2098             if (!lcond.isTrue()) {
2099                 Chain trueJumps = lcond.jumpTrue();
2100                 code.resolve(lcond.falseJumps);
2101                 CondItem rcond = genCond(tree.rhs, CRT_FLOW_TARGET);
2102                 result = items.
2103                     makeCondItem(rcond.opcode,
2104                                  Code.mergeChains(trueJumps, rcond.trueJumps),
2105                                  rcond.falseJumps);
2106             } else {
2107                 result = lcond;
2108             }
2109         } else {
2110             Item od = genExpr(tree.lhs, operator.type.getParameterTypes().head);
2111             od.load();
2112             result = completeBinop(tree.lhs, tree.rhs, operator);
2113         }
2114     }
2115 //where
2116         /** Make a new string buffer.
2117          */
2118         void makeStringBuffer(DiagnosticPosition pos) {
2119             code.emitop2(new_, makeRef(pos, stringBufferType));
2120             code.emitop0(dup);
2121             callMethod(
2122                 pos, stringBufferType, names.init, List.<Type>nil(), false);
2123         }
2124 
2125         /** Append value (on tos) to string buffer (on tos - 1).
2126          */
2127         void appendString(JCTree tree) {
2128             Type t = tree.type.baseType();
2129             if (!t.isPrimitive() && t.tsym != syms.stringType.tsym) {
2130                 t = syms.objectType;
2131             }
2132             items.makeMemberItem(getStringBufferAppend(tree, t), false).invoke();
2133         }
2134         Symbol getStringBufferAppend(JCTree tree, Type t) {
2135             Assert.checkNull(t.constValue());
2136             Symbol method = stringBufferAppend.get(t);
2137             if (method == null) {
2138                 method = rs.resolveInternalMethod(tree.pos(),
2139                                                   attrEnv,
2140                                                   stringBufferType,
2141                                                   names.append,
2142                                                   List.of(t),
2143                                                   null);
2144                 stringBufferAppend.put(t, method);
2145             }
2146             return method;
2147         }
2148 
2149         /** Add all strings in tree to string buffer.
2150          */
2151         void appendStrings(JCTree tree) {
2152             tree = TreeInfo.skipParens(tree);
2153             if (tree.hasTag(PLUS) && tree.type.constValue() == null) {
2154                 JCBinary op = (JCBinary) tree;
2155                 if (op.operator.kind == MTH &&
2156                     ((OperatorSymbol) op.operator).opcode == string_add) {
2157                     appendStrings(op.lhs);
2158                     appendStrings(op.rhs);
2159                     return;
2160                 }
2161             }
2162             genExpr(tree, tree.type).load();
2163             appendString(tree);
2164         }
2165 
2166         /** Convert string buffer on tos to string.
2167          */
2168         void bufferToString(DiagnosticPosition pos) {
2169             callMethod(
2170                 pos,
2171                 stringBufferType,
2172                 names.toString,
2173                 List.<Type>nil(),
2174                 false);
2175         }
2176 
2177         /** Complete generating code for operation, with left operand
2178          *  already on stack.
2179          *  @param lhs       The tree representing the left operand.
2180          *  @param rhs       The tree representing the right operand.
2181          *  @param operator  The operator symbol.
2182          */
2183         Item completeBinop(JCTree lhs, JCTree rhs, OperatorSymbol operator) {
2184             MethodType optype = (MethodType)operator.type;
2185             int opcode = operator.opcode;
2186             if (opcode >= if_icmpeq && opcode <= if_icmple &&
2187                 rhs.type.constValue() instanceof Number &&
2188                 ((Number) rhs.type.constValue()).intValue() == 0) {
2189                 opcode = opcode + (ifeq - if_icmpeq);
2190             } else if (opcode >= if_acmpeq && opcode <= if_acmpne &&
2191                        TreeInfo.isNull(rhs)) {
2192                 opcode = opcode + (if_acmp_null - if_acmpeq);
2193             } else {
2194                 // The expected type of the right operand is
2195                 // the second parameter type of the operator, except for
2196                 // shifts with long shiftcount, where we convert the opcode
2197                 // to a short shift and the expected type to int.
2198                 Type rtype = operator.erasure(types).getParameterTypes().tail.head;
2199                 if (opcode >= ishll && opcode <= lushrl) {
2200                     opcode = opcode + (ishl - ishll);
2201                     rtype = syms.intType;
2202                 }
2203                 // Generate code for right operand and load.
2204                 genExpr(rhs, rtype).load();
2205                 // If there are two consecutive opcode instructions,
2206                 // emit the first now.
2207                 if (opcode >= (1 << preShift)) {
2208                     code.emitop0(opcode >> preShift);
2209                     opcode = opcode & 0xFF;
2210                 }
2211             }
2212             if (opcode >= ifeq && opcode <= if_acmpne ||
2213                 opcode == if_acmp_null || opcode == if_acmp_nonnull) {
2214                 return items.makeCondItem(opcode);
2215             } else {
2216                 code.emitop0(opcode);
2217                 return items.makeStackItem(optype.restype);
2218             }
2219         }
2220 
2221     public void visitTypeCast(JCTypeCast tree) {
2222         setTypeAnnotationPositions(tree.pos);
2223         result = genExpr(tree.expr, tree.clazz.type).load();
2224         // Additional code is only needed if we cast to a reference type
2225         // which is not statically a supertype of the expression's type.
2226         // For basic types, the coerce(...) in genExpr(...) will do
2227         // the conversion.
2228         if (!tree.clazz.type.isPrimitive() &&
2229             types.asSuper(tree.expr.type, tree.clazz.type.tsym) == null) {
2230             code.emitop2(checkcast, makeRef(tree.pos(), tree.clazz.type));
2231         }
2232     }
2233 
2234     public void visitWildcard(JCWildcard tree) {
2235         throw new AssertionError(this.getClass().getName());
2236     }
2237 
2238     public void visitTypeTest(JCInstanceOf tree) {
2239         setTypeAnnotationPositions(tree.pos);
2240         genExpr(tree.expr, tree.expr.type).load();
2241         code.emitop2(instanceof_, makeRef(tree.pos(), tree.clazz.type));
2242         result = items.makeStackItem(syms.booleanType);
2243     }
2244 
2245     public void visitIndexed(JCArrayAccess tree) {
2246         genExpr(tree.indexed, tree.indexed.type).load();
2247         genExpr(tree.index, syms.intType).load();
2248         result = items.makeIndexedItem(tree.type);
2249     }
2250 
2251     public void visitIdent(JCIdent tree) {
2252         Symbol sym = tree.sym;
2253         if (tree.name == names._this || tree.name == names._super) {
2254             Item res = tree.name == names._this
2255                 ? items.makeThisItem()
2256                 : items.makeSuperItem();
2257             if (sym.kind == MTH) {
2258                 // Generate code to address the constructor.
2259                 res.load();
2260                 res = items.makeMemberItem(sym, true);
2261             }
2262             result = res;
2263         } else if (sym.kind == VAR && sym.owner.kind == MTH) {
2264             result = items.makeLocalItem((VarSymbol)sym);
2265         } else if (isInvokeDynamic(sym)) {
2266             result = items.makeDynamicItem(sym);
2267         } else if ((sym.flags() & STATIC) != 0) {
2268             if (!isAccessSuper(env.enclMethod))
2269                 sym = binaryQualifier(sym, env.enclClass.type);
2270             result = items.makeStaticItem(sym);
2271         } else {
2272             items.makeThisItem().load();
2273             sym = binaryQualifier(sym, env.enclClass.type);
2274             result = items.makeMemberItem(sym, (sym.flags() & PRIVATE) != 0);
2275         }
2276     }
2277 
2278     public void visitSelect(JCFieldAccess tree) {
2279         Symbol sym = tree.sym;
2280 
2281         if (tree.name == names._class) {
2282             Assert.check(target.hasClassLiterals());
2283             code.emitLdc(makeRef(tree.pos(), tree.selected.type));
2284             result = items.makeStackItem(pt);
2285             return;
2286        }
2287 
2288         Symbol ssym = TreeInfo.symbol(tree.selected);
2289 
2290         // Are we selecting via super?
2291         boolean selectSuper =
2292             ssym != null && (ssym.kind == TYP || ssym.name == names._super);
2293 
2294         // Are we accessing a member of the superclass in an access method
2295         // resulting from a qualified super?
2296         boolean accessSuper = isAccessSuper(env.enclMethod);
2297 
2298         Item base = (selectSuper)
2299             ? items.makeSuperItem()
2300             : genExpr(tree.selected, tree.selected.type);
2301 
2302         if (sym.kind == VAR && ((VarSymbol) sym).getConstValue() != null) {
2303             // We are seeing a variable that is constant but its selecting
2304             // expression is not.
2305             if ((sym.flags() & STATIC) != 0) {
2306                 if (!selectSuper && (ssym == null || ssym.kind != TYP))
2307                     base = base.load();
2308                 base.drop();
2309             } else {
2310                 base.load();
2311                 genNullCheck(tree.selected.pos());
2312             }
2313             result = items.
2314                 makeImmediateItem(sym.type, ((VarSymbol) sym).getConstValue());
2315         } else {
2316             if (isInvokeDynamic(sym)) {
2317                 result = items.makeDynamicItem(sym);
2318                 return;
2319             } else if (!accessSuper) {
2320                 sym = binaryQualifier(sym, tree.selected.type);
2321             }
2322             if ((sym.flags() & STATIC) != 0) {
2323                 if (!selectSuper && (ssym == null || ssym.kind != TYP))
2324                     base = base.load();
2325                 base.drop();
2326                 result = items.makeStaticItem(sym);
2327             } else {
2328                 base.load();
2329                 if (sym == syms.lengthVar) {
2330                     code.emitop0(arraylength);
2331                     result = items.makeStackItem(syms.intType);
2332                 } else {
2333                     result = items.
2334                         makeMemberItem(sym,
2335                                        (sym.flags() & PRIVATE) != 0 ||
2336                                        selectSuper || accessSuper);
2337                 }
2338             }
2339         }
2340     }
2341 
2342     public boolean isInvokeDynamic(Symbol sym) {
2343         return sym.kind == MTH && ((MethodSymbol)sym).isDynamic();
2344     }
2345 
2346     public void visitLiteral(JCLiteral tree) {
2347         if (tree.type.hasTag(BOT)) {
2348             code.emitop0(aconst_null);
2349             if (types.dimensions(pt) > 1) {
2350                 code.emitop2(checkcast, makeRef(tree.pos(), pt));
2351                 result = items.makeStackItem(pt);
2352             } else {
2353                 result = items.makeStackItem(tree.type);
2354             }
2355         }
2356         else
2357             result = items.makeImmediateItem(tree.type, tree.value);
2358     }
2359 
2360     public void visitLetExpr(LetExpr tree) {
2361         int limit = code.nextreg;
2362         genStats(tree.defs, env);
2363         result = genExpr(tree.expr, tree.expr.type).load();
2364         code.endScopes(limit);
2365     }
2366 
2367     private void generateReferencesToPrunedTree(ClassSymbol classSymbol, Pool pool) {
2368         List<JCTree> prunedInfo = lower.prunedTree.get(classSymbol);
2369         if (prunedInfo != null) {
2370             for (JCTree prunedTree: prunedInfo) {
2371                 prunedTree.accept(classReferenceVisitor);
2372             }
2373         }
2374     }
2375 
2376 /* ************************************************************************
2377  * main method
2378  *************************************************************************/
2379 
2380     /** Generate code for a class definition.
2381      *  @param env   The attribution environment that belongs to the
2382      *               outermost class containing this class definition.
2383      *               We need this for resolving some additional symbols.
2384      *  @param cdef  The tree representing the class definition.
2385      *  @return      True if code is generated with no errors.
2386      */
2387     public boolean genClass(Env<AttrContext> env, JCClassDecl cdef) {
2388         try {
2389             attrEnv = env;
2390             ClassSymbol c = cdef.sym;
2391             this.toplevel = env.toplevel;
2392             this.endPosTable = toplevel.endPositions;
2393             // If this is a class definition requiring Miranda methods,
2394             // add them.
2395             if (generateIproxies &&
2396                 (c.flags() & (INTERFACE|ABSTRACT)) == ABSTRACT
2397                 && !allowGenerics // no Miranda methods available with generics
2398                 )
2399                 implementInterfaceMethods(c);
2400             cdef.defs = normalizeDefs(cdef.defs, c);
2401             c.pool = pool;
2402             pool.reset();
2403             generateReferencesToPrunedTree(c, pool);
2404             Env<GenContext> localEnv =
2405                 new Env<GenContext>(cdef, new GenContext());
2406             localEnv.toplevel = env.toplevel;
2407             localEnv.enclClass = cdef;
2408             for (List<JCTree> l = cdef.defs; l.nonEmpty(); l = l.tail) {
2409                 genDef(l.head, localEnv);
2410             }
2411             if (pool.numEntries() > Pool.MAX_ENTRIES) {
2412                 log.error(cdef.pos(), "limit.pool");
2413                 nerrs++;
2414             }
2415             if (nerrs != 0) {
2416                 // if errors, discard code
2417                 for (List<JCTree> l = cdef.defs; l.nonEmpty(); l = l.tail) {
2418                     if (l.head.hasTag(METHODDEF))
2419                         ((JCMethodDecl) l.head).sym.code = null;
2420                 }
2421             }
2422             cdef.defs = List.nil(); // discard trees
2423             return nerrs == 0;
2424         } finally {
2425             // note: this method does NOT support recursion.
2426             attrEnv = null;
2427             this.env = null;
2428             toplevel = null;
2429             endPosTable = null;
2430             nerrs = 0;
2431         }
2432     }
2433 
2434 /* ************************************************************************
2435  * Auxiliary classes
2436  *************************************************************************/
2437 
2438     /** An abstract class for finalizer generation.
2439      */
2440     abstract class GenFinalizer {
2441         /** Generate code to clean up when unwinding. */
2442         abstract void gen();
2443 
2444         /** Generate code to clean up at last. */
2445         abstract void genLast();
2446 
2447         /** Does this finalizer have some nontrivial cleanup to perform? */
2448         boolean hasFinalizer() { return true; }
2449     }
2450 
2451     /** code generation contexts,
2452      *  to be used as type parameter for environments.
2453      */
2454     static class GenContext {
2455 
2456         /** A chain for all unresolved jumps that exit the current environment.
2457          */
2458         Chain exit = null;
2459 
2460         /** A chain for all unresolved jumps that continue in the
2461          *  current environment.
2462          */
2463         Chain cont = null;
2464 
2465         /** A closure that generates the finalizer of the current environment.
2466          *  Only set for Synchronized and Try contexts.
2467          */
2468         GenFinalizer finalize = null;
2469 
2470         /** Is this a switch statement?  If so, allocate registers
2471          * even when the variable declaration is unreachable.
2472          */
2473         boolean isSwitch = false;
2474 
2475         /** A list buffer containing all gaps in the finalizer range,
2476          *  where a catch all exception should not apply.
2477          */
2478         ListBuffer<Integer> gaps = null;
2479 
2480         /** Add given chain to exit chain.
2481          */
2482         void addExit(Chain c)  {
2483             exit = Code.mergeChains(c, exit);
2484         }
2485 
2486         /** Add given chain to cont chain.
2487          */
2488         void addCont(Chain c) {
2489             cont = Code.mergeChains(c, cont);
2490         }
2491     }
2492 }