1 /*
   2  * Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.tools.javac.jvm;
  27 
  28 import com.sun.tools.javac.tree.TreeInfo.PosKind;
  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.resources.CompilerProperties.Errors;
  43 import com.sun.tools.javac.tree.EndPosTable;
  44 import com.sun.tools.javac.tree.JCTree.*;
  45 
  46 import static com.sun.tools.javac.code.Flags.*;
  47 import static com.sun.tools.javac.code.Kinds.Kind.*;
  48 import static com.sun.tools.javac.code.TypeTag.*;
  49 import static com.sun.tools.javac.jvm.ByteCodes.*;
  50 import static com.sun.tools.javac.jvm.CRTFlags.*;
  51 import static com.sun.tools.javac.main.Option.*;
  52 import static com.sun.tools.javac.tree.JCTree.Tag.*;
  53 
  54 /** This pass maps flat Java (i.e. without inner classes) to bytecodes.
  55  *
  56  *  <p><b>This is NOT part of any supported API.
  57  *  If you write code that depends on this, you do so at your own risk.
  58  *  This code and its internal interfaces are subject to change or
  59  *  deletion without notice.</b>
  60  */
  61 public class Gen extends JCTree.Visitor {
  62     protected static final Context.Key<Gen> genKey = new Context.Key<>();
  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 Name accessDollar;
  72     private final Types types;
  73     private final Lower lower;
  74     private final Annotate annotate;
  75     private final StringConcat concat;
  76 
  77     /** Format of stackmap tables to be generated. */
  78     private final Code.StackMapFormat stackMap;
  79 
  80     /** A type that serves as the expected type for all method expressions.
  81      */
  82     private final Type methodType;
  83 
  84     /**
  85      * Are we presently traversing a let expression ? Yes if depth != 0
  86      */
  87     private int letExprDepth;
  88 
  89     public static Gen instance(Context context) {
  90         Gen instance = context.get(genKey);
  91         if (instance == null)
  92             instance = new Gen(context);
  93         return instance;
  94     }
  95 
  96     /** Constant pool, reset by genClass.
  97      */
  98     private final Pool pool;
  99 
 100     protected Gen(Context context) {
 101         context.put(genKey, this);
 102 
 103         names = Names.instance(context);
 104         log = Log.instance(context);
 105         syms = Symtab.instance(context);
 106         chk = Check.instance(context);
 107         rs = Resolve.instance(context);
 108         make = TreeMaker.instance(context);
 109         target = Target.instance(context);
 110         types = Types.instance(context);
 111         concat = StringConcat.instance(context);
 112 
 113         methodType = new MethodType(null, null, null, syms.methodClass);
 114         accessDollar = names.
 115             fromString("access" + target.syntheticNameChar());
 116         lower = Lower.instance(context);
 117 
 118         Options options = Options.instance(context);
 119         lineDebugInfo =
 120             options.isUnset(G_CUSTOM) ||
 121             options.isSet(G_CUSTOM, "lines");
 122         varDebugInfo =
 123             options.isUnset(G_CUSTOM)
 124             ? options.isSet(G)
 125             : options.isSet(G_CUSTOM, "vars");
 126         genCrt = options.isSet(XJCOV);
 127         debugCode = options.isSet("debug.code");
 128         allowBetterNullChecks = target.hasObjects();
 129         virtualizePrivateAccess = options.isSet("virtualizePrivateAccess");
 130         pool = new Pool(types);
 131 
 132         // ignore cldc because we cannot have both stackmap formats
 133         this.stackMap = StackMapFormat.JSR202;
 134         annotate = Annotate.instance(context);
 135     }
 136 
 137     /** Switches
 138      */
 139     private final boolean lineDebugInfo;
 140     private final boolean varDebugInfo;
 141     private final boolean genCrt;
 142     private final boolean debugCode;
 143     private final boolean allowBetterNullChecks;
 144     private boolean virtualizePrivateAccess;
 145 
 146     /** Code buffer, set by genMethod.
 147      */
 148     private Code code;
 149 
 150     /** Items structure, set by genMethod.
 151      */
 152     private Items items;
 153 
 154     /** Environment for symbol lookup, set by genClass
 155      */
 156     private Env<AttrContext> attrEnv;
 157 
 158     /** The top level tree.
 159      */
 160     private JCCompilationUnit toplevel;
 161 
 162     /** The number of code-gen errors in this class.
 163      */
 164     private int nerrs = 0;
 165 
 166     /** An object containing mappings of syntax trees to their
 167      *  ending source positions.
 168      */
 169     EndPosTable endPosTable;
 170 
 171     /** Generate code to load an integer constant.
 172      *  @param n     The integer to be loaded.
 173      */
 174     void loadIntConst(int n) {
 175         items.makeImmediateItem(syms.intType, n).load();
 176     }
 177 
 178     /** The opcode that loads a zero constant of a given type code.
 179      *  @param tc   The given type code (@see ByteCode).
 180      */
 181     public static int zero(int tc) {
 182         switch(tc) {
 183         case INTcode: case BYTEcode: case SHORTcode: case CHARcode:
 184             return iconst_0;
 185         case LONGcode:
 186             return lconst_0;
 187         case FLOATcode:
 188             return fconst_0;
 189         case DOUBLEcode:
 190             return dconst_0;
 191         default:
 192             throw new AssertionError("zero");
 193         }
 194     }
 195 
 196     /** The opcode that loads a one constant of a given type code.
 197      *  @param tc   The given type code (@see ByteCode).
 198      */
 199     public static int one(int tc) {
 200         return zero(tc) + 1;
 201     }
 202 
 203     /** Generate code to load -1 of the given type code (either int or long).
 204      *  @param tc   The given type code (@see ByteCode).
 205      */
 206     void emitMinusOne(int tc) {
 207         if (tc == LONGcode) {
 208             items.makeImmediateItem(syms.longType, Long.valueOf(-1)).load();
 209         } else {
 210             code.emitop0(iconst_m1);
 211         }
 212     }
 213 
 214     /** Construct a symbol to reflect the qualifying type that should
 215      *  appear in the byte code as per JLS 13.1.
 216      *
 217      *  For {@literal target >= 1.2}: Clone a method with the qualifier as owner (except
 218      *  for those cases where we need to work around VM bugs).
 219      *
 220      *  For {@literal target <= 1.1}: If qualified variable or method is defined in a
 221      *  non-accessible class, clone it with the qualifier class as owner.
 222      *
 223      *  @param sym    The accessed symbol
 224      *  @param site   The qualifier's type.
 225      */
 226     Symbol binaryQualifier(Symbol sym, Type site) {
 227 
 228         if (site.hasTag(ARRAY)) {
 229             if (sym == syms.lengthVar ||
 230                 sym.owner != syms.arrayClass)
 231                 return sym;
 232             // array clone can be qualified by the array type in later targets
 233             Symbol qualifier = new ClassSymbol(Flags.PUBLIC, site.tsym.name,
 234                                                site, syms.noSymbol);
 235             return sym.clone(qualifier);
 236         }
 237 
 238         if (sym.owner == site.tsym ||
 239             (sym.flags() & (STATIC | SYNTHETIC)) == (STATIC | SYNTHETIC)) {
 240             return sym;
 241         }
 242 
 243         // leave alone methods inherited from Object
 244         // JLS 13.1.
 245         if (sym.owner == syms.objectType.tsym)
 246             return sym;
 247 
 248         return sym.clone(site.tsym);
 249     }
 250 
 251     /** Insert a reference to given type in the constant pool,
 252      *  checking for an array with too many dimensions;
 253      *  return the reference's index.
 254      *  @param type   The type for which a reference is inserted.
 255      */
 256     int makeRef(DiagnosticPosition pos, Type type) {
 257         checkDimension(pos, type);
 258         if (type.isAnnotated()) {
 259             return pool.put((Object)type);
 260         } else {
 261             return pool.put(type.hasTag(CLASS) ? (Object)type.tsym : (Object)type);
 262         }
 263     }
 264 
 265     /** Check if the given type is an array with too many dimensions.
 266      */
 267     private void checkDimension(DiagnosticPosition pos, Type t) {
 268         switch (t.getTag()) {
 269         case METHOD:
 270             checkDimension(pos, t.getReturnType());
 271             for (List<Type> args = t.getParameterTypes(); args.nonEmpty(); args = args.tail)
 272                 checkDimension(pos, args.head);
 273             break;
 274         case ARRAY:
 275             if (types.dimensions(t) > ClassFile.MAX_DIMENSIONS) {
 276                 log.error(pos, Errors.LimitDimensions);
 277                 nerrs++;
 278             }
 279             break;
 280         default:
 281             break;
 282         }
 283     }
 284 
 285     /** Create a tempory variable.
 286      *  @param type   The variable's type.
 287      */
 288     LocalItem makeTemp(Type type) {
 289         VarSymbol v = new VarSymbol(Flags.SYNTHETIC,
 290                                     names.empty,
 291                                     type,
 292                                     env.enclMethod.sym);
 293         code.newLocal(v);
 294         return items.makeLocalItem(v);
 295     }
 296 
 297     /** Generate code to call a non-private method or constructor.
 298      *  @param pos         Position to be used for error reporting.
 299      *  @param site        The type of which the method is a member.
 300      *  @param name        The method's name.
 301      *  @param argtypes    The method's argument types.
 302      *  @param isStatic    A flag that indicates whether we call a
 303      *                     static or instance method.
 304      */
 305     void callMethod(DiagnosticPosition pos,
 306                     Type site, Name name, List<Type> argtypes,
 307                     boolean isStatic) {
 308         Symbol msym = rs.
 309             resolveInternalMethod(pos, attrEnv, site, name, argtypes, null);
 310         if (isStatic) items.makeStaticItem(msym).invoke();
 311         else items.makeMemberItem(msym, name == names.init).invoke();
 312     }
 313 
 314     /** Is the given method definition an access method
 315      *  resulting from a qualified super? This is signified by an odd
 316      *  access code.
 317      */
 318     private boolean isAccessSuper(JCMethodDecl enclMethod) {
 319         return
 320             (enclMethod.mods.flags & SYNTHETIC) != 0 &&
 321             isOddAccessName(enclMethod.name);
 322     }
 323 
 324     /** Does given name start with "access$" and end in an odd digit?
 325      */
 326     private boolean isOddAccessName(Name name) {
 327         return
 328             name.startsWith(accessDollar) &&
 329             (name.getByteAt(name.getByteLength() - 1) & 1) == 1;
 330     }
 331 
 332 /* ************************************************************************
 333  * Non-local exits
 334  *************************************************************************/
 335 
 336     /** Generate code to invoke the finalizer associated with given
 337      *  environment.
 338      *  Any calls to finalizers are appended to the environments `cont' chain.
 339      *  Mark beginning of gap in catch all range for finalizer.
 340      */
 341     void genFinalizer(Env<GenContext> env) {
 342         if (code.isAlive() && env.info.finalize != null)
 343             env.info.finalize.gen();
 344     }
 345 
 346     /** Generate code to call all finalizers of structures aborted by
 347      *  a non-local
 348      *  exit.  Return target environment of the non-local exit.
 349      *  @param target      The tree representing the structure that's aborted
 350      *  @param env         The environment current at the non-local exit.
 351      */
 352     Env<GenContext> unwind(JCTree target, Env<GenContext> env) {
 353         Env<GenContext> env1 = env;
 354         while (true) {
 355             genFinalizer(env1);
 356             if (env1.tree == target) break;
 357             env1 = env1.next;
 358         }
 359         return env1;
 360     }
 361 
 362     /** Mark end of gap in catch-all range for finalizer.
 363      *  @param env   the environment which might contain the finalizer
 364      *               (if it does, env.info.gaps != null).
 365      */
 366     void endFinalizerGap(Env<GenContext> env) {
 367         if (env.info.gaps != null && env.info.gaps.length() % 2 == 1)
 368             env.info.gaps.append(code.curCP());
 369     }
 370 
 371     /** Mark end of all gaps in catch-all ranges for finalizers of environments
 372      *  lying between, and including to two environments.
 373      *  @param from    the most deeply nested environment to mark
 374      *  @param to      the least deeply nested environment to mark
 375      */
 376     void endFinalizerGaps(Env<GenContext> from, Env<GenContext> to) {
 377         Env<GenContext> last = null;
 378         while (last != to) {
 379             endFinalizerGap(from);
 380             last = from;
 381             from = from.next;
 382         }
 383     }
 384 
 385     /** Do any of the structures aborted by a non-local exit have
 386      *  finalizers that require an empty stack?
 387      *  @param target      The tree representing the structure that's aborted
 388      *  @param env         The environment current at the non-local exit.
 389      */
 390     boolean hasFinally(JCTree target, Env<GenContext> env) {
 391         while (env.tree != target) {
 392             if (env.tree.hasTag(TRY) && env.info.finalize.hasFinalizer())
 393                 return true;
 394             env = env.next;
 395         }
 396         return false;
 397     }
 398 
 399 /* ************************************************************************
 400  * Normalizing class-members.
 401  *************************************************************************/
 402 
 403     /** Distribute member initializer code into constructors and {@code <clinit>}
 404      *  method.
 405      *  @param defs         The list of class member declarations.
 406      *  @param c            The enclosing class.
 407      */
 408     List<JCTree> normalizeDefs(List<JCTree> defs, ClassSymbol c) {
 409         ListBuffer<JCStatement> initCode = new ListBuffer<>();
 410         ListBuffer<Attribute.TypeCompound> initTAs = new ListBuffer<>();
 411         ListBuffer<JCStatement> clinitCode = new ListBuffer<>();
 412         ListBuffer<Attribute.TypeCompound> clinitTAs = new ListBuffer<>();
 413         ListBuffer<JCTree> methodDefs = new ListBuffer<>();
 414         // Sort definitions into three listbuffers:
 415         //  - initCode for instance initializers
 416         //  - clinitCode for class initializers
 417         //  - methodDefs for method definitions
 418         for (List<JCTree> l = defs; l.nonEmpty(); l = l.tail) {
 419             JCTree def = l.head;
 420             switch (def.getTag()) {
 421             case BLOCK:
 422                 JCBlock block = (JCBlock)def;
 423                 if ((block.flags & STATIC) != 0)
 424                     clinitCode.append(block);
 425                 else if ((block.flags & SYNTHETIC) == 0)
 426                     initCode.append(block);
 427                 break;
 428             case METHODDEF:
 429                 methodDefs.append(def);
 430                 break;
 431             case VARDEF:
 432                 JCVariableDecl vdef = (JCVariableDecl) def;
 433                 VarSymbol sym = vdef.sym;
 434                 checkDimension(vdef.pos(), sym.type);
 435                 if (vdef.init != null) {
 436                     if ((sym.flags() & STATIC) == 0) {
 437                         // Always initialize instance variables.
 438                         JCStatement init = make.at(vdef.pos()).
 439                             Assignment(sym, vdef.init);
 440                         initCode.append(init);
 441                         endPosTable.replaceTree(vdef, init);
 442                         initTAs.addAll(getAndRemoveNonFieldTAs(sym));
 443                     } else if (sym.getConstValue() == null) {
 444                         // Initialize class (static) variables only if
 445                         // they are not compile-time constants.
 446                         JCStatement init = make.at(vdef.pos).
 447                             Assignment(sym, vdef.init);
 448                         clinitCode.append(init);
 449                         endPosTable.replaceTree(vdef, init);
 450                         clinitTAs.addAll(getAndRemoveNonFieldTAs(sym));
 451                     } else {
 452                         checkStringConstant(vdef.init.pos(), sym.getConstValue());
 453                         /* if the init contains a reference to an external class, add it to the
 454                          * constant's pool
 455                          */
 456                         vdef.init.accept(classReferenceVisitor);
 457                     }
 458                 }
 459                 break;
 460             default:
 461                 Assert.error();
 462             }
 463         }
 464         // Insert any instance initializers into all constructors.
 465         if (initCode.length() != 0) {
 466             List<JCStatement> inits = initCode.toList();
 467             initTAs.addAll(c.getInitTypeAttributes());
 468             List<Attribute.TypeCompound> initTAlist = initTAs.toList();
 469             for (JCTree t : methodDefs) {
 470                 normalizeMethod((JCMethodDecl)t, inits, initTAlist);
 471             }
 472         }
 473         // If there are class initializers, create a <clinit> method
 474         // that contains them as its body.
 475         if (clinitCode.length() != 0) {
 476             MethodSymbol clinit = new MethodSymbol(
 477                 STATIC | (c.flags() & STRICTFP),
 478                 names.clinit,
 479                 new MethodType(
 480                     List.nil(), syms.voidType,
 481                     List.nil(), syms.methodClass),
 482                 c);
 483             c.members().enter(clinit);
 484             List<JCStatement> clinitStats = clinitCode.toList();
 485             JCBlock block = make.at(clinitStats.head.pos()).Block(0, clinitStats);
 486             block.endpos = TreeInfo.endPos(clinitStats.last());
 487             methodDefs.append(make.MethodDef(clinit, block));
 488 
 489             if (!clinitTAs.isEmpty())
 490                 clinit.appendUniqueTypeAttributes(clinitTAs.toList());
 491             if (!c.getClassInitTypeAttributes().isEmpty())
 492                 clinit.appendUniqueTypeAttributes(c.getClassInitTypeAttributes());
 493         }
 494         // Return all method definitions.
 495         return methodDefs.toList();
 496     }
 497 
 498     private List<Attribute.TypeCompound> getAndRemoveNonFieldTAs(VarSymbol sym) {
 499         List<TypeCompound> tas = sym.getRawTypeAttributes();
 500         ListBuffer<Attribute.TypeCompound> fieldTAs = new ListBuffer<>();
 501         ListBuffer<Attribute.TypeCompound> nonfieldTAs = new ListBuffer<>();
 502         for (TypeCompound ta : tas) {
 503             Assert.check(ta.getPosition().type != TargetType.UNKNOWN);
 504             if (ta.getPosition().type == TargetType.FIELD) {
 505                 fieldTAs.add(ta);
 506             } else {
 507                 nonfieldTAs.add(ta);
 508             }
 509         }
 510         sym.setTypeAttributes(fieldTAs.toList());
 511         return nonfieldTAs.toList();
 512     }
 513 
 514     /** Check a constant value and report if it is a string that is
 515      *  too large.
 516      */
 517     private void checkStringConstant(DiagnosticPosition pos, Object constValue) {
 518         if (nerrs != 0 || // only complain about a long string once
 519             constValue == null ||
 520             !(constValue instanceof String) ||
 521             ((String)constValue).length() < Pool.MAX_STRING_LENGTH)
 522             return;
 523         log.error(pos, Errors.LimitString);
 524         nerrs++;
 525     }
 526 
 527     /** Insert instance initializer code into initial constructor.
 528      *  @param md        The tree potentially representing a
 529      *                   constructor's definition.
 530      *  @param initCode  The list of instance initializer statements.
 531      *  @param initTAs  Type annotations from the initializer expression.
 532      */
 533     void normalizeMethod(JCMethodDecl md, List<JCStatement> initCode, List<TypeCompound> initTAs) {
 534         if (md.name == names.init && TreeInfo.isInitialConstructor(md)) {
 535             // We are seeing a constructor that does not call another
 536             // constructor of the same class.
 537             List<JCStatement> stats = md.body.stats;
 538             ListBuffer<JCStatement> newstats = new ListBuffer<>();
 539 
 540             if (stats.nonEmpty()) {
 541                 // Copy initializers of synthetic variables generated in
 542                 // the translation of inner classes.
 543                 while (TreeInfo.isSyntheticInit(stats.head)) {
 544                     newstats.append(stats.head);
 545                     stats = stats.tail;
 546                 }
 547                 // Copy superclass constructor call
 548                 newstats.append(stats.head);
 549                 stats = stats.tail;
 550                 // Copy remaining synthetic initializers.
 551                 while (stats.nonEmpty() &&
 552                        TreeInfo.isSyntheticInit(stats.head)) {
 553                     newstats.append(stats.head);
 554                     stats = stats.tail;
 555                 }
 556                 // Now insert the initializer code.
 557                 newstats.appendList(initCode);
 558                 // And copy all remaining statements.
 559                 while (stats.nonEmpty()) {
 560                     newstats.append(stats.head);
 561                     stats = stats.tail;
 562                 }
 563             }
 564             md.body.stats = newstats.toList();
 565             if (md.body.endpos == Position.NOPOS)
 566                 md.body.endpos = TreeInfo.endPos(md.body.stats.last());
 567 
 568             md.sym.appendUniqueTypeAttributes(initTAs);
 569         }
 570     }
 571 
 572 /* ************************************************************************
 573  * Traversal methods
 574  *************************************************************************/
 575 
 576     /** Visitor argument: The current environment.
 577      */
 578     Env<GenContext> env;
 579 
 580     /** Visitor argument: The expected type (prototype).
 581      */
 582     Type pt;
 583 
 584     /** Visitor result: The item representing the computed value.
 585      */
 586     Item result;
 587 
 588     /** Visitor method: generate code for a definition, catching and reporting
 589      *  any completion failures.
 590      *  @param tree    The definition to be visited.
 591      *  @param env     The environment current at the definition.
 592      */
 593     public void genDef(JCTree tree, Env<GenContext> env) {
 594         Env<GenContext> prevEnv = this.env;
 595         try {
 596             this.env = env;
 597             tree.accept(this);
 598         } catch (CompletionFailure ex) {
 599             chk.completionError(tree.pos(), ex);
 600         } finally {
 601             this.env = prevEnv;
 602         }
 603     }
 604 
 605     /** Derived visitor method: check whether CharacterRangeTable
 606      *  should be emitted, if so, put a new entry into CRTable
 607      *  and call method to generate bytecode.
 608      *  If not, just call method to generate bytecode.
 609      *  @see    #genStat(JCTree, Env)
 610      *
 611      *  @param  tree     The tree to be visited.
 612      *  @param  env      The environment to use.
 613      *  @param  crtFlags The CharacterRangeTable flags
 614      *                   indicating type of the entry.
 615      */
 616     public void genStat(JCTree tree, Env<GenContext> env, int crtFlags) {
 617         if (!genCrt) {
 618             genStat(tree, env);
 619             return;
 620         }
 621         int startpc = code.curCP();
 622         genStat(tree, env);
 623         if (tree.hasTag(Tag.BLOCK)) crtFlags |= CRT_BLOCK;
 624         code.crt.put(tree, crtFlags, startpc, code.curCP());
 625     }
 626 
 627     /** Derived visitor method: generate code for a statement.
 628      */
 629     public void genStat(JCTree tree, Env<GenContext> env) {
 630         if (code.isAlive()) {
 631             code.statBegin(tree.pos);
 632             genDef(tree, env);
 633         } else if (env.info.isSwitch && tree.hasTag(VARDEF)) {
 634             // variables whose declarations are in a switch
 635             // can be used even if the decl is unreachable.
 636             code.newLocal(((JCVariableDecl) tree).sym);
 637         }
 638     }
 639 
 640     /** Derived visitor method: check whether CharacterRangeTable
 641      *  should be emitted, if so, put a new entry into CRTable
 642      *  and call method to generate bytecode.
 643      *  If not, just call method to generate bytecode.
 644      *  @see    #genStats(List, Env)
 645      *
 646      *  @param  trees    The list of trees to be visited.
 647      *  @param  env      The environment to use.
 648      *  @param  crtFlags The CharacterRangeTable flags
 649      *                   indicating type of the entry.
 650      */
 651     public void genStats(List<JCStatement> trees, Env<GenContext> env, int crtFlags) {
 652         if (!genCrt) {
 653             genStats(trees, env);
 654             return;
 655         }
 656         if (trees.length() == 1) {        // mark one statement with the flags
 657             genStat(trees.head, env, crtFlags | CRT_STATEMENT);
 658         } else {
 659             int startpc = code.curCP();
 660             genStats(trees, env);
 661             code.crt.put(trees, crtFlags, startpc, code.curCP());
 662         }
 663     }
 664 
 665     /** Derived visitor method: generate code for a list of statements.
 666      */
 667     public void genStats(List<? extends JCTree> trees, Env<GenContext> env) {
 668         for (List<? extends JCTree> l = trees; l.nonEmpty(); l = l.tail)
 669             genStat(l.head, env, CRT_STATEMENT);
 670     }
 671 
 672     /** Derived visitor method: check whether CharacterRangeTable
 673      *  should be emitted, if so, put a new entry into CRTable
 674      *  and call method to generate bytecode.
 675      *  If not, just call method to generate bytecode.
 676      *  @see    #genCond(JCTree,boolean)
 677      *
 678      *  @param  tree     The tree to be visited.
 679      *  @param  crtFlags The CharacterRangeTable flags
 680      *                   indicating type of the entry.
 681      */
 682     public CondItem genCond(JCTree tree, int crtFlags) {
 683         if (!genCrt) return genCond(tree, false);
 684         int startpc = code.curCP();
 685         CondItem item = genCond(tree, (crtFlags & CRT_FLOW_CONTROLLER) != 0);
 686         code.crt.put(tree, crtFlags, startpc, code.curCP());
 687         return item;
 688     }
 689 
 690     /** Derived visitor method: generate code for a boolean
 691      *  expression in a control-flow context.
 692      *  @param _tree         The expression to be visited.
 693      *  @param markBranches The flag to indicate that the condition is
 694      *                      a flow controller so produced conditions
 695      *                      should contain a proper tree to generate
 696      *                      CharacterRangeTable branches for them.
 697      */
 698     public CondItem genCond(JCTree _tree, boolean markBranches) {
 699         JCTree inner_tree = TreeInfo.skipParens(_tree);
 700         if (inner_tree.hasTag(CONDEXPR)) {
 701             JCConditional tree = (JCConditional)inner_tree;
 702             CondItem cond = genCond(tree.cond, CRT_FLOW_CONTROLLER);
 703             if (cond.isTrue()) {
 704                 code.resolve(cond.trueJumps);
 705                 CondItem result = genCond(tree.truepart, CRT_FLOW_TARGET);
 706                 if (markBranches) result.tree = tree.truepart;
 707                 return result;
 708             }
 709             if (cond.isFalse()) {
 710                 code.resolve(cond.falseJumps);
 711                 CondItem result = genCond(tree.falsepart, CRT_FLOW_TARGET);
 712                 if (markBranches) result.tree = tree.falsepart;
 713                 return result;
 714             }
 715             Chain secondJumps = cond.jumpFalse();
 716             code.resolve(cond.trueJumps);
 717             CondItem first = genCond(tree.truepart, CRT_FLOW_TARGET);
 718             if (markBranches) first.tree = tree.truepart;
 719             Chain falseJumps = first.jumpFalse();
 720             code.resolve(first.trueJumps);
 721             Chain trueJumps = code.branch(goto_);
 722             code.resolve(secondJumps);
 723             CondItem second = genCond(tree.falsepart, CRT_FLOW_TARGET);
 724             CondItem result = items.makeCondItem(second.opcode,
 725                                       Code.mergeChains(trueJumps, second.trueJumps),
 726                                       Code.mergeChains(falseJumps, second.falseJumps));
 727             if (markBranches) result.tree = tree.falsepart;
 728             return result;
 729         } else {
 730             CondItem result = genExpr(_tree, syms.booleanType).mkCond();
 731             if (markBranches) result.tree = _tree;
 732             return result;
 733         }
 734     }
 735 
 736     public Code getCode() {
 737         return code;
 738     }
 739 
 740     public Items getItems() {
 741         return items;
 742     }
 743 
 744     public Env<AttrContext> getAttrEnv() {
 745         return attrEnv;
 746     }
 747 
 748     /** Visitor class for expressions which might be constant expressions.
 749      *  This class is a subset of TreeScanner. Intended to visit trees pruned by
 750      *  Lower as long as constant expressions looking for references to any
 751      *  ClassSymbol. Any such reference will be added to the constant pool so
 752      *  automated tools can detect class dependencies better.
 753      */
 754     class ClassReferenceVisitor extends JCTree.Visitor {
 755 
 756         @Override
 757         public void visitTree(JCTree tree) {}
 758 
 759         @Override
 760         public void visitBinary(JCBinary tree) {
 761             tree.lhs.accept(this);
 762             tree.rhs.accept(this);
 763         }
 764 
 765         @Override
 766         public void visitSelect(JCFieldAccess tree) {
 767             if (tree.selected.type.hasTag(CLASS)) {
 768                 makeRef(tree.selected.pos(), tree.selected.type);
 769             }
 770         }
 771 
 772         @Override
 773         public void visitIdent(JCIdent tree) {
 774             if (tree.sym.owner instanceof ClassSymbol) {
 775                 pool.put(tree.sym.owner);
 776             }
 777         }
 778 
 779         @Override
 780         public void visitConditional(JCConditional tree) {
 781             tree.cond.accept(this);
 782             tree.truepart.accept(this);
 783             tree.falsepart.accept(this);
 784         }
 785 
 786         @Override
 787         public void visitUnary(JCUnary tree) {
 788             tree.arg.accept(this);
 789         }
 790 
 791         @Override
 792         public void visitParens(JCParens tree) {
 793             tree.expr.accept(this);
 794         }
 795 
 796         @Override
 797         public void visitTypeCast(JCTypeCast tree) {
 798             tree.expr.accept(this);
 799         }
 800     }
 801 
 802     private ClassReferenceVisitor classReferenceVisitor = new ClassReferenceVisitor();
 803 
 804     /** Visitor method: generate code for an expression, catching and reporting
 805      *  any completion failures.
 806      *  @param tree    The expression to be visited.
 807      *  @param pt      The expression's expected type (proto-type).
 808      */
 809     public Item genExpr(JCTree tree, Type pt) {
 810         Type prevPt = this.pt;
 811         try {
 812             if (tree.type.constValue() != null) {
 813                 // Short circuit any expressions which are constants
 814                 tree.accept(classReferenceVisitor);
 815                 checkStringConstant(tree.pos(), tree.type.constValue());
 816                 result = items.makeImmediateItem(tree.type, tree.type.constValue());
 817             } else {
 818                 this.pt = pt;
 819                 tree.accept(this);
 820             }
 821             return result.coerce(pt);
 822         } catch (CompletionFailure ex) {
 823             chk.completionError(tree.pos(), ex);
 824             code.state.stacksize = 1;
 825             return items.makeStackItem(pt);
 826         } finally {
 827             this.pt = prevPt;
 828         }
 829     }
 830 
 831     /** Derived visitor method: generate code for a list of method arguments.
 832      *  @param trees    The argument expressions to be visited.
 833      *  @param pts      The expression's expected types (i.e. the formal parameter
 834      *                  types of the invoked method).
 835      */
 836     public void genArgs(List<JCExpression> trees, List<Type> pts) {
 837         for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail) {
 838             genExpr(l.head, pts.head).load();
 839             pts = pts.tail;
 840         }
 841         // require lists be of same length
 842         Assert.check(pts.isEmpty());
 843     }
 844 
 845 /* ************************************************************************
 846  * Visitor methods for statements and definitions
 847  *************************************************************************/
 848 
 849     /** Thrown when the byte code size exceeds limit.
 850      */
 851     public static class CodeSizeOverflow extends RuntimeException {
 852         private static final long serialVersionUID = 0;
 853         public CodeSizeOverflow() {}
 854     }
 855 
 856     public void visitMethodDef(JCMethodDecl tree) {
 857         // Create a new local environment that points pack at method
 858         // definition.
 859         Env<GenContext> localEnv = env.dup(tree);
 860         localEnv.enclMethod = tree;
 861         // The expected type of every return statement in this method
 862         // is the method's return type.
 863         this.pt = tree.sym.erasure(types).getReturnType();
 864 
 865         checkDimension(tree.pos(), tree.sym.erasure(types));
 866         genMethod(tree, localEnv, false);
 867     }
 868 //where
 869         /** Generate code for a method.
 870          *  @param tree     The tree representing the method definition.
 871          *  @param env      The environment current for the method body.
 872          *  @param fatcode  A flag that indicates whether all jumps are
 873          *                  within 32K.  We first invoke this method under
 874          *                  the assumption that fatcode == false, i.e. all
 875          *                  jumps are within 32K.  If this fails, fatcode
 876          *                  is set to true and we try again.
 877          */
 878         void genMethod(JCMethodDecl tree, Env<GenContext> env, boolean fatcode) {
 879             MethodSymbol meth = tree.sym;
 880             int extras = 0;
 881             // Count up extra parameters
 882             if (meth.isConstructor()) {
 883                 extras++;
 884                 if (meth.enclClass().isInner() &&
 885                     !meth.enclClass().isStatic()) {
 886                     extras++;
 887                 }
 888             } else if ((tree.mods.flags & STATIC) == 0) {
 889                 extras++;
 890             }
 891             //      System.err.println("Generating " + meth + " in " + meth.owner); //DEBUG
 892             if (Code.width(types.erasure(env.enclMethod.sym.type).getParameterTypes()) + extras >
 893                 ClassFile.MAX_PARAMETERS) {
 894                 log.error(tree.pos(), Errors.LimitParameters);
 895                 nerrs++;
 896             }
 897 
 898             else if (tree.body != null) {
 899                 // Create a new code structure and initialize it.
 900                 int startpcCrt = initCode(tree, env, fatcode);
 901 
 902                 try {
 903                     genStat(tree.body, env);
 904                 } catch (CodeSizeOverflow e) {
 905                     // Failed due to code limit, try again with jsr/ret
 906                     startpcCrt = initCode(tree, env, fatcode);
 907                     genStat(tree.body, env);
 908                 }
 909 
 910                 if (code.state.stacksize != 0) {
 911                     log.error(tree.body.pos(), Errors.StackSimError(tree.sym));
 912                     throw new AssertionError();
 913                 }
 914 
 915                 // If last statement could complete normally, insert a
 916                 // return at the end.
 917                 if (code.isAlive()) {
 918                     code.statBegin(TreeInfo.endPos(tree.body));
 919                     if (env.enclMethod == null ||
 920                         env.enclMethod.sym.type.getReturnType().hasTag(VOID)) {
 921                         code.emitop0(return_);
 922                     } else {
 923                         // sometime dead code seems alive (4415991);
 924                         // generate a small loop instead
 925                         int startpc = code.entryPoint();
 926                         CondItem c = items.makeCondItem(goto_);
 927                         code.resolve(c.jumpTrue(), startpc);
 928                     }
 929                 }
 930                 if (genCrt)
 931                     code.crt.put(tree.body,
 932                                  CRT_BLOCK,
 933                                  startpcCrt,
 934                                  code.curCP());
 935 
 936                 code.endScopes(0);
 937 
 938                 // If we exceeded limits, panic
 939                 if (code.checkLimits(tree.pos(), log)) {
 940                     nerrs++;
 941                     return;
 942                 }
 943 
 944                 // If we generated short code but got a long jump, do it again
 945                 // with fatCode = true.
 946                 if (!fatcode && code.fatcode) genMethod(tree, env, true);
 947 
 948                 // Clean up
 949                 if(stackMap == StackMapFormat.JSR202) {
 950                     code.lastFrame = null;
 951                     code.frameBeforeLast = null;
 952                 }
 953 
 954                 // Compress exception table
 955                 code.compressCatchTable();
 956 
 957                 // Fill in type annotation positions for exception parameters
 958                 code.fillExceptionParameterPositions();
 959             }
 960         }
 961 
 962         private int initCode(JCMethodDecl tree, Env<GenContext> env, boolean fatcode) {
 963             MethodSymbol meth = tree.sym;
 964 
 965             // Create a new code structure.
 966             meth.code = code = new Code(meth,
 967                                         fatcode,
 968                                         lineDebugInfo ? toplevel.lineMap : null,
 969                                         varDebugInfo,
 970                                         stackMap,
 971                                         debugCode,
 972                                         genCrt ? new CRTable(tree, env.toplevel.endPositions)
 973                                                : null,
 974                                         syms,
 975                                         types,
 976                                         pool);
 977             items = new Items(pool, code, syms, types);
 978             if (code.debugCode) {
 979                 System.err.println(meth + " for body " + tree);
 980             }
 981 
 982             // If method is not static, create a new local variable address
 983             // for `this'.
 984             if ((tree.mods.flags & STATIC) == 0) {
 985                 Type selfType = meth.owner.type;
 986                 if (meth.isConstructor() && selfType != syms.objectType)
 987                     selfType = UninitializedType.uninitializedThis(selfType);
 988                 code.setDefined(
 989                         code.newLocal(
 990                             new VarSymbol(FINAL, names._this, selfType, meth.owner)));
 991             }
 992 
 993             // Mark all parameters as defined from the beginning of
 994             // the method.
 995             for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) {
 996                 checkDimension(l.head.pos(), l.head.sym.type);
 997                 code.setDefined(code.newLocal(l.head.sym));
 998             }
 999 
1000             // Get ready to generate code for method body.
1001             int startpcCrt = genCrt ? code.curCP() : 0;
1002             code.entryPoint();
1003 
1004             // Suppress initial stackmap
1005             code.pendingStackMap = false;
1006 
1007             return startpcCrt;
1008         }
1009 
1010     public void visitVarDef(JCVariableDecl tree) {
1011         VarSymbol v = tree.sym;
1012         code.newLocal(v);
1013         if (tree.init != null) {
1014             checkStringConstant(tree.init.pos(), v.getConstValue());
1015             if (v.getConstValue() == null || varDebugInfo) {
1016                 Assert.check(letExprDepth != 0 || code.state.stacksize == 0);
1017                 genExpr(tree.init, v.erasure(types)).load();
1018                 items.makeLocalItem(v).store();
1019                 Assert.check(letExprDepth != 0 || code.state.stacksize == 0);
1020             }
1021         }
1022         checkDimension(tree.pos(), v.type);
1023     }
1024 
1025     public void visitSkip(JCSkip tree) {
1026     }
1027 
1028     public void visitBlock(JCBlock tree) {
1029         int limit = code.nextreg;
1030         Env<GenContext> localEnv = env.dup(tree, new GenContext());
1031         genStats(tree.stats, localEnv);
1032         // End the scope of all block-local variables in variable info.
1033         if (!env.tree.hasTag(METHODDEF)) {
1034             code.statBegin(tree.endpos);
1035             code.endScopes(limit);
1036             code.pendingStatPos = Position.NOPOS;
1037         }
1038     }
1039 
1040     public void visitDoLoop(JCDoWhileLoop tree) {
1041         genLoop(tree, tree.body, tree.cond, List.nil(), false);
1042     }
1043 
1044     public void visitWhileLoop(JCWhileLoop tree) {
1045         genLoop(tree, tree.body, tree.cond, List.nil(), true);
1046     }
1047 
1048     public void visitForLoop(JCForLoop tree) {
1049         int limit = code.nextreg;
1050         genStats(tree.init, env);
1051         genLoop(tree, tree.body, tree.cond, tree.step, true);
1052         code.endScopes(limit);
1053     }
1054     //where
1055         /** Generate code for a loop.
1056          *  @param loop       The tree representing the loop.
1057          *  @param body       The loop's body.
1058          *  @param cond       The loop's controling condition.
1059          *  @param step       "Step" statements to be inserted at end of
1060          *                    each iteration.
1061          *  @param testFirst  True if the loop test belongs before the body.
1062          */
1063         private void genLoop(JCStatement loop,
1064                              JCStatement body,
1065                              JCExpression cond,
1066                              List<JCExpressionStatement> step,
1067                              boolean testFirst) {
1068             Env<GenContext> loopEnv = env.dup(loop, new GenContext());
1069             int startpc = code.entryPoint();
1070             if (testFirst) { //while or for loop
1071                 CondItem c;
1072                 if (cond != null) {
1073                     code.statBegin(cond.pos);
1074                     Assert.check(code.state.stacksize == 0);
1075                     c = genCond(TreeInfo.skipParens(cond), CRT_FLOW_CONTROLLER);
1076                 } else {
1077                     c = items.makeCondItem(goto_);
1078                 }
1079                 Chain loopDone = c.jumpFalse();
1080                 code.resolve(c.trueJumps);
1081                 Assert.check(code.state.stacksize == 0);
1082                 genStat(body, loopEnv, CRT_STATEMENT | CRT_FLOW_TARGET);
1083                 code.resolve(loopEnv.info.cont);
1084                 genStats(step, loopEnv);
1085                 code.resolve(code.branch(goto_), startpc);
1086                 code.resolve(loopDone);
1087             } else {
1088                 genStat(body, loopEnv, CRT_STATEMENT | CRT_FLOW_TARGET);
1089                 code.resolve(loopEnv.info.cont);
1090                 genStats(step, loopEnv);
1091                 if (code.isAlive()) {
1092                     CondItem c;
1093                     if (cond != null) {
1094                         code.statBegin(cond.pos);
1095                         Assert.check(code.state.stacksize == 0);
1096                         c = genCond(TreeInfo.skipParens(cond), CRT_FLOW_CONTROLLER);
1097                     } else {
1098                         c = items.makeCondItem(goto_);
1099                     }
1100                     code.resolve(c.jumpTrue(), startpc);
1101                     Assert.check(code.state.stacksize == 0);
1102                     code.resolve(c.falseJumps);
1103                 }
1104             }
1105             Chain exit = loopEnv.info.exit;
1106             if (exit != null) {
1107                 code.resolve(exit);
1108                 exit.state.defined.excludeFrom(code.nextreg);
1109             }
1110         }
1111 
1112     public void visitForeachLoop(JCEnhancedForLoop tree) {
1113         throw new AssertionError(); // should have been removed by Lower.
1114     }
1115 
1116     public void visitLabelled(JCLabeledStatement tree) {
1117         Env<GenContext> localEnv = env.dup(tree, new GenContext());
1118         genStat(tree.body, localEnv, CRT_STATEMENT);
1119         Chain exit = localEnv.info.exit;
1120         if (exit != null) {
1121             code.resolve(exit);
1122             exit.state.defined.excludeFrom(code.nextreg);
1123         }
1124     }
1125 
1126     public void visitSwitch(JCSwitch tree) {
1127         int limit = code.nextreg;
1128         Assert.check(!tree.selector.type.hasTag(CLASS));
1129         int startpcCrt = genCrt ? code.curCP() : 0;
1130         Assert.check(code.state.stacksize == 0);
1131         Item sel = genExpr(tree.selector, syms.intType);
1132         List<JCCase> cases = tree.cases;
1133         if (cases.isEmpty()) {
1134             // We are seeing:  switch <sel> {}
1135             sel.load().drop();
1136             if (genCrt)
1137                 code.crt.put(TreeInfo.skipParens(tree.selector),
1138                              CRT_FLOW_CONTROLLER, startpcCrt, code.curCP());
1139         } else {
1140             // We are seeing a nonempty switch.
1141             sel.load();
1142             if (genCrt)
1143                 code.crt.put(TreeInfo.skipParens(tree.selector),
1144                              CRT_FLOW_CONTROLLER, startpcCrt, code.curCP());
1145             Env<GenContext> switchEnv = env.dup(tree, new GenContext());
1146             switchEnv.info.isSwitch = true;
1147 
1148             // Compute number of labels and minimum and maximum label values.
1149             // For each case, store its label in an array.
1150             int lo = Integer.MAX_VALUE;  // minimum label.
1151             int hi = Integer.MIN_VALUE;  // maximum label.
1152             int nlabels = 0;               // number of labels.
1153 
1154             int[] labels = new int[cases.length()];  // the label array.
1155             int defaultIndex = -1;     // the index of the default clause.
1156 
1157             List<JCCase> l = cases;
1158             for (int i = 0; i < labels.length; i++) {
1159                 if (l.head.pat != null) {
1160                     int val = ((Number)l.head.pat.type.constValue()).intValue();
1161                     labels[i] = val;
1162                     if (val < lo) lo = val;
1163                     if (hi < val) hi = val;
1164                     nlabels++;
1165                 } else {
1166                     Assert.check(defaultIndex == -1);
1167                     defaultIndex = i;
1168                 }
1169                 l = l.tail;
1170             }
1171 
1172             // Determine whether to issue a tableswitch or a lookupswitch
1173             // instruction.
1174             long table_space_cost = 4 + ((long) hi - lo + 1); // words
1175             long table_time_cost = 3; // comparisons
1176             long lookup_space_cost = 3 + 2 * (long) nlabels;
1177             long lookup_time_cost = nlabels;
1178             int opcode =
1179                 nlabels > 0 &&
1180                 table_space_cost + 3 * table_time_cost <=
1181                 lookup_space_cost + 3 * lookup_time_cost
1182                 ?
1183                 tableswitch : lookupswitch;
1184 
1185             int startpc = code.curCP();    // the position of the selector operation
1186             code.emitop0(opcode);
1187             code.align(4);
1188             int tableBase = code.curCP();  // the start of the jump table
1189             int[] offsets = null;          // a table of offsets for a lookupswitch
1190             code.emit4(-1);                // leave space for default offset
1191             if (opcode == tableswitch) {
1192                 code.emit4(lo);            // minimum label
1193                 code.emit4(hi);            // maximum label
1194                 for (long i = lo; i <= hi; i++) {  // leave space for jump table
1195                     code.emit4(-1);
1196                 }
1197             } else {
1198                 code.emit4(nlabels);    // number of labels
1199                 for (int i = 0; i < nlabels; i++) {
1200                     code.emit4(-1); code.emit4(-1); // leave space for lookup table
1201                 }
1202                 offsets = new int[labels.length];
1203             }
1204             Code.State stateSwitch = code.state.dup();
1205             code.markDead();
1206 
1207             // For each case do:
1208             l = cases;
1209             for (int i = 0; i < labels.length; i++) {
1210                 JCCase c = l.head;
1211                 l = l.tail;
1212 
1213                 int pc = code.entryPoint(stateSwitch);
1214                 // Insert offset directly into code or else into the
1215                 // offsets table.
1216                 if (i != defaultIndex) {
1217                     if (opcode == tableswitch) {
1218                         code.put4(
1219                             tableBase + 4 * (labels[i] - lo + 3),
1220                             pc - startpc);
1221                     } else {
1222                         offsets[i] = pc - startpc;
1223                     }
1224                 } else {
1225                     code.put4(tableBase, pc - startpc);
1226                 }
1227 
1228                 // Generate code for the statements in this case.
1229                 genStats(c.stats, switchEnv, CRT_FLOW_TARGET);
1230             }
1231 
1232             // Resolve all breaks.
1233             Chain exit = switchEnv.info.exit;
1234             if  (exit != null) {
1235                 code.resolve(exit);
1236                 exit.state.defined.excludeFrom(limit);
1237             }
1238 
1239             // If we have not set the default offset, we do so now.
1240             if (code.get4(tableBase) == -1) {
1241                 code.put4(tableBase, code.entryPoint(stateSwitch) - startpc);
1242             }
1243 
1244             if (opcode == tableswitch) {
1245                 // Let any unfilled slots point to the default case.
1246                 int defaultOffset = code.get4(tableBase);
1247                 for (long i = lo; i <= hi; i++) {
1248                     int t = (int)(tableBase + 4 * (i - lo + 3));
1249                     if (code.get4(t) == -1)
1250                         code.put4(t, defaultOffset);
1251                 }
1252             } else {
1253                 // Sort non-default offsets and copy into lookup table.
1254                 if (defaultIndex >= 0)
1255                     for (int i = defaultIndex; i < labels.length - 1; i++) {
1256                         labels[i] = labels[i+1];
1257                         offsets[i] = offsets[i+1];
1258                     }
1259                 if (nlabels > 0)
1260                     qsort2(labels, offsets, 0, nlabels - 1);
1261                 for (int i = 0; i < nlabels; i++) {
1262                     int caseidx = tableBase + 8 * (i + 1);
1263                     code.put4(caseidx, labels[i]);
1264                     code.put4(caseidx + 4, offsets[i]);
1265                 }
1266             }
1267         }
1268         code.endScopes(limit);
1269     }
1270 //where
1271         /** Sort (int) arrays of keys and values
1272          */
1273        static void qsort2(int[] keys, int[] values, int lo, int hi) {
1274             int i = lo;
1275             int j = hi;
1276             int pivot = keys[(i+j)/2];
1277             do {
1278                 while (keys[i] < pivot) i++;
1279                 while (pivot < keys[j]) j--;
1280                 if (i <= j) {
1281                     int temp1 = keys[i];
1282                     keys[i] = keys[j];
1283                     keys[j] = temp1;
1284                     int temp2 = values[i];
1285                     values[i] = values[j];
1286                     values[j] = temp2;
1287                     i++;
1288                     j--;
1289                 }
1290             } while (i <= j);
1291             if (lo < j) qsort2(keys, values, lo, j);
1292             if (i < hi) qsort2(keys, values, i, hi);
1293         }
1294 
1295     public void visitSynchronized(JCSynchronized tree) {
1296         int limit = code.nextreg;
1297         // Generate code to evaluate lock and save in temporary variable.
1298         final LocalItem lockVar = makeTemp(syms.objectType);
1299         Assert.check(code.state.stacksize == 0);
1300         genExpr(tree.lock, tree.lock.type).load().duplicate();
1301         lockVar.store();
1302 
1303         // Generate code to enter monitor.
1304         code.emitop0(monitorenter);
1305         code.state.lock(lockVar.reg);
1306 
1307         // Generate code for a try statement with given body, no catch clauses
1308         // in a new environment with the "exit-monitor" operation as finalizer.
1309         final Env<GenContext> syncEnv = env.dup(tree, new GenContext());
1310         syncEnv.info.finalize = new GenFinalizer() {
1311             void gen() {
1312                 genLast();
1313                 Assert.check(syncEnv.info.gaps.length() % 2 == 0);
1314                 syncEnv.info.gaps.append(code.curCP());
1315             }
1316             void genLast() {
1317                 if (code.isAlive()) {
1318                     lockVar.load();
1319                     code.emitop0(monitorexit);
1320                     code.state.unlock(lockVar.reg);
1321                 }
1322             }
1323         };
1324         syncEnv.info.gaps = new ListBuffer<>();
1325         genTry(tree.body, List.nil(), syncEnv);
1326         code.endScopes(limit);
1327     }
1328 
1329     public void visitTry(final JCTry tree) {
1330         // Generate code for a try statement with given body and catch clauses,
1331         // in a new environment which calls the finally block if there is one.
1332         final Env<GenContext> tryEnv = env.dup(tree, new GenContext());
1333         final Env<GenContext> oldEnv = env;
1334         tryEnv.info.finalize = new GenFinalizer() {
1335             void gen() {
1336                 Assert.check(tryEnv.info.gaps.length() % 2 == 0);
1337                 tryEnv.info.gaps.append(code.curCP());
1338                 genLast();
1339             }
1340             void genLast() {
1341                 if (tree.finalizer != null)
1342                     genStat(tree.finalizer, oldEnv, CRT_BLOCK);
1343             }
1344             boolean hasFinalizer() {
1345                 return tree.finalizer != null;
1346             }
1347         };
1348         tryEnv.info.gaps = new ListBuffer<>();
1349         genTry(tree.body, tree.catchers, tryEnv);
1350     }
1351     //where
1352         /** Generate code for a try or synchronized statement
1353          *  @param body      The body of the try or synchronized statement.
1354          *  @param catchers  The lis of catch clauses.
1355          *  @param env       the environment current for the body.
1356          */
1357         void genTry(JCTree body, List<JCCatch> catchers, Env<GenContext> env) {
1358             int limit = code.nextreg;
1359             int startpc = code.curCP();
1360             Code.State stateTry = code.state.dup();
1361             genStat(body, env, CRT_BLOCK);
1362             int endpc = code.curCP();
1363             boolean hasFinalizer =
1364                 env.info.finalize != null &&
1365                 env.info.finalize.hasFinalizer();
1366             List<Integer> gaps = env.info.gaps.toList();
1367             code.statBegin(TreeInfo.endPos(body));
1368             genFinalizer(env);
1369             code.statBegin(TreeInfo.endPos(env.tree));
1370             Chain exitChain = code.branch(goto_);
1371             endFinalizerGap(env);
1372             if (startpc != endpc) for (List<JCCatch> l = catchers; l.nonEmpty(); l = l.tail) {
1373                 // start off with exception on stack
1374                 code.entryPoint(stateTry, l.head.param.sym.type);
1375                 genCatch(l.head, env, startpc, endpc, gaps);
1376                 genFinalizer(env);
1377                 if (hasFinalizer || l.tail.nonEmpty()) {
1378                     code.statBegin(TreeInfo.endPos(env.tree));
1379                     exitChain = Code.mergeChains(exitChain,
1380                                                  code.branch(goto_));
1381                 }
1382                 endFinalizerGap(env);
1383             }
1384             if (hasFinalizer) {
1385                 // Create a new register segement to avoid allocating
1386                 // the same variables in finalizers and other statements.
1387                 code.newRegSegment();
1388 
1389                 // Add a catch-all clause.
1390 
1391                 // start off with exception on stack
1392                 int catchallpc = code.entryPoint(stateTry, syms.throwableType);
1393 
1394                 // Register all exception ranges for catch all clause.
1395                 // The range of the catch all clause is from the beginning
1396                 // of the try or synchronized block until the present
1397                 // code pointer excluding all gaps in the current
1398                 // environment's GenContext.
1399                 int startseg = startpc;
1400                 while (env.info.gaps.nonEmpty()) {
1401                     int endseg = env.info.gaps.next().intValue();
1402                     registerCatch(body.pos(), startseg, endseg,
1403                                   catchallpc, 0);
1404                     startseg = env.info.gaps.next().intValue();
1405                 }
1406                 code.statBegin(TreeInfo.finalizerPos(env.tree, PosKind.FIRST_STAT_POS));
1407                 code.markStatBegin();
1408 
1409                 Item excVar = makeTemp(syms.throwableType);
1410                 excVar.store();
1411                 genFinalizer(env);
1412                 code.resolvePending();
1413                 code.statBegin(TreeInfo.finalizerPos(env.tree, PosKind.END_POS));
1414                 code.markStatBegin();
1415 
1416                 excVar.load();
1417                 registerCatch(body.pos(), startseg,
1418                               env.info.gaps.next().intValue(),
1419                               catchallpc, 0);
1420                 code.emitop0(athrow);
1421                 code.markDead();
1422 
1423                 // If there are jsr's to this finalizer, ...
1424                 if (env.info.cont != null) {
1425                     // Resolve all jsr's.
1426                     code.resolve(env.info.cont);
1427 
1428                     // Mark statement line number
1429                     code.statBegin(TreeInfo.finalizerPos(env.tree, PosKind.FIRST_STAT_POS));
1430                     code.markStatBegin();
1431 
1432                     // Save return address.
1433                     LocalItem retVar = makeTemp(syms.throwableType);
1434                     retVar.store();
1435 
1436                     // Generate finalizer code.
1437                     env.info.finalize.genLast();
1438 
1439                     // Return.
1440                     code.emitop1w(ret, retVar.reg);
1441                     code.markDead();
1442                 }
1443             }
1444             // Resolve all breaks.
1445             code.resolve(exitChain);
1446 
1447             code.endScopes(limit);
1448         }
1449 
1450         /** Generate code for a catch clause.
1451          *  @param tree     The catch clause.
1452          *  @param env      The environment current in the enclosing try.
1453          *  @param startpc  Start pc of try-block.
1454          *  @param endpc    End pc of try-block.
1455          */
1456         void genCatch(JCCatch tree,
1457                       Env<GenContext> env,
1458                       int startpc, int endpc,
1459                       List<Integer> gaps) {
1460             if (startpc != endpc) {
1461                 List<Pair<List<Attribute.TypeCompound>, JCExpression>> catchTypeExprs
1462                         = catchTypesWithAnnotations(tree);
1463                 while (gaps.nonEmpty()) {
1464                     for (Pair<List<Attribute.TypeCompound>, JCExpression> subCatch1 : catchTypeExprs) {
1465                         JCExpression subCatch = subCatch1.snd;
1466                         int catchType = makeRef(tree.pos(), subCatch.type);
1467                         int end = gaps.head.intValue();
1468                         registerCatch(tree.pos(),
1469                                       startpc,  end, code.curCP(),
1470                                       catchType);
1471                         for (Attribute.TypeCompound tc :  subCatch1.fst) {
1472                                 tc.position.setCatchInfo(catchType, startpc);
1473                         }
1474                     }
1475                     gaps = gaps.tail;
1476                     startpc = gaps.head.intValue();
1477                     gaps = gaps.tail;
1478                 }
1479                 if (startpc < endpc) {
1480                     for (Pair<List<Attribute.TypeCompound>, JCExpression> subCatch1 : catchTypeExprs) {
1481                         JCExpression subCatch = subCatch1.snd;
1482                         int catchType = makeRef(tree.pos(), subCatch.type);
1483                         registerCatch(tree.pos(),
1484                                       startpc, endpc, code.curCP(),
1485                                       catchType);
1486                         for (Attribute.TypeCompound tc :  subCatch1.fst) {
1487                             tc.position.setCatchInfo(catchType, startpc);
1488                         }
1489                     }
1490                 }
1491                 VarSymbol exparam = tree.param.sym;
1492                 code.statBegin(tree.pos);
1493                 code.markStatBegin();
1494                 int limit = code.nextreg;
1495                 code.newLocal(exparam);
1496                 items.makeLocalItem(exparam).store();
1497                 code.statBegin(TreeInfo.firstStatPos(tree.body));
1498                 genStat(tree.body, env, CRT_BLOCK);
1499                 code.endScopes(limit);
1500                 code.statBegin(TreeInfo.endPos(tree.body));
1501             }
1502         }
1503         // where
1504         List<Pair<List<Attribute.TypeCompound>, JCExpression>> catchTypesWithAnnotations(JCCatch tree) {
1505             return TreeInfo.isMultiCatch(tree) ?
1506                     catchTypesWithAnnotationsFromMulticatch((JCTypeUnion)tree.param.vartype, tree.param.sym.getRawTypeAttributes()) :
1507                     List.of(new Pair<>(tree.param.sym.getRawTypeAttributes(), tree.param.vartype));
1508         }
1509         // where
1510         List<Pair<List<Attribute.TypeCompound>, JCExpression>> catchTypesWithAnnotationsFromMulticatch(JCTypeUnion tree, List<TypeCompound> first) {
1511             List<JCExpression> alts = tree.alternatives;
1512             List<Pair<List<TypeCompound>, JCExpression>> res = List.of(new Pair<>(first, alts.head));
1513             alts = alts.tail;
1514 
1515             while(alts != null && alts.head != null) {
1516                 JCExpression alt = alts.head;
1517                 if (alt instanceof JCAnnotatedType) {
1518                     JCAnnotatedType a = (JCAnnotatedType)alt;
1519                     res = res.prepend(new Pair<>(annotate.fromAnnotations(a.annotations), alt));
1520                 } else {
1521                     res = res.prepend(new Pair<>(List.nil(), alt));
1522                 }
1523                 alts = alts.tail;
1524             }
1525             return res.reverse();
1526         }
1527 
1528         /** Register a catch clause in the "Exceptions" code-attribute.
1529          */
1530         void registerCatch(DiagnosticPosition pos,
1531                            int startpc, int endpc,
1532                            int handler_pc, int catch_type) {
1533             char startpc1 = (char)startpc;
1534             char endpc1 = (char)endpc;
1535             char handler_pc1 = (char)handler_pc;
1536             if (startpc1 == startpc &&
1537                 endpc1 == endpc &&
1538                 handler_pc1 == handler_pc) {
1539                 code.addCatch(startpc1, endpc1, handler_pc1,
1540                               (char)catch_type);
1541             } else {
1542                 log.error(pos, Errors.LimitCodeTooLargeForTryStmt);
1543                 nerrs++;
1544             }
1545         }
1546 
1547     public void visitIf(JCIf tree) {
1548         int limit = code.nextreg;
1549         Chain thenExit = null;
1550         Assert.check(code.state.stacksize == 0);
1551         CondItem c = genCond(TreeInfo.skipParens(tree.cond),
1552                              CRT_FLOW_CONTROLLER);
1553         Chain elseChain = c.jumpFalse();
1554         Assert.check(code.state.stacksize == 0);
1555         if (!c.isFalse()) {
1556             code.resolve(c.trueJumps);
1557             genStat(tree.thenpart, env, CRT_STATEMENT | CRT_FLOW_TARGET);
1558             thenExit = code.branch(goto_);
1559         }
1560         if (elseChain != null) {
1561             code.resolve(elseChain);
1562             if (tree.elsepart != null) {
1563                 genStat(tree.elsepart, env,CRT_STATEMENT | CRT_FLOW_TARGET);
1564             }
1565         }
1566         code.resolve(thenExit);
1567         code.endScopes(limit);
1568         Assert.check(code.state.stacksize == 0);
1569     }
1570 
1571     public void visitExec(JCExpressionStatement tree) {
1572         // Optimize x++ to ++x and x-- to --x.
1573         JCExpression e = tree.expr;
1574         switch (e.getTag()) {
1575             case POSTINC:
1576                 ((JCUnary) e).setTag(PREINC);
1577                 break;
1578             case POSTDEC:
1579                 ((JCUnary) e).setTag(PREDEC);
1580                 break;
1581         }
1582         Assert.check(code.state.stacksize == 0);
1583         genExpr(tree.expr, tree.expr.type).drop();
1584         Assert.check(code.state.stacksize == 0);
1585     }
1586 
1587     public void visitBreak(JCBreak tree) {
1588         int tmpPos = code.pendingStatPos;
1589         Env<GenContext> targetEnv = unwind(tree.target, env);
1590         code.pendingStatPos = tmpPos;
1591         Assert.check(code.state.stacksize == 0);
1592         targetEnv.info.addExit(code.branch(goto_));
1593         endFinalizerGaps(env, targetEnv);
1594     }
1595 
1596     public void visitContinue(JCContinue tree) {
1597         int tmpPos = code.pendingStatPos;
1598         Env<GenContext> targetEnv = unwind(tree.target, env);
1599         code.pendingStatPos = tmpPos;
1600         Assert.check(code.state.stacksize == 0);
1601         targetEnv.info.addCont(code.branch(goto_));
1602         endFinalizerGaps(env, targetEnv);
1603     }
1604 
1605     public void visitReturn(JCReturn tree) {
1606         int limit = code.nextreg;
1607         final Env<GenContext> targetEnv;
1608 
1609         /* Save and then restore the location of the return in case a finally
1610          * is expanded (with unwind()) in the middle of our bytecodes.
1611          */
1612         int tmpPos = code.pendingStatPos;
1613         if (tree.expr != null) {
1614             Assert.check(code.state.stacksize == 0);
1615             Item r = genExpr(tree.expr, pt).load();
1616             if (hasFinally(env.enclMethod, env)) {
1617                 r = makeTemp(pt);
1618                 r.store();
1619             }
1620             targetEnv = unwind(env.enclMethod, env);
1621             code.pendingStatPos = tmpPos;
1622             r.load();
1623             code.emitop0(ireturn + Code.truncate(Code.typecode(pt)));
1624         } else {
1625             targetEnv = unwind(env.enclMethod, env);
1626             code.pendingStatPos = tmpPos;
1627             code.emitop0(return_);
1628         }
1629         endFinalizerGaps(env, targetEnv);
1630         code.endScopes(limit);
1631     }
1632 
1633     public void visitThrow(JCThrow tree) {
1634         Assert.check(code.state.stacksize == 0);
1635         genExpr(tree.expr, tree.expr.type).load();
1636         code.emitop0(athrow);
1637         Assert.check(code.state.stacksize == 0);
1638     }
1639 
1640 /* ************************************************************************
1641  * Visitor methods for expressions
1642  *************************************************************************/
1643 
1644     public void visitApply(JCMethodInvocation tree) {
1645         setTypeAnnotationPositions(tree.pos);
1646         // Generate code for method.
1647         Item m = genExpr(tree.meth, methodType);
1648         // Generate code for all arguments, where the expected types are
1649         // the parameters of the method's external type (that is, any implicit
1650         // outer instance of a super(...) call appears as first parameter).
1651         MethodSymbol msym = (MethodSymbol)TreeInfo.symbol(tree.meth);
1652         genArgs(tree.args,
1653                 msym.externalType(types).getParameterTypes());
1654         if (!msym.isDynamic()) {
1655             code.statBegin(tree.pos);
1656         }
1657         result = m.invoke();
1658     }
1659 
1660     public void visitConditional(JCConditional tree) {
1661         Chain thenExit = null;
1662         code.statBegin(tree.cond.pos);
1663         CondItem c = genCond(tree.cond, CRT_FLOW_CONTROLLER);
1664         Chain elseChain = c.jumpFalse();
1665         if (!c.isFalse()) {
1666             code.resolve(c.trueJumps);
1667             int startpc = genCrt ? code.curCP() : 0;
1668             code.statBegin(tree.truepart.pos);
1669             genExpr(tree.truepart, pt).load();
1670             code.state.forceStackTop(tree.type);
1671             if (genCrt) code.crt.put(tree.truepart, CRT_FLOW_TARGET,
1672                                      startpc, code.curCP());
1673             thenExit = code.branch(goto_);
1674         }
1675         if (elseChain != null) {
1676             code.resolve(elseChain);
1677             int startpc = genCrt ? code.curCP() : 0;
1678             code.statBegin(tree.falsepart.pos);
1679             genExpr(tree.falsepart, pt).load();
1680             code.state.forceStackTop(tree.type);
1681             if (genCrt) code.crt.put(tree.falsepart, CRT_FLOW_TARGET,
1682                                      startpc, code.curCP());
1683         }
1684         code.resolve(thenExit);
1685         result = items.makeStackItem(pt);
1686     }
1687 
1688     private void setTypeAnnotationPositions(int treePos) {
1689         MethodSymbol meth = code.meth;
1690         boolean initOrClinit = code.meth.getKind() == javax.lang.model.element.ElementKind.CONSTRUCTOR
1691                 || code.meth.getKind() == javax.lang.model.element.ElementKind.STATIC_INIT;
1692 
1693         for (Attribute.TypeCompound ta : meth.getRawTypeAttributes()) {
1694             if (ta.hasUnknownPosition())
1695                 ta.tryFixPosition();
1696 
1697             if (ta.position.matchesPos(treePos))
1698                 ta.position.updatePosOffset(code.cp);
1699         }
1700 
1701         if (!initOrClinit)
1702             return;
1703 
1704         for (Attribute.TypeCompound ta : meth.owner.getRawTypeAttributes()) {
1705             if (ta.hasUnknownPosition())
1706                 ta.tryFixPosition();
1707 
1708             if (ta.position.matchesPos(treePos))
1709                 ta.position.updatePosOffset(code.cp);
1710         }
1711 
1712         ClassSymbol clazz = meth.enclClass();
1713         for (Symbol s : new com.sun.tools.javac.model.FilteredMemberList(clazz.members())) {
1714             if (!s.getKind().isField())
1715                 continue;
1716 
1717             for (Attribute.TypeCompound ta : s.getRawTypeAttributes()) {
1718                 if (ta.hasUnknownPosition())
1719                     ta.tryFixPosition();
1720 
1721                 if (ta.position.matchesPos(treePos))
1722                     ta.position.updatePosOffset(code.cp);
1723             }
1724         }
1725     }
1726 
1727     public void visitNewClass(JCNewClass tree) {
1728         // Enclosing instances or anonymous classes should have been eliminated
1729         // by now.
1730         Assert.check(tree.encl == null && tree.def == null);
1731         setTypeAnnotationPositions(tree.pos);
1732 
1733         code.emitop2(new_, makeRef(tree.pos(), tree.type));
1734         code.emitop0(dup);
1735 
1736         // Generate code for all arguments, where the expected types are
1737         // the parameters of the constructor's external type (that is,
1738         // any implicit outer instance appears as first parameter).
1739         genArgs(tree.args, tree.constructor.externalType(types).getParameterTypes());
1740 
1741         items.makeMemberItem(tree.constructor, true).invoke();
1742         result = items.makeStackItem(tree.type);
1743     }
1744 
1745     public void visitNewArray(JCNewArray tree) {
1746         setTypeAnnotationPositions(tree.pos);
1747 
1748         if (tree.elems != null) {
1749             Type elemtype = types.elemtype(tree.type);
1750             loadIntConst(tree.elems.length());
1751             Item arr = makeNewArray(tree.pos(), tree.type, 1);
1752             int i = 0;
1753             for (List<JCExpression> l = tree.elems; l.nonEmpty(); l = l.tail) {
1754                 arr.duplicate();
1755                 loadIntConst(i);
1756                 i++;
1757                 genExpr(l.head, elemtype).load();
1758                 items.makeIndexedItem(elemtype).store();
1759             }
1760             result = arr;
1761         } else {
1762             for (List<JCExpression> l = tree.dims; l.nonEmpty(); l = l.tail) {
1763                 genExpr(l.head, syms.intType).load();
1764             }
1765             result = makeNewArray(tree.pos(), tree.type, tree.dims.length());
1766         }
1767     }
1768 //where
1769         /** Generate code to create an array with given element type and number
1770          *  of dimensions.
1771          */
1772         Item makeNewArray(DiagnosticPosition pos, Type type, int ndims) {
1773             Type elemtype = types.elemtype(type);
1774             if (types.dimensions(type) > ClassFile.MAX_DIMENSIONS) {
1775                 log.error(pos, Errors.LimitDimensions);
1776                 nerrs++;
1777             }
1778             int elemcode = Code.arraycode(elemtype);
1779             if (elemcode == 0 || (elemcode == 1 && ndims == 1)) {
1780                 code.emitAnewarray(makeRef(pos, elemtype), type);
1781             } else if (elemcode == 1) {
1782                 code.emitMultianewarray(ndims, makeRef(pos, type), type);
1783             } else {
1784                 code.emitNewarray(elemcode, type);
1785             }
1786             return items.makeStackItem(type);
1787         }
1788 
1789     public void visitParens(JCParens tree) {
1790         result = genExpr(tree.expr, tree.expr.type);
1791     }
1792 
1793     public void visitAssign(JCAssign tree) {
1794         Item l = genExpr(tree.lhs, tree.lhs.type);
1795         genExpr(tree.rhs, tree.lhs.type).load();
1796         if (tree.rhs.type.hasTag(BOT)) {
1797             /* This is just a case of widening reference conversion that per 5.1.5 simply calls
1798                for "regarding a reference as having some other type in a manner that can be proved
1799                correct at compile time."
1800             */
1801             code.state.forceStackTop(tree.lhs.type);
1802         }
1803         result = items.makeAssignItem(l);
1804     }
1805 
1806     public void visitAssignop(JCAssignOp tree) {
1807         OperatorSymbol operator = tree.operator;
1808         Item l;
1809         if (operator.opcode == string_add) {
1810             l = concat.makeConcat(tree);
1811         } else {
1812             // Generate code for first expression
1813             l = genExpr(tree.lhs, tree.lhs.type);
1814 
1815             // If we have an increment of -32768 to +32767 of a local
1816             // int variable we can use an incr instruction instead of
1817             // proceeding further.
1818             if ((tree.hasTag(PLUS_ASG) || tree.hasTag(MINUS_ASG)) &&
1819                 l instanceof LocalItem &&
1820                 tree.lhs.type.getTag().isSubRangeOf(INT) &&
1821                 tree.rhs.type.getTag().isSubRangeOf(INT) &&
1822                 tree.rhs.type.constValue() != null) {
1823                 int ival = ((Number) tree.rhs.type.constValue()).intValue();
1824                 if (tree.hasTag(MINUS_ASG)) ival = -ival;
1825                 ((LocalItem)l).incr(ival);
1826                 result = l;
1827                 return;
1828             }
1829             // Otherwise, duplicate expression, load one copy
1830             // and complete binary operation.
1831             l.duplicate();
1832             l.coerce(operator.type.getParameterTypes().head).load();
1833             completeBinop(tree.lhs, tree.rhs, operator).coerce(tree.lhs.type);
1834         }
1835         result = items.makeAssignItem(l);
1836     }
1837 
1838     public void visitUnary(JCUnary tree) {
1839         OperatorSymbol operator = tree.operator;
1840         if (tree.hasTag(NOT)) {
1841             CondItem od = genCond(tree.arg, false);
1842             result = od.negate();
1843         } else {
1844             Item od = genExpr(tree.arg, operator.type.getParameterTypes().head);
1845             switch (tree.getTag()) {
1846             case POS:
1847                 result = od.load();
1848                 break;
1849             case NEG:
1850                 result = od.load();
1851                 code.emitop0(operator.opcode);
1852                 break;
1853             case COMPL:
1854                 result = od.load();
1855                 emitMinusOne(od.typecode);
1856                 code.emitop0(operator.opcode);
1857                 break;
1858             case PREINC: case PREDEC:
1859                 od.duplicate();
1860                 if (od instanceof LocalItem &&
1861                     (operator.opcode == iadd || operator.opcode == isub)) {
1862                     ((LocalItem)od).incr(tree.hasTag(PREINC) ? 1 : -1);
1863                     result = od;
1864                 } else {
1865                     od.load();
1866                     code.emitop0(one(od.typecode));
1867                     code.emitop0(operator.opcode);
1868                     // Perform narrowing primitive conversion if byte,
1869                     // char, or short.  Fix for 4304655.
1870                     if (od.typecode != INTcode &&
1871                         Code.truncate(od.typecode) == INTcode)
1872                       code.emitop0(int2byte + od.typecode - BYTEcode);
1873                     result = items.makeAssignItem(od);
1874                 }
1875                 break;
1876             case POSTINC: case POSTDEC:
1877                 od.duplicate();
1878                 if (od instanceof LocalItem &&
1879                     (operator.opcode == iadd || operator.opcode == isub)) {
1880                     Item res = od.load();
1881                     ((LocalItem)od).incr(tree.hasTag(POSTINC) ? 1 : -1);
1882                     result = res;
1883                 } else {
1884                     Item res = od.load();
1885                     od.stash(od.typecode);
1886                     code.emitop0(one(od.typecode));
1887                     code.emitop0(operator.opcode);
1888                     // Perform narrowing primitive conversion if byte,
1889                     // char, or short.  Fix for 4304655.
1890                     if (od.typecode != INTcode &&
1891                         Code.truncate(od.typecode) == INTcode)
1892                       code.emitop0(int2byte + od.typecode - BYTEcode);
1893                     od.store();
1894                     result = res;
1895                 }
1896                 break;
1897             case NULLCHK:
1898                 result = od.load();
1899                 code.emitop0(dup);
1900                 genNullCheck(tree);
1901                 break;
1902             default:
1903                 Assert.error();
1904             }
1905         }
1906     }
1907 
1908     /** Generate a null check from the object value at stack top. */
1909     private void genNullCheck(JCTree tree) {
1910         code.statBegin(tree.pos);
1911         if (allowBetterNullChecks) {
1912             callMethod(tree.pos(), syms.objectsType, names.requireNonNull,
1913                     List.of(syms.objectType), true);
1914         } else {
1915             callMethod(tree.pos(), syms.objectType, names.getClass,
1916                     List.nil(), false);
1917         }
1918         code.emitop0(pop);
1919     }
1920 
1921     public void visitBinary(JCBinary tree) {
1922         OperatorSymbol operator = tree.operator;
1923         if (operator.opcode == string_add) {
1924             result = concat.makeConcat(tree);
1925         } else if (tree.hasTag(AND)) {
1926             CondItem lcond = genCond(tree.lhs, CRT_FLOW_CONTROLLER);
1927             if (!lcond.isFalse()) {
1928                 Chain falseJumps = lcond.jumpFalse();
1929                 code.resolve(lcond.trueJumps);
1930                 CondItem rcond = genCond(tree.rhs, CRT_FLOW_TARGET);
1931                 result = items.
1932                     makeCondItem(rcond.opcode,
1933                                  rcond.trueJumps,
1934                                  Code.mergeChains(falseJumps,
1935                                                   rcond.falseJumps));
1936             } else {
1937                 result = lcond;
1938             }
1939         } else if (tree.hasTag(OR)) {
1940             CondItem lcond = genCond(tree.lhs, CRT_FLOW_CONTROLLER);
1941             if (!lcond.isTrue()) {
1942                 Chain trueJumps = lcond.jumpTrue();
1943                 code.resolve(lcond.falseJumps);
1944                 CondItem rcond = genCond(tree.rhs, CRT_FLOW_TARGET);
1945                 result = items.
1946                     makeCondItem(rcond.opcode,
1947                                  Code.mergeChains(trueJumps, rcond.trueJumps),
1948                                  rcond.falseJumps);
1949             } else {
1950                 result = lcond;
1951             }
1952         } else {
1953             Item od = genExpr(tree.lhs, operator.type.getParameterTypes().head);
1954             od.load();
1955             result = completeBinop(tree.lhs, tree.rhs, operator);
1956         }
1957     }
1958 
1959 
1960         /** Complete generating code for operation, with left operand
1961          *  already on stack.
1962          *  @param lhs       The tree representing the left operand.
1963          *  @param rhs       The tree representing the right operand.
1964          *  @param operator  The operator symbol.
1965          */
1966         Item completeBinop(JCTree lhs, JCTree rhs, OperatorSymbol operator) {
1967             MethodType optype = (MethodType)operator.type;
1968             int opcode = operator.opcode;
1969             if (opcode >= if_icmpeq && opcode <= if_icmple &&
1970                 rhs.type.constValue() instanceof Number &&
1971                 ((Number) rhs.type.constValue()).intValue() == 0) {
1972                 opcode = opcode + (ifeq - if_icmpeq);
1973             } else if (opcode >= if_acmpeq && opcode <= if_acmpne &&
1974                        TreeInfo.isNull(rhs)) {
1975                 opcode = opcode + (if_acmp_null - if_acmpeq);
1976             } else {
1977                 // The expected type of the right operand is
1978                 // the second parameter type of the operator, except for
1979                 // shifts with long shiftcount, where we convert the opcode
1980                 // to a short shift and the expected type to int.
1981                 Type rtype = operator.erasure(types).getParameterTypes().tail.head;
1982                 if (opcode >= ishll && opcode <= lushrl) {
1983                     opcode = opcode + (ishl - ishll);
1984                     rtype = syms.intType;
1985                 }
1986                 // Generate code for right operand and load.
1987                 genExpr(rhs, rtype).load();
1988                 // If there are two consecutive opcode instructions,
1989                 // emit the first now.
1990                 if (opcode >= (1 << preShift)) {
1991                     code.emitop0(opcode >> preShift);
1992                     opcode = opcode & 0xFF;
1993                 }
1994             }
1995             if (opcode >= ifeq && opcode <= if_acmpne ||
1996                 opcode == if_acmp_null || opcode == if_acmp_nonnull) {
1997                 return items.makeCondItem(opcode);
1998             } else {
1999                 code.emitop0(opcode);
2000                 return items.makeStackItem(optype.restype);
2001             }
2002         }
2003 
2004     public void visitTypeCast(JCTypeCast tree) {
2005         result = genExpr(tree.expr, tree.clazz.type).load();
2006         setTypeAnnotationPositions(tree.pos);
2007         // Additional code is only needed if we cast to a reference type
2008         // which is not statically a supertype of the expression's type.
2009         // For basic types, the coerce(...) in genExpr(...) will do
2010         // the conversion.
2011         if (!tree.clazz.type.isPrimitive() &&
2012            !types.isSameType(tree.expr.type, tree.clazz.type) &&
2013            types.asSuper(tree.expr.type, tree.clazz.type.tsym) == null) {
2014             code.emitop2(checkcast, makeRef(tree.pos(), tree.clazz.type));
2015         }
2016     }
2017 
2018     public void visitWildcard(JCWildcard tree) {
2019         throw new AssertionError(this.getClass().getName());
2020     }
2021 
2022     public void visitTypeTest(JCInstanceOf tree) {
2023         genExpr(tree.expr, tree.expr.type).load();
2024         setTypeAnnotationPositions(tree.pos);
2025         code.emitop2(instanceof_, makeRef(tree.pos(), tree.clazz.type));
2026         result = items.makeStackItem(syms.booleanType);
2027     }
2028 
2029     public void visitIndexed(JCArrayAccess tree) {
2030         genExpr(tree.indexed, tree.indexed.type).load();
2031         genExpr(tree.index, syms.intType).load();
2032         result = items.makeIndexedItem(tree.type);
2033     }
2034 
2035     public void visitIdent(JCIdent tree) {
2036         Symbol sym = tree.sym;
2037         if (tree.name == names._this || tree.name == names._super) {
2038             Item res = tree.name == names._this
2039                 ? items.makeThisItem()
2040                 : items.makeSuperItem();
2041             if (sym.kind == MTH) {
2042                 // Generate code to address the constructor.
2043                 res.load();
2044                 res = items.makeMemberItem(sym, true);
2045             }
2046             result = res;
2047         } else if (sym.kind == VAR && sym.owner.kind == MTH) {
2048             result = items.makeLocalItem((VarSymbol)sym);
2049         } else if (isInvokeDynamic(sym)) {
2050             result = items.makeDynamicItem(sym);
2051         } else if ((sym.flags() & STATIC) != 0) {
2052             if (!isAccessSuper(env.enclMethod))
2053                 sym = binaryQualifier(sym, env.enclClass.type);
2054             result = items.makeStaticItem(sym);
2055         } else {
2056             items.makeThisItem().load();
2057             sym = binaryQualifier(sym, env.enclClass.type);
2058             result = items.makeMemberItem(sym, nonVirtualForPrivateAccess(sym));
2059         }
2060     }
2061 
2062     //where
2063     private boolean nonVirtualForPrivateAccess(Symbol sym) {
2064         return !(virtualizePrivateAccess || target.hasVirtualPrivateInvoke()) &&
2065                ((sym.flags() & PRIVATE) != 0);
2066     }
2067 
2068     public void visitSelect(JCFieldAccess tree) {
2069         Symbol sym = tree.sym;
2070 
2071         if (tree.name == names._class) {
2072             code.emitLdc(makeRef(tree.pos(), tree.selected.type));
2073             result = items.makeStackItem(pt);
2074             return;
2075        }
2076 
2077         Symbol ssym = TreeInfo.symbol(tree.selected);
2078 
2079         // Are we selecting via super?
2080         boolean selectSuper =
2081             ssym != null && (ssym.kind == TYP || ssym.name == names._super);
2082 
2083         // Are we accessing a member of the superclass in an access method
2084         // resulting from a qualified super?
2085         boolean accessSuper = isAccessSuper(env.enclMethod);
2086 
2087         Item base = (selectSuper)
2088             ? items.makeSuperItem()
2089             : genExpr(tree.selected, tree.selected.type);
2090 
2091         if (sym.kind == VAR && ((VarSymbol) sym).getConstValue() != null) {
2092             // We are seeing a variable that is constant but its selecting
2093             // expression is not.
2094             if ((sym.flags() & STATIC) != 0) {
2095                 if (!selectSuper && (ssym == null || ssym.kind != TYP))
2096                     base = base.load();
2097                 base.drop();
2098             } else {
2099                 base.load();
2100                 genNullCheck(tree.selected);
2101             }
2102             result = items.
2103                 makeImmediateItem(sym.type, ((VarSymbol) sym).getConstValue());
2104         } else {
2105             if (isInvokeDynamic(sym)) {
2106                 result = items.makeDynamicItem(sym);
2107                 return;
2108             } else {
2109                 sym = binaryQualifier(sym, tree.selected.type);
2110             }
2111             if ((sym.flags() & STATIC) != 0) {
2112                 if (!selectSuper && (ssym == null || ssym.kind != TYP))
2113                     base = base.load();
2114                 base.drop();
2115                 result = items.makeStaticItem(sym);
2116             } else {
2117                 base.load();
2118                 if (sym == syms.lengthVar) {
2119                     code.emitop0(arraylength);
2120                     result = items.makeStackItem(syms.intType);
2121                 } else {
2122                     result = items.
2123                         makeMemberItem(sym,
2124                                        nonVirtualForPrivateAccess(sym) ||
2125                                        selectSuper || accessSuper);
2126                 }
2127             }
2128         }
2129     }
2130 
2131     public boolean isInvokeDynamic(Symbol sym) {
2132         return sym.kind == MTH && ((MethodSymbol)sym).isDynamic();
2133     }
2134 
2135     public void visitLiteral(JCLiteral tree) {
2136         if (tree.type.hasTag(BOT)) {
2137             code.emitop0(aconst_null);
2138             result = items.makeStackItem(tree.type);
2139         }
2140         else
2141             result = items.makeImmediateItem(tree.type, tree.value);
2142     }
2143 
2144     public void visitLetExpr(LetExpr tree) {
2145         letExprDepth++;
2146         int limit = code.nextreg;
2147         genStats(tree.defs, env);
2148         result = genExpr(tree.expr, tree.expr.type).load();
2149         code.endScopes(limit);
2150         letExprDepth--;
2151     }
2152 
2153     private void generateReferencesToPrunedTree(ClassSymbol classSymbol, Pool pool) {
2154         List<JCTree> prunedInfo = lower.prunedTree.get(classSymbol);
2155         if (prunedInfo != null) {
2156             for (JCTree prunedTree: prunedInfo) {
2157                 prunedTree.accept(classReferenceVisitor);
2158             }
2159         }
2160     }
2161 
2162 /* ************************************************************************
2163  * main method
2164  *************************************************************************/
2165 
2166     /** Generate code for a class definition.
2167      *  @param env   The attribution environment that belongs to the
2168      *               outermost class containing this class definition.
2169      *               We need this for resolving some additional symbols.
2170      *  @param cdef  The tree representing the class definition.
2171      *  @return      True if code is generated with no errors.
2172      */
2173     public boolean genClass(Env<AttrContext> env, JCClassDecl cdef) {
2174         try {
2175             attrEnv = env;
2176             ClassSymbol c = cdef.sym;
2177             this.toplevel = env.toplevel;
2178             this.endPosTable = toplevel.endPositions;
2179             c.pool = pool;
2180             pool.reset();
2181             /* method normalizeDefs() can add references to external classes into the constant pool
2182              */
2183             cdef.defs = normalizeDefs(cdef.defs, c);
2184             generateReferencesToPrunedTree(c, pool);
2185             Env<GenContext> localEnv = new Env<>(cdef, new GenContext());
2186             localEnv.toplevel = env.toplevel;
2187             localEnv.enclClass = cdef;
2188 
2189             for (List<JCTree> l = cdef.defs; l.nonEmpty(); l = l.tail) {
2190                 genDef(l.head, localEnv);
2191             }
2192             if (pool.numEntries() > Pool.MAX_ENTRIES) {
2193                 log.error(cdef.pos(), Errors.LimitPool);
2194                 nerrs++;
2195             }
2196             if (nerrs != 0) {
2197                 // if errors, discard code
2198                 for (List<JCTree> l = cdef.defs; l.nonEmpty(); l = l.tail) {
2199                     if (l.head.hasTag(METHODDEF))
2200                         ((JCMethodDecl) l.head).sym.code = null;
2201                 }
2202             }
2203             cdef.defs = List.nil(); // discard trees
2204             return nerrs == 0;
2205         } finally {
2206             // note: this method does NOT support recursion.
2207             attrEnv = null;
2208             this.env = null;
2209             toplevel = null;
2210             endPosTable = null;
2211             nerrs = 0;
2212         }
2213     }
2214 
2215 /* ************************************************************************
2216  * Auxiliary classes
2217  *************************************************************************/
2218 
2219     /** An abstract class for finalizer generation.
2220      */
2221     abstract class GenFinalizer {
2222         /** Generate code to clean up when unwinding. */
2223         abstract void gen();
2224 
2225         /** Generate code to clean up at last. */
2226         abstract void genLast();
2227 
2228         /** Does this finalizer have some nontrivial cleanup to perform? */
2229         boolean hasFinalizer() { return true; }
2230     }
2231 
2232     /** code generation contexts,
2233      *  to be used as type parameter for environments.
2234      */
2235     static class GenContext {
2236 
2237         /** A chain for all unresolved jumps that exit the current environment.
2238          */
2239         Chain exit = null;
2240 
2241         /** A chain for all unresolved jumps that continue in the
2242          *  current environment.
2243          */
2244         Chain cont = null;
2245 
2246         /** A closure that generates the finalizer of the current environment.
2247          *  Only set for Synchronized and Try contexts.
2248          */
2249         GenFinalizer finalize = null;
2250 
2251         /** Is this a switch statement?  If so, allocate registers
2252          * even when the variable declaration is unreachable.
2253          */
2254         boolean isSwitch = false;
2255 
2256         /** A list buffer containing all gaps in the finalizer range,
2257          *  where a catch all exception should not apply.
2258          */
2259         ListBuffer<Integer> gaps = null;
2260 
2261         /** Add given chain to exit chain.
2262          */
2263         void addExit(Chain c)  {
2264             exit = Code.mergeChains(c, exit);
2265         }
2266 
2267         /** Add given chain to cont chain.
2268          */
2269         void addCont(Chain c) {
2270             cont = Code.mergeChains(c, cont);
2271         }
2272     }
2273 
2274 }