jdk8-mips64-public/langtools: src/share/classes/com/sun/tools/javac/comp/Lower.java@75e25df50873 (annotated)

src/share/classes/com/sun/tools/javac/comp/Lower.java@75e25df50873 (annotated)

src/share/classes/com/sun/tools/javac/comp/Lower.java

Fri, 18 Feb 2011 15:55:20 -0800

author: darcy
date: Fri, 18 Feb 2011 15:55:20 -0800
changeset 884: 75e25df50873
parent 858: 96d4226bdd60
child 901: 02b699d97a55
permissions: -rw-r--r--

7020047: Project Coin: generate null-check around try-with-resources close call
Reviewed-by: jjg

 /*
  * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
 package com.sun.tools.javac.comp;
 import java.util.*;
 import com.sun.tools.javac.code.*;
 import com.sun.tools.javac.jvm.*;
 import com.sun.tools.javac.main.RecognizedOptions.PkgInfo;
 import com.sun.tools.javac.tree.*;
 import com.sun.tools.javac.util.*;
 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
 import com.sun.tools.javac.util.List;
 import com.sun.tools.javac.code.Symbol.*;
 import com.sun.tools.javac.tree.JCTree.*;
 import com.sun.tools.javac.code.Type.*;
 import com.sun.tools.javac.jvm.Target;
 import static com.sun.tools.javac.code.Flags.*;
 import static com.sun.tools.javac.code.Kinds.*;
 import static com.sun.tools.javac.code.TypeTags.*;
 import static com.sun.tools.javac.jvm.ByteCodes.*;
 /** This pass translates away some syntactic sugar: inner classes,
  *  class literals, assertions, foreach loops, etc.
  *
  *  <p><b>This is NOT part of any supported API.
  *  If you write code that depends on this, you do so at your own risk.
  *  This code and its internal interfaces are subject to change or
  *  deletion without notice.</b>
  */
 public class Lower extends TreeTranslator {
     protected static final Context.Key<Lower> lowerKey =
         new Context.Key<Lower>();
     public static Lower instance(Context context) {
         Lower instance = context.get(lowerKey);
         if (instance == null)
             instance = new Lower(context);
         return instance;
     }
     private Names names;
     private Log log;
     private Symtab syms;
     private Resolve rs;
     private Check chk;
     private Attr attr;
     private TreeMaker make;
     private DiagnosticPosition make_pos;
     private ClassWriter writer;
     private ClassReader reader;
     private ConstFold cfolder;
     private Target target;
     private Source source;
     private boolean allowEnums;
     private final Name dollarAssertionsDisabled;
     private final Name classDollar;
     private Types types;
     private boolean debugLower;
     private PkgInfo pkginfoOpt;
     protected Lower(Context context) {
         context.put(lowerKey, this);
         names = Names.instance(context);
         log = Log.instance(context);
         syms = Symtab.instance(context);
         rs = Resolve.instance(context);
         chk = Check.instance(context);
         attr = Attr.instance(context);
         make = TreeMaker.instance(context);
         writer = ClassWriter.instance(context);
         reader = ClassReader.instance(context);
         cfolder = ConstFold.instance(context);
         target = Target.instance(context);
         source = Source.instance(context);
         allowEnums = source.allowEnums();
         dollarAssertionsDisabled = names.
             fromString(target.syntheticNameChar() + "assertionsDisabled");
         classDollar = names.
             fromString("class" + target.syntheticNameChar());
         types = Types.instance(context);
         Options options = Options.instance(context);
         debugLower = options.isSet("debuglower");
         pkginfoOpt = PkgInfo.get(options);
     }
     /** The currently enclosing class.
      */
     ClassSymbol currentClass;
     /** A queue of all translated classes.
      */
     ListBuffer<JCTree> translated;
     /** Environment for symbol lookup, set by translateTopLevelClass.
      */
     Env<AttrContext> attrEnv;
     /** A hash table mapping syntax trees to their ending source positions.
      */
     Map<JCTree, Integer> endPositions;
 /**************************************************************************
  * Global mappings
  *************************************************************************/
     /** A hash table mapping local classes to their definitions.
      */
     Map<ClassSymbol, JCClassDecl> classdefs;
     /** A hash table mapping virtual accessed symbols in outer subclasses
      *  to the actually referred symbol in superclasses.
      */
     Map<Symbol,Symbol> actualSymbols;
     /** The current method definition.
      */
     JCMethodDecl currentMethodDef;
     /** The current method symbol.
      */
     MethodSymbol currentMethodSym;
     /** The currently enclosing outermost class definition.
      */
     JCClassDecl outermostClassDef;
     /** The currently enclosing outermost member definition.
      */
     JCTree outermostMemberDef;
     /** A navigator class for assembling a mapping from local class symbols
      *  to class definition trees.
      *  There is only one case; all other cases simply traverse down the tree.
      */
     class ClassMap extends TreeScanner {
         /** All encountered class defs are entered into classdefs table.
          */
         public void visitClassDef(JCClassDecl tree) {
             classdefs.put(tree.sym, tree);
             super.visitClassDef(tree);
         }
     }
     ClassMap classMap = new ClassMap();
     /** Map a class symbol to its definition.
      *  @param c    The class symbol of which we want to determine the definition.
      */
     JCClassDecl classDef(ClassSymbol c) {
         // First lookup the class in the classdefs table.
         JCClassDecl def = classdefs.get(c);
         if (def == null && outermostMemberDef != null) {
             // If this fails, traverse outermost member definition, entering all
             // local classes into classdefs, and try again.
             classMap.scan(outermostMemberDef);
             def = classdefs.get(c);
         }
         if (def == null) {
             // If this fails, traverse outermost class definition, entering all
             // local classes into classdefs, and try again.
             classMap.scan(outermostClassDef);
             def = classdefs.get(c);
         }
         return def;
     }
     /** A hash table mapping class symbols to lists of free variables.
      *  accessed by them. Only free variables of the method immediately containing
      *  a class are associated with that class.
      */
     Map<ClassSymbol,List<VarSymbol>> freevarCache;
     /** A navigator class for collecting the free variables accessed
      *  from a local class.
      *  There is only one case; all other cases simply traverse down the tree.
      */
     class FreeVarCollector extends TreeScanner {
         /** The owner of the local class.
          */
         Symbol owner;
         /** The local class.
          */
         ClassSymbol clazz;
         /** The list of owner's variables accessed from within the local class,
          *  without any duplicates.
          */
         List<VarSymbol> fvs;
         FreeVarCollector(ClassSymbol clazz) {
             this.clazz = clazz;
             this.owner = clazz.owner;
             this.fvs = List.nil();
         }
         /** Add free variable to fvs list unless it is already there.
          */
         private void addFreeVar(VarSymbol v) {
             for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail)
                 if (l.head == v) return;
             fvs = fvs.prepend(v);
         }
         /** Add all free variables of class c to fvs list
          *  unless they are already there.
          */
         private void addFreeVars(ClassSymbol c) {
             List<VarSymbol> fvs = freevarCache.get(c);
             if (fvs != null) {
                 for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail) {
                     addFreeVar(l.head);
                 }
             }
         }
         /** If tree refers to a variable in owner of local class, add it to
          *  free variables list.
          */
         public void visitIdent(JCIdent tree) {
             result = tree;
             visitSymbol(tree.sym);
         }
         // where
         private void visitSymbol(Symbol _sym) {
             Symbol sym = _sym;
             if (sym.kind == VAR || sym.kind == MTH) {
                 while (sym != null && sym.owner != owner)
                     sym = proxies.lookup(proxyName(sym.name)).sym;
                 if (sym != null && sym.owner == owner) {
                     VarSymbol v = (VarSymbol)sym;
                     if (v.getConstValue() == null) {
                         addFreeVar(v);
                     }
                 } else {
                     if (outerThisStack.head != null &&
                         outerThisStack.head != _sym)
                         visitSymbol(outerThisStack.head);
                 }
             }
         }
         /** If tree refers to a class instance creation expression
          *  add all free variables of the freshly created class.
          */
         public void visitNewClass(JCNewClass tree) {
             ClassSymbol c = (ClassSymbol)tree.constructor.owner;
             addFreeVars(c);
             if (tree.encl == null &&
                 c.hasOuterInstance() &&
                 outerThisStack.head != null)
                 visitSymbol(outerThisStack.head);
             super.visitNewClass(tree);
         }
         /** If tree refers to a qualified this or super expression
          *  for anything but the current class, add the outer this
          *  stack as a free variable.
          */
         public void visitSelect(JCFieldAccess tree) {
             if ((tree.name == names._this || tree.name == names._super) &&
                 tree.selected.type.tsym != clazz &&
                 outerThisStack.head != null)
                 visitSymbol(outerThisStack.head);
             super.visitSelect(tree);
         }
         /** If tree refers to a superclass constructor call,
          *  add all free variables of the superclass.
          */
         public void visitApply(JCMethodInvocation tree) {
             if (TreeInfo.name(tree.meth) == names._super) {
                 addFreeVars((ClassSymbol) TreeInfo.symbol(tree.meth).owner);
                 Symbol constructor = TreeInfo.symbol(tree.meth);
                 ClassSymbol c = (ClassSymbol)constructor.owner;
                 if (c.hasOuterInstance() &&
                     tree.meth.getTag() != JCTree.SELECT &&
                     outerThisStack.head != null)
                     visitSymbol(outerThisStack.head);
             }
             super.visitApply(tree);
         }
     }
     /** Return the variables accessed from within a local class, which
      *  are declared in the local class' owner.
      *  (in reverse order of first access).
      */
     List<VarSymbol> freevars(ClassSymbol c)  {
         if ((c.owner.kind & (VAR | MTH)) != 0) {
             List<VarSymbol> fvs = freevarCache.get(c);
             if (fvs == null) {
                 FreeVarCollector collector = new FreeVarCollector(c);
                 collector.scan(classDef(c));
                 fvs = collector.fvs;
                 freevarCache.put(c, fvs);
             }
             return fvs;
         } else {
             return List.nil();
         }
     }
     Map<TypeSymbol,EnumMapping> enumSwitchMap = new LinkedHashMap<TypeSymbol,EnumMapping>();
     EnumMapping mapForEnum(DiagnosticPosition pos, TypeSymbol enumClass) {
         EnumMapping map = enumSwitchMap.get(enumClass);
         if (map == null)
             enumSwitchMap.put(enumClass, map = new EnumMapping(pos, enumClass));
         return map;
     }
     /** This map gives a translation table to be used for enum
      *  switches.
      *
      *  <p>For each enum that appears as the type of a switch
      *  expression, we maintain an EnumMapping to assist in the
      *  translation, as exemplified by the following example:
      *
      *  <p>we translate
      *  <pre>
      *          switch(colorExpression) {
      *          case red: stmt1;
      *          case green: stmt2;
      *          }
      *  </pre>
      *  into
      *  <pre>
      *          switch(Outer$0.$EnumMap$Color[colorExpression.ordinal()]) {
      *          case 1: stmt1;
      *          case 2: stmt2
      *          }
      *  </pre>
      *  with the auxiliary table initialized as follows:
      *  <pre>
      *          class Outer$0 {
      *              synthetic final int[] $EnumMap$Color = new int[Color.values().length];
      *              static {
      *                  try { $EnumMap$Color[red.ordinal()] = 1; } catch (NoSuchFieldError ex) {}
      *                  try { $EnumMap$Color[green.ordinal()] = 2; } catch (NoSuchFieldError ex) {}
      *              }
      *          }
      *  </pre>
      *  class EnumMapping provides mapping data and support methods for this translation.
      */
     class EnumMapping {
         EnumMapping(DiagnosticPosition pos, TypeSymbol forEnum) {
             this.forEnum = forEnum;
             this.values = new LinkedHashMap<VarSymbol,Integer>();
             this.pos = pos;
             Name varName = names
                 .fromString(target.syntheticNameChar() +
                             "SwitchMap" +
                             target.syntheticNameChar() +
                             writer.xClassName(forEnum.type).toString()
                             .replace('/', '.')
                             .replace('.', target.syntheticNameChar()));
             ClassSymbol outerCacheClass = outerCacheClass();
             this.mapVar = new VarSymbol(STATIC | SYNTHETIC | FINAL,
                                         varName,
                                         new ArrayType(syms.intType, syms.arrayClass),
                                         outerCacheClass);
             enterSynthetic(pos, mapVar, outerCacheClass.members());
         }
         DiagnosticPosition pos = null;
         // the next value to use
         int next = 1; // 0 (unused map elements) go to the default label
         // the enum for which this is a map
         final TypeSymbol forEnum;
         // the field containing the map
         final VarSymbol mapVar;
         // the mapped values
         final Map<VarSymbol,Integer> values;
         JCLiteral forConstant(VarSymbol v) {
             Integer result = values.get(v);
             if (result == null)
                 values.put(v, result = next++);
             return make.Literal(result);
         }
         // generate the field initializer for the map
         void translate() {
             make.at(pos.getStartPosition());
             JCClassDecl owner = classDef((ClassSymbol)mapVar.owner);
             // synthetic static final int[] $SwitchMap$Color = new int[Color.values().length];
             MethodSymbol valuesMethod = lookupMethod(pos,
                                                      names.values,
                                                      forEnum.type,
                                                      List.<Type>nil());
             JCExpression size = make // Color.values().length
                 .Select(make.App(make.QualIdent(valuesMethod)),
                         syms.lengthVar);
             JCExpression mapVarInit = make
                 .NewArray(make.Type(syms.intType), List.of(size), null)
                 .setType(new ArrayType(syms.intType, syms.arrayClass));
             // try { $SwitchMap$Color[red.ordinal()] = 1; } catch (java.lang.NoSuchFieldError ex) {}
             ListBuffer<JCStatement> stmts = new ListBuffer<JCStatement>();
             Symbol ordinalMethod = lookupMethod(pos,
                                                 names.ordinal,
                                                 forEnum.type,
                                                 List.<Type>nil());
             List<JCCatch> catcher = List.<JCCatch>nil()
                 .prepend(make.Catch(make.VarDef(new VarSymbol(PARAMETER, names.ex,
                                                               syms.noSuchFieldErrorType,
                                                               syms.noSymbol),
                                                 null),
                                     make.Block(0, List.<JCStatement>nil())));
             for (Map.Entry<VarSymbol,Integer> e : values.entrySet()) {
                 VarSymbol enumerator = e.getKey();
                 Integer mappedValue = e.getValue();
                 JCExpression assign = make
                     .Assign(make.Indexed(mapVar,
                                          make.App(make.Select(make.QualIdent(enumerator),
                                                               ordinalMethod))),
                             make.Literal(mappedValue))
                     .setType(syms.intType);
                 JCStatement exec = make.Exec(assign);
                 JCStatement _try = make.Try(make.Block(0, List.of(exec)), catcher, null);
                 stmts.append(_try);
             }
             owner.defs = owner.defs
                 .prepend(make.Block(STATIC, stmts.toList()))
                 .prepend(make.VarDef(mapVar, mapVarInit));
         }
     }
 /**************************************************************************
  * Tree building blocks
  *************************************************************************/
     /** Equivalent to make.at(pos.getStartPosition()) with side effect of caching
      *  pos as make_pos, for use in diagnostics.
      **/
     TreeMaker make_at(DiagnosticPosition pos) {
         make_pos = pos;
         return make.at(pos);
     }
     /** Make an attributed tree representing a literal. This will be an
      *  Ident node in the case of boolean literals, a Literal node in all
      *  other cases.
      *  @param type       The literal's type.
      *  @param value      The literal's value.
      */
     JCExpression makeLit(Type type, Object value) {
         return make.Literal(type.tag, value).setType(type.constType(value));
     }
     /** Make an attributed tree representing null.
      */
     JCExpression makeNull() {
         return makeLit(syms.botType, null);
     }
     /** Make an attributed class instance creation expression.
      *  @param ctype    The class type.
      *  @param args     The constructor arguments.
      */
     JCNewClass makeNewClass(Type ctype, List<JCExpression> args) {
         JCNewClass tree = make.NewClass(null,
             null, make.QualIdent(ctype.tsym), args, null);
         tree.constructor = rs.resolveConstructor(
             make_pos, attrEnv, ctype, TreeInfo.types(args), null, false, false);
         tree.type = ctype;
         return tree;
     }
     /** Make an attributed unary expression.
      *  @param optag    The operators tree tag.
      *  @param arg      The operator's argument.
      */
     JCUnary makeUnary(int optag, JCExpression arg) {
         JCUnary tree = make.Unary(optag, arg);
         tree.operator = rs.resolveUnaryOperator(
             make_pos, optag, attrEnv, arg.type);
         tree.type = tree.operator.type.getReturnType();
         return tree;
     }
     /** Make an attributed binary expression.
      *  @param optag    The operators tree tag.
      *  @param lhs      The operator's left argument.
      *  @param rhs      The operator's right argument.
      */
     JCBinary makeBinary(int optag, JCExpression lhs, JCExpression rhs) {
         JCBinary tree = make.Binary(optag, lhs, rhs);
         tree.operator = rs.resolveBinaryOperator(
             make_pos, optag, attrEnv, lhs.type, rhs.type);
         tree.type = tree.operator.type.getReturnType();
         return tree;
     }
     /** Make an attributed assignop expression.
      *  @param optag    The operators tree tag.
      *  @param lhs      The operator's left argument.
      *  @param rhs      The operator's right argument.
      */
     JCAssignOp makeAssignop(int optag, JCTree lhs, JCTree rhs) {
         JCAssignOp tree = make.Assignop(optag, lhs, rhs);
         tree.operator = rs.resolveBinaryOperator(
             make_pos, tree.getTag() - JCTree.ASGOffset, attrEnv, lhs.type, rhs.type);
         tree.type = lhs.type;
         return tree;
     }
     /** Convert tree into string object, unless it has already a
      *  reference type..
      */
     JCExpression makeString(JCExpression tree) {
         if (tree.type.tag >= CLASS) {
             return tree;
         } else {
             Symbol valueOfSym = lookupMethod(tree.pos(),
                                              names.valueOf,
                                              syms.stringType,
                                              List.of(tree.type));
             return make.App(make.QualIdent(valueOfSym), List.of(tree));
         }
     }
     /** Create an empty anonymous class definition and enter and complete
      *  its symbol. Return the class definition's symbol.
      *  and create
      *  @param flags    The class symbol's flags
      *  @param owner    The class symbol's owner
      */
     ClassSymbol makeEmptyClass(long flags, ClassSymbol owner) {
         // Create class symbol.
         ClassSymbol c = reader.defineClass(names.empty, owner);
         c.flatname = chk.localClassName(c);
         c.sourcefile = owner.sourcefile;
         c.completer = null;
         c.members_field = new Scope(c);
         c.flags_field = flags;
         ClassType ctype = (ClassType) c.type;
         ctype.supertype_field = syms.objectType;
         ctype.interfaces_field = List.nil();
         JCClassDecl odef = classDef(owner);
         // Enter class symbol in owner scope and compiled table.
         enterSynthetic(odef.pos(), c, owner.members());
         chk.compiled.put(c.flatname, c);
         // Create class definition tree.
         JCClassDecl cdef = make.ClassDef(
             make.Modifiers(flags), names.empty,
             List.<JCTypeParameter>nil(),
             null, List.<JCExpression>nil(), List.<JCTree>nil());
         cdef.sym = c;
         cdef.type = c.type;
         // Append class definition tree to owner's definitions.
         odef.defs = odef.defs.prepend(cdef);
         return c;
     }
 /**************************************************************************
  * Symbol manipulation utilities
  *************************************************************************/
     /** Enter a synthetic symbol in a given scope, but complain if there was already one there.
      *  @param pos           Position for error reporting.
      *  @param sym           The symbol.
      *  @param s             The scope.
      */
     private void enterSynthetic(DiagnosticPosition pos, Symbol sym, Scope s) {
         s.enter(sym);
     }
     /** Create a fresh synthetic name within a given scope - the unique name is
      *  obtained by appending '$' chars at the end of the name until no match
      *  is found.
      *
      * @param name base name
      * @param s scope in which the name has to be unique
      * @return fresh synthetic name
      */
     private Name makeSyntheticName(Name name, Scope s) {
         do {
             name = name.append(
                     target.syntheticNameChar(),
                     names.empty);
         } while (lookupSynthetic(name, s) != null);
         return name;
     }
     /** Check whether synthetic symbols generated during lowering conflict
      *  with user-defined symbols.
      *
      *  @param translatedTrees lowered class trees
      */
     void checkConflicts(List<JCTree> translatedTrees) {
         for (JCTree t : translatedTrees) {
             t.accept(conflictsChecker);
         }
     }
     JCTree.Visitor conflictsChecker = new TreeScanner() {
         TypeSymbol currentClass;
         @Override
         public void visitMethodDef(JCMethodDecl that) {
             chk.checkConflicts(that.pos(), that.sym, currentClass);
             super.visitMethodDef(that);
         }
         @Override
         public void visitVarDef(JCVariableDecl that) {
             if (that.sym.owner.kind == TYP) {
                 chk.checkConflicts(that.pos(), that.sym, currentClass);
             }
             super.visitVarDef(that);
         }
         @Override
         public void visitClassDef(JCClassDecl that) {
             TypeSymbol prevCurrentClass = currentClass;
             currentClass = that.sym;
             try {
                 super.visitClassDef(that);
             }
             finally {
                 currentClass = prevCurrentClass;
             }
         }
     };
     /** Look up a synthetic name in a given scope.
      *  @param scope        The scope.
      *  @param name         The name.
      */
     private Symbol lookupSynthetic(Name name, Scope s) {
         Symbol sym = s.lookup(name).sym;
         return (sym==null || (sym.flags()&SYNTHETIC)==0) ? null : sym;
     }
     /** Look up a method in a given scope.
      */
     private MethodSymbol lookupMethod(DiagnosticPosition pos, Name name, Type qual, List<Type> args) {
         return rs.resolveInternalMethod(pos, attrEnv, qual, name, args, null);
     }
     /** Look up a constructor.
      */
     private MethodSymbol lookupConstructor(DiagnosticPosition pos, Type qual, List<Type> args) {
         return rs.resolveInternalConstructor(pos, attrEnv, qual, args, null);
     }
     /** Look up a field.
      */
     private VarSymbol lookupField(DiagnosticPosition pos, Type qual, Name name) {
         return rs.resolveInternalField(pos, attrEnv, qual, name);
     }
     /** Anon inner classes are used as access constructor tags.
      * accessConstructorTag will use an existing anon class if one is available,
      * and synthethise a class (with makeEmptyClass) if one is not available.
      * However, there is a small possibility that an existing class will not
      * be generated as expected if it is inside a conditional with a constant
      * expression. If that is found to be the case, create an empty class here.
      */
     private void checkAccessConstructorTags() {
         for (List<ClassSymbol> l = accessConstrTags; l.nonEmpty(); l = l.tail) {
             ClassSymbol c = l.head;
             if (isTranslatedClassAvailable(c))
                 continue;
             // Create class definition tree.
             JCClassDecl cdef = make.ClassDef(
                 make.Modifiers(STATIC | SYNTHETIC), names.empty,
                 List.<JCTypeParameter>nil(),
                 null, List.<JCExpression>nil(), List.<JCTree>nil());
             cdef.sym = c;
             cdef.type = c.type;
             // add it to the list of classes to be generated
             translated.append(cdef);
         }
     }
     // where
     private boolean isTranslatedClassAvailable(ClassSymbol c) {
         for (JCTree tree: translated) {
             if (tree.getTag() == JCTree.CLASSDEF
                     && ((JCClassDecl) tree).sym == c) {
                 return true;
             }
         }
         return false;
     }
 /**************************************************************************
  * Access methods
  *************************************************************************/
     /** Access codes for dereferencing, assignment,
      *  and pre/post increment/decrement.
      *  Access codes for assignment operations are determined by method accessCode
      *  below.
      *
      *  All access codes for accesses to the current class are even.
      *  If a member of the superclass should be accessed instead (because
      *  access was via a qualified super), add one to the corresponding code
      *  for the current class, making the number odd.
      *  This numbering scheme is used by the backend to decide whether
      *  to issue an invokevirtual or invokespecial call.
      *
      *  @see Gen.visitSelect(Select tree)
      */
     private static final int
         DEREFcode = 0,
         ASSIGNcode = 2,
         PREINCcode = 4,
         PREDECcode = 6,
         POSTINCcode = 8,
         POSTDECcode = 10,
         FIRSTASGOPcode = 12;
     /** Number of access codes
      */
     private static final int NCODES = accessCode(ByteCodes.lushrl) + 2;
     /** A mapping from symbols to their access numbers.
      */
     private Map<Symbol,Integer> accessNums;
     /** A mapping from symbols to an array of access symbols, indexed by
      *  access code.
      */
     private Map<Symbol,MethodSymbol[]> accessSyms;
     /** A mapping from (constructor) symbols to access constructor symbols.
      */
     private Map<Symbol,MethodSymbol> accessConstrs;
     /** A list of all class symbols used for access constructor tags.
      */
     private List<ClassSymbol> accessConstrTags;
     /** A queue for all accessed symbols.
      */
     private ListBuffer<Symbol> accessed;
     /** Map bytecode of binary operation to access code of corresponding
      *  assignment operation. This is always an even number.
      */
     private static int accessCode(int bytecode) {
         if (ByteCodes.iadd <= bytecode && bytecode <= ByteCodes.lxor)
             return (bytecode - iadd) * 2 + FIRSTASGOPcode;
         else if (bytecode == ByteCodes.string_add)
             return (ByteCodes.lxor + 1 - iadd) * 2 + FIRSTASGOPcode;
         else if (ByteCodes.ishll <= bytecode && bytecode <= ByteCodes.lushrl)
             return (bytecode - ishll + ByteCodes.lxor + 2 - iadd) * 2 + FIRSTASGOPcode;
         else
             return -1;
     }
     /** return access code for identifier,
      *  @param tree     The tree representing the identifier use.
      *  @param enclOp   The closest enclosing operation node of tree,
      *                  null if tree is not a subtree of an operation.
      */
     private static int accessCode(JCTree tree, JCTree enclOp) {
         if (enclOp == null)
             return DEREFcode;
         else if (enclOp.getTag() == JCTree.ASSIGN &&
                  tree == TreeInfo.skipParens(((JCAssign) enclOp).lhs))
             return ASSIGNcode;
         else if (JCTree.PREINC <= enclOp.getTag() && enclOp.getTag() <= JCTree.POSTDEC &&
                  tree == TreeInfo.skipParens(((JCUnary) enclOp).arg))
             return (enclOp.getTag() - JCTree.PREINC) * 2 + PREINCcode;
         else if (JCTree.BITOR_ASG <= enclOp.getTag() && enclOp.getTag() <= JCTree.MOD_ASG &&
                  tree == TreeInfo.skipParens(((JCAssignOp) enclOp).lhs))
             return accessCode(((OperatorSymbol) ((JCAssignOp) enclOp).operator).opcode);
         else
             return DEREFcode;
     }
     /** Return binary operator that corresponds to given access code.
      */
     private OperatorSymbol binaryAccessOperator(int acode) {
         for (Scope.Entry e = syms.predefClass.members().elems;
              e != null;
              e = e.sibling) {
             if (e.sym instanceof OperatorSymbol) {
                 OperatorSymbol op = (OperatorSymbol)e.sym;
                 if (accessCode(op.opcode) == acode) return op;
             }
         }
         return null;
     }
     /** Return tree tag for assignment operation corresponding
      *  to given binary operator.
      */
     private static int treeTag(OperatorSymbol operator) {
         switch (operator.opcode) {
         case ByteCodes.ior: case ByteCodes.lor:
             return JCTree.BITOR_ASG;
         case ByteCodes.ixor: case ByteCodes.lxor:
             return JCTree.BITXOR_ASG;
         case ByteCodes.iand: case ByteCodes.land:
             return JCTree.BITAND_ASG;
         case ByteCodes.ishl: case ByteCodes.lshl:
         case ByteCodes.ishll: case ByteCodes.lshll:
             return JCTree.SL_ASG;
         case ByteCodes.ishr: case ByteCodes.lshr:
         case ByteCodes.ishrl: case ByteCodes.lshrl:
             return JCTree.SR_ASG;
         case ByteCodes.iushr: case ByteCodes.lushr:
         case ByteCodes.iushrl: case ByteCodes.lushrl:
             return JCTree.USR_ASG;
         case ByteCodes.iadd: case ByteCodes.ladd:
         case ByteCodes.fadd: case ByteCodes.dadd:
         case ByteCodes.string_add:
             return JCTree.PLUS_ASG;
         case ByteCodes.isub: case ByteCodes.lsub:
         case ByteCodes.fsub: case ByteCodes.dsub:
             return JCTree.MINUS_ASG;
         case ByteCodes.imul: case ByteCodes.lmul:
         case ByteCodes.fmul: case ByteCodes.dmul:
             return JCTree.MUL_ASG;
         case ByteCodes.idiv: case ByteCodes.ldiv:
         case ByteCodes.fdiv: case ByteCodes.ddiv:
             return JCTree.DIV_ASG;
         case ByteCodes.imod: case ByteCodes.lmod:
         case ByteCodes.fmod: case ByteCodes.dmod:
             return JCTree.MOD_ASG;
         default:
             throw new AssertionError();
         }
     }
     /** The name of the access method with number `anum' and access code `acode'.
      */
     Name accessName(int anum, int acode) {
         return names.fromString(
             "access" + target.syntheticNameChar() + anum + acode / 10 + acode % 10);
     }
     /** Return access symbol for a private or protected symbol from an inner class.
      *  @param sym        The accessed private symbol.
      *  @param tree       The accessing tree.
      *  @param enclOp     The closest enclosing operation node of tree,
      *                    null if tree is not a subtree of an operation.
      *  @param protAccess Is access to a protected symbol in another
      *                    package?
      *  @param refSuper   Is access via a (qualified) C.super?
      */
     MethodSymbol accessSymbol(Symbol sym, JCTree tree, JCTree enclOp,
                               boolean protAccess, boolean refSuper) {
         ClassSymbol accOwner = refSuper && protAccess
             // For access via qualified super (T.super.x), place the
             // access symbol on T.
             ? (ClassSymbol)((JCFieldAccess) tree).selected.type.tsym
             // Otherwise pretend that the owner of an accessed
             // protected symbol is the enclosing class of the current
             // class which is a subclass of the symbol's owner.
             : accessClass(sym, protAccess, tree);
         Symbol vsym = sym;
         if (sym.owner != accOwner) {
             vsym = sym.clone(accOwner);
             actualSymbols.put(vsym, sym);
         }
         Integer anum              // The access number of the access method.
             = accessNums.get(vsym);
         if (anum == null) {
             anum = accessed.length();
             accessNums.put(vsym, anum);
             accessSyms.put(vsym, new MethodSymbol[NCODES]);
             accessed.append(vsym);
             // System.out.println("accessing " + vsym + " in " + vsym.location());
         }
         int acode;                // The access code of the access method.
         List<Type> argtypes;      // The argument types of the access method.
         Type restype;             // The result type of the access method.
         List<Type> thrown;        // The thrown exceptions of the access method.
         switch (vsym.kind) {
         case VAR:
             acode = accessCode(tree, enclOp);
             if (acode >= FIRSTASGOPcode) {
                 OperatorSymbol operator = binaryAccessOperator(acode);
                 if (operator.opcode == string_add)
                     argtypes = List.of(syms.objectType);
                 else
                     argtypes = operator.type.getParameterTypes().tail;
             } else if (acode == ASSIGNcode)
                 argtypes = List.of(vsym.erasure(types));
             else
                 argtypes = List.nil();
             restype = vsym.erasure(types);
             thrown = List.nil();
             break;
         case MTH:
             acode = DEREFcode;
             argtypes = vsym.erasure(types).getParameterTypes();
             restype = vsym.erasure(types).getReturnType();
             thrown = vsym.type.getThrownTypes();
             break;
         default:
             throw new AssertionError();
         }
         // For references via qualified super, increment acode by one,
         // making it odd.
         if (protAccess && refSuper) acode++;
         // Instance access methods get instance as first parameter.
         // For protected symbols this needs to be the instance as a member
         // of the type containing the accessed symbol, not the class
         // containing the access method.
         if ((vsym.flags() & STATIC) == 0) {
             argtypes = argtypes.prepend(vsym.owner.erasure(types));
         }
         MethodSymbol[] accessors = accessSyms.get(vsym);
         MethodSymbol accessor = accessors[acode];
         if (accessor == null) {
             accessor = new MethodSymbol(
                 STATIC | SYNTHETIC,
                 accessName(anum.intValue(), acode),
                 new MethodType(argtypes, restype, thrown, syms.methodClass),
                 accOwner);
             enterSynthetic(tree.pos(), accessor, accOwner.members());
             accessors[acode] = accessor;
         }
         return accessor;
     }
     /** The qualifier to be used for accessing a symbol in an outer class.
      *  This is either C.sym or C.this.sym, depending on whether or not
      *  sym is static.
      *  @param sym   The accessed symbol.
      */
     JCExpression accessBase(DiagnosticPosition pos, Symbol sym) {
         return (sym.flags() & STATIC) != 0
             ? access(make.at(pos.getStartPosition()).QualIdent(sym.owner))
             : makeOwnerThis(pos, sym, true);
     }
     /** Do we need an access method to reference private symbol?
      */
     boolean needsPrivateAccess(Symbol sym) {
         if ((sym.flags() & PRIVATE) == 0 || sym.owner == currentClass) {
             return false;
         } else if (sym.name == names.init && (sym.owner.owner.kind & (VAR | MTH)) != 0) {
             // private constructor in local class: relax protection
             sym.flags_field &= ~PRIVATE;
             return false;
         } else {
             return true;
         }
     }
     /** Do we need an access method to reference symbol in other package?
      */
     boolean needsProtectedAccess(Symbol sym, JCTree tree) {
         if ((sym.flags() & PROTECTED) == 0 ||
             sym.owner.owner == currentClass.owner || // fast special case
             sym.packge() == currentClass.packge())
             return false;
         if (!currentClass.isSubClass(sym.owner, types))
             return true;
         if ((sym.flags() & STATIC) != 0 ||
             tree.getTag() != JCTree.SELECT ||
             TreeInfo.name(((JCFieldAccess) tree).selected) == names._super)
             return false;
         return !((JCFieldAccess) tree).selected.type.tsym.isSubClass(currentClass, types);
     }
     /** The class in which an access method for given symbol goes.
      *  @param sym        The access symbol
      *  @param protAccess Is access to a protected symbol in another
      *                    package?
      */
     ClassSymbol accessClass(Symbol sym, boolean protAccess, JCTree tree) {
         if (protAccess) {
             Symbol qualifier = null;
             ClassSymbol c = currentClass;
             if (tree.getTag() == JCTree.SELECT && (sym.flags() & STATIC) == 0) {
                 qualifier = ((JCFieldAccess) tree).selected.type.tsym;
                 while (!qualifier.isSubClass(c, types)) {
                     c = c.owner.enclClass();
                 }
                 return c;
             } else {
                 while (!c.isSubClass(sym.owner, types)) {
                     c = c.owner.enclClass();
                 }
             }
             return c;
         } else {
             // the symbol is private
             return sym.owner.enclClass();
         }
     }
     /** Ensure that identifier is accessible, return tree accessing the identifier.
      *  @param sym      The accessed symbol.
      *  @param tree     The tree referring to the symbol.
      *  @param enclOp   The closest enclosing operation node of tree,
      *                  null if tree is not a subtree of an operation.
      *  @param refSuper Is access via a (qualified) C.super?
      */
     JCExpression access(Symbol sym, JCExpression tree, JCExpression enclOp, boolean refSuper) {
         // Access a free variable via its proxy, or its proxy's proxy
         while (sym.kind == VAR && sym.owner.kind == MTH &&
             sym.owner.enclClass() != currentClass) {
             // A constant is replaced by its constant value.
             Object cv = ((VarSymbol)sym).getConstValue();
             if (cv != null) {
                 make.at(tree.pos);
                 return makeLit(sym.type, cv);
             }
             // Otherwise replace the variable by its proxy.
             sym = proxies.lookup(proxyName(sym.name)).sym;
             Assert.check(sym != null && (sym.flags_field & FINAL) != 0);
             tree = make.at(tree.pos).Ident(sym);
         }
         JCExpression base = (tree.getTag() == JCTree.SELECT) ? ((JCFieldAccess) tree).selected : null;
         switch (sym.kind) {
         case TYP:
             if (sym.owner.kind != PCK) {
                 // Convert type idents to
                 // <flat name> or <package name> . <flat name>
                 Name flatname = Convert.shortName(sym.flatName());
                 while (base != null &&
                        TreeInfo.symbol(base) != null &&
                        TreeInfo.symbol(base).kind != PCK) {
                     base = (base.getTag() == JCTree.SELECT)
                         ? ((JCFieldAccess) base).selected
                         : null;
                 }
                 if (tree.getTag() == JCTree.IDENT) {
                     ((JCIdent) tree).name = flatname;
                 } else if (base == null) {
                     tree = make.at(tree.pos).Ident(sym);
                     ((JCIdent) tree).name = flatname;
                 } else {
                     ((JCFieldAccess) tree).selected = base;
                     ((JCFieldAccess) tree).name = flatname;
                 }
             }
             break;
         case MTH: case VAR:
             if (sym.owner.kind == TYP) {
                 // Access methods are required for
                 //  - private members,
                 //  - protected members in a superclass of an
                 //    enclosing class contained in another package.
                 //  - all non-private members accessed via a qualified super.
                 boolean protAccess = refSuper && !needsPrivateAccess(sym)
                     || needsProtectedAccess(sym, tree);
                 boolean accReq = protAccess || needsPrivateAccess(sym);
                 // A base has to be supplied for
                 //  - simple identifiers accessing variables in outer classes.
                 boolean baseReq =
                     base == null &&
                     sym.owner != syms.predefClass &&
                     !sym.isMemberOf(currentClass, types);
                 if (accReq || baseReq) {
                     make.at(tree.pos);
                     // Constants are replaced by their constant value.
                     if (sym.kind == VAR) {
                         Object cv = ((VarSymbol)sym).getConstValue();
                         if (cv != null) return makeLit(sym.type, cv);
                     }
                     // Private variables and methods are replaced by calls
                     // to their access methods.
                     if (accReq) {
                         List<JCExpression> args = List.nil();
                         if ((sym.flags() & STATIC) == 0) {
                             // Instance access methods get instance
                             // as first parameter.
                             if (base == null)
                                 base = makeOwnerThis(tree.pos(), sym, true);
                             args = args.prepend(base);
                             base = null;   // so we don't duplicate code
                         }
                         Symbol access = accessSymbol(sym, tree,
                                                      enclOp, protAccess,
                                                      refSuper);
                         JCExpression receiver = make.Select(
                             base != null ? base : make.QualIdent(access.owner),
                             access);
                         return make.App(receiver, args);
                     // Other accesses to members of outer classes get a
                     // qualifier.
                     } else if (baseReq) {
                         return make.at(tree.pos).Select(
                             accessBase(tree.pos(), sym), sym).setType(tree.type);
                     }
                 }
             }
         }
         return tree;
     }
     /** Ensure that identifier is accessible, return tree accessing the identifier.
      *  @param tree     The identifier tree.
      */
     JCExpression access(JCExpression tree) {
         Symbol sym = TreeInfo.symbol(tree);
         return sym == null ? tree : access(sym, tree, null, false);
     }
     /** Return access constructor for a private constructor,
      *  or the constructor itself, if no access constructor is needed.
      *  @param pos       The position to report diagnostics, if any.
      *  @param constr    The private constructor.
      */
     Symbol accessConstructor(DiagnosticPosition pos, Symbol constr) {
         if (needsPrivateAccess(constr)) {
             ClassSymbol accOwner = constr.owner.enclClass();
             MethodSymbol aconstr = accessConstrs.get(constr);
             if (aconstr == null) {
                 List<Type> argtypes = constr.type.getParameterTypes();
                 if ((accOwner.flags_field & ENUM) != 0)
                     argtypes = argtypes
                         .prepend(syms.intType)
                         .prepend(syms.stringType);
                 aconstr = new MethodSymbol(
                     SYNTHETIC,
                     names.init,
                     new MethodType(
                         argtypes.append(
                             accessConstructorTag().erasure(types)),
                         constr.type.getReturnType(),
                         constr.type.getThrownTypes(),
                         syms.methodClass),
                     accOwner);
                 enterSynthetic(pos, aconstr, accOwner.members());
                 accessConstrs.put(constr, aconstr);
                 accessed.append(constr);
             }
             return aconstr;
         } else {
             return constr;
         }
     }
     /** Return an anonymous class nested in this toplevel class.
      */
     ClassSymbol accessConstructorTag() {
         ClassSymbol topClass = currentClass.outermostClass();
         Name flatname = names.fromString("" + topClass.getQualifiedName() +
                                          target.syntheticNameChar() +
                                          "1");
         ClassSymbol ctag = chk.compiled.get(flatname);
         if (ctag == null)
             ctag = makeEmptyClass(STATIC | SYNTHETIC, topClass);
         // keep a record of all tags, to verify that all are generated as required
         accessConstrTags = accessConstrTags.prepend(ctag);
         return ctag;
     }
     /** Add all required access methods for a private symbol to enclosing class.
      *  @param sym       The symbol.
      */
     void makeAccessible(Symbol sym) {
         JCClassDecl cdef = classDef(sym.owner.enclClass());
         if (cdef == null) Assert.error("class def not found: " + sym + " in " + sym.owner);
         if (sym.name == names.init) {
             cdef.defs = cdef.defs.prepend(
                 accessConstructorDef(cdef.pos, sym, accessConstrs.get(sym)));
         } else {
             MethodSymbol[] accessors = accessSyms.get(sym);
             for (int i = 0; i < NCODES; i++) {
                 if (accessors[i] != null)
                     cdef.defs = cdef.defs.prepend(
                         accessDef(cdef.pos, sym, accessors[i], i));
             }
         }
     }
     /** Construct definition of an access method.
      *  @param pos        The source code position of the definition.
      *  @param vsym       The private or protected symbol.
      *  @param accessor   The access method for the symbol.
      *  @param acode      The access code.
      */
     JCTree accessDef(int pos, Symbol vsym, MethodSymbol accessor, int acode) {
 //      System.err.println("access " + vsym + " with " + accessor);//DEBUG
         currentClass = vsym.owner.enclClass();
         make.at(pos);
         JCMethodDecl md = make.MethodDef(accessor, null);
         // Find actual symbol
         Symbol sym = actualSymbols.get(vsym);
         if (sym == null) sym = vsym;
         JCExpression ref;           // The tree referencing the private symbol.
         List<JCExpression> args;    // Any additional arguments to be passed along.
         if ((sym.flags() & STATIC) != 0) {
             ref = make.Ident(sym);
             args = make.Idents(md.params);
         } else {
             ref = make.Select(make.Ident(md.params.head), sym);
             args = make.Idents(md.params.tail);
         }
         JCStatement stat;          // The statement accessing the private symbol.
         if (sym.kind == VAR) {
             // Normalize out all odd access codes by taking floor modulo 2:
             int acode1 = acode - (acode & 1);
             JCExpression expr;      // The access method's return value.
             switch (acode1) {
             case DEREFcode:
                 expr = ref;
                 break;
             case ASSIGNcode:
                 expr = make.Assign(ref, args.head);
                 break;
             case PREINCcode: case POSTINCcode: case PREDECcode: case POSTDECcode:
                 expr = makeUnary(
                     ((acode1 - PREINCcode) >> 1) + JCTree.PREINC, ref);
                 break;
             default:
                 expr = make.Assignop(
                     treeTag(binaryAccessOperator(acode1)), ref, args.head);
                 ((JCAssignOp) expr).operator = binaryAccessOperator(acode1);
             }
             stat = make.Return(expr.setType(sym.type));
         } else {
             stat = make.Call(make.App(ref, args));
         }
         md.body = make.Block(0, List.of(stat));
         // Make sure all parameters, result types and thrown exceptions
         // are accessible.
         for (List<JCVariableDecl> l = md.params; l.nonEmpty(); l = l.tail)
             l.head.vartype = access(l.head.vartype);
         md.restype = access(md.restype);
         for (List<JCExpression> l = md.thrown; l.nonEmpty(); l = l.tail)
             l.head = access(l.head);
         return md;
     }
     /** Construct definition of an access constructor.
      *  @param pos        The source code position of the definition.
      *  @param constr     The private constructor.
      *  @param accessor   The access method for the constructor.
      */
     JCTree accessConstructorDef(int pos, Symbol constr, MethodSymbol accessor) {
         make.at(pos);
         JCMethodDecl md = make.MethodDef(accessor,
                                       accessor.externalType(types),
                                       null);
         JCIdent callee = make.Ident(names._this);
         callee.sym = constr;
         callee.type = constr.type;
         md.body =
             make.Block(0, List.<JCStatement>of(
                 make.Call(
                     make.App(
                         callee,
                         make.Idents(md.params.reverse().tail.reverse())))));
         return md;
     }
 /**************************************************************************
  * Free variables proxies and this$n
  *************************************************************************/
     /** A scope containing all free variable proxies for currently translated
      *  class, as well as its this$n symbol (if needed).
      *  Proxy scopes are nested in the same way classes are.
      *  Inside a constructor, proxies and any this$n symbol are duplicated
      *  in an additional innermost scope, where they represent the constructor
      *  parameters.
      */
     Scope proxies;
     /** A scope containing all unnamed resource variables/saved
      *  exception variables for translated TWR blocks
      */
     Scope twrVars;
     /** A stack containing the this$n field of the currently translated
      *  classes (if needed) in innermost first order.
      *  Inside a constructor, proxies and any this$n symbol are duplicated
      *  in an additional innermost scope, where they represent the constructor
      *  parameters.
      */
     List<VarSymbol> outerThisStack;
     /** The name of a free variable proxy.
      */
     Name proxyName(Name name) {
         return names.fromString("val" + target.syntheticNameChar() + name);
     }
     /** Proxy definitions for all free variables in given list, in reverse order.
      *  @param pos        The source code position of the definition.
      *  @param freevars   The free variables.
      *  @param owner      The class in which the definitions go.
      */
     List<JCVariableDecl> freevarDefs(int pos, List<VarSymbol> freevars, Symbol owner) {
         long flags = FINAL | SYNTHETIC;
         if (owner.kind == TYP &&
             target.usePrivateSyntheticFields())
             flags |= PRIVATE;
         List<JCVariableDecl> defs = List.nil();
         for (List<VarSymbol> l = freevars; l.nonEmpty(); l = l.tail) {
             VarSymbol v = l.head;
             VarSymbol proxy = new VarSymbol(
                 flags, proxyName(v.name), v.erasure(types), owner);
             proxies.enter(proxy);
             JCVariableDecl vd = make.at(pos).VarDef(proxy, null);
             vd.vartype = access(vd.vartype);
             defs = defs.prepend(vd);
         }
         return defs;
     }
     /** The name of a this$n field
      *  @param type   The class referenced by the this$n field
      */
     Name outerThisName(Type type, Symbol owner) {
         Type t = type.getEnclosingType();
         int nestingLevel = 0;
         while (t.tag == CLASS) {
             t = t.getEnclosingType();
             nestingLevel++;
         }
         Name result = names.fromString("this" + target.syntheticNameChar() + nestingLevel);
         while (owner.kind == TYP && ((ClassSymbol)owner).members().lookup(result).scope != null)
             result = names.fromString(result.toString() + target.syntheticNameChar());
         return result;
     }
     /** Definition for this$n field.
      *  @param pos        The source code position of the definition.
      *  @param owner      The class in which the definition goes.
      */
     JCVariableDecl outerThisDef(int pos, Symbol owner) {
         long flags = FINAL | SYNTHETIC;
         if (owner.kind == TYP &&
             target.usePrivateSyntheticFields())
             flags |= PRIVATE;
         Type target = types.erasure(owner.enclClass().type.getEnclosingType());
         VarSymbol outerThis = new VarSymbol(
             flags, outerThisName(target, owner), target, owner);
         outerThisStack = outerThisStack.prepend(outerThis);
         JCVariableDecl vd = make.at(pos).VarDef(outerThis, null);
         vd.vartype = access(vd.vartype);
         return vd;
     }
     /** Return a list of trees that load the free variables in given list,
      *  in reverse order.
      *  @param pos          The source code position to be used for the trees.
      *  @param freevars     The list of free variables.
      */
     List<JCExpression> loadFreevars(DiagnosticPosition pos, List<VarSymbol> freevars) {
         List<JCExpression> args = List.nil();
         for (List<VarSymbol> l = freevars; l.nonEmpty(); l = l.tail)
             args = args.prepend(loadFreevar(pos, l.head));
         return args;
     }
 //where
         JCExpression loadFreevar(DiagnosticPosition pos, VarSymbol v) {
             return access(v, make.at(pos).Ident(v), null, false);
         }
     /** Construct a tree simulating the expression <C.this>.
      *  @param pos           The source code position to be used for the tree.
      *  @param c             The qualifier class.
      */
     JCExpression makeThis(DiagnosticPosition pos, TypeSymbol c) {
         if (currentClass == c) {
             // in this case, `this' works fine
             return make.at(pos).This(c.erasure(types));
         } else {
             // need to go via this$n
             return makeOuterThis(pos, c);
         }
     }
     /**
      * Optionally replace a try statement with the desugaring of a
      * try-with-resources statement.  The canonical desugaring of
      *
      * try ResourceSpecification
      *   Block
      *
      * is
      *
      * {
      *   final VariableModifiers_minus_final R #resource = Expression;
      *   Throwable #primaryException = null;
      *
      *   try ResourceSpecificationtail
      *     Block
      *   catch (Throwable #t) {
      *     #primaryException = t;
      *     throw #t;
      *   } finally {
      *     if (#resource != null) {
      *       if (#primaryException != null) {
      *         try {
      *           #resource.close();
      *         } catch(Throwable #suppressedException) {
      *           #primaryException.addSuppressed(#suppressedException);
      *         }
      *       } else {
      *         #resource.close();
      *       }
      *     }
      *   }
      *
      * @param tree  The try statement to inspect.
      * @return A a desugared try-with-resources tree, or the original
      * try block if there are no resources to manage.
      */
     JCTree makeTwrTry(JCTry tree) {
         make_at(tree.pos());
         twrVars = twrVars.dup();
         JCBlock twrBlock = makeTwrBlock(tree.resources, tree.body, 0);
         if (tree.catchers.isEmpty() && tree.finalizer == null)
             result = translate(twrBlock);
         else
             result = translate(make.Try(twrBlock, tree.catchers, tree.finalizer));
         twrVars = twrVars.leave();
         return result;
     }
     private JCBlock makeTwrBlock(List<JCTree> resources, JCBlock block, int depth) {
         if (resources.isEmpty())
             return block;
         // Add resource declaration or expression to block statements
         ListBuffer<JCStatement> stats = new ListBuffer<JCStatement>();
         JCTree resource = resources.head;
         JCExpression expr = null;
         if (resource instanceof JCVariableDecl) {
             JCVariableDecl var = (JCVariableDecl) resource;
             expr = make.Ident(var.sym).setType(resource.type);
             stats.add(var);
         } else {
             Assert.check(resource instanceof JCExpression);
             VarSymbol syntheticTwrVar =
             new VarSymbol(SYNTHETIC | FINAL,
                           makeSyntheticName(names.fromString("twrVar" +
                                            depth), twrVars),
                           (resource.type.tag == TypeTags.BOT) ?
                           syms.autoCloseableType : resource.type,
                           currentMethodSym);
             twrVars.enter(syntheticTwrVar);
             JCVariableDecl syntheticTwrVarDecl =
                 make.VarDef(syntheticTwrVar, (JCExpression)resource);
             expr = (JCExpression)make.Ident(syntheticTwrVar);
             stats.add(syntheticTwrVarDecl);
         }
         // Add primaryException declaration
         VarSymbol primaryException =
             new VarSymbol(SYNTHETIC,
                           makeSyntheticName(names.fromString("primaryException" +
                           depth), twrVars),
                           syms.throwableType,
                           currentMethodSym);
         twrVars.enter(primaryException);
         JCVariableDecl primaryExceptionTreeDecl = make.VarDef(primaryException, makeNull());
         stats.add(primaryExceptionTreeDecl);
         // Create catch clause that saves exception and then rethrows it
         VarSymbol param =
             new VarSymbol(FINAL|SYNTHETIC,
                           names.fromString("t" +
                                            target.syntheticNameChar()),
                           syms.throwableType,
                           currentMethodSym);
         JCVariableDecl paramTree = make.VarDef(param, null);
         JCStatement assign = make.Assignment(primaryException, make.Ident(param));
         JCStatement rethrowStat = make.Throw(make.Ident(param));
         JCBlock catchBlock = make.Block(0L, List.<JCStatement>of(assign, rethrowStat));
         JCCatch catchClause = make.Catch(paramTree, catchBlock);
         int oldPos = make.pos;
         make.at(TreeInfo.endPos(block));
         JCBlock finallyClause = makeTwrFinallyClause(primaryException, expr);
         make.at(oldPos);
         JCTry outerTry = make.Try(makeTwrBlock(resources.tail, block, depth + 1),
                                   List.<JCCatch>of(catchClause),
                                   finallyClause);
         stats.add(outerTry);
         return make.Block(0L, stats.toList());
     }
     private JCBlock makeTwrFinallyClause(Symbol primaryException, JCExpression resource) {
         // primaryException.addSuppressed(catchException);
         VarSymbol catchException =
             new VarSymbol(0, make.paramName(2),
                           syms.throwableType,
                           currentMethodSym);
         JCStatement addSuppressionStatement =
             make.Exec(makeCall(make.Ident(primaryException),
                                names.addSuppressed,
                                List.<JCExpression>of(make.Ident(catchException))));
         // try { resource.close(); } catch (e) { primaryException.addSuppressed(e); }
         JCBlock tryBlock =
             make.Block(0L, List.<JCStatement>of(makeResourceCloseInvocation(resource)));
         JCVariableDecl catchExceptionDecl = make.VarDef(catchException, null);
         JCBlock catchBlock = make.Block(0L, List.<JCStatement>of(addSuppressionStatement));
         List<JCCatch> catchClauses = List.<JCCatch>of(make.Catch(catchExceptionDecl, catchBlock));
         JCTry tryTree = make.Try(tryBlock, catchClauses, null);
         // if (primaryException != null) {try...} else resourceClose;
         JCIf closeIfStatement = make.If(makeNonNullCheck(make.Ident(primaryException)),
                                         tryTree,
                                         makeResourceCloseInvocation(resource));
         // if (#resource != null) { if (primaryException ...  }
         return make.Block(0L,
                           List.<JCStatement>of(make.If(makeNonNullCheck(resource),
                                                        closeIfStatement,
                                                        null)));
     }
     private JCStatement makeResourceCloseInvocation(JCExpression resource) {
         // create resource.close() method invocation
         JCExpression resourceClose = makeCall(resource,
                                               names.close,
                                               List.<JCExpression>nil());
         return make.Exec(resourceClose);
     }
     private JCExpression makeNonNullCheck(JCExpression expression) {
         return makeBinary(JCTree.NE, expression, makeNull());
     }
     /** Construct a tree that represents the outer instance
      *  <C.this>. Never pick the current `this'.
      *  @param pos           The source code position to be used for the tree.
      *  @param c             The qualifier class.
      */
     JCExpression makeOuterThis(DiagnosticPosition pos, TypeSymbol c) {
         List<VarSymbol> ots = outerThisStack;
         if (ots.isEmpty()) {
             log.error(pos, "no.encl.instance.of.type.in.scope", c);
             Assert.error();
             return makeNull();
         }
         VarSymbol ot = ots.head;
         JCExpression tree = access(make.at(pos).Ident(ot));
         TypeSymbol otc = ot.type.tsym;
         while (otc != c) {
             do {
                 ots = ots.tail;
                 if (ots.isEmpty()) {
                     log.error(pos,
                               "no.encl.instance.of.type.in.scope",
                               c);
                     Assert.error(); // should have been caught in Attr
                     return tree;
                 }
                 ot = ots.head;
             } while (ot.owner != otc);
             if (otc.owner.kind != PCK && !otc.hasOuterInstance()) {
                 chk.earlyRefError(pos, c);
                 Assert.error(); // should have been caught in Attr
                 return makeNull();
             }
             tree = access(make.at(pos).Select(tree, ot));
             otc = ot.type.tsym;
         }
         return tree;
     }
     /** Construct a tree that represents the closest outer instance
      *  <C.this> such that the given symbol is a member of C.
      *  @param pos           The source code position to be used for the tree.
      *  @param sym           The accessed symbol.
      *  @param preciseMatch  should we accept a type that is a subtype of
      *                       sym's owner, even if it doesn't contain sym
      *                       due to hiding, overriding, or non-inheritance
      *                       due to protection?
      */
     JCExpression makeOwnerThis(DiagnosticPosition pos, Symbol sym, boolean preciseMatch) {
         Symbol c = sym.owner;
         if (preciseMatch ? sym.isMemberOf(currentClass, types)
                          : currentClass.isSubClass(sym.owner, types)) {
             // in this case, `this' works fine
             return make.at(pos).This(c.erasure(types));
         } else {
             // need to go via this$n
             return makeOwnerThisN(pos, sym, preciseMatch);
         }
     }
     /**
      * Similar to makeOwnerThis but will never pick "this".
      */
     JCExpression makeOwnerThisN(DiagnosticPosition pos, Symbol sym, boolean preciseMatch) {
         Symbol c = sym.owner;
         List<VarSymbol> ots = outerThisStack;
         if (ots.isEmpty()) {
             log.error(pos, "no.encl.instance.of.type.in.scope", c);
             Assert.error();
             return makeNull();
         }
         VarSymbol ot = ots.head;
         JCExpression tree = access(make.at(pos).Ident(ot));
         TypeSymbol otc = ot.type.tsym;
         while (!(preciseMatch ? sym.isMemberOf(otc, types) : otc.isSubClass(sym.owner, types))) {
             do {
                 ots = ots.tail;
                 if (ots.isEmpty()) {
                     log.error(pos,
                         "no.encl.instance.of.type.in.scope",
                         c);
                     Assert.error();
                     return tree;
                 }
                 ot = ots.head;
             } while (ot.owner != otc);
             tree = access(make.at(pos).Select(tree, ot));
             otc = ot.type.tsym;
         }
         return tree;
     }
     /** Return tree simulating the assignment <this.name = name>, where
      *  name is the name of a free variable.
      */
     JCStatement initField(int pos, Name name) {
         Scope.Entry e = proxies.lookup(name);
         Symbol rhs = e.sym;
         Assert.check(rhs.owner.kind == MTH);
         Symbol lhs = e.next().sym;
         Assert.check(rhs.owner.owner == lhs.owner);
         make.at(pos);
         return
             make.Exec(
                 make.Assign(
                     make.Select(make.This(lhs.owner.erasure(types)), lhs),
                     make.Ident(rhs)).setType(lhs.erasure(types)));
     }
     /** Return tree simulating the assignment <this.this$n = this$n>.
      */
     JCStatement initOuterThis(int pos) {
         VarSymbol rhs = outerThisStack.head;
         Assert.check(rhs.owner.kind == MTH);
         VarSymbol lhs = outerThisStack.tail.head;
         Assert.check(rhs.owner.owner == lhs.owner);
         make.at(pos);
         return
             make.Exec(
                 make.Assign(
                     make.Select(make.This(lhs.owner.erasure(types)), lhs),
                     make.Ident(rhs)).setType(lhs.erasure(types)));
     }
 /**************************************************************************
  * Code for .class
  *************************************************************************/
     /** Return the symbol of a class to contain a cache of
      *  compiler-generated statics such as class$ and the
      *  $assertionsDisabled flag.  We create an anonymous nested class
      *  (unless one already exists) and return its symbol.  However,
      *  for backward compatibility in 1.4 and earlier we use the
      *  top-level class itself.
      */
     private ClassSymbol outerCacheClass() {
         ClassSymbol clazz = outermostClassDef.sym;
         if ((clazz.flags() & INTERFACE) == 0 &&
             !target.useInnerCacheClass()) return clazz;
         Scope s = clazz.members();
         for (Scope.Entry e = s.elems; e != null; e = e.sibling)
             if (e.sym.kind == TYP &&
                 e.sym.name == names.empty &&
                 (e.sym.flags() & INTERFACE) == 0) return (ClassSymbol) e.sym;
         return makeEmptyClass(STATIC | SYNTHETIC, clazz);
     }
     /** Return symbol for "class$" method. If there is no method definition
      *  for class$, construct one as follows:
      *
      *    class class$(String x0) {
      *      try {
      *        return Class.forName(x0);
      *      } catch (ClassNotFoundException x1) {
      *        throw new NoClassDefFoundError(x1.getMessage());
      *      }
      *    }
      */
     private MethodSymbol classDollarSym(DiagnosticPosition pos) {
         ClassSymbol outerCacheClass = outerCacheClass();
         MethodSymbol classDollarSym =
             (MethodSymbol)lookupSynthetic(classDollar,
                                           outerCacheClass.members());
         if (classDollarSym == null) {
             classDollarSym = new MethodSymbol(
                 STATIC | SYNTHETIC,
                 classDollar,
                 new MethodType(
                     List.of(syms.stringType),
                     types.erasure(syms.classType),
                     List.<Type>nil(),
                     syms.methodClass),
                 outerCacheClass);
             enterSynthetic(pos, classDollarSym, outerCacheClass.members());
             JCMethodDecl md = make.MethodDef(classDollarSym, null);
             try {
                 md.body = classDollarSymBody(pos, md);
             } catch (CompletionFailure ex) {
                 md.body = make.Block(0, List.<JCStatement>nil());
                 chk.completionError(pos, ex);
             }
             JCClassDecl outerCacheClassDef = classDef(outerCacheClass);
             outerCacheClassDef.defs = outerCacheClassDef.defs.prepend(md);
         }
         return classDollarSym;
     }
     /** Generate code for class$(String name). */
     JCBlock classDollarSymBody(DiagnosticPosition pos, JCMethodDecl md) {
         MethodSymbol classDollarSym = md.sym;
         ClassSymbol outerCacheClass = (ClassSymbol)classDollarSym.owner;
         JCBlock returnResult;
         // in 1.4.2 and above, we use
         // Class.forName(String name, boolean init, ClassLoader loader);
         // which requires we cache the current loader in cl$
         if (target.classLiteralsNoInit()) {
             // clsym = "private static ClassLoader cl$"
             VarSymbol clsym = new VarSymbol(STATIC|SYNTHETIC,
                                             names.fromString("cl" + target.syntheticNameChar()),
                                             syms.classLoaderType,
                                             outerCacheClass);
             enterSynthetic(pos, clsym, outerCacheClass.members());
             // emit "private static ClassLoader cl$;"
             JCVariableDecl cldef = make.VarDef(clsym, null);
             JCClassDecl outerCacheClassDef = classDef(outerCacheClass);
             outerCacheClassDef.defs = outerCacheClassDef.defs.prepend(cldef);
             // newcache := "new cache$1[0]"
             JCNewArray newcache = make.
                 NewArray(make.Type(outerCacheClass.type),
                          List.<JCExpression>of(make.Literal(INT, 0).setType(syms.intType)),
                          null);
             newcache.type = new ArrayType(types.erasure(outerCacheClass.type),
                                           syms.arrayClass);
             // forNameSym := java.lang.Class.forName(
             //     String s,boolean init,ClassLoader loader)
             Symbol forNameSym = lookupMethod(make_pos, names.forName,
                                              types.erasure(syms.classType),
                                              List.of(syms.stringType,
                                                      syms.booleanType,
                                                      syms.classLoaderType));
             // clvalue := "(cl$ == null) ?
             // $newcache.getClass().getComponentType().getClassLoader() : cl$"
             JCExpression clvalue =
                 make.Conditional(
                     makeBinary(JCTree.EQ, make.Ident(clsym), makeNull()),
                     make.Assign(
                         make.Ident(clsym),
                         makeCall(
                             makeCall(makeCall(newcache,
                                               names.getClass,
                                               List.<JCExpression>nil()),
                                      names.getComponentType,
                                      List.<JCExpression>nil()),
                             names.getClassLoader,
                             List.<JCExpression>nil())).setType(syms.classLoaderType),
                     make.Ident(clsym)).setType(syms.classLoaderType);
             // returnResult := "{ return Class.forName(param1, false, cl$); }"
             List<JCExpression> args = List.of(make.Ident(md.params.head.sym),
                                               makeLit(syms.booleanType, 0),
                                               clvalue);
             returnResult = make.
                 Block(0, List.<JCStatement>of(make.
                               Call(make. // return
                                    App(make.
                                        Ident(forNameSym), args))));
         } else {
             // forNameSym := java.lang.Class.forName(String s)
             Symbol forNameSym = lookupMethod(make_pos,
                                              names.forName,
                                              types.erasure(syms.classType),
                                              List.of(syms.stringType));
             // returnResult := "{ return Class.forName(param1); }"
             returnResult = make.
                 Block(0, List.of(make.
                           Call(make. // return
                               App(make.
                                   QualIdent(forNameSym),
                                   List.<JCExpression>of(make.
                                                         Ident(md.params.
                                                               head.sym))))));
         }
         // catchParam := ClassNotFoundException e1
         VarSymbol catchParam =
             new VarSymbol(0, make.paramName(1),
                           syms.classNotFoundExceptionType,
                           classDollarSym);
         JCStatement rethrow;
         if (target.hasInitCause()) {
             // rethrow = "throw new NoClassDefFoundError().initCause(e);
             JCTree throwExpr =
                 makeCall(makeNewClass(syms.noClassDefFoundErrorType,
                                       List.<JCExpression>nil()),
                          names.initCause,
                          List.<JCExpression>of(make.Ident(catchParam)));
             rethrow = make.Throw(throwExpr);
         } else {
             // getMessageSym := ClassNotFoundException.getMessage()
             Symbol getMessageSym = lookupMethod(make_pos,
                                                 names.getMessage,
                                                 syms.classNotFoundExceptionType,
                                                 List.<Type>nil());
             // rethrow = "throw new NoClassDefFoundError(e.getMessage());"
             rethrow = make.
                 Throw(makeNewClass(syms.noClassDefFoundErrorType,
                           List.<JCExpression>of(make.App(make.Select(make.Ident(catchParam),
                                                                      getMessageSym),
                                                          List.<JCExpression>nil()))));
         }
         // rethrowStmt := "( $rethrow )"
         JCBlock rethrowStmt = make.Block(0, List.of(rethrow));
         // catchBlock := "catch ($catchParam) $rethrowStmt"
         JCCatch catchBlock = make.Catch(make.VarDef(catchParam, null),
                                       rethrowStmt);
         // tryCatch := "try $returnResult $catchBlock"
         JCStatement tryCatch = make.Try(returnResult,
                                         List.of(catchBlock), null);
         return make.Block(0, List.of(tryCatch));
     }
     // where
         /** Create an attributed tree of the form left.name(). */
         private JCMethodInvocation makeCall(JCExpression left, Name name, List<JCExpression> args) {
             Assert.checkNonNull(left.type);
             Symbol funcsym = lookupMethod(make_pos, name, left.type,
                                           TreeInfo.types(args));
             return make.App(make.Select(left, funcsym), args);
         }
     /** The Name Of The variable to cache T.class values.
      *  @param sig      The signature of type T.
      */
     private Name cacheName(String sig) {
         StringBuffer buf = new StringBuffer();
         if (sig.startsWith("[")) {
             buf = buf.append("array");
             while (sig.startsWith("[")) {
                 buf = buf.append(target.syntheticNameChar());
                 sig = sig.substring(1);
             }
             if (sig.startsWith("L")) {
                 sig = sig.substring(0, sig.length() - 1);
             }
         } else {
             buf = buf.append("class" + target.syntheticNameChar());
         }
         buf = buf.append(sig.replace('.', target.syntheticNameChar()));
         return names.fromString(buf.toString());
     }
     /** The variable symbol that caches T.class values.
      *  If none exists yet, create a definition.
      *  @param sig      The signature of type T.
      *  @param pos      The position to report diagnostics, if any.
      */
     private VarSymbol cacheSym(DiagnosticPosition pos, String sig) {
         ClassSymbol outerCacheClass = outerCacheClass();
         Name cname = cacheName(sig);
         VarSymbol cacheSym =
             (VarSymbol)lookupSynthetic(cname, outerCacheClass.members());
         if (cacheSym == null) {
             cacheSym = new VarSymbol(
                 STATIC | SYNTHETIC, cname, types.erasure(syms.classType), outerCacheClass);
             enterSynthetic(pos, cacheSym, outerCacheClass.members());
             JCVariableDecl cacheDef = make.VarDef(cacheSym, null);
             JCClassDecl outerCacheClassDef = classDef(outerCacheClass);
             outerCacheClassDef.defs = outerCacheClassDef.defs.prepend(cacheDef);
         }
         return cacheSym;
     }
     /** The tree simulating a T.class expression.
      *  @param clazz      The tree identifying type T.
      */
     private JCExpression classOf(JCTree clazz) {
         return classOfType(clazz.type, clazz.pos());
     }
     private JCExpression classOfType(Type type, DiagnosticPosition pos) {
         switch (type.tag) {
         case BYTE: case SHORT: case CHAR: case INT: case LONG: case FLOAT:
         case DOUBLE: case BOOLEAN: case VOID:
             // replace with <BoxedClass>.TYPE
             ClassSymbol c = types.boxedClass(type);
             Symbol typeSym =
                 rs.access(
                     rs.findIdentInType(attrEnv, c.type, names.TYPE, VAR),
                     pos, c.type, names.TYPE, true);
             if (typeSym.kind == VAR)
                 ((VarSymbol)typeSym).getConstValue(); // ensure initializer is evaluated
             return make.QualIdent(typeSym);
         case CLASS: case ARRAY:
             if (target.hasClassLiterals()) {
                 VarSymbol sym = new VarSymbol(
                         STATIC | PUBLIC | FINAL, names._class,
                         syms.classType, type.tsym);
                 return make_at(pos).Select(make.Type(type), sym);
             }
             // replace with <cache == null ? cache = class$(tsig) : cache>
             // where
             //  - <tsig>  is the type signature of T,
             //  - <cache> is the cache variable for tsig.
             String sig =
                 writer.xClassName(type).toString().replace('/', '.');
             Symbol cs = cacheSym(pos, sig);
             return make_at(pos).Conditional(
                 makeBinary(JCTree.EQ, make.Ident(cs), makeNull()),
                 make.Assign(
                     make.Ident(cs),
                     make.App(
                         make.Ident(classDollarSym(pos)),
                         List.<JCExpression>of(make.Literal(CLASS, sig)
                                               .setType(syms.stringType))))
                 .setType(types.erasure(syms.classType)),
                 make.Ident(cs)).setType(types.erasure(syms.classType));
         default:
             throw new AssertionError();
         }
     }
 /**************************************************************************
  * Code for enabling/disabling assertions.
  *************************************************************************/
     // This code is not particularly robust if the user has
     // previously declared a member named '$assertionsDisabled'.
     // The same faulty idiom also appears in the translation of
     // class literals above.  We should report an error if a
     // previous declaration is not synthetic.
     private JCExpression assertFlagTest(DiagnosticPosition pos) {
         // Outermost class may be either true class or an interface.
         ClassSymbol outermostClass = outermostClassDef.sym;
         // note that this is a class, as an interface can't contain a statement.
         ClassSymbol container = currentClass;
         VarSymbol assertDisabledSym =
             (VarSymbol)lookupSynthetic(dollarAssertionsDisabled,
                                        container.members());
         if (assertDisabledSym == null) {
             assertDisabledSym =
                 new VarSymbol(STATIC | FINAL | SYNTHETIC,
                               dollarAssertionsDisabled,
                               syms.booleanType,
                               container);
             enterSynthetic(pos, assertDisabledSym, container.members());
             Symbol desiredAssertionStatusSym = lookupMethod(pos,
                                                             names.desiredAssertionStatus,
                                                             types.erasure(syms.classType),
                                                             List.<Type>nil());
             JCClassDecl containerDef = classDef(container);
             make_at(containerDef.pos());
             JCExpression notStatus = makeUnary(JCTree.NOT, make.App(make.Select(
                     classOfType(types.erasure(outermostClass.type),
                                 containerDef.pos()),
                     desiredAssertionStatusSym)));
             JCVariableDecl assertDisabledDef = make.VarDef(assertDisabledSym,
                                                    notStatus);
             containerDef.defs = containerDef.defs.prepend(assertDisabledDef);
         }
         make_at(pos);
         return makeUnary(JCTree.NOT, make.Ident(assertDisabledSym));
     }
 /**************************************************************************
  * Building blocks for let expressions
  *************************************************************************/
     interface TreeBuilder {
         JCTree build(JCTree arg);
     }
     /** Construct an expression using the builder, with the given rval
      *  expression as an argument to the builder.  However, the rval
      *  expression must be computed only once, even if used multiple
      *  times in the result of the builder.  We do that by
      *  constructing a "let" expression that saves the rvalue into a
      *  temporary variable and then uses the temporary variable in
      *  place of the expression built by the builder.  The complete
      *  resulting expression is of the form
      *  <pre>
      *    (let <b>TYPE</b> <b>TEMP</b> = <b>RVAL</b>;
      *     in (<b>BUILDER</b>(<b>TEMP</b>)))
      *  </pre>
      *  where <code><b>TEMP</b></code> is a newly declared variable
      *  in the let expression.
      */
     JCTree abstractRval(JCTree rval, Type type, TreeBuilder builder) {
         rval = TreeInfo.skipParens(rval);
         switch (rval.getTag()) {
         case JCTree.LITERAL:
             return builder.build(rval);
         case JCTree.IDENT:
             JCIdent id = (JCIdent) rval;
             if ((id.sym.flags() & FINAL) != 0 && id.sym.owner.kind == MTH)
                 return builder.build(rval);
         }
         VarSymbol var =
             new VarSymbol(FINAL|SYNTHETIC,
                           names.fromString(
                                           target.syntheticNameChar()
                                           + "" + rval.hashCode()),
                                       type,
                                       currentMethodSym);
         rval = convert(rval,type);
         JCVariableDecl def = make.VarDef(var, (JCExpression)rval); // XXX cast
         JCTree built = builder.build(make.Ident(var));
         JCTree res = make.LetExpr(def, built);
         res.type = built.type;
         return res;
     }
     // same as above, with the type of the temporary variable computed
     JCTree abstractRval(JCTree rval, TreeBuilder builder) {
         return abstractRval(rval, rval.type, builder);
     }
     // same as above, but for an expression that may be used as either
     // an rvalue or an lvalue.  This requires special handling for
     // Select expressions, where we place the left-hand-side of the
     // select in a temporary, and for Indexed expressions, where we
     // place both the indexed expression and the index value in temps.
     JCTree abstractLval(JCTree lval, final TreeBuilder builder) {
         lval = TreeInfo.skipParens(lval);
         switch (lval.getTag()) {
         case JCTree.IDENT:
             return builder.build(lval);
         case JCTree.SELECT: {
             final JCFieldAccess s = (JCFieldAccess)lval;
             JCTree selected = TreeInfo.skipParens(s.selected);
             Symbol lid = TreeInfo.symbol(s.selected);
             if (lid != null && lid.kind == TYP) return builder.build(lval);
             return abstractRval(s.selected, new TreeBuilder() {
                     public JCTree build(final JCTree selected) {
                         return builder.build(make.Select((JCExpression)selected, s.sym));
                     }
                 });
         }
         case JCTree.INDEXED: {
             final JCArrayAccess i = (JCArrayAccess)lval;
             return abstractRval(i.indexed, new TreeBuilder() {
                     public JCTree build(final JCTree indexed) {
                         return abstractRval(i.index, syms.intType, new TreeBuilder() {
                                 public JCTree build(final JCTree index) {
                                     JCTree newLval = make.Indexed((JCExpression)indexed,
                                                                 (JCExpression)index);
                                     newLval.setType(i.type);
                                     return builder.build(newLval);
                                 }
                             });
                     }
                 });
         }
         case JCTree.TYPECAST: {
             return abstractLval(((JCTypeCast)lval).expr, builder);
         }
         }
         throw new AssertionError(lval);
     }
     // evaluate and discard the first expression, then evaluate the second.
     JCTree makeComma(final JCTree expr1, final JCTree expr2) {
         return abstractRval(expr1, new TreeBuilder() {
                 public JCTree build(final JCTree discarded) {
                     return expr2;
                 }
             });
     }
 /**************************************************************************
  * Translation methods
  *************************************************************************/
     /** Visitor argument: enclosing operator node.
      */
     private JCExpression enclOp;
     /** Visitor method: Translate a single node.
      *  Attach the source position from the old tree to its replacement tree.
      */
     public <T extends JCTree> T translate(T tree) {
         if (tree == null) {
             return null;
         } else {
             make_at(tree.pos());
             T result = super.translate(tree);
             if (endPositions != null && result != tree) {
                 Integer endPos = endPositions.remove(tree);
                 if (endPos != null) endPositions.put(result, endPos);
             }
             return result;
         }
     }
     /** Visitor method: Translate a single node, boxing or unboxing if needed.
      */
     public <T extends JCTree> T translate(T tree, Type type) {
         return (tree == null) ? null : boxIfNeeded(translate(tree), type);
     }
     /** Visitor method: Translate tree.
      */
     public <T extends JCTree> T translate(T tree, JCExpression enclOp) {
         JCExpression prevEnclOp = this.enclOp;
         this.enclOp = enclOp;
         T res = translate(tree);
         this.enclOp = prevEnclOp;
         return res;
     }
     /** Visitor method: Translate list of trees.
      */
     public <T extends JCTree> List<T> translate(List<T> trees, JCExpression enclOp) {
         JCExpression prevEnclOp = this.enclOp;
         this.enclOp = enclOp;
         List<T> res = translate(trees);
         this.enclOp = prevEnclOp;
         return res;
     }
     /** Visitor method: Translate list of trees.
      */
     public <T extends JCTree> List<T> translate(List<T> trees, Type type) {
         if (trees == null) return null;
         for (List<T> l = trees; l.nonEmpty(); l = l.tail)
             l.head = translate(l.head, type);
         return trees;
     }
     public void visitTopLevel(JCCompilationUnit tree) {
         if (needPackageInfoClass(tree)) {
             Name name = names.package_info;
             long flags = Flags.ABSTRACT | Flags.INTERFACE;
             if (target.isPackageInfoSynthetic())
                 // package-info is marked SYNTHETIC in JDK 1.6 and later releases
                 flags = flags | Flags.SYNTHETIC;
             JCClassDecl packageAnnotationsClass
                 = make.ClassDef(make.Modifiers(flags,
                                                tree.packageAnnotations),
                                 name, List.<JCTypeParameter>nil(),
                                 null, List.<JCExpression>nil(), List.<JCTree>nil());
             ClassSymbol c = tree.packge.package_info;
             c.flags_field |= flags;
             c.attributes_field = tree.packge.attributes_field;
             ClassType ctype = (ClassType) c.type;
             ctype.supertype_field = syms.objectType;
             ctype.interfaces_field = List.nil();
             packageAnnotationsClass.sym = c;
             translated.append(packageAnnotationsClass);
         }
     }
     // where
     private boolean needPackageInfoClass(JCCompilationUnit tree) {
         switch (pkginfoOpt) {
             case ALWAYS:
                 return true;
             case LEGACY:
                 return tree.packageAnnotations.nonEmpty();
             case NONEMPTY:
                 for (Attribute.Compound a: tree.packge.attributes_field) {
                     Attribute.RetentionPolicy p = types.getRetention(a);
                     if (p != Attribute.RetentionPolicy.SOURCE)
                         return true;
                 }
                 return false;
         }
         throw new AssertionError();
     }
     public void visitClassDef(JCClassDecl tree) {
         ClassSymbol currentClassPrev = currentClass;
         MethodSymbol currentMethodSymPrev = currentMethodSym;
         currentClass = tree.sym;
         currentMethodSym = null;
         classdefs.put(currentClass, tree);
         proxies = proxies.dup(currentClass);
         List<VarSymbol> prevOuterThisStack = outerThisStack;
         // If this is an enum definition
         if ((tree.mods.flags & ENUM) != 0 &&
             (types.supertype(currentClass.type).tsym.flags() & ENUM) == 0)
             visitEnumDef(tree);
         // If this is a nested class, define a this$n field for
         // it and add to proxies.
         JCVariableDecl otdef = null;
         if (currentClass.hasOuterInstance())
             otdef = outerThisDef(tree.pos, currentClass);
         // If this is a local class, define proxies for all its free variables.
         List<JCVariableDecl> fvdefs = freevarDefs(
             tree.pos, freevars(currentClass), currentClass);
         // Recursively translate superclass, interfaces.
         tree.extending = translate(tree.extending);
         tree.implementing = translate(tree.implementing);
         // Recursively translate members, taking into account that new members
         // might be created during the translation and prepended to the member
         // list `tree.defs'.
         List<JCTree> seen = List.nil();
         while (tree.defs != seen) {
             List<JCTree> unseen = tree.defs;
             for (List<JCTree> l = unseen; l.nonEmpty() && l != seen; l = l.tail) {
                 JCTree outermostMemberDefPrev = outermostMemberDef;
                 if (outermostMemberDefPrev == null) outermostMemberDef = l.head;
                 l.head = translate(l.head);
                 outermostMemberDef = outermostMemberDefPrev;
             }
             seen = unseen;
         }
         // Convert a protected modifier to public, mask static modifier.
         if ((tree.mods.flags & PROTECTED) != 0) tree.mods.flags |= PUBLIC;
         tree.mods.flags &= ClassFlags;
         // Convert name to flat representation, replacing '.' by '$'.
         tree.name = Convert.shortName(currentClass.flatName());
         // Add this$n and free variables proxy definitions to class.
         for (List<JCVariableDecl> l = fvdefs; l.nonEmpty(); l = l.tail) {
             tree.defs = tree.defs.prepend(l.head);
             enterSynthetic(tree.pos(), l.head.sym, currentClass.members());
         }
         if (currentClass.hasOuterInstance()) {
             tree.defs = tree.defs.prepend(otdef);
             enterSynthetic(tree.pos(), otdef.sym, currentClass.members());
         }
         proxies = proxies.leave();
         outerThisStack = prevOuterThisStack;
         // Append translated tree to `translated' queue.
         translated.append(tree);
         currentClass = currentClassPrev;
         currentMethodSym = currentMethodSymPrev;
         // Return empty block {} as a placeholder for an inner class.
         result = make_at(tree.pos()).Block(0, List.<JCStatement>nil());
     }
     /** Translate an enum class. */
     private void visitEnumDef(JCClassDecl tree) {
         make_at(tree.pos());
         // add the supertype, if needed
         if (tree.extending == null)
             tree.extending = make.Type(types.supertype(tree.type));
         // classOfType adds a cache field to tree.defs unless
         // target.hasClassLiterals().
         JCExpression e_class = classOfType(tree.sym.type, tree.pos()).
             setType(types.erasure(syms.classType));
         // process each enumeration constant, adding implicit constructor parameters
         int nextOrdinal = 0;
         ListBuffer<JCExpression> values = new ListBuffer<JCExpression>();
         ListBuffer<JCTree> enumDefs = new ListBuffer<JCTree>();
         ListBuffer<JCTree> otherDefs = new ListBuffer<JCTree>();
         for (List<JCTree> defs = tree.defs;
              defs.nonEmpty();
              defs=defs.tail) {
             if (defs.head.getTag() == JCTree.VARDEF && (((JCVariableDecl) defs.head).mods.flags & ENUM) != 0) {
                 JCVariableDecl var = (JCVariableDecl)defs.head;
                 visitEnumConstantDef(var, nextOrdinal++);
                 values.append(make.QualIdent(var.sym));
                 enumDefs.append(var);
             } else {
                 otherDefs.append(defs.head);
             }
         }
         // private static final T[] #VALUES = { a, b, c };
         Name valuesName = names.fromString(target.syntheticNameChar() + "VALUES");
         while (tree.sym.members().lookup(valuesName).scope != null) // avoid name clash
             valuesName = names.fromString(valuesName + "" + target.syntheticNameChar());
         Type arrayType = new ArrayType(types.erasure(tree.type), syms.arrayClass);
         VarSymbol valuesVar = new VarSymbol(PRIVATE|FINAL|STATIC|SYNTHETIC,
                                             valuesName,
                                             arrayType,
                                             tree.type.tsym);
         JCNewArray newArray = make.NewArray(make.Type(types.erasure(tree.type)),
                                           List.<JCExpression>nil(),
                                           values.toList());
         newArray.type = arrayType;
         enumDefs.append(make.VarDef(valuesVar, newArray));
         tree.sym.members().enter(valuesVar);
         Symbol valuesSym = lookupMethod(tree.pos(), names.values,
                                         tree.type, List.<Type>nil());
         List<JCStatement> valuesBody;
         if (useClone()) {
             // return (T[]) $VALUES.clone();
             JCTypeCast valuesResult =
                 make.TypeCast(valuesSym.type.getReturnType(),
                               make.App(make.Select(make.Ident(valuesVar),
                                                    syms.arrayCloneMethod)));
             valuesBody = List.<JCStatement>of(make.Return(valuesResult));
         } else {
             // template: T[] $result = new T[$values.length];
             Name resultName = names.fromString(target.syntheticNameChar() + "result");
             while (tree.sym.members().lookup(resultName).scope != null) // avoid name clash
                 resultName = names.fromString(resultName + "" + target.syntheticNameChar());
             VarSymbol resultVar = new VarSymbol(FINAL|SYNTHETIC,
                                                 resultName,
                                                 arrayType,
                                                 valuesSym);
             JCNewArray resultArray = make.NewArray(make.Type(types.erasure(tree.type)),
                                   List.of(make.Select(make.Ident(valuesVar), syms.lengthVar)),
                                   null);
             resultArray.type = arrayType;
             JCVariableDecl decl = make.VarDef(resultVar, resultArray);
             // template: System.arraycopy($VALUES, 0, $result, 0, $VALUES.length);
             if (systemArraycopyMethod == null) {
                 systemArraycopyMethod =
                     new MethodSymbol(PUBLIC | STATIC,
                                      names.fromString("arraycopy"),
                                      new MethodType(List.<Type>of(syms.objectType,
                                                             syms.intType,
                                                             syms.objectType,
                                                             syms.intType,
                                                             syms.intType),
                                                     syms.voidType,
                                                     List.<Type>nil(),
                                                     syms.methodClass),
                                      syms.systemType.tsym);
             }
             JCStatement copy =
                 make.Exec(make.App(make.Select(make.Ident(syms.systemType.tsym),
                                                systemArraycopyMethod),
                           List.of(make.Ident(valuesVar), make.Literal(0),
                                   make.Ident(resultVar), make.Literal(0),
                                   make.Select(make.Ident(valuesVar), syms.lengthVar))));
             // template: return $result;
             JCStatement ret = make.Return(make.Ident(resultVar));
             valuesBody = List.<JCStatement>of(decl, copy, ret);
         }
         JCMethodDecl valuesDef =
              make.MethodDef((MethodSymbol)valuesSym, make.Block(0, valuesBody));
         enumDefs.append(valuesDef);
         if (debugLower)
             System.err.println(tree.sym + ".valuesDef = " + valuesDef);
         /** The template for the following code is:
          *
          *     public static E valueOf(String name) {
          *         return (E)Enum.valueOf(E.class, name);
          *     }
          *
          *  where E is tree.sym
          */
         MethodSymbol valueOfSym = lookupMethod(tree.pos(),
                          names.valueOf,
                          tree.sym.type,
                          List.of(syms.stringType));
         Assert.check((valueOfSym.flags() & STATIC) != 0);
         VarSymbol nameArgSym = valueOfSym.params.head;
         JCIdent nameVal = make.Ident(nameArgSym);
         JCStatement enum_ValueOf =
             make.Return(make.TypeCast(tree.sym.type,
                                       makeCall(make.Ident(syms.enumSym),
                                                names.valueOf,
                                                List.of(e_class, nameVal))));
         JCMethodDecl valueOf = make.MethodDef(valueOfSym,
                                            make.Block(0, List.of(enum_ValueOf)));
         nameVal.sym = valueOf.params.head.sym;
         if (debugLower)
             System.err.println(tree.sym + ".valueOf = " + valueOf);
         enumDefs.append(valueOf);
         enumDefs.appendList(otherDefs.toList());
         tree.defs = enumDefs.toList();
         // Add the necessary members for the EnumCompatibleMode
         if (target.compilerBootstrap(tree.sym)) {
             addEnumCompatibleMembers(tree);
         }
     }
         // where
         private MethodSymbol systemArraycopyMethod;
         private boolean useClone() {
             try {
                 Scope.Entry e = syms.objectType.tsym.members().lookup(names.clone);
                 return (e.sym != null);
             }
             catch (CompletionFailure e) {
                 return false;
             }
         }
     /** Translate an enumeration constant and its initializer. */
     private void visitEnumConstantDef(JCVariableDecl var, int ordinal) {
         JCNewClass varDef = (JCNewClass)var.init;
         varDef.args = varDef.args.
             prepend(makeLit(syms.intType, ordinal)).
             prepend(makeLit(syms.stringType, var.name.toString()));
     }
     public void visitMethodDef(JCMethodDecl tree) {
         if (tree.name == names.init && (currentClass.flags_field&ENUM) != 0) {
             // Add "String $enum$name, int $enum$ordinal" to the beginning of the
             // argument list for each constructor of an enum.
             JCVariableDecl nameParam = make_at(tree.pos()).
                 Param(names.fromString(target.syntheticNameChar() +
                                        "enum" + target.syntheticNameChar() + "name"),
                       syms.stringType, tree.sym);
             nameParam.mods.flags |= SYNTHETIC; nameParam.sym.flags_field |= SYNTHETIC;
             JCVariableDecl ordParam = make.
                 Param(names.fromString(target.syntheticNameChar() +
                                        "enum" + target.syntheticNameChar() +
                                        "ordinal"),
                       syms.intType, tree.sym);
             ordParam.mods.flags |= SYNTHETIC; ordParam.sym.flags_field |= SYNTHETIC;
             tree.params = tree.params.prepend(ordParam).prepend(nameParam);
             MethodSymbol m = tree.sym;
             Type olderasure = m.erasure(types);
             m.erasure_field = new MethodType(
                 olderasure.getParameterTypes().prepend(syms.intType).prepend(syms.stringType),
                 olderasure.getReturnType(),
                 olderasure.getThrownTypes(),
                 syms.methodClass);
             if (target.compilerBootstrap(m.owner)) {
                 // Initialize synthetic name field
                 Symbol nameVarSym = lookupSynthetic(names.fromString("$name"),
                                                     tree.sym.owner.members());
                 JCIdent nameIdent = make.Ident(nameParam.sym);
                 JCIdent id1 = make.Ident(nameVarSym);
                 JCAssign newAssign = make.Assign(id1, nameIdent);
                 newAssign.type = id1.type;
                 JCExpressionStatement nameAssign = make.Exec(newAssign);
                 nameAssign.type = id1.type;
                 tree.body.stats = tree.body.stats.prepend(nameAssign);
                 // Initialize synthetic ordinal field
                 Symbol ordinalVarSym = lookupSynthetic(names.fromString("$ordinal"),
                                                        tree.sym.owner.members());
                 JCIdent ordIdent = make.Ident(ordParam.sym);
                 id1 = make.Ident(ordinalVarSym);
                 newAssign = make.Assign(id1, ordIdent);
                 newAssign.type = id1.type;
                 JCExpressionStatement ordinalAssign = make.Exec(newAssign);
                 ordinalAssign.type = id1.type;
                 tree.body.stats = tree.body.stats.prepend(ordinalAssign);
             }
         }
         JCMethodDecl prevMethodDef = currentMethodDef;
         MethodSymbol prevMethodSym = currentMethodSym;
         try {
             currentMethodDef = tree;
             currentMethodSym = tree.sym;
             visitMethodDefInternal(tree);
         } finally {
             currentMethodDef = prevMethodDef;
             currentMethodSym = prevMethodSym;
         }
     }
     //where
     private void visitMethodDefInternal(JCMethodDecl tree) {
         if (tree.name == names.init &&
             (currentClass.isInner() ||
              (currentClass.owner.kind & (VAR | MTH)) != 0)) {
             // We are seeing a constructor of an inner class.
             MethodSymbol m = tree.sym;
             // Push a new proxy scope for constructor parameters.
             // and create definitions for any this$n and proxy parameters.
             proxies = proxies.dup(m);
             List<VarSymbol> prevOuterThisStack = outerThisStack;
             List<VarSymbol> fvs = freevars(currentClass);
             JCVariableDecl otdef = null;
             if (currentClass.hasOuterInstance())
                 otdef = outerThisDef(tree.pos, m);
             List<JCVariableDecl> fvdefs = freevarDefs(tree.pos, fvs, m);
             // Recursively translate result type, parameters and thrown list.
             tree.restype = translate(tree.restype);
             tree.params = translateVarDefs(tree.params);
             tree.thrown = translate(tree.thrown);
             // when compiling stubs, don't process body
             if (tree.body == null) {
                 result = tree;
                 return;
             }
             // Add this$n (if needed) in front of and free variables behind
             // constructor parameter list.
             tree.params = tree.params.appendList(fvdefs);
             if (currentClass.hasOuterInstance())
                 tree.params = tree.params.prepend(otdef);
             // If this is an initial constructor, i.e., it does not start with
             // this(...), insert initializers for this$n and proxies
             // before (pre-1.4, after) the call to superclass constructor.
             JCStatement selfCall = translate(tree.body.stats.head);
             List<JCStatement> added = List.nil();
             if (fvs.nonEmpty()) {
                 List<Type> addedargtypes = List.nil();
                 for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail) {
                     if (TreeInfo.isInitialConstructor(tree))
                         added = added.prepend(
                             initField(tree.body.pos, proxyName(l.head.name)));
                     addedargtypes = addedargtypes.prepend(l.head.erasure(types));
                 }
                 Type olderasure = m.erasure(types);
                 m.erasure_field = new MethodType(
                     olderasure.getParameterTypes().appendList(addedargtypes),
                     olderasure.getReturnType(),
                     olderasure.getThrownTypes(),
                     syms.methodClass);
             }
             if (currentClass.hasOuterInstance() &&
                 TreeInfo.isInitialConstructor(tree))
             {
                 added = added.prepend(initOuterThis(tree.body.pos));
             }
             // pop local variables from proxy stack
             proxies = proxies.leave();
             // recursively translate following local statements and
             // combine with this- or super-call
             List<JCStatement> stats = translate(tree.body.stats.tail);
             if (target.initializeFieldsBeforeSuper())
                 tree.body.stats = stats.prepend(selfCall).prependList(added);
             else
                 tree.body.stats = stats.prependList(added).prepend(selfCall);
             outerThisStack = prevOuterThisStack;
         } else {
             super.visitMethodDef(tree);
         }
         result = tree;
     }
     public void visitTypeCast(JCTypeCast tree) {
         tree.clazz = translate(tree.clazz);
         if (tree.type.isPrimitive() != tree.expr.type.isPrimitive())
             tree.expr = translate(tree.expr, tree.type);
         else
             tree.expr = translate(tree.expr);
         result = tree;
     }
     public void visitNewClass(JCNewClass tree) {
         ClassSymbol c = (ClassSymbol)tree.constructor.owner;
         // Box arguments, if necessary
         boolean isEnum = (tree.constructor.owner.flags() & ENUM) != 0;
         List<Type> argTypes = tree.constructor.type.getParameterTypes();
         if (isEnum) argTypes = argTypes.prepend(syms.intType).prepend(syms.stringType);
         tree.args = boxArgs(argTypes, tree.args, tree.varargsElement);
         tree.varargsElement = null;
         // If created class is local, add free variables after
         // explicit constructor arguments.
         if ((c.owner.kind & (VAR | MTH)) != 0) {
             tree.args = tree.args.appendList(loadFreevars(tree.pos(), freevars(c)));
         }
         // If an access constructor is used, append null as a last argument.
         Symbol constructor = accessConstructor(tree.pos(), tree.constructor);
         if (constructor != tree.constructor) {
             tree.args = tree.args.append(makeNull());
             tree.constructor = constructor;
         }
         // If created class has an outer instance, and new is qualified, pass
         // qualifier as first argument. If new is not qualified, pass the
         // correct outer instance as first argument.
         if (c.hasOuterInstance()) {
             JCExpression thisArg;
             if (tree.encl != null) {
                 thisArg = attr.makeNullCheck(translate(tree.encl));
                 thisArg.type = tree.encl.type;
             } else if ((c.owner.kind & (MTH | VAR)) != 0) {
                 // local class
                 thisArg = makeThis(tree.pos(), c.type.getEnclosingType().tsym);
             } else {
                 // nested class
                 thisArg = makeOwnerThis(tree.pos(), c, false);
             }
             tree.args = tree.args.prepend(thisArg);
         }
         tree.encl = null;
         // If we have an anonymous class, create its flat version, rather
         // than the class or interface following new.
         if (tree.def != null) {
             translate(tree.def);
             tree.clazz = access(make_at(tree.clazz.pos()).Ident(tree.def.sym));
             tree.def = null;
         } else {
             tree.clazz = access(c, tree.clazz, enclOp, false);
         }
         result = tree;
     }
     // Simplify conditionals with known constant controlling expressions.
     // This allows us to avoid generating supporting declarations for
     // the dead code, which will not be eliminated during code generation.
     // Note that Flow.isFalse and Flow.isTrue only return true
     // for constant expressions in the sense of JLS 15.27, which
     // are guaranteed to have no side-effects.  More aggressive
     // constant propagation would require that we take care to
     // preserve possible side-effects in the condition expression.
     /** Visitor method for conditional expressions.
      */
     public void visitConditional(JCConditional tree) {
         JCTree cond = tree.cond = translate(tree.cond, syms.booleanType);
         if (cond.type.isTrue()) {
             result = convert(translate(tree.truepart, tree.type), tree.type);
         } else if (cond.type.isFalse()) {
             result = convert(translate(tree.falsepart, tree.type), tree.type);
         } else {
             // Condition is not a compile-time constant.
             tree.truepart = translate(tree.truepart, tree.type);
             tree.falsepart = translate(tree.falsepart, tree.type);
             result = tree;
         }
     }
 //where
         private JCTree convert(JCTree tree, Type pt) {
             if (tree.type == pt || tree.type.tag == TypeTags.BOT)
                 return tree;
             JCTree result = make_at(tree.pos()).TypeCast(make.Type(pt), (JCExpression)tree);
             result.type = (tree.type.constValue() != null) ? cfolder.coerce(tree.type, pt)
                                                            : pt;
             return result;
         }
     /** Visitor method for if statements.
      */
     public void visitIf(JCIf tree) {
         JCTree cond = tree.cond = translate(tree.cond, syms.booleanType);
         if (cond.type.isTrue()) {
             result = translate(tree.thenpart);
         } else if (cond.type.isFalse()) {
             if (tree.elsepart != null) {
                 result = translate(tree.elsepart);
             } else {
                 result = make.Skip();
             }
         } else {
             // Condition is not a compile-time constant.
             tree.thenpart = translate(tree.thenpart);
             tree.elsepart = translate(tree.elsepart);
             result = tree;
         }
     }
     /** Visitor method for assert statements. Translate them away.
      */
     public void visitAssert(JCAssert tree) {
         DiagnosticPosition detailPos = (tree.detail == null) ? tree.pos() : tree.detail.pos();
         tree.cond = translate(tree.cond, syms.booleanType);
         if (!tree.cond.type.isTrue()) {
             JCExpression cond = assertFlagTest(tree.pos());
             List<JCExpression> exnArgs = (tree.detail == null) ?
                 List.<JCExpression>nil() : List.of(translate(tree.detail));
             if (!tree.cond.type.isFalse()) {
                 cond = makeBinary
                     (JCTree.AND,
                      cond,
                      makeUnary(JCTree.NOT, tree.cond));
             }
             result =
                 make.If(cond,
                         make_at(detailPos).
                            Throw(makeNewClass(syms.assertionErrorType, exnArgs)),
                         null);
         } else {
             result = make.Skip();
         }
     }
     public void visitApply(JCMethodInvocation tree) {
         Symbol meth = TreeInfo.symbol(tree.meth);
         List<Type> argtypes = meth.type.getParameterTypes();
         if (allowEnums &&
             meth.name==names.init &&
             meth.owner == syms.enumSym)
             argtypes = argtypes.tail.tail;
         tree.args = boxArgs(argtypes, tree.args, tree.varargsElement);
         tree.varargsElement = null;
         Name methName = TreeInfo.name(tree.meth);
         if (meth.name==names.init) {
             // We are seeing a this(...) or super(...) constructor call.
             // If an access constructor is used, append null as a last argument.
             Symbol constructor = accessConstructor(tree.pos(), meth);
             if (constructor != meth) {
                 tree.args = tree.args.append(makeNull());
                 TreeInfo.setSymbol(tree.meth, constructor);
             }
             // If we are calling a constructor of a local class, add
             // free variables after explicit constructor arguments.
             ClassSymbol c = (ClassSymbol)constructor.owner;
             if ((c.owner.kind & (VAR | MTH)) != 0) {
                 tree.args = tree.args.appendList(loadFreevars(tree.pos(), freevars(c)));
             }
             // If we are calling a constructor of an enum class, pass
             // along the name and ordinal arguments
             if ((c.flags_field&ENUM) != 0 || c.getQualifiedName() == names.java_lang_Enum) {
                 List<JCVariableDecl> params = currentMethodDef.params;
                 if (currentMethodSym.owner.hasOuterInstance())
                     params = params.tail; // drop this$n
                 tree.args = tree.args
                     .prepend(make_at(tree.pos()).Ident(params.tail.head.sym)) // ordinal
                     .prepend(make.Ident(params.head.sym)); // name
             }
             // If we are calling a constructor of a class with an outer
             // instance, and the call
             // is qualified, pass qualifier as first argument in front of
             // the explicit constructor arguments. If the call
             // is not qualified, pass the correct outer instance as
             // first argument.
             if (c.hasOuterInstance()) {
                 JCExpression thisArg;
                 if (tree.meth.getTag() == JCTree.SELECT) {
                     thisArg = attr.
                         makeNullCheck(translate(((JCFieldAccess) tree.meth).selected));
                     tree.meth = make.Ident(constructor);
                     ((JCIdent) tree.meth).name = methName;
                 } else if ((c.owner.kind & (MTH | VAR)) != 0 || methName == names._this){
                     // local class or this() call
                     thisArg = makeThis(tree.meth.pos(), c.type.getEnclosingType().tsym);
                 } else {
                     // super() call of nested class
                     thisArg = makeOwnerThis(tree.meth.pos(), c, false);
                 }
                 tree.args = tree.args.prepend(thisArg);
             }
         } else {
             // We are seeing a normal method invocation; translate this as usual.
             tree.meth = translate(tree.meth);
             // If the translated method itself is an Apply tree, we are
             // seeing an access method invocation. In this case, append
             // the method arguments to the arguments of the access method.
             if (tree.meth.getTag() == JCTree.APPLY) {
                 JCMethodInvocation app = (JCMethodInvocation)tree.meth;
                 app.args = tree.args.prependList(app.args);
                 result = app;
                 return;
             }
         }
         result = tree;
     }
     List<JCExpression> boxArgs(List<Type> parameters, List<JCExpression> _args, Type varargsElement) {
         List<JCExpression> args = _args;
         if (parameters.isEmpty()) return args;
         boolean anyChanges = false;
         ListBuffer<JCExpression> result = new ListBuffer<JCExpression>();
         while (parameters.tail.nonEmpty()) {
             JCExpression arg = translate(args.head, parameters.head);
             anyChanges |= (arg != args.head);
             result.append(arg);
             args = args.tail;
             parameters = parameters.tail;
         }
         Type parameter = parameters.head;
         if (varargsElement != null) {
             anyChanges = true;
             ListBuffer<JCExpression> elems = new ListBuffer<JCExpression>();
             while (args.nonEmpty()) {
                 JCExpression arg = translate(args.head, varargsElement);
                 elems.append(arg);
                 args = args.tail;
             }
             JCNewArray boxedArgs = make.NewArray(make.Type(varargsElement),
                                                List.<JCExpression>nil(),
                                                elems.toList());
             boxedArgs.type = new ArrayType(varargsElement, syms.arrayClass);
             result.append(boxedArgs);
         } else {
             if (args.length() != 1) throw new AssertionError(args);
             JCExpression arg = translate(args.head, parameter);
             anyChanges |= (arg != args.head);
             result.append(arg);
             if (!anyChanges) return _args;
         }
         return result.toList();
     }
     /** Expand a boxing or unboxing conversion if needed. */
     @SuppressWarnings("unchecked") // XXX unchecked
     <T extends JCTree> T boxIfNeeded(T tree, Type type) {
         boolean havePrimitive = tree.type.isPrimitive();
         if (havePrimitive == type.isPrimitive())
             return tree;
         if (havePrimitive) {
             Type unboxedTarget = types.unboxedType(type);
             if (unboxedTarget.tag != NONE) {
                 if (!types.isSubtype(tree.type, unboxedTarget)) //e.g. Character c = 89;
                     tree.type = unboxedTarget.constType(tree.type.constValue());
                 return (T)boxPrimitive((JCExpression)tree, type);
             } else {
                 tree = (T)boxPrimitive((JCExpression)tree);
             }
         } else {
             tree = (T)unbox((JCExpression)tree, type);
         }
         return tree;
     }
     /** Box up a single primitive expression. */
     JCExpression boxPrimitive(JCExpression tree) {
         return boxPrimitive(tree, types.boxedClass(tree.type).type);
     }
     /** Box up a single primitive expression. */
     JCExpression boxPrimitive(JCExpression tree, Type box) {
         make_at(tree.pos());
         if (target.boxWithConstructors()) {
             Symbol ctor = lookupConstructor(tree.pos(),
                                             box,
                                             List.<Type>nil()
                                             .prepend(tree.type));
             return make.Create(ctor, List.of(tree));
         } else {
             Symbol valueOfSym = lookupMethod(tree.pos(),
                                              names.valueOf,
                                              box,
                                              List.<Type>nil()
                                              .prepend(tree.type));
             return make.App(make.QualIdent(valueOfSym), List.of(tree));
         }
     }
     /** Unbox an object to a primitive value. */
     JCExpression unbox(JCExpression tree, Type primitive) {
         Type unboxedType = types.unboxedType(tree.type);
         if (unboxedType.tag == NONE) {
             unboxedType = primitive;
             if (!unboxedType.isPrimitive())
                 throw new AssertionError(unboxedType);
             make_at(tree.pos());
             tree = make.TypeCast(types.boxedClass(unboxedType).type, tree);
         } else {
             // There must be a conversion from unboxedType to primitive.
             if (!types.isSubtype(unboxedType, primitive))
                 throw new AssertionError(tree);
         }
         make_at(tree.pos());
         Symbol valueSym = lookupMethod(tree.pos(),
                                        unboxedType.tsym.name.append(names.Value), // x.intValue()
                                        tree.type,
                                        List.<Type>nil());
         return make.App(make.Select(tree, valueSym));
     }
     /** Visitor method for parenthesized expressions.
      *  If the subexpression has changed, omit the parens.
      */
     public void visitParens(JCParens tree) {
         JCTree expr = translate(tree.expr);
         result = ((expr == tree.expr) ? tree : expr);
     }
     public void visitIndexed(JCArrayAccess tree) {
         tree.indexed = translate(tree.indexed);
         tree.index = translate(tree.index, syms.intType);
         result = tree;
     }
     public void visitAssign(JCAssign tree) {
         tree.lhs = translate(tree.lhs, tree);
         tree.rhs = translate(tree.rhs, tree.lhs.type);
         // If translated left hand side is an Apply, we are
         // seeing an access method invocation. In this case, append
         // right hand side as last argument of the access method.
         if (tree.lhs.getTag() == JCTree.APPLY) {
             JCMethodInvocation app = (JCMethodInvocation)tree.lhs;
             app.args = List.of(tree.rhs).prependList(app.args);
             result = app;
         } else {
             result = tree;
         }
     }
     public void visitAssignop(final JCAssignOp tree) {
         if (!tree.lhs.type.isPrimitive() &&
             tree.operator.type.getReturnType().isPrimitive()) {
             // boxing required; need to rewrite as x = (unbox typeof x)(x op y);
             // or if x == (typeof x)z then z = (unbox typeof x)((typeof x)z op y)
             // (but without recomputing x)
             JCTree newTree = abstractLval(tree.lhs, new TreeBuilder() {
                     public JCTree build(final JCTree lhs) {
                         int newTag = tree.getTag() - JCTree.ASGOffset;
                         // Erasure (TransTypes) can change the type of
                         // tree.lhs.  However, we can still get the
                         // unerased type of tree.lhs as it is stored
                         // in tree.type in Attr.
                         Symbol newOperator = rs.resolveBinaryOperator(tree.pos(),
                                                                       newTag,
                                                                       attrEnv,
                                                                       tree.type,
                                                                       tree.rhs.type);
                         JCExpression expr = (JCExpression)lhs;
                         if (expr.type != tree.type)
                             expr = make.TypeCast(tree.type, expr);
                         JCBinary opResult = make.Binary(newTag, expr, tree.rhs);
                         opResult.operator = newOperator;
                         opResult.type = newOperator.type.getReturnType();
                         JCTypeCast newRhs = make.TypeCast(types.unboxedType(tree.type),
                                                           opResult);
                         return make.Assign((JCExpression)lhs, newRhs).setType(tree.type);
                     }
                 });
             result = translate(newTree);
             return;
         }
         tree.lhs = translate(tree.lhs, tree);
         tree.rhs = translate(tree.rhs, tree.operator.type.getParameterTypes().tail.head);
         // If translated left hand side is an Apply, we are
         // seeing an access method invocation. In this case, append
         // right hand side as last argument of the access method.
         if (tree.lhs.getTag() == JCTree.APPLY) {
             JCMethodInvocation app = (JCMethodInvocation)tree.lhs;
             // if operation is a += on strings,
             // make sure to convert argument to string
             JCExpression rhs = (((OperatorSymbol)tree.operator).opcode == string_add)
               ? makeString(tree.rhs)
               : tree.rhs;
             app.args = List.of(rhs).prependList(app.args);
             result = app;
         } else {
             result = tree;
         }
     }
     /** Lower a tree of the form e++ or e-- where e is an object type */
     JCTree lowerBoxedPostop(final JCUnary tree) {
         // translate to tmp1=lval(e); tmp2=tmp1; tmp1 OP 1; tmp2
         // or
         // translate to tmp1=lval(e); tmp2=tmp1; (typeof tree)tmp1 OP 1; tmp2
         // where OP is += or -=
         final boolean cast = TreeInfo.skipParens(tree.arg).getTag() == JCTree.TYPECAST;
         return abstractLval(tree.arg, new TreeBuilder() {
                 public JCTree build(final JCTree tmp1) {
                     return abstractRval(tmp1, tree.arg.type, new TreeBuilder() {
                             public JCTree build(final JCTree tmp2) {
                                 int opcode = (tree.getTag() == JCTree.POSTINC)
                                     ? JCTree.PLUS_ASG : JCTree.MINUS_ASG;
                                 JCTree lhs = cast
                                     ? make.TypeCast(tree.arg.type, (JCExpression)tmp1)
                                     : tmp1;
                                 JCTree update = makeAssignop(opcode,
                                                              lhs,
                                                              make.Literal(1));
                                 return makeComma(update, tmp2);
                             }
                         });
                 }
             });
     }
     public void visitUnary(JCUnary tree) {
         boolean isUpdateOperator =
             JCTree.PREINC <= tree.getTag() && tree.getTag() <= JCTree.POSTDEC;
         if (isUpdateOperator && !tree.arg.type.isPrimitive()) {
             switch(tree.getTag()) {
             case JCTree.PREINC:            // ++ e
                     // translate to e += 1
             case JCTree.PREDEC:            // -- e
                     // translate to e -= 1
                 {
                     int opcode = (tree.getTag() == JCTree.PREINC)
                         ? JCTree.PLUS_ASG : JCTree.MINUS_ASG;
                     JCAssignOp newTree = makeAssignop(opcode,
                                                     tree.arg,
                                                     make.Literal(1));
                     result = translate(newTree, tree.type);
                     return;
                 }
             case JCTree.POSTINC:           // e ++
             case JCTree.POSTDEC:           // e --
                 {
                     result = translate(lowerBoxedPostop(tree), tree.type);
                     return;
                 }
             }
             throw new AssertionError(tree);
         }
         tree.arg = boxIfNeeded(translate(tree.arg, tree), tree.type);
         if (tree.getTag() == JCTree.NOT && tree.arg.type.constValue() != null) {
             tree.type = cfolder.fold1(bool_not, tree.arg.type);
         }
         // If translated left hand side is an Apply, we are
         // seeing an access method invocation. In this case, return
         // that access method invocation as result.
         if (isUpdateOperator && tree.arg.getTag() == JCTree.APPLY) {
             result = tree.arg;
         } else {
             result = tree;
         }
     }
     public void visitBinary(JCBinary tree) {
         List<Type> formals = tree.operator.type.getParameterTypes();
         JCTree lhs = tree.lhs = translate(tree.lhs, formals.head);
         switch (tree.getTag()) {
         case JCTree.OR:
             if (lhs.type.isTrue()) {
                 result = lhs;
                 return;
             }
             if (lhs.type.isFalse()) {
                 result = translate(tree.rhs, formals.tail.head);
                 return;
             }
             break;
         case JCTree.AND:
             if (lhs.type.isFalse()) {
                 result = lhs;
                 return;
             }
             if (lhs.type.isTrue()) {
                 result = translate(tree.rhs, formals.tail.head);
                 return;
             }
             break;
         }
         tree.rhs = translate(tree.rhs, formals.tail.head);
         result = tree;
     }
     public void visitIdent(JCIdent tree) {
         result = access(tree.sym, tree, enclOp, false);
     }
     /** Translate away the foreach loop.  */
     public void visitForeachLoop(JCEnhancedForLoop tree) {
         if (types.elemtype(tree.expr.type) == null)
             visitIterableForeachLoop(tree);
         else
             visitArrayForeachLoop(tree);
     }
         // where
         /**
          * A statement of the form
          *
          * <pre>
          *     for ( T v : arrayexpr ) stmt;
          * </pre>
          *
          * (where arrayexpr is of an array type) gets translated to
          *
          * <pre>
          *     for ( { arraytype #arr = arrayexpr;
          *             int #len = array.length;
          *             int #i = 0; };
          *           #i < #len; i$++ ) {
          *         T v = arr$[#i];
          *         stmt;
          *     }
          * </pre>
          *
          * where #arr, #len, and #i are freshly named synthetic local variables.
          */
         private void visitArrayForeachLoop(JCEnhancedForLoop tree) {
             make_at(tree.expr.pos());
             VarSymbol arraycache = new VarSymbol(0,
                                                  names.fromString("arr" + target.syntheticNameChar()),
                                                  tree.expr.type,
                                                  currentMethodSym);
             JCStatement arraycachedef = make.VarDef(arraycache, tree.expr);
             VarSymbol lencache = new VarSymbol(0,
                                                names.fromString("len" + target.syntheticNameChar()),
                                                syms.intType,
                                                currentMethodSym);
             JCStatement lencachedef = make.
                 VarDef(lencache, make.Select(make.Ident(arraycache), syms.lengthVar));
             VarSymbol index = new VarSymbol(0,
                                             names.fromString("i" + target.syntheticNameChar()),
                                             syms.intType,
                                             currentMethodSym);
             JCVariableDecl indexdef = make.VarDef(index, make.Literal(INT, 0));
             indexdef.init.type = indexdef.type = syms.intType.constType(0);
             List<JCStatement> loopinit = List.of(arraycachedef, lencachedef, indexdef);
             JCBinary cond = makeBinary(JCTree.LT, make.Ident(index), make.Ident(lencache));
             JCExpressionStatement step = make.Exec(makeUnary(JCTree.PREINC, make.Ident(index)));
             Type elemtype = types.elemtype(tree.expr.type);
             JCExpression loopvarinit = make.Indexed(make.Ident(arraycache),
                                                     make.Ident(index)).setType(elemtype);
             JCVariableDecl loopvardef = (JCVariableDecl)make.VarDef(tree.var.mods,
                                                   tree.var.name,
                                                   tree.var.vartype,
                                                   loopvarinit).setType(tree.var.type);
             loopvardef.sym = tree.var.sym;
             JCBlock body = make.
                 Block(0, List.of(loopvardef, tree.body));
             result = translate(make.
                                ForLoop(loopinit,
                                        cond,
                                        List.of(step),
                                        body));
             patchTargets(body, tree, result);
         }
         /** Patch up break and continue targets. */
         private void patchTargets(JCTree body, final JCTree src, final JCTree dest) {
             class Patcher extends TreeScanner {
                 public void visitBreak(JCBreak tree) {
                     if (tree.target == src)
                         tree.target = dest;
                 }
                 public void visitContinue(JCContinue tree) {
                     if (tree.target == src)
                         tree.target = dest;
                 }
                 public void visitClassDef(JCClassDecl tree) {}
             }
             new Patcher().scan(body);
         }
         /**
          * A statement of the form
          *
          * <pre>
          *     for ( T v : coll ) stmt ;
          * </pre>
          *
          * (where coll implements Iterable<? extends T>) gets translated to
          *
          * <pre>
          *     for ( Iterator<? extends T> #i = coll.iterator(); #i.hasNext(); ) {
          *         T v = (T) #i.next();
          *         stmt;
          *     }
          * </pre>
          *
          * where #i is a freshly named synthetic local variable.
          */
         private void visitIterableForeachLoop(JCEnhancedForLoop tree) {
             make_at(tree.expr.pos());
             Type iteratorTarget = syms.objectType;
             Type iterableType = types.asSuper(types.upperBound(tree.expr.type),
                                               syms.iterableType.tsym);
             if (iterableType.getTypeArguments().nonEmpty())
                 iteratorTarget = types.erasure(iterableType.getTypeArguments().head);
             Type eType = tree.expr.type;
             tree.expr.type = types.erasure(eType);
             if (eType.tag == TYPEVAR && eType.getUpperBound().isCompound())
                 tree.expr = make.TypeCast(types.erasure(iterableType), tree.expr);
             Symbol iterator = lookupMethod(tree.expr.pos(),
                                            names.iterator,
                                            types.erasure(syms.iterableType),
                                            List.<Type>nil());
             VarSymbol itvar = new VarSymbol(0, names.fromString("i" + target.syntheticNameChar()),
                                             types.erasure(iterator.type.getReturnType()),
                                             currentMethodSym);
             JCStatement init = make.
                 VarDef(itvar,
                        make.App(make.Select(tree.expr, iterator)));
             Symbol hasNext = lookupMethod(tree.expr.pos(),
                                           names.hasNext,
                                           itvar.type,
                                           List.<Type>nil());
             JCMethodInvocation cond = make.App(make.Select(make.Ident(itvar), hasNext));
             Symbol next = lookupMethod(tree.expr.pos(),
                                        names.next,
                                        itvar.type,
                                        List.<Type>nil());
             JCExpression vardefinit = make.App(make.Select(make.Ident(itvar), next));
             if (tree.var.type.isPrimitive())
                 vardefinit = make.TypeCast(types.upperBound(iteratorTarget), vardefinit);
             else
                 vardefinit = make.TypeCast(tree.var.type, vardefinit);
             JCVariableDecl indexDef = (JCVariableDecl)make.VarDef(tree.var.mods,
                                                   tree.var.name,
                                                   tree.var.vartype,
                                                   vardefinit).setType(tree.var.type);
             indexDef.sym = tree.var.sym;
             JCBlock body = make.Block(0, List.of(indexDef, tree.body));
             body.endpos = TreeInfo.endPos(tree.body);
             result = translate(make.
                 ForLoop(List.of(init),
                         cond,
                         List.<JCExpressionStatement>nil(),
                         body));
             patchTargets(body, tree, result);
         }
     public void visitVarDef(JCVariableDecl tree) {
         MethodSymbol oldMethodSym = currentMethodSym;
         tree.mods = translate(tree.mods);
         tree.vartype = translate(tree.vartype);
         if (currentMethodSym == null) {
             // A class or instance field initializer.
             currentMethodSym =
                 new MethodSymbol((tree.mods.flags&STATIC) | BLOCK,
                                  names.empty, null,
                                  currentClass);
         }
         if (tree.init != null) tree.init = translate(tree.init, tree.type);
         result = tree;
         currentMethodSym = oldMethodSym;
     }
     public void visitBlock(JCBlock tree) {
         MethodSymbol oldMethodSym = currentMethodSym;
         if (currentMethodSym == null) {
             // Block is a static or instance initializer.
             currentMethodSym =
                 new MethodSymbol(tree.flags | BLOCK,
                                  names.empty, null,
                                  currentClass);
         }
         super.visitBlock(tree);
         currentMethodSym = oldMethodSym;
     }
     public void visitDoLoop(JCDoWhileLoop tree) {
         tree.body = translate(tree.body);
         tree.cond = translate(tree.cond, syms.booleanType);
         result = tree;
     }
     public void visitWhileLoop(JCWhileLoop tree) {
         tree.cond = translate(tree.cond, syms.booleanType);
         tree.body = translate(tree.body);
         result = tree;
     }
     public void visitForLoop(JCForLoop tree) {
         tree.init = translate(tree.init);
         if (tree.cond != null)
             tree.cond = translate(tree.cond, syms.booleanType);
         tree.step = translate(tree.step);
         tree.body = translate(tree.body);
         result = tree;
     }
     public void visitReturn(JCReturn tree) {
         if (tree.expr != null)
             tree.expr = translate(tree.expr,
                                   types.erasure(currentMethodDef
                                                 .restype.type));
         result = tree;
     }
     public void visitSwitch(JCSwitch tree) {
         Type selsuper = types.supertype(tree.selector.type);
         boolean enumSwitch = selsuper != null &&
             (tree.selector.type.tsym.flags() & ENUM) != 0;
         boolean stringSwitch = selsuper != null &&
             types.isSameType(tree.selector.type, syms.stringType);
         Type target = enumSwitch ? tree.selector.type :
             (stringSwitch? syms.stringType : syms.intType);
         tree.selector = translate(tree.selector, target);
         tree.cases = translateCases(tree.cases);
         if (enumSwitch) {
             result = visitEnumSwitch(tree);
         } else if (stringSwitch) {
             result = visitStringSwitch(tree);
         } else {
             result = tree;
         }
     }
     public JCTree visitEnumSwitch(JCSwitch tree) {
         TypeSymbol enumSym = tree.selector.type.tsym;
         EnumMapping map = mapForEnum(tree.pos(), enumSym);
         make_at(tree.pos());
         Symbol ordinalMethod = lookupMethod(tree.pos(),
                                             names.ordinal,
                                             tree.selector.type,
                                             List.<Type>nil());
         JCArrayAccess selector = make.Indexed(map.mapVar,
                                         make.App(make.Select(tree.selector,
                                                              ordinalMethod)));
         ListBuffer<JCCase> cases = new ListBuffer<JCCase>();
         for (JCCase c : tree.cases) {
             if (c.pat != null) {
                 VarSymbol label = (VarSymbol)TreeInfo.symbol(c.pat);
                 JCLiteral pat = map.forConstant(label);
                 cases.append(make.Case(pat, c.stats));
             } else {
                 cases.append(c);
             }
         }
         JCSwitch enumSwitch = make.Switch(selector, cases.toList());
         patchTargets(enumSwitch, tree, enumSwitch);
         return enumSwitch;
     }
     public JCTree visitStringSwitch(JCSwitch tree) {
         List<JCCase> caseList = tree.getCases();
         int alternatives = caseList.size();
         if (alternatives == 0) { // Strange but legal possibility
             return make.at(tree.pos()).Exec(attr.makeNullCheck(tree.getExpression()));
         } else {
             /*
              * The general approach used is to translate a single
              * string switch statement into a series of two chained
              * switch statements: the first a synthesized statement
              * switching on the argument string's hash value and
              * computing a string's position in the list of original
              * case labels, if any, followed by a second switch on the
              * computed integer value.  The second switch has the same
              * code structure as the original string switch statement
              * except that the string case labels are replaced with
              * positional integer constants starting at 0.
              *
              * The first switch statement can be thought of as an
              * inlined map from strings to their position in the case
              * label list.  An alternate implementation would use an
              * actual Map for this purpose, as done for enum switches.
              *
              * With some additional effort, it would be possible to
              * use a single switch statement on the hash code of the
              * argument, but care would need to be taken to preserve
              * the proper control flow in the presence of hash
              * collisions and other complications, such as
              * fallthroughs.  Switch statements with one or two
              * alternatives could also be specially translated into
              * if-then statements to omit the computation of the hash
              * code.
              *
              * The generated code assumes that the hashing algorithm
              * of String is the same in the compilation environment as
              * in the environment the code will run in.  The string
              * hashing algorithm in the SE JDK has been unchanged
              * since at least JDK 1.2.  Since the algorithm has been
              * specified since that release as well, it is very
              * unlikely to be changed in the future.
              *
              * Different hashing algorithms, such as the length of the
              * strings or a perfect hashing algorithm over the
              * particular set of case labels, could potentially be
              * used instead of String.hashCode.
              */
             ListBuffer<JCStatement> stmtList = new ListBuffer<JCStatement>();
             // Map from String case labels to their original position in
             // the list of case labels.
             Map<String, Integer> caseLabelToPosition =
                 new LinkedHashMap<String, Integer>(alternatives + 1, 1.0f);
             // Map of hash codes to the string case labels having that hashCode.
             Map<Integer, Set<String>> hashToString =
                 new LinkedHashMap<Integer, Set<String>>(alternatives + 1, 1.0f);
             int casePosition = 0;
             for(JCCase oneCase : caseList) {
                 JCExpression expression = oneCase.getExpression();
                 if (expression != null) { // expression for a "default" case is null
                     String labelExpr = (String) expression.type.constValue();
                     Integer mapping = caseLabelToPosition.put(labelExpr, casePosition);
                     Assert.checkNull(mapping);
                     int hashCode = labelExpr.hashCode();
                     Set<String> stringSet = hashToString.get(hashCode);
                     if (stringSet == null) {
                         stringSet = new LinkedHashSet<String>(1, 1.0f);
                         stringSet.add(labelExpr);
                         hashToString.put(hashCode, stringSet);
                     } else {
                         boolean added = stringSet.add(labelExpr);
                         Assert.check(added);
                     }
                 }
                 casePosition++;
             }
             // Synthesize a switch statement that has the effect of
             // mapping from a string to the integer position of that
             // string in the list of case labels.  This is done by
             // switching on the hashCode of the string followed by an
             // if-then-else chain comparing the input for equality
             // with all the case labels having that hash value.
             /*
              * s$ = top of stack;
              * tmp$ = -1;
              * switch($s.hashCode()) {
              *     case caseLabel.hashCode:
              *         if (s$.equals("caseLabel_1")
              *           tmp$ = caseLabelToPosition("caseLabel_1");
              *         else if (s$.equals("caseLabel_2"))
              *           tmp$ = caseLabelToPosition("caseLabel_2");
              *         ...
              *         break;
              * ...
              * }
              */
             VarSymbol dollar_s = new VarSymbol(FINAL|SYNTHETIC,
                                                names.fromString("s" + tree.pos + target.syntheticNameChar()),
                                                syms.stringType,
                                                currentMethodSym);
             stmtList.append(make.at(tree.pos()).VarDef(dollar_s, tree.getExpression()).setType(dollar_s.type));
             VarSymbol dollar_tmp = new VarSymbol(SYNTHETIC,
                                                  names.fromString("tmp" + tree.pos + target.syntheticNameChar()),
                                                  syms.intType,
                                                  currentMethodSym);
             JCVariableDecl dollar_tmp_def =
                 (JCVariableDecl)make.VarDef(dollar_tmp, make.Literal(INT, -1)).setType(dollar_tmp.type);
             dollar_tmp_def.init.type = dollar_tmp.type = syms.intType;
             stmtList.append(dollar_tmp_def);
             ListBuffer<JCCase> caseBuffer = ListBuffer.lb();
             // hashCode will trigger nullcheck on original switch expression
             JCMethodInvocation hashCodeCall = makeCall(make.Ident(dollar_s),
                                                        names.hashCode,
                                                        List.<JCExpression>nil()).setType(syms.intType);
             JCSwitch switch1 = make.Switch(hashCodeCall,
                                         caseBuffer.toList());
             for(Map.Entry<Integer, Set<String>> entry : hashToString.entrySet()) {
                 int hashCode = entry.getKey();
                 Set<String> stringsWithHashCode = entry.getValue();
                 Assert.check(stringsWithHashCode.size() >= 1);
                 JCStatement elsepart = null;
                 for(String caseLabel : stringsWithHashCode ) {
                     JCMethodInvocation stringEqualsCall = makeCall(make.Ident(dollar_s),
                                                                    names.equals,
                                                                    List.<JCExpression>of(make.Literal(caseLabel)));
                     elsepart = make.If(stringEqualsCall,
                                        make.Exec(make.Assign(make.Ident(dollar_tmp),
                                                              make.Literal(caseLabelToPosition.get(caseLabel))).
                                                  setType(dollar_tmp.type)),
                                        elsepart);
                 }
                 ListBuffer<JCStatement> lb = ListBuffer.lb();
                 JCBreak breakStmt = make.Break(null);
                 breakStmt.target = switch1;
                 lb.append(elsepart).append(breakStmt);
                 caseBuffer.append(make.Case(make.Literal(hashCode), lb.toList()));
             }
             switch1.cases = caseBuffer.toList();
             stmtList.append(switch1);
             // Make isomorphic switch tree replacing string labels
             // with corresponding integer ones from the label to
             // position map.
             ListBuffer<JCCase> lb = ListBuffer.lb();
             JCSwitch switch2 = make.Switch(make.Ident(dollar_tmp), lb.toList());
             for(JCCase oneCase : caseList ) {
                 // Rewire up old unlabeled break statements to the
                 // replacement switch being created.
                 patchTargets(oneCase, tree, switch2);
                 boolean isDefault = (oneCase.getExpression() == null);
                 JCExpression caseExpr;
                 if (isDefault)
                     caseExpr = null;
                 else {
                     caseExpr = make.Literal(caseLabelToPosition.get((String)oneCase.
                                                                     getExpression().
                                                                     type.constValue()));
                 }
                 lb.append(make.Case(caseExpr,
                                     oneCase.getStatements()));
             }
             switch2.cases = lb.toList();
             stmtList.append(switch2);
             return make.Block(0L, stmtList.toList());
         }
     }
     public void visitNewArray(JCNewArray tree) {
         tree.elemtype = translate(tree.elemtype);
         for (List<JCExpression> t = tree.dims; t.tail != null; t = t.tail)
             if (t.head != null) t.head = translate(t.head, syms.intType);
         tree.elems = translate(tree.elems, types.elemtype(tree.type));
         result = tree;
     }
     public void visitSelect(JCFieldAccess tree) {
         // need to special case-access of the form C.super.x
         // these will always need an access method.
         boolean qualifiedSuperAccess =
             tree.selected.getTag() == JCTree.SELECT &&
             TreeInfo.name(tree.selected) == names._super;
         tree.selected = translate(tree.selected);
         if (tree.name == names._class)
             result = classOf(tree.selected);
         else if (tree.name == names._this || tree.name == names._super)
             result = makeThis(tree.pos(), tree.selected.type.tsym);
         else
             result = access(tree.sym, tree, enclOp, qualifiedSuperAccess);
     }
     public void visitLetExpr(LetExpr tree) {
         tree.defs = translateVarDefs(tree.defs);
         tree.expr = translate(tree.expr, tree.type);
         result = tree;
     }
     // There ought to be nothing to rewrite here;
     // we don't generate code.
     public void visitAnnotation(JCAnnotation tree) {
         result = tree;
     }
     @Override
     public void visitTry(JCTry tree) {
         if (tree.resources.isEmpty()) {
             super.visitTry(tree);
         } else {
             result = makeTwrTry(tree);
         }
     }
 /**************************************************************************
  * main method
  *************************************************************************/
     /** Translate a toplevel class and return a list consisting of
      *  the translated class and translated versions of all inner classes.
      *  @param env   The attribution environment current at the class definition.
      *               We need this for resolving some additional symbols.
      *  @param cdef  The tree representing the class definition.
      */
     public List<JCTree> translateTopLevelClass(Env<AttrContext> env, JCTree cdef, TreeMaker make) {
         ListBuffer<JCTree> translated = null;
         try {
             attrEnv = env;
             this.make = make;
             endPositions = env.toplevel.endPositions;
             currentClass = null;
             currentMethodDef = null;
             outermostClassDef = (cdef.getTag() == JCTree.CLASSDEF) ? (JCClassDecl)cdef : null;
             outermostMemberDef = null;
             this.translated = new ListBuffer<JCTree>();
             classdefs = new HashMap<ClassSymbol,JCClassDecl>();
             actualSymbols = new HashMap<Symbol,Symbol>();
             freevarCache = new HashMap<ClassSymbol,List<VarSymbol>>();
             proxies = new Scope(syms.noSymbol);
             twrVars = new Scope(syms.noSymbol);
             outerThisStack = List.nil();
             accessNums = new HashMap<Symbol,Integer>();
             accessSyms = new HashMap<Symbol,MethodSymbol[]>();
             accessConstrs = new HashMap<Symbol,MethodSymbol>();
             accessConstrTags = List.nil();
             accessed = new ListBuffer<Symbol>();
             translate(cdef, (JCExpression)null);
             for (List<Symbol> l = accessed.toList(); l.nonEmpty(); l = l.tail)
                 makeAccessible(l.head);
             for (EnumMapping map : enumSwitchMap.values())
                 map.translate();
             checkConflicts(this.translated.toList());
             checkAccessConstructorTags();
             translated = this.translated;
         } finally {
             // note that recursive invocations of this method fail hard
             attrEnv = null;
             this.make = null;
             endPositions = null;
             currentClass = null;
             currentMethodDef = null;
             outermostClassDef = null;
             outermostMemberDef = null;
             this.translated = null;
             classdefs = null;
             actualSymbols = null;
             freevarCache = null;
             proxies = null;
             outerThisStack = null;
             accessNums = null;
             accessSyms = null;
             accessConstrs = null;
             accessConstrTags = null;
             accessed = null;
             enumSwitchMap.clear();
         }
         return translated.toList();
     }
     //////////////////////////////////////////////////////////////
     // The following contributed by Borland for bootstrapping purposes
     //////////////////////////////////////////////////////////////
     private void addEnumCompatibleMembers(JCClassDecl cdef) {
         make_at(null);
         // Add the special enum fields
         VarSymbol ordinalFieldSym = addEnumOrdinalField(cdef);
         VarSymbol nameFieldSym = addEnumNameField(cdef);
         // Add the accessor methods for name and ordinal
         MethodSymbol ordinalMethodSym = addEnumFieldOrdinalMethod(cdef, ordinalFieldSym);
         MethodSymbol nameMethodSym = addEnumFieldNameMethod(cdef, nameFieldSym);
         // Add the toString method
         addEnumToString(cdef, nameFieldSym);
         // Add the compareTo method
         addEnumCompareTo(cdef, ordinalFieldSym);
     }
     private VarSymbol addEnumOrdinalField(JCClassDecl cdef) {
         VarSymbol ordinal = new VarSymbol(PRIVATE|FINAL|SYNTHETIC,
                                           names.fromString("$ordinal"),
                                           syms.intType,
                                           cdef.sym);
         cdef.sym.members().enter(ordinal);
         cdef.defs = cdef.defs.prepend(make.VarDef(ordinal, null));
         return ordinal;
     }
     private VarSymbol addEnumNameField(JCClassDecl cdef) {
         VarSymbol name = new VarSymbol(PRIVATE|FINAL|SYNTHETIC,
                                           names.fromString("$name"),
                                           syms.stringType,
                                           cdef.sym);
         cdef.sym.members().enter(name);
         cdef.defs = cdef.defs.prepend(make.VarDef(name, null));
         return name;
     }
     private MethodSymbol addEnumFieldOrdinalMethod(JCClassDecl cdef, VarSymbol ordinalSymbol) {
         // Add the accessor methods for ordinal
         Symbol ordinalSym = lookupMethod(cdef.pos(),
                                          names.ordinal,
                                          cdef.type,
                                          List.<Type>nil());
         Assert.check(ordinalSym instanceof MethodSymbol);
         JCStatement ret = make.Return(make.Ident(ordinalSymbol));
         cdef.defs = cdef.defs.append(make.MethodDef((MethodSymbol)ordinalSym,
                                                     make.Block(0L, List.of(ret))));
         return (MethodSymbol)ordinalSym;
     }
     private MethodSymbol addEnumFieldNameMethod(JCClassDecl cdef, VarSymbol nameSymbol) {
         // Add the accessor methods for name
         Symbol nameSym = lookupMethod(cdef.pos(),
                                    names._name,
                                    cdef.type,
                                    List.<Type>nil());
         Assert.check(nameSym instanceof MethodSymbol);
         JCStatement ret = make.Return(make.Ident(nameSymbol));
         cdef.defs = cdef.defs.append(make.MethodDef((MethodSymbol)nameSym,
                                                     make.Block(0L, List.of(ret))));
         return (MethodSymbol)nameSym;
     }
     private MethodSymbol addEnumToString(JCClassDecl cdef,
                                          VarSymbol nameSymbol) {
         Symbol toStringSym = lookupMethod(cdef.pos(),
                                           names.toString,
                                           cdef.type,
                                           List.<Type>nil());
         JCTree toStringDecl = null;
         if (toStringSym != null)
             toStringDecl = TreeInfo.declarationFor(toStringSym, cdef);
         if (toStringDecl != null)
             return (MethodSymbol)toStringSym;
         JCStatement ret = make.Return(make.Ident(nameSymbol));
         JCTree resTypeTree = make.Type(syms.stringType);
         MethodType toStringType = new MethodType(List.<Type>nil(),
                                                  syms.stringType,
                                                  List.<Type>nil(),
                                                  cdef.sym);
         toStringSym = new MethodSymbol(PUBLIC,
                                        names.toString,
                                        toStringType,
                                        cdef.type.tsym);
         toStringDecl = make.MethodDef((MethodSymbol)toStringSym,
                                       make.Block(0L, List.of(ret)));
         cdef.defs = cdef.defs.prepend(toStringDecl);
         cdef.sym.members().enter(toStringSym);
         return (MethodSymbol)toStringSym;
     }
     private MethodSymbol addEnumCompareTo(JCClassDecl cdef, VarSymbol ordinalSymbol) {
         Symbol compareToSym = lookupMethod(cdef.pos(),
                                    names.compareTo,
                                    cdef.type,
                                    List.of(cdef.sym.type));
         Assert.check(compareToSym instanceof MethodSymbol);
         JCMethodDecl compareToDecl = (JCMethodDecl) TreeInfo.declarationFor(compareToSym, cdef);
         ListBuffer<JCStatement> blockStatements = new ListBuffer<JCStatement>();
         JCModifiers mod1 = make.Modifiers(0L);
         Name oName = names.fromString("o");
         JCVariableDecl par1 = make.Param(oName, cdef.type, compareToSym);
         JCIdent paramId1 = make.Ident(names.java_lang_Object);
         paramId1.type = cdef.type;
         paramId1.sym = par1.sym;
         ((MethodSymbol)compareToSym).params = List.of(par1.sym);
         JCIdent par1UsageId = make.Ident(par1.sym);
         JCIdent castTargetIdent = make.Ident(cdef.sym);
         JCTypeCast cast = make.TypeCast(castTargetIdent, par1UsageId);
         cast.setType(castTargetIdent.type);
         Name otherName = names.fromString("other");
         VarSymbol otherVarSym = new VarSymbol(mod1.flags,
                                               otherName,
                                               cdef.type,
                                               compareToSym);
         JCVariableDecl otherVar = make.VarDef(otherVarSym, cast);
         blockStatements.append(otherVar);
         JCIdent id1 = make.Ident(ordinalSymbol);
         JCIdent fLocUsageId = make.Ident(otherVarSym);
         JCExpression sel = make.Select(fLocUsageId, ordinalSymbol);
         JCBinary bin = makeBinary(JCTree.MINUS, id1, sel);
         JCReturn ret = make.Return(bin);
         blockStatements.append(ret);
         JCMethodDecl compareToMethod = make.MethodDef((MethodSymbol)compareToSym,
                                                    make.Block(0L,
                                                               blockStatements.toList()));
         compareToMethod.params = List.of(par1);
         cdef.defs = cdef.defs.append(compareToMethod);
         return (MethodSymbol)compareToSym;
     }
     //////////////////////////////////////////////////////////////
     // The above contributed by Borland for bootstrapping purposes
     //////////////////////////////////////////////////////////////
 }

Mercurial > jdk8-mips64-public > langtools / annotate

src/share/classes/com/sun/tools/javac/comp/Lower.java@75e25df50873 (annotated)

src/share/classes/com/sun/tools/javac/comp/Lower.java