JDK-5058132 : (enum) poor performance in compiler-generated Enum.valueOf(String)
  • Type: Bug
  • Component: tools
  • Sub-Component: javac
  • Affected Version: 5.0
  • Priority: P4
  • Status: Closed
  • Resolution: Fixed
  • OS: solaris_8,windows_xp
  • CPU: generic,x86
  • Submitted: 2004-06-06
  • Updated: 2006-10-23
  • Resolved: 2004-11-06
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JDK 6
6 b12Fixed
Related Reports
Duplicate :  
JDK-6352179 - Modify generated valueOf method for enum (performance enhancement)
Description
The compiler-generated code for the static method valueOf(String) in every enum
type scans the list of enumeration constants linearly.  Correct but not very
efficient.  Better would be to delegate to Enum.valueOf(Class,String), which
uses a Map maintained in the class object.
Comments
CONVERTED DATA BugTraq+ Release Management Values COMMIT TO FIX: dragon mustang
11-09-2004
SUGGESTED FIX --- /tmp/geta9993 2004-09-10 01:46:12.351894400 -0700 +++ Lower.java 2004-09-10 01:15:57.706762392 -0700 @@ -2090,42 +2090,33 @@ enumDefs.append(valuesDef); // public static E valueOf(String name) { - // for (E #e : VALUES) - // if (#e.name().equals(name)) - // return #e; - // throw new IllegalArgumentException(name); + // return Enum.valueOf(ValueOf.class, name); // } - Symbol valueOfSym = lookupMethod(tree.pos, + MethodSymbol valueOfSym = lookupMethod(tree.pos, names.valueOf, tree.sym.type, Type.emptyList.prepend(syms.stringType)); assert (valueOfSym.flags() & STATIC) != 0; - VarSymbol nameArgSym = ((MethodSymbol)valueOfSym).params.head; + VarSymbol nameArgSym = valueOfSym.params.head; Ident nameVal = (Ident)make.Ident(nameArgSym); - VarSymbol eSym = new VarSymbol(SYNTHETIC|FINAL, - names.fromString(target.syntheticNameChar() + "E"), - tree.type, - valueOfSym); - Tree returnE = make.Return(make.Ident(eSym)); - Tree eName = makeCall(make.Ident(eSym), names._name, Tree.emptyList); - Tree condition = makeCall(eName, names.fromString("equals"), Tree.emptyList.prepend(nameVal)); - Tree ifStmt = make.If(condition, returnE, null); - Tree foreachLoop = make.ForeachLoop(make.VarDef(eSym, null), make.Ident(valuesVar), ifStmt); - NewClass newclass = make.NewClass(null, - null, - make.Ident(syms.illegalArgumentExceptionType.tsym), - Tree.emptyList.prepend(nameVal), - null); - newclass.type = syms.illegalArgumentExceptionType; - newclass.constructor = lookupMethod(tree.pos, - names.init, - syms.illegalArgumentExceptionType, - Type.emptyList.prepend(syms.stringType)); - Tree throwStatement = make.Throw(newclass); + Tree thisEnum_class = classOfType(tree.type, tree.pos). + setType(new ClassType + (syms.classType.outer(), + Type.emptyList.prepend(types.erasure(tree.type)), + syms.classType.tsym)); + List<Type> enumValueOfArgTypes = Type.emptyList. + prepend(syms.stringType). + prepend(thisEnum_class.type); + Tree enumValueOf = + make.Return(make.TypeCast(tree.type, + makeCall(make.Ident(syms.enumSym), + names.valueOf, + Tree.emptyList. + prepend(nameVal). + prepend(thisEnum_class)))); MethodDef valueOf = make.MethodDef((MethodSymbol)valueOfSym, make.Block(0, Tree.emptyList. - prepend(throwStatement). - prepend(foreachLoop))); + prepend(enumValueOf))); nameVal.sym = valueOf.params.head.sym; enumDefs.append(valueOf); ###@###.### 2004-09-10
10-09-2004
EVALUATION Will do. ###@###.### 2004-06-06
06-06-2004