Name: tb29552 Date: 03/09/98


Compile and run the following code (in the file MyObject.java)

public class MyObject {

  private boolean isZero( int d ) {
    switch (d) {
    case 0:
      return true;
    default:
      return false;
    }
  }

  void useSecondArgument( String a, int b ) {
    if ( !isZero( b ) )
      System.out.println( "isZero(0) returns false?!" );
  }

  public static void main( String[] args ) {
    MyObject object = new MyObject();
    object.useSecondArgument( "42", 0 );
  }

}


% javac -O MyObject.java
% java MyObject
isZero(0) returns false?!
%

The program should execute quietly but writes
the text above to the console. When compiled
without -O it (of course) executes correctly.

Decompilation of the generated bytecode:

/* Decompiled by Mocha from MyObject.class */
/* Originally compiled from MyObject.java */

import java.io.PrintStream;

public synchronized class MyObject
{
    public MyObject()
    {
    }

    private boolean isZero(int i)
    {
        switch (i)
        {
        case 0:
            return true;

        default:
            return false;
        }
    }

    public static void main(String astring[])
    {
        MyObject myObject = new MyObject();
        myObject.useSecondArgument("42", 0);
    }

    void useSecondArgument(String string, int i)
    {
        switch (string)
        {
        case 0:
            break;

        default:
            System.out.println("isZero(0) returns false?!");
            break;
        }
    }
}

This indicates a bug in the inlining of the method isZero().
The first argument is used in the expanded inline code
instead of the second one.


Apart from in jdk1.2beta2 this bug exists also in
jdk1.1.4 and jdk1.1.5.
(Review ID: 26239)
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