[BUG] Loop optimize error for ^= (64Bit Runtime1.6.0_18)

Question

Hi,
I don't know if I should make bug report or not. I have found a strange error within a loop iteration up to Integer.MAXVALUE.
Here is the source:
public class problem64bit
      * @param args
     public static void main(final String[] args)
          System.out.println("java.version = \t"
                    + System.getProperty("java.version") + " "
                    + System.getProperty("java.vm.name") + " ("
                    + System.getProperty("sun.arch.data.model") + "Bit)");
          System.out.println("OS = \t\t" + System.getProperty("os.name") + " ("
                    + System.getProperty("os.version") + ")\n");
          booleanInvert(Integer.MAX_VALUE);
          booleanInvert(Integer.MAX_VALUE - 1);
          booleanInvert(Integer.MAX_VALUE - 2);
     private static void booleanInvert(final int max)
          System.out.println("BooleanInvert with max = " + max + " iterations");
          long timeStart = System.currentTimeMillis();
          boolean test1 = false;
          boolean test2 = false;
          boolean test3 = false;
          for (int i = 0; i < max; i++)
               test1 = !test1;
          for (int i = 0; i < max; i++)
               test2 = test2 ? false : true;
          for (int i = 0; i < max; i++)
               test3 ^= true;
          System.out.println("Time: " + (System.currentTimeMillis() - timeStart)
                    + "ms");
          if (test1 != test2 || test1 != test3)
               System.out.println("ERROR: Boolean invert\n\ttest1=" + test1
                         + "\n\ttest2=" + test2 + "\n\ttest3=" + test3);
          } else
               System.out.println("Everything as it should be!");
}The result is different between a x32JRE and a x64JRE
Results on a x32JRE:
java.version =      1.6.0_18 Java HotSpot(TM) Client VM (32Bit)
OS =           Windows 7 (6.1)
BooleanInvert with max = 2147483647 iterations
Time: 7812ms
Everything as it should be!
BooleanInvert with max = 2147483646 iterations
Time: 7469ms
Everything as it should be!
BooleanInvert with max = 2147483645 iterations
Time: 8801ms
Everything as it should be!and here are the results on a x64JRE
java.version =      1.6.0_18 Java HotSpot(TM) 64-Bit Server VM (64Bit)
OS =           Windows 7 (6.1)
BooleanInvert with max = 2147483647 iterations
Time: 13ms
ERROR: Boolean invert
     test1=true
     test2=true
     test3=false
BooleanInvert with max = 2147483646 iterations
Time: 11ms
Everything as it should be!
BooleanInvert with max = 2147483645 iterations
Time: 0ms
Everything as it should be!as you can see, the result on the x32 JRE is the expected one. The x64 JRE is very fast but there seems to be a nasty bug in the optimization code for the loops because only with Interger.MAXVALUE there is a problem.
What to do now - can anybody reproduce the error and sould i report it as a bug? Is it only in the Win(7) x64 JRE?
greetings
Edited by: GandalfTheWhite on Feb 13, 2010 6:30 AM
Edited by: GandalfTheWhite on Feb 13, 2010 6:38 AM
Edited by: GandalfTheWhite on Feb 13, 2010 6:50 AM

Answer 1

Hi,
well this is the first time I hear that eclipse uses its own compiler! But nothing is impossible :-) -> as I know now eclipse uses its own incremental compiler :-(.
Here are the javap codes of the two class files (minimized example!)
But I will update my eclipse with the lates stable build an have a look at the problem again. Thx for your help!
eclipse.class
Compiled from "problem64Bit.java"
public class problem64Bit extends java.lang.Object{
public problem64Bit();
  Code:
   0:     aload_0
   1:     invokespecial     #8; //Method java/lang/Object."<init>":()V
   4:     return
public static void main(java.lang.String[]);
  Code:
   0:     ldc     #16; //int 2147483647
   2:     invokestatic     #17; //Method booleanInvert:(I)V
   5:     ldc     #21; //int 2147483646
   7:     invokestatic     #17; //Method booleanInvert:(I)V
   10:     return
private static void booleanInvert(int);
  Code:
   0:     iconst_0
   1:     istore_1
   2:     iconst_0
   3:     istore_2
   4:     iconst_0
   5:     istore_3
   6:     goto     22
   9:     iload_1
   10:     ifeq     17
   13:     iconst_0
   14:     goto     18
   17:     iconst_1
   18:     istore_1
   19:     iinc     3, 1
   22:     iload_3
   23:     iload_0
   24:     if_icmplt     9
   27:     iconst_0
   28:     istore_3
   29:     goto     39
   32:     iload_2
   33:     iconst_1
   34:     ixor
   35:     istore_2
   36:     iinc     3, 1
   39:     iload_3
   40:     iload_0
   41:     if_icmplt     32
   44:     iload_1
   45:     iload_2
   46:     if_icmpeq     83
   49:     getstatic     #24; //Field java/lang/System.out:Ljava/io/PrintStream;
   52:     new     #30; //class java/lang/StringBuilder
   55:     dup
   56:     ldc     #32; //String ERROR: Boolean invert\n\ttest1=
   58:     invokespecial     #34; //Method java/lang/StringBuilder."<init>":(Ljava/lang/String;)V
   61:     iload_1
   62:     invokevirtual     #37; //Method java/lang/StringBuilder.append:(Z)Ljava/lang/StringBuilder;
   65:     ldc     #41; //String \n\ttest2=
   67:     invokevirtual     #43; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
   70:     iload_2
   71:     invokevirtual     #37; //Method java/lang/StringBuilder.append:(Z)Ljava/lang/StringBuilder;
   74:     invokevirtual     #46; //Method java/lang/StringBuilder.toString:()Ljava/lang/String;
   77:     invokevirtual     #50; //Method java/io/PrintStream.println:(Ljava/lang/String;)V
   80:     goto     91
   83:     getstatic     #24; //Field java/lang/System.out:Ljava/io/PrintStream;
   86:     ldc     #55; //String Everything as it should be!
   88:     invokevirtual     #50; //Method java/io/PrintStream.println:(Ljava/lang/String;)V
   91:     returnconsole.class
Compiled from "problem64Bit.java"
public class problem64Bit extends java.lang.Object{
public problem64Bit();
  Code:
   0:     aload_0
   1:     invokespecial     #1; //Method java/lang/Object."<init>":()V
   4:     return
public static void main(java.lang.String[]);
  Code:
   0:     ldc     #2; //int 2147483647
   2:     invokestatic     #3; //Method booleanInvert:(I)V
   5:     ldc     #4; //int 2147483646
   7:     invokestatic     #3; //Method booleanInvert:(I)V
   10:     return
private static void booleanInvert(int);
  Code:
   0:     iconst_0
   1:     istore_1
   2:     iconst_0
   3:     istore_2
   4:     iconst_0
   5:     istore_3
   6:     iload_3
   7:     iload_0
   8:     if_icmpge     27
   11:     iload_1
   12:     ifne     19
   15:     iconst_1
   16:     goto     20
   19:     iconst_0
   20:     istore_1
   21:     iinc     3, 1
   24:     goto     6
   27:     iconst_0
   28:     istore_3
   29:     iload_3
   30:     iload_0
   31:     if_icmpge     44
   34:     iload_2
   35:     iconst_1
   36:     ixor
   37:     istore_2
   38:     iinc     3, 1
   41:     goto     29
   44:     iload_1
   45:     iload_2
   46:     if_icmpeq     86
   49:     getstatic     #5; //Field java/lang/System.out:Ljava/io/PrintStream;
   52:     new     #6; //class java/lang/StringBuilder
   55:     dup
   56:     invokespecial     #7; //Method java/lang/StringBuilder."<init>":()V
   59:     ldc     #8; //String ERROR: Boolean invert\n\ttest1=
   61:     invokevirtual     #9; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
   64:     iload_1
   65:     invokevirtual     #10; //Method java/lang/StringBuilder.append:(Z)Ljava/lang/StringBuilder;
   68:     ldc     #11; //String \n\ttest2=
   70:     invokevirtual     #9; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
   73:     iload_2
   74:     invokevirtual     #10; //Method java/lang/StringBuilder.append:(Z)Ljava/lang/StringBuilder;
   77:     invokevirtual     #12; //Method java/lang/StringBuilder.toString:()Ljava/lang/String;
   80:     invokevirtual     #13; //Method java/io/PrintStream.println:(Ljava/lang/String;)V
   83:     goto     94
   86:     getstatic     #5; //Field java/lang/System.out:Ljava/io/PrintStream;
   89:     ldc     #14; //String Everything as it should be!
   91:     invokevirtual     #13; //Method java/io/PrintStream.println:(Ljava/lang/String;)V
   94:     returnas far as i can see... there a some differences but more could not make out of it.
greeting gandalf
ps here the source for the smaler sample
public class problem64Bit
      * @param args
      *            Arguments
     public static void main(final String[] args)
          booleanInvert(Integer.MAX_VALUE);
          booleanInvert(Integer.MAX_VALUE - 1);
     private static void booleanInvert(final int max)
          boolean test1 = false;
          boolean test2 = false;
          for (int i = 0; i < max; i++)
               test1 = !test1;
          for (int i = 0; i < max; i++)
               test2 ^= true;
          if (test1 != test2)
               System.out.println("ERROR: Boolean invert\n\ttest1=" + test1
                         + "\n\ttest2=" + test2);
          } else
               System.out.println("Everything as it should be!");
}Edited by: GandalfTheWhite on Feb 16, 2010 11:33 AM