incorrect local variable attribute generated by javac

Name: nt126004 Date: 04/10/2002


FULL PRODUCT VERSION :
java version "1.4.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)

FULL OPERATING SYSTEM VERSION :

Microsoft Windows 2000 [Version 5.00.2195]

A DESCRIPTION OF THE PROBLEM :
Javac is generating the incorrect pc value for variables
declared in catch statements (i.e. catch(Exception myEVar)

So code that looks like:

try
{
}
catch(Exception e)
{
   System.out.println(e.toString())
}

when in a debugger such as jdb and at a breakpoint on the
system.out.println line, e will not show up in the local
variables list... See sample below for sample source and
javap output showing problem...



STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the simple HelloWorld.java source provided for
debug using javac.

Now load resulting class into jdb and follow this session:

D:\test_projects\helloWorld>java -version
java version "1.4.0"
Java(TM) 2 Runtime Environment, Standard Edition (build
1.4.0-b
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)

D:\test_projects\helloWorld>jdb HelloWorld
Initializing jdb ...
> stop at HelloWorld:16
Deferring breakpoint HelloWorld:16.
It will be set after the class is loaded.
> run
run HelloWorld
>
VM Started: Set deferred breakpoint HelloWorld:16
Hello World!
i = 10 is an even number.

Breakpoint hit: "thread=main", HelloWorld.main(), line=16
bci=9
16 System.out.println("Exception caught!" + e);

main[1] locals
Method arguments:
args = instance of java.lang.String[0] (id=287)
Local variables:
i = 10
main[1]



EXPECTED VERSUS ACTUAL BEHAVIOR :
When I printed local variables for my sample in jdb, it
only showed the my local int i and the args to main. It
should have also listed e...

This bug can be reproduced always.

---------- BEGIN SOURCE ----------
HelloWorld.java:

import java.io.*;

public class HelloWorld {
   public static void main(String[] args) {
     int i = 10;
     System.out.println("Hello World!");
     try {
       if ((i % 2) == 0) {
         System.out.println("i = " + i + " is an even number.");
         Integer.parseInt("zzz200");
       } else {
         System.out.println("i = " + i + " is an odd number.");
         Thread.sleep(10);
       }
     } catch (Exception e) {
         System.out.println("Exception caught!" + e);
     }

     System.out.println("Bye");
   }
}


javap dump showing incorrect local var table generated for e:

D:\test_projects\helloWorld>javap -c -l HelloWorld
Compiled from HelloWorld.java
public class HelloWorld extends java.lang.Object {
    public HelloWorld();
    public static void main(java.lang.String[]);
}

Method HelloWorld()
   0 aload_0
   1 invokespecial #1 <Method java.lang.Object()>
   4 return

Line numbers for method HelloWorld()
   line 3: 0

Local variables for method HelloWorld()
   HelloWorld this pc=0, length=5, slot=0

Method void main(java.lang.String[])
   0 bipush 10
   2 istore_1
   3 getstatic #2 <Field java.io.PrintStream out>
   6 ldc #3 <String "Hello World!">
   8 invokevirtual #4 <Method void println(java.lang.String)>
  11 iload_1
  12 iconst_2
  13 irem
  14 ifne 56
  17 getstatic #2 <Field java.io.PrintStream out>
  20 new #5 <Class java.lang.StringBuffer>
  23 dup
  24 invokespecial #6 <Method java.lang.StringBuffer()>
  27 ldc #7 <String "i = ">
  29 invokevirtual #8 <Method java.lang.StringBuffer append(java.lang.String)
  32 iload_1
  33 invokevirtual #9 <Method java.lang.StringBuffer append(int)>
  36 ldc #10 <String " is an even number.">
  38 invokevirtual #8 <Method java.lang.StringBuffer append(java.lang.String)
  41 invokevirtual #11 <Method java.lang.String toString()>
  44 invokevirtual #4 <Method void println(java.lang.String)>
  47 ldc #12 <String "zzz200">
  49 invokestatic #13 <Method int parseInt(java.lang.String)>
  52 pop
  53 goto 92
  56 getstatic #2 <Field java.io.PrintStream out>
  59 new #5 <Class java.lang.StringBuffer>
  62 dup
  63 invokespecial #6 <Method java.lang.StringBuffer()>
  66 ldc #7 <String "i = ">
  68 invokevirtual #8 <Method java.lang.StringBuffer append(java.lang.String)
  71 iload_1
  72 invokevirtual #9 <Method java.lang.StringBuffer append(int)>
  75 ldc #14 <String " is an odd number.">
  77 invokevirtual #8 <Method java.lang.StringBuffer append(java.lang.String)
  80 invokevirtual #11 <Method java.lang.String toString()>
  83 invokevirtual #4 <Method void println(java.lang.String)>
  86 ldc2_w #15 <Long 10>
  89 invokestatic #17 <Method void sleep(long)>
  92 goto 121
  95 astore_2
  96 getstatic #2 <Field java.io.PrintStream out>
  99 new #5 <Class java.lang.StringBuffer>
 102 dup
 103 invokespecial #6 <Method java.lang.StringBuffer()>
 106 ldc #19 <String "Exception caught!">
 108 invokevirtual #8 <Method java.lang.StringBuffer append(java.lang.String)
 111 aload_2
 112 invokevirtual #20 <Method java.lang.StringBuffer append(java.lang.Object
 115 invokevirtual #11 <Method java.lang.String toString()>
 118 invokevirtual #4 <Method void println(java.lang.String)>
 121 getstatic #2 <Field java.io.PrintStream out>
 124 ldc #21 <String "Bye">
 126 invokevirtual #4 <Method void println(java.lang.String)>
 129 return
Exception table:
   from to target type
    11 92 95 <Class java.lang.Exception>

Line numbers for method void main(java.lang.String[])
   line 5: 0
   line 6: 3
   line 8: 11
   line 9: 17
   line 10: 47
   line 12: 56
   line 13: 86
   line 15: 92
   line 16: 95
   line 19: 121
   line 20: 129

Local variables for method void main(java.lang.String[])
   java.lang.String[] args pc=0, length=130, slot=0
   int i pc=3, length=126, slot=1
   java.lang.Exception e pc=96, length=25, slot=2

NOTE : pc should have been 95 not 96 in the above table for e...



---------- END SOURCE ----------
(Review ID: 144945)
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