Exception handler question

[Roman Kennke]

Hi,

I have a question regarding exception handlers. If I have code like
this:

synchronized (o)
     {
       x();
     }

produces bytecode like this:

0:   aload_1
     1:   dup
     2:   astore_2
     3:   monitorenter
#   4:   aload_0
#   5:   invokevirtual   #2; //Method x:()V
#   8:   aload_2
#   9:   monitorexit
     10:  goto    18
*   13:  astore_3
*   14:  aload_2
*   15:  monitorexit
     16:  aload_3
     17:  athrow
     18:  return
   Exception table:
    from   to  target type
#    4    10    13   any
*   13    16    13   any

The code marked with # has an exception handler, which is marked with *.
This is clearly ok, it is made so that the monitors are correctly exited
when an exception is thrown in the sync block.

My question is, why does the exception handler * point to itself?
Wouldn't that catapult the VM into a loop, if monitorexit fails? A
scenario that comes to mind is when x() is a JNI function that does a
monitorexit. I'd like to understand why this code is generated like
this.

/Roman
-- 
Dipl.-Inform. (FH) Roman Kennke, Software Engineer, http://kennke.org
aicas Allerton Interworks Computer Automated Systems GmbH
Haid-und-Neu-Straße 18 * D-76131 Karlsruhe * Germany
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