>>>>> "Dan" == Apache Harmony Bootstrap JVM <[EMAIL PROTECTED]> writes:
Dan> I agree that the verifier should look into this, but what happens if
Dan> you get a divide by zero error? Or a null pointer exception? These
Dan> are not available to the verifier, but are runtime conditions that
Dan> do not arise in advance.
The bytecode verifier doesn't need to know about exceptions at all.
"Checked" exceptions are purely a language thing. They are not
checked by the runtime.
Dan> Therefore, they need to be checked at
Dan> run time and exceptions thrown.
True.
Dan> One question that I have is that in 'jvm/src/opcode.c' there are
Dan> a number of references to thread_throw_exception(). The first
Dan> parameter is the type of event, either a java.lang.Error or a
Dan> java.lang.Exception or a java.lang.Throwable. Can I get by
Dan> without java.lang.Throwable?
I read through the exception code a bit. From my reading, I see a few
flaws.
First, there is no need to differentiate between throwable, exception,
and error in the JVM. 'athrow' merely throws an object whose type is
a subclass of Throwable. The catch handlers do the type comparison at
runtime to see if they should run.
It isn't clear to me how THREAD_STATUS_THREW_UNCAUGHT is ever set.
But, it doesn't matter, since I think this isn't needed. Instead it
is more typical to set up a base frame in the thread which essentially
looks like this:
try {
.. run the thread's code
} catch (Throwable) { // this catches any "uncaught" exception
.. forward to ThreadGroup
}
I.E, you don't need a special flag.
In thread.h it looks as though the exception being thrown is thrown by
class name:
rchar *pThrowableEvent; /**< Exception, Error, or Throwable
* that was thrown by this thread.
* @link #rnull [EMAIL PROTECTED]
* if nothing was thrown.
*/
Typically it is simpler to unify the exception handling code so that
internally generated exceptions (e.g., an NPE) are thrown using the
same mechanism as user-code-generated exceptions. In other words, I
think you're going to want an object reference here.
Tom
