Re: Re: Re: Adding try/finally block

problem solved ... just one missing goto  :(

cheers
Nikolas

Nikolas Nehmer schrieb:
> Hi,
>
> I have a follow up problem extending and creating try/catch/finally
> blocks.
>
> I'm trying to implement a try block depth counter on bytecode level. For
> every try block entered the counter is incremented and for a try block
> left the counter is decremented. Of course, there are 3 different use
> cases.
> 1. try block is executed completely
> 2. try block is terminated by an exception that is caught by one of the
> corresponding handlers
> 3. try block is terminated by an exception not caught by one of the
> corresponding handlers
>
> For cases where a complete try/catch/finally structure already exists in
> the source code this apporach works perfectly. But I have serious
> problems rebuilding the finally block structure by myself for the 3rd
> case. By studying several simple try/catch/finally examples I came up
> with the following "general" structure of try/catch/finally blocks:
>
> try block start label
> ...
> some code
> ...
> try block end label
> JumpInsn to normalExecutionFinallyBlockLabel
>
> exception handler start label
> exception handler code
> cloned finally block code
> JumpInsn to End of try block
>
> exception handler start label
> exception handler code
> cloned finally block code
> JumpInsn to End of try block
>
> ... continued for every exception handler
>
> exceptionalExecutionFinallyBlock Label
> FrameInsn
> ASTORE
> cloned finally block code
> ALOAD
> ATHROW
>
> normalExecutionFinallyBlock Label
> cloned finally block code
>
> end of try block label
>
> Assuming this structure is correct, I came up with a solution for the 3
> cases mentioned above. The first two are quite simple to solve. I'm just
> inserting my counter decrement behind the
> normalExecutionFinallyBlockLabel and behind the
> ExcetionHandlerBlockStartLabels. For the third case I would like to add
> my counter decrement to the exceptionalExecutionFinallyBlockLabel. In
> case the finally block structure already exists in the application code,
> this works perfectly. BUT if I have to add the complete finally block
> logic to the code (in case there ony exists a try/catch block within the
> code) a java.lang.VerifyError (Inconsistent stack height 0 != 1) is
> raised. In fact this exception is raised when I'm trying to add a new
> TryCatchBlockNode specifying the corresponding finally block (for case
> 3).
>
> Any help will be appreciated ;-)
>
> Best regards
> Nikolas
>
>   


-- 
Dipl.-Inf. Nikolas Nehmer,
Dept. of Computer Science. University of Kaiserslautern 
P.O. Box 3049, 67653 Kaiserslautern, Germany.
room 36/308, phone: +49 (0) 631 - 205 2644, fax: +49 (0) 631 - 205 3299
mail: [email protected]

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