[Soot-list] PatchingChain.insertBefore(Chain<E> toInsert, E point): bug?

[Eric Bodden]

Seems to cause no problems... This is now committed in revision 3351.

Thanks again,
Eric

--
Eric Bodden
Software Technology Group, Technische Universität Darmstadt, Germany
Tel: +49 6151 16-5478    Fax: +49 6151 16-5410
Mailing Address: S2|02 A209, Hochschulstraße 10, 64289 Darmstadt



2009/12/10 Eric Bodden <bodden at st.informatik.tu-darmstadt.de>:
> Hi Khilan.
>
> Thanks for the patch. This looks like a correct patch to an actual bug
> to me. I will try it out with our test suite today.
> Eric
>
> --
> Eric Bodden
> Software Technology Group, Technische Universität Darmstadt, Germany
> Tel: +49 6151 16-5478    Fax: +49 6151 16-5410
> Mailing Address: S2|02 A209, Hochschulstraße 10, 64289 Darmstadt
>
>
>
> 2009/12/9 Khilan Gudka <khilan at doc.ic.ac.uk>:
>> Hi,
>> The method PatchingChain.insertBefore(Chain<E> toInsert, E point) inserts
>> the chain "toInsert" just before "point" in the receiver chain. It does this
>> by calling PatchingChain.insertBefore(E toInsert, E point) for each Unit in
>> a reversed version of toInsert. To keep the correct control flow,
>> PatchingChain.insertBefore(E toInsert, E point) redirects jumps to "point"
>> to jump to "toInsert" instead. However, I've found that this leads to bugs
>> when inserting a chain that contains jumps itself. For example, inserting
>> the jimple code:
>>         if $r == 0 goto label0;
>>         staticinvoke <mypackage.MyClass: void m()>();
>>      label0:
>>         staticinvoke <mypackage.MyClass: void n()>();
>> Which corresponds to:
>> if($r) {
>>     MyClass.m();
>> }
>> MyClass.n();
>> Would be turned into the following when using the
>> above PatchingChain.insertBefore(Chain<E> toInsert, E point) method:
>>      label0:
>>         if $r == 0 goto label0;
>>         staticinvoke <mypackage.MyClass: void m()>();
>>         staticinvoke <mypackage.MyClass: void n()>();
>> The reason being that when insertBefore(E toInsert, E point) is repeatedly
>> called, the jump to "staticinvoke <mypackage.MyClass: void n()>();" is
>> redirected to the first statement "if $r == 0 goto label0;".
>> I think the solution is to, lastly, redirect jumps to "point" to the first
>> unit in toInsert (here is a snippet from the bottom
>> of PatchingChain.insertBefore(Chain<E> toInsert, E point) and the proposed
>> changes are in bold):
>>         E previousPoint = point;
>>         Iterator<E> it = backwardList.iterator();
>>         while (it.hasNext())
>>         {
>>             E o = it.next();
>>             insertBeforeNoRedirect(o, previousPoint);
>>             previousPoint = o;
>>         }
>>         ((Unit) point).redirectJumpsToThisTo((Unit) toInsert.getFirst());
>> Does this make sense or have I overlooked something?
>> Thanks,
>> Khilan
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>>
>>
>