[LLVMdev] GCMetadataPrinter::finishAssembly not executed?

[Pedro Artigas]

Hello Yiannis,

I am not an expert on metadata or the CG information but one of the two has to happen:

- Simply moving the deleter pass to a different spot
- Changing the doFinalization of another pass (Printer?) to do the deleter pass job (this should work now because the doFinalization order is the reverse of the doInitialization order)

Option 1 is a smaller change, option 2 will make the code cleaner and prevent issues like this in the future, so it sounds like a better solution.

Thanks

Pedro

On Feb 15, 2013, at 4:25 AM, Yiannis Tsiouris <gtsiour at softlab.ntua.gr> wrote:

> Hi Pedro (et al.),
> 
> On 02/14/2013 11:43 PM, Pedro Artigas wrote:
>> I believe what is going on is that there is an issue with the way that information is deleted (the CG information).
> Yeap, that's exactly the problem! :-) I noticed that the GCModuleInfo::iterator (line 931 in lib/CodeGen/AsmPrinter/AsmPrinter.cpp) is empty and, thus, GCMetadataPrinter::finishAssembly is never called.
> 
>> Right now there is a pass whose only job is to delete that information (CGInfoDeleter) and that pass deletes the info before the AsmPrinter has a chance to call the finishAssembly function. Right now the order that the doFinalization is called on passes is the reverse order of doInitialization (and that makes sense as if a pass depends on some other pass it has to initialize after that pass and clean up before it) so the deleter pass would have to be added in the pass order after the AsmPrinter pass as that pass clearly depends on the Deleter pass (passes that have dependencies on other passes should finalize before the pass it depends on does).
>> 
>> I have a hunch that the very need for the Deleter pass is that the order of deletion was somewhat undefined before and by having an specific pass one could place the deletion wherever she/he sees fit. Now that the doFinalization order is the reverse of the doInitialization one can probably just not have a deleter and free the info inside the printer pass. The AsmPrinter depends on the Printer pass so the new order should take care of initialization and finalization at the right time.
>> 
>> Does this make sense?
> Hmm, I see what happens with the doInitialization/doFinalization and the pass dependencies. This makes sense to me.
> 
> One question though: does this mean that someone has to modify the GCMetadataPrinter instance to explicitly take care of the deletion of the metadata or changing the order of the Deleter/Printer passes should do the trick? If I got it right, this should happen automatically.
> 
> yiannis
> 
> -- 
> Yiannis Tsiouris
> Ph.D. student,
> Software Engineering Laboratory,
> National Technical University of Athens
> WWW: http://www.softlab.ntua.gr/~gtsiour
>