[LLVMdev] Problems understanding alias analysis validation logic

Robert Zeh robert.a.zeh at gmail.com
Fri Aug 15 14:42:05 PDT 2008


I thought the pass manager was supposed to insulate you from the  
specifics of which passes invalidated which analysis passes.

It is possible to at least add the same analysis instance to avoid  
multiple allocations from the heap?

Robert

On Aug 15, 2008, at 12:31 PM, Matthijs Kooijman wrote:

> Hi Damien,
>
> I think the problem is that when the passmanager sees an Alias  
> Analysis
> available, it will use that, but when none is available, it will  
> always run
> the default implementation (BasicAA), regardless of any alias  
> analysis's run
> before. This means you should insert Andersen's before any pass that  
> needs it.
> I suspect (not sure though) that the passmanager will not rerun  
> Andersen's if
> it is still available, even when you explicitely add it.
>
> Gr.
>
> Matthijs
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