llvm dev - Aug 2009 - [LLVMdev] DSA getNodeForValue() Returning NULL Sometimes

I'm iterating over all LoadInst and StoreInst-type Instructions in a 
Function, and getNodeForValue() is sometimes returning NULL.  Why is 
this happening?  Shouldn't every load from or store to memory correspond 
to some DSNode?

--Patrick

On Fri, Aug 7, 2009 at 4:45 PM, Patrick Alexander
Simmons<simmon12 at cs.uiuc.edu> wrote:
> I'm iterating over all LoadInst and StoreInst-type Instructions in a
> Function, and getNodeForValue() is sometimes returning NULL.  Why is
> this happening?  Shouldn't every load from or store to memory
correspond
> to some DSNode?

Not if the pointer is null or the pointer contains no information in
the pass you are querying.

Andrew

Andrew Lenharth wrote:
> On Fri, Aug 7, 2009 at 4:45 PM, Patrick Alexander
> Simmons<simmon12 at cs.uiuc.edu> wrote:
>   
>> I'm iterating over all LoadInst and StoreInst-type Instructions in
a
>> Function, and getNodeForValue() is sometimes returning NULL.  Why is
>> this happening?  Shouldn't every load from or store to memory
correspond
>> to some DSNode?
>>     
>
>
> Not if the pointer is null or the pointer contains no information in
> the pass you are querying.
>
> Andrew
>
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>   
The program I'm analyzing is not dereferencing NULL pointers.  I'm 
querying the EquivBUDataStructures pass; what instances would cause the 
DSGraph not to have any information about the pointer (and I thought 
Unknown DSNodes were created for when we couldn't figure out the pointer 
value?).

Thanks,
--Patrick