llvm dev - Apr 2013 - [LLVMdev] Custom AA implementation is not used

Hello LLVM devs,

I'm trying to write my own alias analysis that only contributes 
information to the getModRefBehavior query, and should be in its own 
library loadable by opt.

However, even though my pass is run (and executed immediately before the 
client pass that is calling AA.doesNotAccessMemory(F)), the queries 
never reach my implementation. What am I missing?

Thanks in advance,
Julian
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Julian Oppermann wrote:
> Hello LLVM devs,
>
> I'm trying to write my own alias analysis that only contributes
> information to the getModRefBehavior query, and should be in its own
> library loadable by opt.
>
> However, even though my pass is run (and executed immediately before the
> client pass that is calling AA.doesNotAccessMemory(F)), the queries
> never reach my implementation. What am I missing?
You don't provide an implementation of getAdjustedAnalysisPointer. This 
is a stab in the dark, but try adding that? Something like:

     virtual void *getAdjustedAnalysisPointer(const void *ID) {
       if (ID == &AliasAnalysis::ID)
         return (AliasAnalysis*)this;
       return this;
     }

Nick

Am 03.05.2013 20:02, schrieb Nick Lewycky:
> Julian Oppermann wrote:
>> Hello LLVM devs,
>>
>> I'm trying to write my own alias analysis that only contributes
>> information to the getModRefBehavior query, and should be in its own
>> library loadable by opt.
>>
>> However, even though my pass is run (and executed immediately before
the
>> client pass that is calling AA.doesNotAccessMemory(F)), the queries
>> never reach my implementation. What am I missing?
>
> You don't provide an implementation of getAdjustedAnalysisPointer. This
> is a stab in the dark, but try adding that? Something like:
>
>      virtual void *getAdjustedAnalysisPointer(const void *ID) {
>        if (ID == &AliasAnalysis::ID)
>          return (AliasAnalysis*)this;
>        return this;
>      }
Yes, this was the missing piece. Thank you!

Julian