[LLVMdev] How to make Polly ignore some non-affine memory accesses

Tobias Grosser tobias at grosser.es
Sun Dec 4 02:42:04 PST 2011

On 11/21/2011 12:44 PM, Marcello Maggioni wrote:
> 2011/11/21 Tobias Grosser<tobias at grosser.es>:
>> On 11/20/2011 04:36 PM, Marcello Maggioni wrote:
>>> Sorry for the noobish question, but what kind of subscripts generate a
>>> SCEVCouldNotCompute  from the SCEV engine?
>>> I tried for a while but I wasn't able to trigger that
>> Hi Marcello,
>> the SCEV returns SCEVCouldNotCompute in case it cannot analyze an expression
>> or if the analysis would be to complicated. I am currently
>> not sure if this may actually happen when calling getSCEV(), because
>> getSCEV() could just return a SCEVUnknown referencing the Value itself.
>> Maybe SCEVCouldNotCompute is just generated by functions like
>> SE->getBackedgeTakenCount()?
>> In case you cannot generate a test case that yields to this, I don't think
>> there is a need to try more. Even without such a test case the patch should
>> be OK.
>> Cheers
>> Tobi
> Ok, thanks, I'll try other test cases to check if everything is ok,
> better being sure.

Hi Marcello,

any news here? I would love to commit your patch. Do you happen to have 
a final version ready?


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