[LLVMdev] [polly] Polly Loop info and LoopSimplify functionality

Sergei Larin slarin at codeaurora.org
Thu May 16 11:03:12 PDT 2013


  Thank you for the exceptional turnaround time. The second fix (r181987)
appears to get it. The real issue seems to be that we have never added the
newly created (child) loop to the parent loop. It in turn was confusing the
LoopInfo regeneration in some scenarios... I am still testing the fix, but
thank you again for such a prompt reaction.


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> -----Original Message-----
> From: Tobias Grosser [mailto:tobias at grosser.es]
> Sent: Thursday, May 16, 2013 1:58 AM
> To: Sergei Larin
> Cc: 'Sebastian Pop'; llvmdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] [polly] Polly Loop info and LoopSimplify
> On 05/15/2013 07:08 PM, Sergei Larin wrote:
> >
> > Tobias,
> [..]
> >
> > ...or as always I might be missing a big picture here, and I
> > appreciate if you can explain the original intent.
> Hi Sergei,
> thanks for reporting this issue in so much detail. I am afraid there is no
> story. For some reason the update of the LoopInfo was not included in the
> original patch of the code generation, but we still claimed it is updated
> because otherwise the scop detection would be invalidated as soon as code
> generation is run the first time. This was obviously a hack and the fact
> you were bitten by it shows that adding such hacks is not a good thing.
> I am actively working on removing such hacks and this one was one of the
> larger ones remaining. I had two patches in my queue to address this.
> The first one makes Polly create loops in an already loop rotated form.
> The second patch adds the missing loop information updates. I committed
> these patches in r181986 and r181987.
> Could you check if those patches work for you and possibly even post
> the commits in general.
> Thanks,
> Tobias

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