[polly] r246161 - Do not detect Scops with only one loop.

[Johannes Doerfert via llvm-commits]

On 08/28, Tobias Grosser wrote:
> >>What about the following:
> >>
> >>Algorithm:
> >>
> >>   loopNum = 0;
> >>
> >>   entryNodeLoop = LI->getLoopFor(R->getEntry)
> >>
> >>   if loop in R
> >>     children = loop->getParent()->children
> >>   else if loop not in R:
> >>     children = loop->children
> >>   else // no loop at all
> >>     children = LI->getoutermostloops
> >>
> >>   for child in children
> >>     if (R->contains(child)) {
> >>       loopNum++;
> >>       if (child->subloops > 0)
> >>         loopNum++;
> >>
> >>       if (loopNum >= 2)
> >>         return true;
> >>     }
> >>   return false;
> >
> >I am not convinced that the loops we see and count should be in any kind
> >related to the entry block of the region. What about code like this:
> >
> >   if (...)
> >     LoopNest
> >
> >can't that be a region? Even if not, I think there is some kind of code
> >with many loops but none of them contains the entry block. Do you
> >disagree?
> 
> That will be the second or the third case of the code above. The second in
> case the scop is part of a larger loop and the third case if no loop surrounds
> the scop.
OK, got it now.

Some special handling if entryNodeLoop is a toplevel loop but other than
that it should work.

Sorry for the hassle, I should have read it more carefully.

-- 

Johannes Doerfert
Researcher / PhD Student

Compiler Design Lab (Prof. Hack)
Saarland University, Computer Science
Building E1.3, Room 4.31

Tel. +49 (0)681 302-57521 : doerfert at cs.uni-saarland.de
Fax. +49 (0)681 302-3065  : http://www.cdl.uni-saarland.de/people/doerfert
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