[PATCH] [Refactor] Replace RegionPasses by FunctionPasses

[Johannes Doerfert]

On 03/04, Tobias Grosser wrote:
> On 04.03.2015 11:14, Johannes Doerfert wrote:
> >Hey Tobias,
> >
> >I attached 2 lnt reports to this mail. The first (report_region.json)
> >was created using the current polly/master. The second
> >(report_function.json) was created with the region->function pass patch.
> >Note that this patch is not yet at its full capacity, however over the 3
> >runs I measured I got:
> >
> >   Performance Regressions  16
> >   Performance Improvements  159
> >   Unchanged Tests   817
> >   Total Tests   992
> >
> >Where as the execution time changes (only 8 in total) should be jitter.
> >
> >The point I try to make here is, 3 runs with the region pass manager take
> >
> >   2:35:27 (3 runs region passes)
> >
> >but 3 runs with the function pass manager only
> >
> >   2:07:48 (3 runs function passes)
> >
> >hence we save ~18% of the lnt time (if I didn't do a stupid math mistake).
> >
> >To be precise, we save compile time "only" for larger functions with small SCoP
> >coverage but we do not pay for it in any other case.
> 
> Amazing. The performance results are really interesting.
> 
> >Does this convince you that region passes have a bad impact on compile time?
> 
> Sure.
> 
> (Even before I was convinced going somewhere in this direction is a good
> idea, but I wanted to understand the reasons/motivations for the changes as
> I had the feeling there are several good reasons to go into this direction).
> 
> What are the next steps you would like to take? Is this the patch you would
> like me to review or are you planning to split/change something beforehand?
See below.

> I currently only commented on the DependenceInfo changes, but I have the
> feeling they could possibly be split out nicely without yet having any
> performance impact. What do you think?
I wanted (positive) initial feedback first before I put more work into this.

I will split the patch and commit it in 2-5 parts that are will be more
or less small and self contained. However, the actual change from Region
to Function pass in ScopPass will be a bit more complicated.

P.S.
  What's your opinion on the renaming of Dependences to DependenceInfo?

-- 

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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