[Bug middle-end/37372] [graphite] SCoP detection splits bbs / Define SCoPs with single entry and exit edge

["spop at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #1 from spop at gcc dot gnu dot org  2008-09-05 16:19 -------
(In reply to comment #0)
> During SCoP detection we split bbs (e.g. in "scopdet_edge_info"), but the SCoP
> detection should only detect SCoPs and not modify anything.

No, we want to split BBs to increase the scop boundaries by moving
code in different BBs.

> Also it splits bbs in inner loops, that do not need to be splitted.
> 

More precisely: we split the basic block that is the destination of a
single exit loop, and that has multiple successors.

I think this is not a big problem right now, but indeed this bb_split
is not needed.  We can remove the bb_split by slightly modifying the
scop detection algorithm: putting the code that splits the bbs after
we determine whether the loop exit should be the place for a new scop,
i.e. computing result.next after we determine result.difficult.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37372