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Re: cfg merge part 17 - loop datastructure updates
- From: Jan Hubicka <jh at suse dot cz>
- To: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- Cc: Richard Henderson <rth at redhat dot com>, Jan Hubicka <jh at suse dot cz>,gcc-patches at gcc dot gnu dot org, gcc-pdo at atrey dot karlin dot mff dot cuni dot cz,m dot hayes at elec dot canterbury dot ac dot nz
- Date: Sat, 1 Jun 2002 20:20:39 +0200
- Subject: Re: cfg merge part 17 - loop datastructure updates
- References: <20020513130251.GJ17596@atrey.karlin.mff.cuni.cz> <20020530130603.A5362@redhat.com> <20020531094721.GG1108@atrey.karlin.mff.cuni.cz> <20020531184056.GA2521@atrey.karlin.mff.cuni.cz> <20020531163939.A6183@redhat.com> <20020601181238.GA4030@atrey.karlin.mff.cuni.cz>
> > > Here is the patch (also updated after bb renumbering removal).
> > Thanks. Nearly ok.
> > > + /* We could not redirect edges freely here. On the other hand,
> > > + we know that no abnormal edge enters this block, so we can simply
> > > + split the edge from entry block. */
> > Actually, it is possible for the first block to be the target
> > of an abnormal edge. There could be a computed jump to a label
> > at the beginning of the function. But certainly that's not
> > worth handling beyond not setting the header bit if we find one.
> > Ok with that change.
> Actually it is not possible -- as otherwise this block would not be
> taken as loop header.
I think it can be taken in case it is reached by abnormal edge outside
the loop. (so the loopback edge is normal).
Still the code does split_edge (entry_edge) that is correct and will
work even in presnece of abnormals.