[Bug tree-optimization/21883] [4.1 Regression] jump threading causing excessive code duplication

[law at redhat dot com]

------- Comment #8 from law at redhat dot com  2005-11-04 20:10 -------
Subject: Re:  [4.1 Regression] jump threading
        causing excessive code duplication

On Mon, 2005-10-31 at 18:56 -0700, Jeffrey A Law wrote:
> On Mon, 2005-10-31 at 03:43 +0000, mmitchel at gcc dot gnu dot org
> wrote:
> > 
> > ------- Comment #5 from mmitchel at gcc dot gnu dot org  2005-10-31 03:43 -------
> > Downgraded to P2.  Important, but not a showstopper.  We really should have
> > some kind of throttle, even if it's a bit simplistic.
> We could easily put in a trivial throttle.    If there's more than N
> statements + phis, then the block is considered not threadable.  Choose
> N and it'll take about 5 minutes of work (and 3 hours to test :-)
> 
> I'll throw out 50 as a very very very conservative number.  If we're OK
> with that number, then let's do it.
> 
> We might be better around 10, but 50 ought to catch the pathological
> cases without impacting much of anything.
Here's what I actually checked in.  This should be enough to allow
us to delay final resolution of this PR till 4.2 (probably using
Steven's prototype, which I like better).

Bootstrapped and regression tested on i686-pc-linux-gnu.


------- Comment #9 from law at redhat dot com  2005-11-04 20:10 -------
Created an attachment (id=10148)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=10148&action=view)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21883