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[Bug tree-optimization/21883] [4.1 Regression] jump threading causing excessive code duplication
- From: "law at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 1 Nov 2005 01:56:24 -0000
- Subject: [Bug tree-optimization/21883] [4.1 Regression] jump threading causing excessive code duplication
- References: <bug-21883-87@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #6 from law at redhat dot com 2005-11-01 01:56 -------
Subject: Re: [4.1 Regression] jump threading
causing excessive code duplication
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.
Jeff
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21883