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Re: 3.3 compile time regression (22400%)
- From: "John David Anglin" <dave at hiauly1 dot hia dot nrc dot ca>
- To: matz at suse dot de (Michael Matz)
- Cc: gcc at gcc dot gnu dot org
- Date: Wed, 19 Mar 2003 14:21:00 -0500 (EST)
- Subject: Re: 3.3 compile time regression (22400%)
> On Tue, 18 Mar 2003, John David Anglin wrote:
>
> > I was finally successful in building Dialogs.C from LyX 1.3.0 on
> > hppa2.0-hp-hpux11.11 with -O2 and -fno-default-inline:
> >
> > life analysis :17359.67 (92%) usr 9.10 (16%) sys17522.54 (90%) wall
>
> Yikes! Such behaviour would normally only be expected from fully
> connected CFGs if at all, or CFGs with big tree-width, but normal C++ code
> even if using exceptions doesn't result in a CFG _that_ ugly. Do you care
> enough to reduce the file a bit (so you have a chance to play with it
> without becoming dust), create a profileable cc1plus and post the
> hotspots?
One thing that I noticed in working on PR10062 is that the code
generated for computed gotos seems horribly inefficient, at least
in some circumstances. Where we needed the long branch fix, there
was a linear sequence of ~1500 comparisons of the same register
with a constant int. The value of the constant int increased
by one at each step.
Dave
--
J. David Anglin dave dot anglin at nrc-cnrc dot gc dot ca
National Research Council of Canada (613) 990-0752 (FAX: 952-6602)