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Re: dataflow branch merging plans.
- From: "Steven Bosscher" <stevenb dot gcc at gmail dot com>
- To: "Bernd Schmidt" <bernds_cb1 at t-online dot de>
- Cc: "Kenneth Zadeck" <zadeck at naturalbridge dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>, "Park, Seongbae" <seongbae dot park at gmail dot com>, "Bonzini, Paolo" <bonzini at gnu dot org>, "Serge Belyshev" <belyshev at depni dot sinp dot msu dot ru>, richard dot earnshaw at arm dot com, echristo at apple dot com, "Pinski, Andrew" <andrew_pinski at playstation dot sony dot com>, "Weigand, Ulrich" <Ulrich dot Weigand at de dot ibm dot com>, "Ian Lance Taylor" <iant at google dot com>, "Edelsohn, David" <dje at watson dot ibm dot com>, "Berlin, Daniel" <dberlin at dberlin dot org>
- Date: Thu, 24 May 2007 22:44:26 +0200
- Subject: Re: dataflow branch merging plans.
- References: <46543F49.8060104@naturalbridge.com> <46557380.9060105@t-online.de>
On 5/24/07, Bernd Schmidt <bernds_cb1@t-online.de> wrote:
Kenneth Zadeck wrote:
> I believe that the dataflow branch is now ready to merge into the
> mainline. We have fixed almost all of the performance problems
> associated with it. While there are still some left, we feel
> confident that these can be addressed during the rest of stage I and
> during stage II.
Vlad's last benchmark run still showed up to 11% compile time
regression, didn't it?
No, 8% in ia64, and somewhere between 5% and 6% on the other targets
Vlad's tested. The 5-6% is mostly due to computing more accurate
liveness information and keeping the operands cache up to date. We'd
win a significant amount of time back if more passes would actually
use this information (esp. gcse's CPROP, and regmove, and combine).
The additional slowdown for ia64 is in the scheduler, which apparently
has more insns available to schedule. Note that the scheduler on ia64
is already dog slow even on the trunk. The DFA for Itanium is the
problem here.
Gr.
Steven