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Re: LTO: Speedup.
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Toon Moene <toon at moene dot org>
- Cc: gcc mailing list <gcc at gcc dot gnu dot org>
- Date: Tue, 6 Oct 2009 23:41:08 +0200
- Subject: Re: LTO: Speedup.
- References: <4ACBA42B.8040107@moene.org>
> L.S.,
>
> On our weather forecasting code (compiled with -O3 -flto and linked with
> -O3 -flto -fwhole-program) I get a speedup of 65 seconds per time step
> in the model integration vs. 75 seconds with -O3 alone.
There is bug making -fwhole-program disabled with LTO compilations.
I hope to get this fixed in mainline tomorrow.
It will be interesting to see how much difference -fwhole-program makes
for you. Also ipa-sra was finally enabled at -O2 and I would be greatly
interested if it makes any difference (in general it should help to
fortran codebases by eliminating need to pass stuff around by reference)
Honza