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Re: Simple Value Range Propagation
- From: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- To: Gerald Pfeifer <pfeifer at dbai dot tuwien dot ac dot at>
- Cc: Josef Zlomek <zlomj9am at artax dot karlin dot mff dot cuni dot cz>,gcc-patches at gcc dot gnu dot org
- Date: Tue, 10 Jun 2003 17:13:03 +0200
- Subject: Re: Simple Value Range Propagation
- References: <Pine.BSF.4.55.0306101248070.21183@acrux.dbai.tuwien.ac.at>
Hello,
> On Sun, 8 Jun 2003, Josef Zlomek wrote:
> > It takes 2% of compile time and adds 0.5 % overall performance on
> > SPECint2000.
>
> Say that 35 times, and you'll end up with a compiler that is twice as
> slow.
>
> And, in fact, GCC 3.3 _is_ already about twice as slow as GCC 2.95 for
> my application (without overall improvement in code quality, though,
> unlike your patch).
say this at every new optimization (because with the current structure
of gcc you cannot get much cheaper, considering that just a pass over
insns takes 1% of time), and you will end up with gcc 2.95 :-)
Zdenek