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Thread: recompiling Qt install with -ffast-math to speed things up ...

  1. #1
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    Default recompiling Qt install with -ffast-math to speed things up ...

    I just found out that an app I have been making in Borland runs a lot faster than the same app in Qt/Mingw with Eclipse (16 sec versus 26 sec). There is little difference in release and debug. After searching and trying it appears to be the math operations like sqrt, powl and so on are causing this. I found this site:
    http://www.willus.com/mingw/_all.shtml
    I decided to experiment with the fast-math switch. This decreases the run time to 20 sec.
    I am now recompiling the Qt install with the fast-math switch to see what that does. Anybody has this experience, or knows how to link in a faster method for powl and so on?

    thanks

  2. #2
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    Default Re: recompiling Qt install with -ffast-math to speed things up ...

    recompiling all with fast-math didn't change the perfomance and sqlite didn't compile (buit the main libs did). SO I'll stick to adding fast-math to my owb project

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