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GCC Compiler Tests At A Variety Of Optimization Levels Using Clear Linux

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  • GCC Compiler Tests At A Variety Of Optimization Levels Using Clear Linux

    Phoronix: GCC Compiler Tests At A Variety Of Optimization Levels Using Clear Linux

    For those curious about the impact of GCC compiler optimization levels, a variety of benchmarks were carried out using GCC 6.3 on Intel's Clear Linux platform.

    http://www.phoronix.com/vr.php?view=24425

  • #2
    This is great info.

    Would be really interesting to see how the Intel compiler (and maybe others?) compares as well. Back in the day it had a rather large advantage compared to GCC regardless of optimization settings, but who knows if that is still the case.

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    • #3
      It's too bad AMD isn't developing Open64 anymore. It was the closest thing we ever had to a real replacement to GCC. It never was able to build everything, but it was closer and closer a while back. And it definitely outperformed GCC on the performance of generated binaries.

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      • #4
        For SciMark, "-O3 -march=native" slower than "-O3" ? Probably not the only edge case.

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        • #5
          Originally posted by indepe View Post
          For SciMark, "-O3 -march=native" slower than "-O3" ? Probably not the only edge case.
          It most commonly happens if -march=native is added to what aren't the most optimal flags.

          Interesting that I had different results with some of the programs where I did find improvements using -march=native, but none appeared in these tests.

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          • #6
            it seems (from my limited understanding) that "-O2 -march=native" seems the be the optimal setting with the potential flaws of -O3 not making it worth while for such a small performance jump

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            • #7
              Thank you for adding the time and size charts as well!

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              • #8
                Nice seeing -Og doing its job

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                • #9
                  Originally posted by carewolf View Post
                  Nice seeing -Og doing its job
                  Yes, I just thought I should look into using it more often for dev builds.

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                  • #10
                    Interesting, but I think it also depends on the architecture you build for. These may also vary. -Os is said to be sometimes a little better for older CPUs with small caches. For my normal machines I guess I'll stay with -O2 wich is said to be stable, while -O3 is suspected to occasionally produce hiccups on complex code.
                    Stop TCPA, stupid software patents and corrupt politicians!

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