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GCC g++ version 8 very slow to compile

Terry Barnaby

With the latest gcc-arm-none-eabi-8-2018-q4-major-linux.tar.bz2 compiler tools release, g++ is very slow to compile relative to the older gcc-arm-none-eabi-7-2017-q4-major-linux.tar.bz2 release.

I am seeing it take over 3 times longer than the previous compiler. A previously 45 second build now takes 2.5 minutes.

Is this to be expected ?

Are there any compiler flags that will speed this up (less optimisations) as it is now taking a significant time to build things ?

Parents Reply Children
  • 0 in reply to Tejas Belagod

    I will try and attach a simple example (assuming this web system allows it) that I hope shows the issue. I have just put a bit of C++ code in one file to simplify the test. It is really a bit to small and thus quick to compile, if it doesn't show the issue I will get a lump of C++ code that will compile up. I think the issue is just with C++ code. It seems generally 3x slower with any C++ code.

    With the attached example compiling with gcc-arm-none-eabi-7-2017-q4-major-linux.tar.bz2 takes 0.085 seconds.

    With the attached example compiling with gcc-arm-none-eabi-8-2018-q4-major-linux.tar.bz2 takes 0.241 seconds.

    To test:

    make clean; sleep 2; time make

    I am testing on Fedora29 Linux with all updates to date on a 4 core Xeon system but all other Fedora29 systems I have tried show the same issue.

    Ok, is there a way to attach a tar file or an email address to send one to with the example ?

  • 0 in reply to Terry Barnaby

    Can you please provide me with info of how i can send you an example showing this problem (email address,  website upload ability etc.) ?

  • 0 Arm Employee Badge in reply to Terry Barnaby

    Hi Terry, it is likely easiest to raise a support case, which will allow you to pass attachments securely. Please mention this forum posting so we can track internally.

  • 0 in reply to Ronan Synnott

    Ok, I have added a case: CAS-127711-P6Y6X7 with a simple example, mind you it doesn't seem to be code specific, the g++ compiler just seems 3x slower on any C++ code when running under Fedora29 Linux (haven't tried any other OS).

  • 0 Arm Employee Badge in reply to Terry Barnaby

    Thanks for the case. We shall investigate and get back to you.