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Possible improvement of 64-bit integer arithmetic in 32-bit code RRS feed

  • General discussion

  • When doing arithmetic on 64-bit integers in 32-bit code (__int 64 / long long), the compiler inserts calls to helper functions in the C runtime library (_alldiv etc.).

    While working on a project I discovered these helper functions might have room for some improvement. I wrote about it in this blog post:

    http://www.hardtoc.com/archives/154

    Basically, on current hardware it looks like it is possible to get speed improvements ranging from a few percent up to 50% in the most favorable cases.

    I don't know if this might be of interest to the people working on the C runtime library, and possibly the CLR as well since the functions appear to be in the .net runtime.

    Tuesday, September 21, 2010 12:25 PM

All replies

  • ibse,

    Thank you for the feedback!  I have forwarded your blog post and concern on to the appropriate team here.

    In the future the best place to give feedback like this is through Microsoft Connect -- https://connect.microsoft.com/


    SDET Windows C++ CodeGenerationTeam - Performance
    Friday, November 12, 2010 8:47 PM