Re: MSVC 7.1 Compile Time Slowdown

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From: Andre Kaufmann (_NO_SPAM_andre.kaufmann_ad_t-online._xxx_de)
Date: 09/14/04

  • Next message: Mike Hall: "Re: MSVC 7.1 Compile Time Slowdown" 
    Date: Tue, 14 Sep 2004 20:55:56 +0200

    "Mike Hall" <mjh@nospam.nospam> wrote in message news:eZ3WRWbmEHA.3872@TK2MSFTNGP09.phx.gbl...
    > Hi. I have recently migrated some of my code to use the new 7.1 Visual
    > C++ compiler, and noticed some dramatically longer compile times. The
    > greatest increase in time seems to be between code compiled with /O1
    > under MSVC 6.0 and MSVC 7.1. If I turn off global optimizations (i.e.:
    > /Og-) only then my compile times drop down dramatically, but at the cost

    When you are using global optimizations the linker effectively "compiles" the code,
    the compiler will generate "preparsed" intermediate code.
    I donīt know it for sure, but it seems that the "linker" is doing something like a full
    re-build - even if only code in a cpp file has been changed.

    But since global optimizations are "global", that makes sense.
    Many unnecessary function calls and code may be eliminated,
    because the linker has information about the whole code and not
    only about the included code and does code inlining at the linker stage.

    The downside is that compilation needs more time (!full build!).
    I would recommend global optimization only for release builds,
    and during development debug or release builds without
    global optimization turned on.

    I wonder why you experience such a high difference in code size,
    o.k. global optimization reduces significantly code size, but i didnīt experience
    such a high difference.

    Andre

  • Next message: Mike Hall: "Re: MSVC 7.1 Compile Time Slowdown"

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