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    SubjectRe: optimizing out inline functions
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    On Thu, 2008-05-29 at 05:27 +0200, Johannes Weiner wrote:
    > James Kosin <jkosin@beta.intcomgrp.com> writes:
    > >> But we do not have KCONFIG_DEBUG_SOMETHING available
    > >> so the second best is to use an empty function
    > >> to keep the typechecking in place.
    > >> IIRC gcc optimize both away.
    > > Another way would be to have:
    > > static inline void some_debug_function(var1)
    > > {
    > > #ifdef KCONFIG_DEBUG_SOMETHING
    > > something = var1;
    > > printk(some debug text);
    > > #endif
    > > }

    A potential issue is a possible unnecessary call of any
    function used as an argument to some_debug_function.

    int unnecessary_debug_test(void)
    {
    int foo;
    []
    return foo;
    }

    static inline void some_debug_function(int bar)
    {
    }

    some_debug_function(unnecessary_debug_test())

    unnecessary_debug_test will still get called

    Macro wrappers/statement expressions can be used to avoid
    the function call. see kernel.h/pr_debug for an example.

    #ifdef DEBUG
    /* If you are writing a driver, please use dev_dbg instead */
    #define pr_debug(fmt, arg...) \
    printk(KERN_DEBUG fmt, ##arg)
    #else
    #define pr_debug(fmt, arg...) \
    ({ if (0) printk(KERN_DEBUG fmt, ##arg); 0; })
    #endif




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