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SubjectRe: optimizing out inline functions
On Wed, May 28, 2008 at 02:51:02PM -0500, Steve French wrote:
> In trying to remove some macros, I ran across another kernel style
> question. I see two ways that people try to let the compiler optimize
> out unused code and would like to know which is preferred. The first
> example uses an empty inline function and trusts the compiler will
> optimize it out.
>
> #ifdef CONFIG_DEBUG_SOMETHING
> static inline void some_debug_function(var1)
> {
> something = var1;
> printk(some debug text);
> }
> #else
> static inline void some_debug_function(var1)
> {
> /* empty function */
> }
> #endif

With reference to a recent thread about kconfig
I would prefer:
static inline void some_debug_function(var1)
{
if (KCONFIG_DEBUG_SOMETHING) {
something = var1;
printk(some debug text);
}
}


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.

Sam


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