Messages in this thread | | | Date | Wed, 26 Sep 2012 16:50:44 -0700 | From | Andrew Morton <> | Subject | Re: Please be aware that __always_inline doesn't mean "always inline"! |
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On Wed, 26 Sep 2012 18:20:44 -0500 Daniel Santos <danielfsantos@att.net> wrote:
> I've noticed that there's a lot of misperception about the meaning of > the __always_inline, or more specifically, > __attribute__((always_inline)), which does not actually cause the > function to always be inlined. Rather, it *allows* gcc to inline the > function, even when compiling without optimizations. Here is the > description of the attribute from gcc's docs > (http://gcc.gnu.org/onlinedocs/gcc-4.7.2/gcc/Function-Attributes.html) > > always_inline > Generally, functions are not inlined unless optimization is specified. > For functions declared inline, this attribute inlines the function even > if no optimization level was specified. > > This would even appear to imply that such functions aren't even marked > as "inline" (something I wasn't aware of until today). The only > mechanism I'm currently aware of to force gcc to inline a function is > the flatten attribute (see https://lkml.org/lkml/2012/9/25/643) which > works backwards, you declare it on the calling function, and it forces > gcc to inline all functions (marked as inline) that it calls.
As I mentioned in the other thread, the __always_inline's in fs/namei.c (at least) are doing exactly what we want them to do, so some more investigation is needed here?
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