On Sun, Oct 30, 2005 at 11:42:52AM -0500, John David Anglin wrote:
> > > I really don't think it makes any difference. Such a function (returning
> > > always 0) is always going to be inlined, and the only difference between
> > > static inline and extern inline is what happens when it can't be inlined.
> >
> > On !alpha we are defining inline to __attribute__((always_inline)) for
> > any non-ancient gcc making this a zero difference.
>
> It looks as if there are subtle differences between "always_inline"
> and "extern inline". From the GCC extensions document:
>
> [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.
>
> [extern inline]
> If you specify both @code{inline} and @code{extern} in the function
> definition, then the definition is used only for inlining. In no case
> is the function compiled on its own, not even if you refer to its
> address explicitly. Such an address becomes an external reference, as
> if you had only declared the function, and had not defined it.
>
> The primary difference between "static inline" and "extern inline"
> is in what happens when the address of the function is referenced.
> With "extern inline", you need a unique library function to resolve
> external references. With "static inline", you may end up with
> multiple copies of a function if its address is taken.
>...
In the kernel, "static inline" expands to
"static inline __attribute__((always_inline))" and
"extern inline" expands to
"extern inline __attribute__((always_inline))".
> Dave
cu
Adrian
--
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
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