Re: kernel compiler

[Jakub Jelinek <jakub@redhat.com>]

On Fri, Oct 26, 2001 at 11:18:46AM +0200, Allan Sandfeld wrote:
> > Last paragraph is the key. Perhaps previous gcc'd did not all his work
> > as the manual says (ie, did not kill the non-inline version, bug),
> > but people has got used to the bug, and see it as a feature.
> 
> I believe '-fkeep-inline-functions' is your friend in this case. I haven't 
> tested it though on the kernel.

Definitely not. -fkeep-inline-functions will not only prevent in compiler
eyes unused static functions from beeing optimized away, but you'll get tons
of code you really don't need.
__attribute__((used)) is what you can use in current gcc trunk to just say
the compiler that it should not optimize away a particular function even if
it seems to be unused at -O3 (e.g. it might be referenced from inline assembly,
whatever).
No matter what, using -O3 for kernel builds is a bad idea, in vast majority
functions which make sense to be inlined are in the kernel marked so with
inline keyword, and the rest does not. With -O3 for kernel you just get
bigger code with no gains (if there are some gains somewhere, then it should
be considered to be marked inline on a case by case basis).

	Jakub