Re: [patch 00/2] improve .text size on gcc 4.0 and newer compilers

Jakub Jelinek
2005-12-29T15:44:18Z

On Thu, Dec 29, 2005 at 04:35:29PM +0100, Adrian Bunk wrote:
> > You describe a nice utopia where only the most essential functions are
> > inlined.. but so far that hasn't worked out all that well ;) Turning
> > "inline" back into the hint to the compiler that the C language makes it
> > is maybe a cop-out, but it's a sustainable approach at least.
> >...
>
> But shouldn't nowadays gcc be able to know best even without an "inline"
> hint?

Only for static functions (and in -funit-at-a-time mode).
Anything else would require full IMA over the whole kernel and we aren't
there yet. So inline hints are useful. But most of the inline keywords
in the kernel really should be that, hints, because e.g. while it can be
beneficial to inline something on one arch, it may be not beneficial on
another arch, depending on cache sizes, number of general registers
available to the compiler, register preassure, speed of the call/ret
pair, calling convention and many other factors.

Jakub