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

Arjan van de Ven
2005-12-28T19:35:01Z

>
> The forced inlining is not just a good idea. Several versions of gcc would
> NOT COMPILE the kernel without it.

yup that's why the patch only does it for gcc4, in which the inlining
heuristics finally got rewritten to something that seems to resemble
sanity...

> Also, the inlining patch apparently makes code larger in some cases, so
> it's not even a unconditional win.

.... as long as you give the inlining algorithm enough information.
-fno-unit-at-a-time prevents gcc from having the information, and the
decisions it makes are then less optimal...

(unit-at-a-time allows gcc to look at the entire .c file, eg things like
number of callers etc etc, disabling that tells gcc to do the .c file as
single pass top-to-bottom only)