Le 19/10/2020 à 10:32, Segher Boessenkool a écrit :
On Mon, Oct 19, 2020 at 07:50:41AM +0200, Christophe Leroy wrote:
Le 19/10/2020 à 06:55, Joel Stanley a écrit :
In the old days, marking a function 'static inline' was forcing
GCC to inline, but since commit ac7c3e4ff401 ("compiler: enable
CONFIG_OPTIMIZE_INLINING forcibly") GCC may decide to not inline
a function.
It looks like GCC 10 is taking poor decisions on this.
1952 bytes smaller with your patch applied. Did you raise this with
anyone from GCC?
Yes I did, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97445
For the time being, it's at a standstill.
The kernel should just use __always_inline if that is what it *wants*;
that is true here most likely. GCC could perhaps improve its heuristics
so that it no longer thinks these functions are often too big for
inlining (they *are* pretty big, but not after basic optimisations with
constant integer arguments).
Yes I guess __always_inline is to be added on functions like this defined in headers for exactly
that, and that's the purpose of this patch.
However I find it odd that get_order() is outlined by GCC even in some object files that don't use
it at all, for instance in fs/pipe.o
Christophe
