https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86141
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-06-14
CC| |hubicka at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
When you rename main() to foo() the calls are inlined. GCC doesn't inline them
into main() because it knows they are executed exactly once which means they
are cold and thus code growth doesn't outweight performance increase.
With -Winline you see:
t.C: In function ‘int main()’:
t.C:31:1: warning: inlining failed in call to ‘void DisplayViewType(const
ViewType&)’: call is unlikely and code size would grow [-Winline]
DisplayViewType( const ViewType& view ) {
^~~~~~~~~~~~~~~
t.C:38:20: note: called from here
DisplayViewType( ViewType::view2( data ) );
~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
t.C:31:1: warning: inlining failed in call to ‘void DisplayViewType(const
ViewType&)’: call is unlikely and code size would grow [-Winline]
DisplayViewType( const ViewType& view ) {
^~~~~~~~~~~~~~~
t.C:37:20: note: called from here
DisplayViewType( ViewType::view1( data ) );
~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
of course in the end the size heuristics are off and inlining would reduce
code size.
