[Bug c++/56493] Performance regression in google dense hashmap

[andrewjcg at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56493

--- Comment #10 from Andrew Gallagher <andrewjcg at gmail dot com> 2013-04-13 01:44:27 UTC ---
I did several attempts at bisecting this.  Whenever I (hackily) reverted the
change which caused the regression, it just popped up a few hundred revs later.
 This seems to be gcc assigning new weights to functions, which determines
whether the functions is early inlined or not.  So I *think* this is really an
early inlining v. late inlining issue, and we happened to get lucky with the
weights that 4.6 selected (I don't think there is a really effective way for
gcc to predict how subsequent optimizations will/can benefit by early
inlining).

Also, as far as I can see, there is no way to force early inlining (other than
switching to macros).