[Bug ipa/114531] Feature proposal for an `-finline-functions-aggressive` compiler option

["rsandifo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114531

--- Comment #17 from Richard Sandiford <rsandifo at gcc dot gnu.org> ---
I can see that it's useful to ask whether the current -O2 & -O3 inlining
heuristics are making the right trade-off.  But I think that's really a
different issue from the one that is raised in the PR.  (Unless we think that
-O2 and -O3 should always have the same inlining heuristics henceforward, but
that seems unlikely.)

At the moment, -O3 is essentially -O2 + some -f options + some --param options.
 Users who want to pick & chose some of the -f options can do so, and can add
them to stable build systems.  Normally, obsolete -f options are turned into
no-ops rather than removed.  But users can't pick & choose the --params, and
add them to stable build systems, because we reserve the right to remove
--params without warning.

So IMO, we should have an -f option that represents “the inlining parameters
enabled by -O3”, whatever they happen to be for a given release.  It's OK if
the set is empty.

For such a change, it doesn't really matter whether the current --params are
the right ones.  It just matters that the --params are the ones that we
currently use.  If the --params are changed later, the -f option and -O3 will
automatically stay in sync.