[Bug tree-optimization/92738] [10 regression] Large code size growth for -O2 binaries between 2019-05-19...2019-05-29

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92738

--- Comment #12 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to Wilco from comment #11)

> Would using -frepack-arrays solve this issue? I proposed making that the
> default a while back. It would do any repacking that is necessary at call
> sites rather than creating multiple copies of all loops in every function.

I'm not convinced that that is the answer - this would penalize (at runtime)
programs which use non-contiguous memory when _not_ passing them to
an explicit size or assumed size paramter. For example, all the optimizations
for passing a transposed argument would then no longer work.

What we could do instead is to introduce another option, -frepack-inline
(or whatever we want to call it) and enable this by default at all -O
except at -Os. People who have problems can then enable that option for
the specific files they have the problems with.