[Bug ipa/65076] [5 Regression] 16% tramp3d-v4.cpp compile time regression

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65076

--- Comment #16 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
The chkp stuff is IMO bit problematic. I was thinking about cutting the
optimization queue but was always hesitant to do so because of the cache
locality and other implications. I am not sure if that was considered with chkp
approach and if the split is really needed. Not something to track for GCC 5
though.

The slowdown
http://gcc.opensuse.org/c++bench-frescobaldi/tramp3d/split-build.html
is quite gradual, while the code size jump
http://gcc.opensuse.org/c++bench-frescobaldi/tramp3d/
happened at one point.  I looked once into the code size with Jakub and part of
that seems to be due to unwind info no longer using cfi directives at older
gases. Part is the new heuristics.

I am still hopping to understand better the code size part. To get performance
back we however probalby look for several little factors contributing to the
slowdown.