[Bug ipa/63671] New: [5 Regression] 21% tramp3d-v4 performance hit due to -fdevirtualize

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63671

            Bug ID: 63671
           Summary: [5 Regression] 21% tramp3d-v4 performance hit due to
                    -fdevirtualize
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
                CC: hubicka at gcc dot gnu.org

On my AMD machine I get:

markus@x4 ~ % time g++ -Ofast tramp3d-v4.cpp
23.540 total
markus@x4 ~ % ./a.out --cartvis 1.0 0.0 --rhomin 1e-8 -n 20
...
Time spent in iteration: 3.79717

markus@x4 ~ % time g++ -Ofast -fno-devirtualize tramp3d-v4.cpp
22.163 total
markus@x4 ~ % ./a.out --cartvis 1.0 0.0 --rhomin 1e-8 -n 20
...
Time spent in iteration: 2.97514

For gcc-4.9 -fno-devirtualize makes no difference and I get on both cases:
Time spent in iteration: 3.02253