[Bug fortran/78611] -march=native makes code 3x slower

[pepalogik at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78611

--- Comment #1 from Jan Lachnitt <pepalogik at seznam dot cz> ---
Created attachment 40200
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40200&action=edit
Smaller test case

Here is a smaller test case, which runs for a second only, not hours.

without -march=native:
real    0m0.610s
user    0m0.560s
sys     0m0.000s

with -march=native:
real    0m1.271s
user    0m1.268s
sys     0m0.000s