[Bug rtl-optimization/63577] [4.9/5/6 Regression]: Huge compile time and memory usage with -O and not -fPIC

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63577

--- Comment #12 from Segher Boessenkool <segher at gcc dot gnu.org> ---
I cannot reproduce the problem with GCC 6, combine takes about 1%
time and little memory.  I do not know what changed.