https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86448
--- Comment #2 from kelvin at gcc dot gnu.org --- Using the GCC8 branch, svn version id 262483 (the same version tested by Michael), I'm getting the following results: -mcpu=power8 -mcpu=power9 28.57 28.79 28.41 28.61 28.54 28.21 28.53 28.55 29.02 28.59 28.54 27.34 28.25 26.63 28.56 29.13 delta Percent average 28.5525 28.23125 0.32125 1.13% As with my trunk measurements, I'm not seeing a 2% difference. Rnd I am seeing that targeting power9 produces slightly better performance than targeting power8. It may be that we're running with different optimization flags. I used OPTIMIZE = -Ofast -mcpu=power9 (or -mcpu=power8) LDOPT = -m64 -Wl,-q -Wl,-rpath=%{BASE_DIR}/lib64 I'm inclined to close this issue unless Michael can point me to a different set of options to explore...