https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101301
--- Comment #4 from Thomas Koenig <tkoenig at gcc dot gnu.org> --- (In reply to Segher Boessenkool from comment #3) > What CPU is in your Power system, and what -mcpu= did you compile with? > What is the ABI you are using? (That last one doesn't seem to matter in > this particular case, but :-) ) The machine is gcc135 from the gcc compile farm. cat /proc/cpuinfo says processor : 0 cpu : POWER9, altivec supported clock : 3800.000000MHz revision : 2.2 (pvr 004e 1202) ... I compiled without -mcpu. With -mcpu=native, the times are [tkoenig@gcc135 ~]$ gcc -mcpu=native -O3 bench.c a.c && ./a.out foo: 5.679413 foo2: 6.799938 [tkoenig@gcc135 ~]$ gcc -mcpu=native -O3 -DFULL bench.c a.c && ./a.out foo: 5.713161 foo2: 6.137598 so -mcpu=native makes a difference there. The version of the compiler is gcc-Version 12.0.0 20210701 (experimental) (GCC) HTH.
