https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101865
--- Comment #13 from Peter Bergner <bergner at gcc dot gnu.org> --- (In reply to Tulio Magno Quites Machado Filho from comment #12) > There is a chance, that my previous comment is wrong with regards the > generation of VSX instructions for Power8. > > I don't know what the second command means: > > $ gcc-11 -mcpu=power10 -dM -E - < /dev/null | grep -E 'VECTOR|VSX|ALTIVEC' > #define __VSX__ 1 > #define __ALTIVEC__ 1 > #define __POWER9_VECTOR__ 1 > #define __APPLE_ALTIVEC__ 1 > #define __POWER8_VECTOR__ 1 > $ gcc-11 -mcpu=power10 -mno-power8-vector -dM -E - < /dev/null | grep -E > 'VECTOR|VSX|ALTIVEC' > #define __VSX__ 1 > #define __ALTIVEC__ 1 > #define __APPLE_ALTIVEC__ 1 __VSX__ doesn't mean all of VSX is enabled. IIRC, __VSX__ is the macro you would use to see whether you have POWER7 VSX support. For POWER8's VSX support, you'd use __POWER8_VECTOR__, etc. So in your last compile, you disabled vector support from POWER8 onwards, but that leaves vector support from POWER7 and earlier, ie, __VSX__ and __ALTIVEC__. If you had used -mno-vsx, you'd still have __ALTIVEC__ and __APPLE_ALTIVEC__ defined. Finally, if you have used -mno-altivec, then you would have disabled all vector support.
