https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101865
--- Comment #14 from wschmidt at linux dot ibm.com --- On 8/31/21 11:09 AM, bergner at gcc dot gnu.org wrote: > 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. > I disagree with that. You should use __VSX__ && _ARCH_PWR9 to check for P9 vector support, etc. The __POWERn_VECTOR__ things really are not great and I wish they had never been added.
