On 2 September 2015 at 12:21, Jonathan Wakely wrote: > On 2 September 2015 at 12:10, Mason wrote: >> On 02/09/2015 12:13, Jonathan Wakely wrote: >> >>> On 2 September 2015 at 08:43, Mason wrote: >>>> Is there a way to say: >>>> "Use any instruction available for this uarch, but optimize code >>>> for this other uarch / class of uarches (mtune=generic)" ?? >>> >>> Yes, just use both -march and -mtune. e.g. >>> >>> -march=pentium3 -mtune-generic >> >> The doc states: >> >> "Specifying -march=cpu-type implies -mtune=cpu-type." >> >> Are you suggesting that -mtune can later be overridden? > > Yes. > >> In which case order matters (-march first, then -mtune) right? > > Yes. This is no different to just using -mtune several times: -mtune=pentiumpro -mtune=pentium3 -mtune=pentiumpro The last such option will be used. Specifying march=arch implies -mtune=arch, but a later -mtune will override it, just like it will override any explicit uses of -mtune that came earlier.
