It should have, although it would be slower. Possibly even slower than if you had used "-march=x86_64".
EDIT: -march implies -mtune. Don't use -mtune.
Yes, march implies mtune, but not vice-versa.
I will give -march=x86_64 a try, thanks for the suggestion.
no bueno on x86_64, possibly my version of gcc is too old, not sure.
error: bad value (x86_64) for -march= switch
EDIT: NVM, should be x86-64.