On Sun, Jun 11, 2017 at 4:43 PM, Toby Douglass <toby.douglass@xxxxxxxxxxx> wrote: > And in fact; > > minnow@minnow:~$ gcc -mtune=native -dM -E - < /dev/null | grep 86 > #define __i586 1 > #define __DBL_MAX__ ((double)1.79769313486231570815e+308L) > #define __i386 1 > #define __i586__ 1 > #define __i386__ 1 > #define i386 1 > > The docs say; > > "While picking a specific cpu-type will schedule things appropriately > for that particular chip, the compiler will not generate any code that > does not run on the i386 without the -march=cpu-type option being > used." > > But in fact if I understand the output of the command Ruoyao provided, > tune *is* setting arch (whilst not setting tune =-) so this compiler > in this specific case ends up setting arch correctly. This is rubbish. All that's happening is that in the absence of march, the default arch is being used.
