On Thu, 2021-09-16 at 22:46 -0400, NightStrike via Gcc-help wrote:
> On Tue, Sep 7, 2021 at 3:57 AM Jonathan Wakely via Gcc-help
> <gcc-help@xxxxxxxxxxx> wrote:
> >
> > On Tue, 7 Sep 2021, 08:03 unlvsur unlvsur via Gcc-help, <
> > gcc-help@xxxxxxxxxxx> wrote:
> >
> > > I try to cross compile to another slower machine. -march=native
> > > works on
> > > that architectures, but I would like to know what is the value of
> > > -march=??? For -march=native. Is there a way to print march value
> > > out??
> > >
> >
> > It doesn't choose a single value. It enables all the individual
> > options
> > like -msse and that combination of options might not correspond to any
> > particular -march value.
>
> Is that true? I mean, in principle, I know I've reported a bug where
> -march=native scanned /proc/cpuinfo (or however it got the info) and
> came up with a different result than -march=k8 (or whatever I was
> reporting at the time), but that was a bug that some helpful people
> fixed. If gcc doesn't have an -march for a particular esoteric arch,
> then fine, but if it does, I'd think that this would be a bug similar
> to what I experienced previously.
It's documented clearly:
native
This selects the CPU to generate code for at compilation time
by determining the processor type of the compiling machine.
Using -march=native enables all instruction subsets supported
by the local machine (hence the result might not run on
different machines). Using -mtune=native produces code
optimized for the local machine under the constraints of the
selected instruction set.
However if it produce something can't run on your machine,
this is a bug.
--
Xi Ruoyao <xry111@xxxxxxxxxxxxxxxx>
School of Aerospace Science and Technology, Xidian University
