gcc-4.3.x and Core 2 Duo, safe way
On Mon, 09 Jun 2008 06:43:41 +0100
Graham Murray <email@example.com> wrote:
> Andrew Gaydenko <firstname.lastname@example.org> writes:
> > gcc-4.3.1 is umasked now. I'm on ~amd64 with Core 2 Duo CPU. Is it
> > sufficient just to set
> > CFLAGS="-O2 -march=core2 -mtune=core2 -pipe"
> > instead of
> > CFLAGS="-O2 -march=native -mtune=native -pipe"
> > which I have in make.conf now? Are there any other things to do?
> Should the two not be equivalent? On a core2 processor, should
> -march=native not generate code for the core2?
If we are going to get picky about this, it should be noted the -march
implies -mtune, at least according to the gcc man pages, and I will
trust them to know.
I can't remember which will actually be implemented if both are
specified, but march is a essentially a stronger version of mtune which
breaks compatibility with other CPUs within the same ARCH type. (i.e.
march=pentium4 may not run on a pentium3, but should run faster than
mtune on a pentium4)
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