From: Nikos Chantziaras <realnc@arcor.de>
To: gentoo-user@lists.gentoo.org
Subject: [gentoo-user] Re: -march=native is *EXTREMELY* conservative
Date: Sat, 17 Dec 2011 23:58:36 +0200 [thread overview]
Message-ID: <jcj39r$cf4$1@dough.gmane.org> (raw)
In-Reply-To: <20111217210709.GA1740@waltdnes.org>
On 12/17/2011 11:07 PM, Walter Dnes wrote:
>
> Then I ran "gcc -march=native -Q --help=target" and got a major shock.
> It's a long output listing of what -march=native thinks about my cpu.
> Here are some relevant items...
>
> -march= core2
> -mmmx [disabled]
> -msse [disabled]
> -msse2 [disabled]
> -msse3 [disabled]
> -mssse3 [disabled]
>
> It properly identified the cpu as "core2". But mmx, sse, sse2, sse3
> (aka pni), and ssse3 are disabled!!!
The output lies. It's a known issue. Use this instead:
echo | gcc -dM -E - -march=native
You should see stuff like:
#define __MMX__ 1
#define __SSE3__ 1
next prev parent reply other threads:[~2011-12-17 22:00 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-17 21:07 [gentoo-user] -march=native is *EXTREMELY* conservative Walter Dnes
2011-12-17 21:53 ` Dale
2011-12-17 21:58 ` Nikos Chantziaras [this message]
2011-12-18 1:10 ` [gentoo-user] " Walter Dnes
2011-12-18 10:34 ` Walter Dnes
2011-12-18 10:45 ` Nikos Chantziaras
2011-12-18 18:10 ` Andrea Conti
2011-12-19 0:05 ` [gentoo-user] A tale of computing thud and blunder Walter Dnes
2011-12-19 0:17 ` Dale
2011-12-19 5:41 ` Pandu Poluan
2011-12-19 6:15 ` Dale
2011-12-19 6:49 ` [gentoo-user] " Nikos Chantziaras
2011-12-19 7:21 ` Dale
2011-12-19 12:49 ` walt
2011-12-19 8:14 ` [gentoo-user] " Pandu Poluan
2011-12-19 16:37 ` Paul Hartman
2011-12-18 1:15 ` [gentoo-user] -march=native is *EXTREMELY* conservative Paul Hartman
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