nightmorph 09/07/19 02:05:08 Modified: gcc-optimization.xml Log: add some information about -march=native
Revision Changes Path 1.16 xml/htdocs/doc/en/gcc-optimization.xml file : http://sources.gentoo.org/viewcvs.py/gentoo/xml/htdocs/doc/en/gcc-optimization.xml?rev=1.16&view=markup plain: http://sources.gentoo.org/viewcvs.py/gentoo/xml/htdocs/doc/en/gcc-optimization.xml?rev=1.16&content-type=text/plain diff : http://sources.gentoo.org/viewcvs.py/gentoo/xml/htdocs/doc/en/gcc-optimization.xml?r1=1.15&r2=1.16 Index: gcc-optimization.xml =================================================================== RCS file: /var/cvsroot/gentoo/xml/htdocs/doc/en/gcc-optimization.xml,v retrieving revision 1.15 retrieving revision 1.16 diff -u -r1.15 -r1.16 --- gcc-optimization.xml 26 Jun 2009 03:33:21 -0000 1.15 +++ gcc-optimization.xml 19 Jul 2009 02:05:08 -0000 1.16 @@ -1,6 +1,6 @@ <?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> -<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/gcc-optimization.xml,v 1.15 2009/06/26 03:33:21 nightmorph Exp $ --> +<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/gcc-optimization.xml,v 1.16 2009/07/19 02:05:08 nightmorph Exp $ --> <guide link="/doc/en/gcc-optimization.xml"> <title>Compilation Optimization Guide</title> @@ -19,8 +19,8 @@ <!-- See http://creativecommons.org/licenses/by-sa/2.5 --> <license/> -<version>1.10</version> -<date>2009-06-25</date> +<version>1.11</version> +<date>2009-07-18</date> <chapter> <title>Introduction</title> @@ -195,6 +195,21 @@ CXXFLAGS="${CFLAGS}" </pre> +<p> +If you still aren't sure what kind of CPU you have, you may just want to use +<c>-march=native</c>. When this flag is used, GCC will detect your processor and +automatically set appropriate flags for it. <brite>However, this should not be +used if you intend to compile packages for a different CPU!</brite> +</p> + +<p> +So if you're compiling packages on one computer, but intend to run them on a +different computer (such as when using a fast computer to build for an older, +slower machine), then <e>do not</e> use <c>-march=native</c>. "Native" means +that the code produced will run <e>only</e> on that type of CPU. The +applications built with <c>-march=native</c> on an AMD Athlon 64 CPU will not be +able to run on an old VIA C3 CPU. +</p> <p> Also available are the <c>-mtune</c> and <c>-mcpu</c> flags. These flags are
