/[gentoo]/xml/htdocs/doc/en/faq.xml
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12<author title="Editor"><mail link="peesh@gentoo.org">Jorge Paulo</mail></author> 12<author title="Editor"><mail link="peesh@gentoo.org">Jorge Paulo</mail></author>
13<author title="Editor"><mail link="swift@gentoo.org">Sven Vermeulen</mail></author> 13<author title="Editor"><mail link="swift@gentoo.org">Sven Vermeulen</mail></author>
14<abstract>This FAQ is a collection of questions and answers collected from the gentoo-dev mailing list and from IRC -- if you have any questions (or answers!) to add, please contact either an author or a member of the documentation team.</abstract> 14<abstract>This FAQ is a collection of questions and answers collected from the gentoo-dev mailing list and from IRC -- if you have any questions (or answers!) to add, please contact either an author or a member of the documentation team.</abstract>
15 15
16<version>1.1.4</version> 16<version>1.1.4</version>
17<date>23 May 2003</date> 17<date>23 June 2003</date>
18 18
19<chapter> 19<chapter>
20 <title>Getting Started</title> 20 <title>Getting Started</title>
21 21
22 <section> 22 <section>
96</section> 96</section>
97 <section> 97 <section>
98 <title>I'm finding things to be really unstable and I'm using "-O9 -ffast-math 98 <title>I'm finding things to be really unstable and I'm using "-O9 -ffast-math
99 -fomit-frame-pointer" optimizations. What gives?</title> 99 -fomit-frame-pointer" optimizations. What gives?</title>
100 <body> 100 <body>
101 <p>When you use any optimizations beyond <c>-O3</c>, you're really taking the risk of 101 <p>Don't bother using anything higher than <c>-O3<c> since it isn't support by current versions
102 having broken packages.
103 Very aggressive optimizations sometimes cause the compiler to streamline the assembly code 102 of gcc. Very aggressive optimizations sometimes cause the compiler to streamline the assembly code
104 to the point where it doesn't quite do the same thing anymore. A possible setting based on <e>Loc-Dog</e> (on IRC)'s CFLAGS 103 to the point where it doesn't quite do the same thing anymore. A possible setting based on <e>Loc-Dog</e> (on IRC)'s CFLAGS
105 is <c>-O3 -mcpu=i686 -march=i686 -fforce-addr -fomit-frame-pointer -funroll-loops 104 is <c>-O3 -mcpu=i686 -march=i686 -fforce-addr -fomit-frame-pointer -funroll-loops
106 -frerun-cse-after-loop -frerun-loop-opt -falign-functions=4</c>, which is about 105 -frerun-cse-after-loop -frerun-loop-opt -falign-functions=4</c>, which is about
107 as much as I'd want to push global optimization settings. Beyond this, it's best to use 106 as much as I'd want to push global optimization settings. Beyond this, it's best to use
108 ultra-high optimizations only with specific packages where you really need that extra 2%, 107 ultra-high optimizations only with specific packages where you really need that extra 2%,

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