Hi all..
I think what -O3 is not _dangerous_ when you know how to use, a few posts ago someone mentioned not all of packages can be compiled using -O3, if I am not wrong was GCC and OpenOffice.org.
The thing is: -O3 is not a _damage_ is an carefully flag to compile for some packages..
In some webpages I people said : ".. -O3 is not used by developer because come troubles when you want to do a debug..".
But:
http://www.nersc.gov/vendor_docs/intel/f_ug2/dbg_opt.htm,
http://linuxgazette.net/121/hegde.html,
http://publib.boulder.ibm.com/infocenter/macxhelp/v6v81/index.jsp?topic=/com.ibm.xlf81m.doc/pgs/ug42.htm.
"...The following setting is the "Optimizations". You shouldn't use O3 as
it takes longer to compile, the generated code will be sometimes
faster, sometimes slower and almost always larger. For example, a
program that was compiled with the O2 level of optimization is 250KB
large and is quite fast, the same program compiled with the O3 level of
optimization can take more time to compile, produce a larger binary,
depending on the code, even 500-700KB large and it can be slower or
faster. Therefore, the O3 optimization level isn't recommended. Use O2
if you need the best optimization without adding the risk of obtaining
large binaries, which need a long time to be loaded before being
executed and are not always faster..." take of http://www.softpedia.com/reviews/linux/Gentoo-Review-20543.shtml.
On 4/11/07, Bo Ørsted Andresen <bo.andresen@zlin.dk> wrote:
On Wednesday 11 April 2007 12:56:43 Daniel Iliev wrote:
> Sorry, I don't get it. Perhaps it is my poor English but I couldn't
> understand two things:
> - Is -O3 supported by Gentoo or not?
-O3 is supported by Gentoo.
> - What's the special thing about Gentoo ebuilds that makes -O3 dangerous?
No no. The special thing about Gentoo ebuilds is that -O3 in make.conf is safe
for all packages because those packages for which -O3 isn't safe are
replacing it with -O2 in the ebuilds (or eclasses).
--
Bo Andresen
--
['Cause without love I won't survive, I love you]. I
Francisco Rivas
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