Date: Wed, 5 Jan 2000 12:44:40 -0600 From: Dan Nelson <dnelson@emsphone.com> To: "Ronald F. Guilmette" <rfg@monkeys.com> Cc: Martin Cracauer <cracauer@cons.org>, mauzi@poli.hu, hackers@FreeBSD.ORG Subject: Re: [OFFTOPIC] alt. C compiler Message-ID: <20000105124439.A28602@dan.emsphone.com> In-Reply-To: <99736.947095986@monkeys.com>; from "Ronald F. Guilmette" on Wed Jan 5 10:13:06 GMT 2000 References: <20000105100909.B63545@cons.org> <99736.947095986@monkeys.com>
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In the last episode (Jan 05), Ronald F. Guilmette said:
> Martin Cracauer <cracauer@cons.org> wrote:
> >
> >When your code breaks when using -O2 or higher, don't do that, use
> >just -O!
>
> Ah, excuse me, but -O is equivalent to -O2.
/usr/src/contrib/gcc/toplev.c:4821
if (!strcmp (argv[i], "-O"))
{
optimize = 1;
optimize_size = 0;
}
So, -O is equivalent to -O1. Go down one page from there, and you'll
see the individual optiomizations enabled by each level. Also note
that for stock gcc, there is nothing above -O3 (If you see someone
using anything higher, you can be sure they're using pgcc). The -Os
flag automatically sets -O2.
--
Dan Nelson
dnelson@emsphone.com
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