Date: Thu, 5 Dec 2002 05:11:30 -0800 From: David Schultz <dschultz@uclink.Berkeley.EDU> To: Evren Yurtesen <eyurtese@turkuamk.fi> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: -O3 optimization? Message-ID: <20021205131130.GB11161@HAL9000.homeunix.com> In-Reply-To: <Pine.A41.4.10.10212051227480.117918-100000@bessel.tekniikka.turkuamk.fi> References: <Pine.A41.4.10.10212051227480.117918-100000@bessel.tekniikka.turkuamk.fi>
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Thus spake Evren Yurtesen <eyurtese@turkuamk.fi>: > I wonder if a source is compiled with -O3 without any problems, might > there be any problems in binaries which might create crashes? You're welcome to try it out, but it isn't supported. GCC has a few obscure misfeatures at -O3. Some applications break at -O3, usually because they violate C's aliasing rules or contain broken inline assembly. At one point, the kernel's TCP checksum code had some difficult-to-solve problems with -O3, and I'm not sure whether that has been fixed. Despite all of that, I built world and kernel with -O2 a while ago and noticed no problems whatsoever. Just note that you've been warned, and you probably won't see a significant performance improvement anyway. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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