Date: Fri, 26 Jul 2013 17:44:58 -0700 From: Warner Losh <imp@bsdimp.com> To: John-Mark Gurney <jmg@funkthat.com> Cc: Andriy Gapon <avg@freebsd.org>, freebsd-arch@freebsd.org Subject: Re: amd64: -O2 even with DEBUG Message-ID: <C24CE895-60CC-4438-A5D8-377AF4B17096@bsdimp.com> In-Reply-To: <20130726185425.GS26412@funkthat.com> References: <51F221D4.8040308@FreeBSD.org> <20130726185425.GS26412@funkthat.com>
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On Jul 26, 2013, at 11:54 AM, John-Mark Gurney wrote: > Andriy Gapon wrote this message on Fri, Jul 26, 2013 at 10:14 +0300: >> I wonder why amd64 is distinguished to have -O2 in COPTFLAGS even when DEBUG is >> defined. For all other archs it's -O for that case. >> >> Perhaps, this was discussed / explained in the past, but I would appreciate it >> being said again (or even written as a comment in kern.pre.mk). > > It's probably because at least gcc produces terrible amd64 code w/o > it... It will constantly reload the register it uses to do relative > loads w/ the same value even though nothing changed... makes performance > suck... Still looks like it is implemented wrongly though... Warnerhome | help
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