From owner-freebsd-arch Sat May 19 8:38:57 2001 Delivered-To: freebsd-arch@freebsd.org Received: from warsaw.newsscope.com (warsaw.newsscope.com [64.21.68.186]) by hub.freebsd.org (Postfix) with ESMTP id 69C0137B42C; Sat, 19 May 2001 08:38:54 -0700 (PDT) (envelope-from chuck@newsscope.com) Received: from localhost (chuck@localhost) by warsaw.newsscope.com (8.11.1/8.11.1) with ESMTP id f4JH8xd63820; Sat, 19 May 2001 13:08:59 -0400 (EDT) (envelope-from chuck@newsscope.com) Date: Sat, 19 May 2001 13:08:59 -0400 (EDT) From: Chuck Youse To: Terry Lambert Cc: Peter Pentchev , Ruslan Ermilov , Nik Clayton , arch@FreeBSD.ORG Subject: Re: [PATCH] syscons ioctl() to grab text mode buffer In-Reply-To: <200105171816.LAA09113@usr05.primenet.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Thu, 17 May 2001, Terry Lambert wrote: > On a practical note, the code generated merely inverts the sense > of the same cmpl at default optimization, and at -O2 ends up being > either: > > testl %eax,%eax > jge .L3 > > or: > > cmpl $-1,%eax > jne .L3 > > So the number of instruction cycles is identical. Off the top of Well, the second sequence is longer by a byte. I don't have the data sheets handy, it probably also takes another cycle as it involves an immediate operand sign-extended to 32-bits instead of just a register-register compare. Just nitpicking Chuck To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message