Date: Sat, 19 May 2001 13:08:59 -0400 (EDT) From: Chuck Youse <chuck@newsscope.com> To: Terry Lambert <tlambert@primenet.com> Cc: Peter Pentchev <roam@orbitel.bg>, Ruslan Ermilov <ru@FreeBSD.ORG>, Nik Clayton <nik@FreeBSD.ORG>, arch@FreeBSD.ORG Subject: Re: [PATCH] syscons ioctl() to grab text mode buffer Message-ID: <Pine.BSF.4.21.0105191306460.38086-100000@warsaw.newsscope.com> In-Reply-To: <200105171816.LAA09113@usr05.primenet.com>
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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
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