Date: Mon, 5 Jun 2000 16:58:38 -0700 From: Alfred Perlstein <bright@wintelcom.net> To: "Daniel C. Sobral" <dcs@newsguy.com> Cc: hackers@FreeBSD.ORG Subject: Re: Optimization Message-ID: <20000605165838.W17973@fw.wintelcom.net> In-Reply-To: <200006052347.IAA00583@daniel.sobral>; from dcs@newsguy.com on Tue, Jun 06, 2000 at 08:47:42AM %2B0900 References: <200006052347.IAA00583@daniel.sobral>
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* Daniel C. Sobral <dcs@newsguy.com> [000605 16:47] wrote: > Can someone discuss the performance trade-offs of the following two > alternative codes (and maybe suggest alternatives)? > > Problem: I need to retrieve two values from a table. > > Alternative A: > > x = table[i].x; > y = table[i].y; > > Alternative B: > > d = table[i]; > x = d & MASK; > y = d >> SHIFT; x = table[i]; y = x >> SHIFT; x &= MASK; ? I would run gcc -O3 -S on the code on several archs and see what comes up. -Alfred To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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