Date: Wed, 13 Dec 2000 16:04:13 -0700 From: Warner Losh <imp@village.org> To: Marc Tardif <intmktg@CAM.ORG> Cc: Alfred Perlstein <bright@wintelcom.net>, freebsd-hackers@FreeBSD.ORG Subject: Re: syscall assembly Message-ID: <200012132304.QAA42447@harmony.village.org> In-Reply-To: Your message of "Wed, 13 Dec 2000 17:12:40 EST." <Pine.LNX.4.10.10012131707550.12495-100000@Gloria.CAM.ORG> References: <Pine.LNX.4.10.10012131707550.12495-100000@Gloria.CAM.ORG>
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In message <Pine.LNX.4.10.10012131707550.12495-100000@Gloria.CAM.ORG> Marc Tardif writes: : So why is %esp displaced by 16 bytes when only 8 bytes : are necessary (4 for $0 and 4 for $.LC0)? And couldn't : the compiler use a single instruction such as : subl $16,%esp or addl $-16,%esp? Are two instructions : used for pipelining purposes, where subl is synchro- : nised with the first pushl and addl with the second : pushl? gcc tries to align stack to 16 byte boundaries as a speed optiminzation. Why it doesn't do this in one instruction is beyond me. Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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