Date: Fri, 16 Jul 2010 17:17:04 +0300 From: Andrey Simonenko <simon@comsys.ntu-kpi.kiev.ua> To: remko@FreeBSD.org Cc: freebsd-i386@FreeBSD.org Subject: Re: i386/79091: [i386] [patch] Small optimization for i386/support.s Message-ID: <20100716141704.GA8965@pm513-1.comsys.ntu-kpi.kiev.ua> In-Reply-To: <201007140707.o6E773ff067326@freefall.freebsd.org> References: <201007140707.o6E773ff067326@freefall.freebsd.org>
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On Wed, Jul 14, 2010 at 07:07:03AM +0000, remko@FreeBSD.org wrote: > Synopsis: [i386] [patch] Small optimization for i386/support.s > > State-Changed-From-To: open->feedback > State-Changed-By: remko > State-Changed-When: Wed Jul 14 07:06:16 UTC 2010 > State-Changed-Why: > Hello, the code in question is using 'rcx' now instead of 'ecx'to restore > the registers. That might have solved your problem can you please have a look at that please and confirm whether it's still relevant? That PR was about optimization for suword() and similar functions for i386 and amd64 architectures. %ecx is used for i386 and %rcx is used for amd64, but the idea is the same. I do not understand why these lines are necessary for suword-like functions, all fuword-like functions do not reinitialize %ecx and %rcx registers after MOV instruction that potentially can generate some exception (eg. page fault).
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