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Date:      Fri, 04 Apr 2003 23:09:22 +0200
From:      des@ofug.org (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=)
To:        Kris Kennaway <kris@obsecurity.org>
Cc:        cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sys/alpha/alpha support.s src/sys/i386/i386 identcpu.c support.s src/sys/i386/include md_var.h src/sys/i386/isa npx.c src/sys/ia64/ia64 support.s src/sys/powerpc/powerpc bcopy.c src/sys/sparc64/sparc64 support.S ...
Message-ID:  <xzpn0j6c6m5.fsf@flood.ping.uio.no>
In-Reply-To: <20030404182223.GA36706@HAL9000.homeunix.com> (David Schultz's message of "Fri, 4 Apr 2003 10:22:23 -0800")
References:  <200304041729.h34HTtVb027430@repoman.freebsd.org> <20030404173635.GA22147@rot13.obsecurity.org> <20030404182223.GA36706@HAL9000.homeunix.com>

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David Schultz <das@FreeBSD.ORG> writes:
> BTW, why does this change convert bcopy from a function pointer to
> a function that jumps to the address of a pointer?  This looks
> like a net gain in lines of code and a net gain in pipeline
> stalls.  Is there something in particular that it makes easier?

Just code hygiene.  There is no such optimization for bzero or any of
the other functions in support.s (copyin, copyout), and it required an
i386-specific declaration in <sys/systm.h>.  Of course, if the
consensus is that this micro-optimization is desirable, I'll back out
this part of the patch, but in that case I'll turn the other functions
into pointers as well rather than have a mixed bag.

DES
--=20
Dag-Erling Sm=F8rgrav - des@ofug.org



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