From:	Damian Yerrick <Bullcr_pd_yerrick AT hotmail DOT comRemoveBullcr_p>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: either I'm stupid or GCC once again has random behaviour
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NNTP-Posting-Date:	Fri, 05 Jan 2001 14:26:04 GMT
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Date:	Fri, 05 Jan 2001 14:26:04 GMT
To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

On Tue, 2 Jan 2001 17:41:07 -0500, "Alexei A. Frounze"
<dummy_addressee AT hotmail DOT com> wrote:

>Why unrolling? There is a perfect instruction REP STOSB/W/D.
>What do you mean?

On modern x86 CPUs a loop of simple instructions (which can be split
among the U and V (and W in PII) pipelines) is actually _faster_ than
the string instructions (which are complex, run in microcode, and can
fit only in U).  To fit code into the pipeline without time-consuming
branching, unrolling loops is a necessity.

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