Message-ID:	<387C8B0E.156C3493@softhome.net>
Date:	Wed, 12 Jan 2000 16:09:18 +0200
From:	Laurynas Biveinis <lauras AT softhome DOT net>
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To:	djgpp AT delorie DOT com
Subject:	Re: Is there any point in MMX?
References:	<8599nt$1uo3r$1 AT reader2 DOT wxs DOT nl> <83d7r7y7vp DOT fsf AT mercury DOT st DOT hmc DOT edu>
Reply-To:	djgpp AT delorie DOT com

Nate Eldredge wrote:
> As I understand it, no.  There aren't extra registers.  They overload
> the floating-point registers into "vector" registers, and add some

This makes things even more harder - mixing MMX and floating point
code kills perfomance.

> vector arithmetic.  This means you could parallelize some of your
> arithmetic (i.e. do two or four or eight additions with one
> instruction).  But you'll probably have to do it in assembly; it's a
> difficult thing for a compiler to handle, and GCC currently doesn't
> (though I believe there are some special patches).

Pentium GCC supports it from version 2.95. As they say, on Pentium
the gain is very tiny, and a little bit better on Pentium II.

Laurynas Biveinis

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