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Subject: Re: 64-bit machines

Author: Sune Fischer

Date: 02:21:54 02/06/03

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On February 06, 2003 at 00:54:58, Robert Hyatt wrote:
>
>
>In the case of the x86, GP registers can be used for "general purpose" stuff.
>Including integer math, address calculations, indexing, loop counting, etc.
>The MMX stuff uses the FP processor registers in a bizarre way so that you
>can execute a single instruction that will operate on multiple parts of one
>of the 64 bit FP registers at the same time.  IE increment each of the 8 bytes
>at the same time, a form of SIMD operation...  I'm not sure what XMM would
>apply to...  But having several types is not uncommon.  The cray had 64 bit
>scalar registers, 32 bit address calculation/indexing registers, and 8
>vector registers with 128 words of data per register...  It also had 64
>"temp" scalar registers that couldn't be used for calculations, but they
>could be used as 1-cycle-access-time places to store the scalar registers
>if you "ran out"...  ditto for 64 address temps for the 32 bit address
>registers.

What is a "vector" register?

I've seen you talk about how this sped up move generation because you did some
vector thing. Is that true and if so, how did it work?

-S.



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