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Subject: Re: An Opteron note

Author: Daniel Clausen

Date: 03:05:04 11/27/03

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On November 27, 2003 at 05:54:15, Gerd Isenberg wrote:

>On November 27, 2003 at 05:33:17, Gian-Carlo Pascutto wrote:
>
>>On November 27, 2003 at 05:29:43, Gerd Isenberg wrote:
>>
>>>Be aware of the "signed extension" penalty if using signed 32-bit variables as
>>>array indicies, "long" is still 32-bit with msc but 64-bit in gcc:
>>
>>Ugh, that sucks! Of course all indexes are int here...
>
>Yes, the point is to avoid signed 32-bit int as index, due to the additional
>sign extension instruction. A signed 64-bit register variable as index register
>don't has this problem, but of course that should not imply to use explicitely
>64-bit long (gcc) or long long (gcc) or __int64 (msc) as index variables, unless
>your arrays are that huge ;-)
>
>Gerd
>
>>
>>--
>>GCP

So using unsigned 32-bit would be a good idea, right?

Sargon



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