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Subject: Re: An Opteron note

Author: Gerd Isenberg

Date: 02:54:15 11/27/03

Go up one level in this thread

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

• Re: An Opteron note Daniel Clausen 03:05:04 11/27/03
  • It gets slower Gian-Carlo Pascutto 04:55:17 11/27/03
    • It gets faster Gian-Carlo Pascutto 06:24:11 11/27/03
      • It gets significantly faster Gian-Carlo Pascutto 06:34:51 11/27/03
    • Re: It gets slower Gerd Isenberg 06:14:25 11/27/03
    • ParSOS gets faster Gian-Carlo Pascutto 06:03:27 11/27/03
  • Re: An Opteron note Gerd Isenberg 03:34:39 11/27/03

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