Thread: Using MMX & XMM Registers

  1. 07-14-2007 #1
    HyperShadow
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    Talking Using MMX & XMM Registers

    Hello, I was trying to look into using some of the new instruction sets for parallel processing and was wondering if anyone here has had any experience using these. I've looked into some documentation on MSDN and even played around with XMM registers a bit and was wondering if there is any downside to using these that I should be aware of. I'm assuming these instruction sets are supported on a Pentium III and upwards as well as AMD's hardware?

    I was considering trying XMM registers considering I am dealing with mathematical computations on large vectors, but am worried that for some reason unknown to me that I might have to go back through all my code and remove all this code for standard c code... any opinions would be greatly appreciated. Also, in the documentation it considers these instruction sets as "multimedia" enhancers of sorts.. wtf does that mean?
  2. 07-14-2007 #2
    Salem
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    How (or even if) you get to them depends entirely on your compiler.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
  3. 07-14-2007 #3
    dwks
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    Doesn't look good . . . (MSVC)
    The other bad news is that the MMX instrinsics still produce awful code, although this is only pertinent to x86 since the AMD64 compiler doesn't support MMX instructions
    http://www.virtualdub.org/blog/pivot/entry.php?id=46
    dwk

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  4. 07-14-2007 #4
    HyperShadow
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    Was going to go with intrinsics in MSVC 2005.. I read the link you posted and it more-or-less scared me away from intrinsics although I'm still intrigued. So whats the deal should I attempt to go with intrinsics? Bad idea?
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