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Old 2007-07-13, 01:02   #2
ewmayer
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Sep 2002
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Depends very much on the application, and how much time/skill you possess.

To use some Mersenne-realted examples: the big-FFT code used in LL testing benefits far more from careful high-level coding and data movement considerations than from ASM. (Note that ASM gave much more bang on the x86 in the early days of the project, when there were no really good HLL compilers for the x86). I can get about 2/3 the performance of George's hand-tuned Prime95 code using a simple MSVC build of my C code, and the nice thing is, the C code is portable t other platforms.

Now, for smaller snippets of code, however, a whiff of ASM can often get you a lot of bang for your buck.

The general rule is: if you have a relatively small amount of code which dominates your compute time (e.g. a critical inner-loop section or macro), then ASM is worth playing with.
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