I Wish Intel CPU's Had A Linear Interpolate Instruction
Crossbones+ - Reputation: 18743
Posted 28 October 2012 - 02:36 PM
Why linear only, why not all the other interpolation functions?
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Crossbones+ - Reputation: 1740
Posted 28 October 2012 - 06:58 PM
That said there are more important instructions we need in the future like those predicate instructions to remove branch pipeline flushes.
Edited by Sirisian, 28 October 2012 - 06:58 PM.
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Senior Moderators - Reputation: 5047
Posted 28 October 2012 - 09:48 PM
DPPS in SSE4 handles the matrix multiplication case perfectly fine. You're not likely to ever see a single matrix multiply instruction on the x64 platform. MADD is about as good as it'll get (i.e. DPPS)
Agreed. Linear interpolation is not even a blip on the performance radar.
Branch misprediction is a big one. Frequent operations like matrix multiply are another big one.
The branch misprediction one is perhaps the largest one I can thank of that stands out as far as performance critical code goes.
Edited by Washu, 28 October 2012 - 09:54 PM.
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Moderators - Reputation: 29747
Posted 28 October 2012 - 09:58 PM
While we're at it, does x86 have fsel (or conditional-move for all register types)?
Edited by Hodgman, 28 October 2012 - 10:00 PM.
Crossbones+ - Reputation: 4216
Posted 28 October 2012 - 11:03 PM
x86 has quite a lot of conditional-move opcodes, but I don't remember if all register types are supported or not. I believe that GPR and FPU registers are supported, but not sure about MMX/XMM/YMM.
Edited by Nypyren, 28 October 2012 - 11:08 PM.
Crossbones+ - Reputation: 8694
Posted 29 October 2012 - 07:31 AM
[...] Additionally, Branch Hints were introduced. These hint prefixes are used to help the processor perform better branch prediction.
hwnt - Hint Weakly Not Taken.
hst - Hint Strongly Taken.
The slowsort algorithm is a perfect illustration of the multiply and surrender paradigm, which is perhaps the single most important paradigm in the development of reluctant algorithms. The basic multiply and surrender strategy consists in replacing the problem at hand by two or more subproblems, each slightly simpler than the original, and continue multiplying subproblems and subsubproblems recursively in this fashion as long as possible. At some point the subproblems will all become so simple that their solution can no longer be postponed, and we will have to surrender. Experience shows that, in most cases, by the time this point is reached the total work will be substantially higher than what could have been wasted by a more direct approach.
- Pessimal Algorithms and Simplexity Analysis