[PD] 64 bit PD

[Tim Blechmann]

> By 'move' do you mean process calculations on the CPU?  You would be 
> describing SIMD and really bad MMX style SIMD at that.  Modern CPUs 
> have 128 bit wide vector units like Altivec and SSE which are
> fantastic if actually used.
the main question is, what can the compiler actually do with the
hardware ... 
i'm not familiar with the amd64 architecture, but i suppose it's similar
to simd instructions ... 
- to use them, the memory regions have to be aligned ... otherwise it
  would not take the optimum of one command move data from memory to
  registers
- it can only be used if algorithms _can_ be vectorized ... that's not a
  problem with simple multiplications, but complex algorithms like
  filters, or interpolation algorithms will not take advantage of
  that...
- and the compiler will have to know the instructions and _use_ them ...
  as for now i can say that any compiler i tried (gcc 3.2/3.3, icc) had
  problems generating the optimal sse instructions ... (this is possibly
  related to dsp block allocation as it's done in pd at the moment)

that's why i somehow doubt that 64bit processors will bring a huge
speedup for dsp algorithms ...

cheers ... tim

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