On Sun, Aug 15, 2010 at 2:35 AM, Ben Kloosterman <[email protected]> wrote: > Thanks for pointing this out , I also note on Neon SIMD is limited to 64bit > ..while mentally im focusing on the move to 256 bit this year on x86.
That's not quite accurate. The NEON has 64-bit D registers and 128-bit Q registers (a bit like MMX and XMM on Intel, only much better thought out) which is actually quite useful for integer code because you can multiply 2 vectors of uintN_t's in D registers directly into a vector of uint2N_t's in a Q register, whereas doing the equivalent on SSE is really awkward. (Actually 2 Ds alias onto one Q register, a bit like I gather the XMM's will alias onto YMM registers. Nothing new under the sun :-) ) The one thing that is explicitly mentioned against various times on ARM lists is trying to used SIMD for things other than actual SIMD processing, because all the design tradeoff decisions were taken purely on the basis of multimedia usage. Regards, David Steven Tweed _______________________________________________ bitc-dev mailing list [email protected] http://www.coyotos.org/mailman/listinfo/bitc-dev
