3 ms·
There is probably a lot of merit in the advantages of vectors but it weakens the article to set them up as against SIMD when the presented facts are dubious at
by chx 8y ago
There is probably a lot of merit in the advantages of vectors but it weakens the article to set them up as against SIMD when the presented facts are dubious at best:
> An architect partitions the existing 64-bit registers
> The IA-32 instruction set has grown from 80 to around 1400 instructions since 1978, largely fueled by SIMD.
Wait, what. IA-32 started in 1985 not 1978. It didn't have any existing 64 bit registers. It was called IA-32 because of the 32 bit registers, like EAX and EBX. And then looking at the 1986 reference manual https://css.csail.mit.edu/6.858/2014/readings/i386.pdf https://css.csail.mit.edu/6.858/2014/readings/i386.pdf I count 96 instructions under 17.2.2.11. The IA-32 instruction set didn't grow much all these years, IA-64 did to the best my knowledge but please let me know if I am wrong here. As for IA-64, I looked at https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf https://www.intel.com/content/dam/www/public/us/en/documents... and it's hard to get an accurate count because some instructions are grouped together, it's either 627 or 996 (and I may have made a counting mistake given I started from a PDF, but it should be close) which is indeed very high but even our best attempt only finds a tenfold growth (and perhaps only a 6.5) instead of the 17.5 the article suggested.
- Iwan-Zotow 8y agowell, he might be counting AMD and things like 3dnow! which are now defunct but was (another) legit extension to IA-32
- CalChris 8y agoSmall nit. IA-64 refers to Itanium. I think you meant Intel 64. https://en.wikipedia.org/wiki/IA-64 https://en.wikipedia.org/wiki/IA-64
- chx 8y agoYou are correct.