Very simple SIMD programming

[bearophile]

Walter Bright:

> Making SIMD code that delivers performance turns out to be a 
> highly quirky and subtle exercise, one that is resistant to 
> formalization.

I have written some SIMD code, with mixed results, so I 
understand part of such problems, despite my total experience on 
such things is limited.

Despite those problems and their failures I think it's important 
to support computer scientists that try to invent languages that 
try to offer medium-level means to write such kind of code :-) 
Reading and studying CS papers is important.


> Manu is on the daily front lines of doing competitive, real 
> world SIMD programming. He leads a team doing SIMD work. Hence, 
> I am going to strongly weight his opinions on any high level 
> SIMD design constructs.

I respect both Manu and his work (and you Walter are the one at 
the top of my list of programming heroes).


> Interestingly, both of us have rejected the 
> "auto-vectorization" approach popular in C/C++ compilers, for 
> very different reasons.

The authors of that paper too have rejected it. It doesn't give 
enough semantics to the compilers. They have explored a different 
solution.

Bye,
bearophile