SIMD/intrinsincs questions

[Walter Bright]

Mike Farnsworth wrote:
> For my purposes, runtime detection is probably out the window, unless
> the tests for it can happen infrequently enough to reduce the
> overhead.  There are too many SSE variations to switch on them all,
> and they incrementally provide better and better functionality that I
> could make use of.  I'd rather compile different executables for
> different hardware and distribute them all (e.g. detect the SSE
> version at compile time).  Really, high performance graphics is an
> exercise in getting tightly vectorized code to inline appropriately,
> eliminate as many loads and stores as possible, and then on top of
> that build algorithms that don't suck in runtime or memory/cache
> complexity.

The way to do it is to not distribute multiple executables, but have the 
initialization code detect the chip. Then, you compile the same code for 
different instructions, and have a high level runtime switch between them.

I used to do this for machines with and without x87 support.