Proper way to enable SSE4 on a per-function / per-block of code basis?

Question

For one of my OS X programs, I have a few optimized cases which use SSE4.1 instructions. On SSE3-only machines, the non-optimized branch is ran:

// SupportsSSE4         


        

Answer 1

Depending on the OS you might be able to use something like Function Multiversioning in the future. I'm working on the feature right now, but it'll be a while before it's ready for use in a production compiler.

See http://gcc.gnu.org/wiki/FunctionMultiVersioning for more details.