I wonder how much these last set of instructions are used.
It should be incorporated in drivers or (very) low level programming for games.
Aren't most programmers using high level compilers these days?
Or is it possible to compile (optimize?) a program with two instruction sets, auto-detecting which one to use on the client's computer?
Is it incorporated in things like DirectX?
In fact, they are going the SSE route. I think Barcelona uses SSE4A and they are developing SSE5 for their 2009 CPU (unless there is a delay).
From what little I understand AMD's SSE4A is kinda like Intel's SSE4 but AMD is not using all the extensions from Intel's SSE4. On top of that, those extensions that they are using will be applied differently. I assume AMD introduces their own extensions as well.
So will SSE4A boost performance? No, not until software developers decide to support it. Not many developers supported 3DNow! to the best of my knowledge.
Will processors with SSE4A take advantage of programs that incorporates SSE4? Doubtful, or very little. Like I said before, AMD is not using all the extensions and those that they are using will not be used in the exact same manner.
Do any of these different types of "multi-media" extensions have any impact on games? Based on some old articles I've read in the past, the performance boost is little to negligible.