XP systems?

[Carl S. Gutekunst]

>Are there any XP systems out there?

Sure. That's the MIServer CPU.

>I consider doing an extension to GCC to generate the three address
>instructions, supported by these systems.

Alas, these were dropped. It was one of those things that seemed like a pretty
neat idea at the time, and the CPU people thought it would be trivial to add
them to the new pipeline of the XP CPU. But a lot of people (including some of
the compiler folks) weren't convinced they were that useful, and would have
created binary incompatibility between the machines as well. When it appeared
that release schedules might slip, work on the three operand instructions was
quietly dropped. (Note that it was three *operand*, not three *address*.)

There are some new instructions in the XP CPU, but they are applicable to the
kernel only -- extending the architecture out to >8 CPUs, for example.

<csg>