Oppolzer - Informatik / Blog

This is IMHO the old RISC - CISC discussion.

Should we have machine instructions to compute a polynome of grade n? I don't
think so (but there were machines in the 60s which did just that, and - in that
period - they were faster by using such instructions).

Should we have machine instructions to do a lookup in a binary tree? Maybe ...

Should we have machine instructions for compression and decompression using the
Lempel-Ziv algorithm? Of course, especially if DB2 with data compression is to
be run on that hardware.

So I think the instruction set and the design decisions should not be driven by
nostalgia (of course we have to take care of legacy workload), but by two
things:

- the kind of workload that will be run on the machine and performance goals to
be met

- and the needs of the compiler writers (they don't need MANY instructions)

The comfort or discomfort of the ASSEMBLER programmers is not significant in
this context, in my believe. Due to pipelining and cache issues, clever
compilers will sooner or later outperform hand-written ASSEMBLER programs.

Kind regards

Bernd