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 Am 30.08.2011 16:15, schrieb John P Kalinich:
In 1997, I left the Atlanta SHARE meeting early on Thursday morning. Gene Amdahl was waiting for the shuttle bus with me. On the way to the airport, I had the opportunity to ask him some S/360 questions as we were the only 2 people on the bus. One of which was, how did you ever come up with that ED (it) instruction? His reply, "oh, we had fun with that one". Regards, John K
