Path: utzoo!attcan!uunet!sco!seanf From: seanf@sco.COM (Sean Fagan) Newsgroups: comp.arch Subject: Re: Compilers taking advantage of architectural enhancements Message-ID: <8424@scolex.sco.COM> Date: 26 Oct 90 09:05:03 GMT References: <1990Oct9> <3300194@m.cs.uiuc.edu> <11922@ganymede.inmos.co.uk> <339@fjcp60.GOV> <2661@l.cc.purdue.edu> Sender: news@sco.COM Reply-To: seanf (Sean Fagan) Organization: The Santa Cruz Operation, Inc. Lines: 42 In article <2661@l.cc.purdue.edu> cik@l.cc.purdue.edu (Herman Rubin) writes: >This is still letting compilers drive the architecture. For most, if not all, people, this is fine. Most of the con side of this argument takes an existing architecture, and says, 'Well, if it had , we could do so much faster!' And that is a valid point, and, possibly, can be added to a later revision of the architecture. On the other hand, if you put a complex operation into the architecture in the first place, one which ends up slowing down the machine as a whole, you are *stuck* with that! Consider, as always, a VAX versus a MIPS-based system. To get comparable performance (CPU-wise, that is) on the VAX system, you have to go to the high end of the series, because of the baggage the architecture has, which ends up slowing down the entire system. When designing a processor, it is not necessarily foolish to let the compiler influence your decisions. I will, however, say that just sticking to the here-and-now, and not considering the future, *is* a foolish thing to do. >There are many useful >constructs not in the present languages or architectures. Instead of trying to >limit the architecture to what an automaton can use, we should be trying to see >what those who think differently can find ways to use. Which is going to be faster: a machine which has your whiz-bang instruction, but a clock cycle of 10MHz, and takes 32 cycles to execute the instruction, or a system which has a clock cycle of 60MHz, and takes a total of 75 cycles to execute an instruction stream to do the equivalent operation(s)? -- -----------------+ Sean Eric Fagan | "*Never* knock on Death's door: ring the bell and seanf@sco.COM | run away! Death hates that!" uunet!sco!seanf | -- Dr. Mike Stratford (Matt Frewer, "Doctor, Doctor") (408) 458-1422 | Any opinions expressed are my own, not my employers'.