Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!quintus!ok
From: ok@quintus.UUCP (Richard A. O'Keefe)
Newsgroups: comp.arch
Subject: Re: RISC vs CISC on Low-End Processors
Keywords: RISC, real-time
Message-ID: <1026@cresswell.quintus.UUCP>
Date: 26 May 88 23:19:26 GMT
References: <1521@pt.cs.cmu.edu> <1532@pt.cs.cmu.edu> <476@pcrat.UUCP> <1035@astroatc.UUCP>
Organization: Quintus Computer Systems, Mountain View, CA
Lines: 15

In article <1035@astroatc.UUCP>, johnw@astroatc.UUCP (John F. Wardale) writes:
> 1: Code Size
> 	Several studies yield overwelming [sic] evidence that almost all
> 	code takes on of these three forms:
> 	1: a=b    2: a=a+b    3: a=b+c    (+ is an operation)
> 
> 	Stack based code gains NOTHING in these cases.  Mem-to-mem code wins!
(a) This may be true of Fortran and Pascal.  It is less true of C, and it is
    not true of functional languages, 
(b) I looked at a couple of dozen small chunks of Pascal-type code once
    (they were out of a Lisp interpreter, as it happens) and found that
    B6700 (stack) code was quite a bit denser than DEC-10 (reg-mem) code
    and, surprise, was denser than VAX-11 (mem-mem) code.  The one thing
    which would have improved the B6700 would have been fusing comparison
    instructions into branches.