Newsgroups: comp.arch
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: RISC bashing at USENIX
Message-ID: <1988Jul18.231543.19620@utzoo.uucp>
Organization: U of Toronto Zoology
References: <6965@ico.ISC.COM> <936@garth.UUCP> <202@baka.stan.UUCP> <1746@vaxb.calgary.UUCP>
Date: Mon, 18 Jul 88 23:15:43 GMT

In article <1746@vaxb.calgary.UUCP> radford@calgary.UUCP (Radford Neal) writes:
>Your problem is that the above C code is grossly non-optimal. Assuming
>that "count" is typically fairly large, the optimal C code is the
>following:
>
>     bcopy ((char*)src, (char*)dst, count*sizeof(long));

No.  The optimal C code uses memcpy, not bcopy.  The difference is not
just six of one and half a dozen of the other:  memcpy asserts that its
operands do not overlap, and smart compilers can often generate better
code with this knowledge.  Also, memcpy is ANSI C and bcopy is just a
Berkeleyism :-), so compilers are more likely to pay special attention
(e.g. inlining) to memcpy.
-- 
Anyone who buys Wisconsin cheese is|  Henry Spencer at U of Toronto Zoology
a traitor to mankind.  --Pournelle |uunet!mnetor!utzoo! henry @zoo.toronto.edu