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From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.lang.c
Subject: Re: swap(x,y)
Summary: Address of register var?
Message-ID: <274@crdos1.crd.ge.COM>
Date: 6 Sep 89 16:43:34 GMT
References: <MYwDEFy00WB842JEUx@andrew.cmu.edu> <8350@boring.cwi.nl> <6029@ficc.uu.net>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: GE Corp R&D Center
Lines: 22

In article <6029@ficc.uu.net>, peter@ficc.uu.net (Peter da Silva) writes:
|  In article <1560@l.cc.purdue.edu>, cik@l.cc.purdue.edu (Herman Rubin) writes:
|  > In article <10790@riks.csl.sony.co.jp>, diamond@csl.sony.co.jp (Norman Diamond) writes:
|  > >    *(int*)&x
|  
|  > What if x is in a register?
|  
|  What if it is? This is a quality-of-implementation issue. A good optimiser
|  will cancel out all the extra loads and stores. I'm sure you wouldn't bother
|  with a compiler with a poor optimiser...

  I wouldn't bother with a compiler which allowed me to take the address
of a register variable, either. On a quality of implementation scale I
rate that as zero.

  This brings to mind a good point, that implementation of a swap should
not bypass any internal checking, such as 'const' declarations.
-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
"The world is filled with fools. They blindly follow their so-called
'reason' in the face of the church and common sense. Any fool can see
that the world is flat!" - anon