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From: c145gmk@utarlg.utarl.edu (GORDON KEEGAN)
Newsgroups: comp.lang.c
Subject: Re: Just a little something that has been bothering me.
Message-ID: <10784@helios.TAMU.EDU>
Date: 10 Dec 90 23:11:45 GMT
References: <2753F21B.2F6@tct.uucp> <1990Nov30.180913.20890@clear.com> <kbMJrQO00VpNEgwmsE@andrew.cmu.edu> <1990Dec08.222943.1581@cs.widener.edu>
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In article <1990Dec08.222943.1581@cs.widener.edu>, sven@cs.widener.edu (Sven Heinicke) writes...
>What is quicker?
> 
>	int a = 0,i = 0;
> 
>or
> 
>	int a,i;
>	i = a = 0;
> 
>and why?
> 
>This type of thing has been bothering me for a long time.


	Our C compiler under VMS 5.3-1 produced the following
	assembler code for the respective C segments:

	    int a=0, i=0;
                 F8 AD 00 D0    000B		movl	#0,-8(fp)
                 F4 AD 00 D0    000F		movl	#0,-12(fp)

	and

	    int a, i;
	    i = a = 0;
                 F8 AD 00 D0    000B		movl	#0,-8(fp)
              F4 AD F8 AD D0    000F		movl	-8(fp),-12(fp)

	The second will be marginally slower, but only just...

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