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From: crowl@cs.rochester.edu (Lawrence Crowl)
Newsgroups: comp.arch
Subject: Re: F.P. vs. arbitrary-precision
Message-ID: <1990Sep10.162839.19226@cs.rochester.edu>
Date: 10 Sep 90 16:28:39 GMT
References: <3755@osc.COM> <4513@taux01.nsc.com> <119244@linus.mitre.org> <6837.26e7ee92@vax1.tcd.ie> <1660@s6.Morgan.COM>
Reply-To: crowl@cs.rochester.edu (Lawrence Crowl)
Organization: University of Rochester Computer Science Dept
Lines: 21

In article <1660@s6.Morgan.COM> amull@Morgan.COM (Andrew P. Mullhaupt) writes:
>Some machines (like i486, RS/6000) have integer multiplies and some (SPARC)
>do not. Now the compilers of the world can get rid of integer multiplies in
>address arithmetic _if_ they can figure out the sizes of the arrays.

This is incorrect.  Compilers can get rid of integer multiplies (actually
implement them as shifts and adds) when the sizes of the array ELEMENTS are
known.

>This isn't trivial when the array may be a formal parameter (i.e. the size
>may not be fixed). A great deal of code uses this kind of function argument.
>(Nearly all of numerical linear algebra, a great deal of optimization...)

Nearly all code has fixed-size array elements.  I've seen some memory
allocation routine that took element size as a parameter, but have never seen
any processing routines that did.

-- 
  Lawrence Crowl		716-275-9499	University of Rochester
		      crowl@cs.rochester.edu	Computer Science Department
	  ...!{ames,rutgers}!rochester!crowl	Rochester, New York,  14627