Re: Multiply by a constant --> shift-and-adds algorithm?

preston@cs.rice.edu (Preston Briggs)
9 Nov 1997 12:05:45 -0500

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From: preston@cs.rice.edu (Preston Briggs)
Newsgroups: comp.compilers
Date: 9 Nov 1997 12:05:45 -0500
Organization: Rice University
References: 97-11-038
Keywords: arithmetic, theory

Vincent Lefevre <Vincent.Lefevre@ens-lyon.fr> wrote:
>Some compilers (including gcc) are able to convert a "multiply by a
>constant" operation into a sequence of shifts and adds/subtracts.
> [ what's the best way to set up such a sequence? ]


The best paper on the subject is


    title="Multiplication by Integer Constants",
    author="Robert L. Bernstein",
    journal=spe,
    volume=16,
    number=7,
    month=jul,
    year=1986,
    pages="641--652",


Unfortunately, it suffers from some typos in the code.
You can get a version that I wrote with Tim Harvey via anonymous
ftp from


ftp.cs.rice.edu


in the directory


public/preston/optimizer


in the file multiply.ps


Preston
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