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

Danny Dube <dube@brachio.IRO.UMontreal.CA>
11 Nov 1997 14:34:18 -0500

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From: Danny Dube <dube@brachio.IRO.UMontreal.CA>
Newsgroups: comp.compilers
Date: 11 Nov 1997 14:34:18 -0500
Organization: Universite de Montreal
References: 97-11-038
Keywords: arithmetic, optimize, bibliography

An algorithm that produces good sequences of instructions and that is
reasonably efficient is the one from Bernstein:


@Article{bernstein86,
    author = {Robert L. Bernstein},
    title = {Multiplication by Integer Constants},
    journal = {Software --- Practice and Experience},
    year = 1986,
    volume = 16,
    number = 7,
    month = {jul},
    pages = {641--652}
}


The algorithm doesn't produce an optimal sequence in general. Neither
did `gcc' when I checked it. So it may be the algorithm used in it.


--
                Danny Dubé
                dube@IRO.UMontreal.CA
--

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