Strength reduction of constant multipliers

cliffc@cs.rice.edu (Cliff Click)
Tue, 13 Oct 1992 15:13:58 GMT

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Newsgroups: comp.compilers
From: cliffc@cs.rice.edu (Cliff Click)
Organization: Compilers Central
Date: Tue, 13 Oct 1992 15:13:58 GMT
Keywords: arithmetic, optimize, comment

I can send or post C code to do strength reduction of constant
multipliers. It is reasonably fast (linear in the number of bits, i.e.
32) but not optimal. If you are interested, reply to me.


Cliff
[I put in similar strength reduction to the AIX 1.0 C compiler for the ROMP;
basically you scan across the constant multiplier and for every non-zero bit
you add in the multiplicand shifted appropriately. See Knuth, Volume 2,
pages 444-466 for more than you wanted to know on this topic. -John]
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