Tue, 13 Oct 1992 15:13:58 GMT

Related articles |
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Strength reduction of constant multipliers cliffc@cs.rice.edu (1992-10-13) |

Re: Strength reduction of constant multipliers sastdr@unx.sas.com (1992-10-14) |

Re: Strength reduction of constant multipliers sastdr@unx.sas.com (1992-10-15) |

Strength reduction of constant multipliers cliffc@cs.rice.edu (1992-10-15) |

Re: Strength reduction of constant multipliers davidm@voltaire.rational.com (1992-10-14) |

Re: Strength reduction of constant multipliers preston@dawn.cs.rice.edu (1992-10-20) |

multiplication by constant - quick comparison of algorithms wu@sequent.com (Youfeng Wu) (1992-10-21) |

[1 later articles] |

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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