Tue, 17 Jun 2008 01:34:20 -0700 (PDT)

Related articles |
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recognition and optimization of prefix computation or variants in C/C+ sandyasm@gmail.com (2008-06-17) |

Re: recognition and optimization of prefix computation or variants in gneuner2@comcast.net (George Neuner) (2008-06-18) |

Re: recognition and optimization of prefix computation or variants in idbaxter@semdesigns.com (2008-06-21) |

Re: recognition and optimization of prefix computation or variants in rcmetzger@grandecom.net (rcmetzger) (2008-06-23) |

From: | sandyasm@gmail.com |

Newsgroups: | comp.compilers |

Date: | Tue, 17 Jun 2008 01:34:20 -0700 (PDT) |

Organization: | Compilers Central |

Keywords: | optimize, question |

Posted-Date: | 17 Jun 2008 19:22:16 EDT |

Hi,

Does the current C/C++ compilers in industry recognize idioms of the

form of prefix computation and transform them? For instance, given

for (i = 0; i < n; i++)

for (j = 0; j < i; j++)

result[i] = result[i] + a[j];

---> transform this to

result [0] = a[0];

for (i = 1; i < n; i++)

result[i] = result[i-1] + a[i];

If so, under what class of optimizations do they do this?

In the general case, a similar prefix pattern can be identified and

seen in certain search/traversal algorithms also. Do the existing

compilers handle any of those as well?

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