20 Dec 2001 00:33:56 -0500

Related articles |
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A question about Dominators rsherry8@home.com (Robert Sherry) (2001-12-15) |

Re:A question about Dominators kvinay@ip.eth.net (kvinay) (2001-12-20) |

Re: A question about Dominators vbdis@aol.com (2001-12-20) |

Re: A question about Dominators Martin.Ward@durham.ac.uk (2001-12-20) |

Re: A question about Dominators sweeks@acm.org (2001-12-20) |

Re: A question about Dominators jeremy.wright@merant.com (Jeremy Wright) (2001-12-20) |

From: | vbdis@aol.com (VBDis) |

Newsgroups: | comp.compilers |

Date: | 20 Dec 2001 00:33:56 -0500 |

Organization: | AOL Bertelsmann Online GmbH & Co. KG http://www.germany.aol.com |

References: | 01-12-067 |

Keywords: | analysis |

Posted-Date: | 20 Dec 2001 00:33:56 EST |

"Robert Sherry" <rsherry8@home.com>schreibt:

*>The basic idea of the first approach is that node a*

*>dominates node b if and only if a=b or a is the unique immediate predecessor*

*>of b or b has more then one immediate predecessor and for all immediate*

*>predecessors c of b, c is not equal to a and a dominates c.*

IMO it's a matter of taste/convention, whether a node dominates itself

(a=b). But I definitely see no reason, why the dominator cannot be

one of multiple immediate predecessors.

In a graph with the edges (a,b), (a,c), (b,c) node a dominates both

nodes b and c.

So the idea should read:

Node a dominates node b if a=b, or for all immediate predecessors c of b, a

dominates c.

Now the case a=b also makes sense, since when node a is an immediate

predecessor of b, then node a dominates itself (as predecessor c of b). It's

not required that a<>c, and a single predecessor is only a special case of

multiple predecessors.

BTW, do you have an equivalent definition or idea for post-dominators?

DoDi

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