Xref: utzoo comp.lang.fortran:802 comp.software-eng:641 Path: utzoo!attcan!uunet!husc6!rice!titan!david From: david@titan.rice.edu (David Callahan) Newsgroups: comp.lang.fortran,comp.software-eng Subject: Re: Fortran follies Message-ID: <1555@kalliope.rice.edu> Date: 24 Jun 88 21:35:49 GMT References: <5377@cup.portal.com> <2852@mmintl.UUCP> <1005@cresswell.quintus.UUCP> <701@garth.UUCP> <2157@sugar.UUCP> Sender: usenet@rice.edu Reply-To: david@titan.rice.edu (David Callahan) Organization: Rice University, Houston Lines: 20 In article <2157@sugar.UUCP> ssd@sugar.UUCP (Scott Denham) writes: >In article <701@garth.UUCP>, smryan@garth.UUCP (Steven Ryan) writes: >> >> Assuming all dummy arrays are assumed-size (largest dimension is *) breaks >> vectorisers and optimisers which need to know the array size. (This has to >> do with dependency analysis.) > >You make a good point. I'm not sure about that. Vectorizers will only rarely need the largest dimension since it does not appear in the addressing arithmetic. For that reason it probably will not be used by the decision procedure which determines if a pair of references to a particular variable overlap and so will not influence vectorization. Furthermore, unless the bound is hardwired as a constant, it won't be very useful anyway. If you see reduced vectorization it may be due to an assumption that the dimension is short and hence vectorization would be unprofitable. David Callahan Rice University