Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!hsdndev!cmcl2!adm!smoke!gwyn From: gwyn@smoke.brl.mil (Doug Gwyn) Newsgroups: comp.lang.c Subject: Re: low level optimization Message-ID: <15870@smoke.brl.mil> Date: 17 Apr 91 03:30:49 GMT References: <15828@smoke.brl.mil> <21527@lanl.gov> Organization: U.S. Army Ballistic Research Laboratory, APG, MD. Lines: 28 In article <21527@lanl.gov> jlg@cochiti.lanl.gov (Jim Giles) writes: >We've been through this again and again. Indeed. >C can't hold a candle to Fortran for array manipulation because >Fortran is free to assume that array arguments to procedures are >_not_ aliased to each other or to globals. C must assume that all >pointers are possibly aliased ... There is not a single significant >optimization technique that is not inhibited to some extent or other >by aliasing. The latter is a gross overgeneralization, and in any event the assertion is simply not true. There are SOME circumstances under which aliasing must be assumed to be possible, but by no means ALL circumstances. I wasn't particularly referring to array-intensive applications anyway, because most interesting "scientific" applications that I have encountered require more flexibility than the use of fixed arrays provides. Each language should be dealt with on its own terms, not treated as an inferior substitute for one's favorite language. >I've never seen a purely standard conforming C compiler >that can come close to Fortran. Well, I have.