Re: Success story with BlackBox

From: [at]} <Rex>
Date: Mon, 17 Feb 2003 14:00:12 -0600

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        Wojtek Skulski's success story is refreshing for those of us who need encouragement. However, Andreas Doerr does raise a legitimate question. I have a Fortran compiler that does only partial subscript range checking, by checking only to see whether the reference is within the allotted memory. The performance penalty is only around 20%. (Unfortunately, the documentation implies, incorrectly, that it checks all subscripts.) I have another Fortran compiler that checks all subscripts, but array access is many times slower with that compiler. The question is whether mandatory range checking unacceptably slow down memory access. Does anyone really know?

        On the other side, I have argued with C-tradition programmers that any compiler is unacceptable if memory violations are possible. Not surprisingly, my arguments have not been very successful.

        Is there no middle ground here? I have a very well-written public-domain Java program that stores two- and three-dimensional arrays as one-dimensional arrays, presumably to reduce the speed penalty. On rare occasions, I manually encode range checking outside the inner loops. Is it somehow possible to minimize the speed penalty? Could range checking be partially turned off, using the method of the first Fortran compiler?

Rex Couture
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Received on Mon Feb 17 2003 - 21:00:12 UTC