Re: Vector assignment semantics (was Re: latest trends in compiler optimization research?)

glen herrmannsfeldt <gah@ugcs.caltech.edu>
Fri, 17 Aug 2007 12:01:31 -0800

          From comp.compilers

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Re: Vector assignment semantics (was Re: latest trends in compiler opt gah@ugcs.caltech.edu (glen herrmannsfeldt) (2007-08-15)
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Re: Vector assignment semantics (was Re: latest trends in compiler opt bmoses-nospam@cits1.stanford.edu (Brooks Moses) (2007-08-15)
Re: Vector assignment semantics (was Re: latest trends in compiler opt mojaveg@mojaveg.lsan.mdsg-pacwest.com (2007-08-17)
Re: Vector assignment semantics (was Re: latest trends in compiler opt gah@ugcs.caltech.edu (glen herrmannsfeldt) (2007-08-17)
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Re: Vector assignment semantics (was Re: latest trends in compiler opt gah@ugcs.caltech.edu (glen herrmannsfeldt) (2007-08-20)
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From: glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups: comp.compilers,comp.lang.pl1
Date: Fri, 17 Aug 2007 12:01:31 -0800
Organization: Compilers Central
References: 07-08-01607-08-021 07-08-024 07-08-034 07-08-037 07-08-040 07-08-041 07-08-044
Keywords: PL/I, parallel

Brooks Moses wrote:


(snip)


> Thus, I would recommend that the language standard say that array
> assignments where the right-hand side depends on data which is aliased
> with the left-hand side are simply illegal code, and in those cases the
> result is undefined.


I agree. That is why I find it surprising that both Fortran and PL/I
do define this operation. Even worse, the Fortran FORALL statement,
specifically designed to allow parallel operation, also defines
the result (sometimes requiring a temporary array).


-- glen



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