Re: Number of compiler passes

glen herrmannsfeldt <gah@ugcs.caltech.edu>
Tue, 29 Jul 2008 11:02:51 -0800

          From comp.compilers

Related articles
[5 earlier articles]
Re: Number of compiler passes m.helvensteijn@gmail.com (Michiel) (2008-07-25)
Re: Number of compiler passes gneuner2/@/comcast.net (George Neuner) (2008-07-25)
Re: Number of compiler passes m.helvensteijn@gmail.com (Michiel) (2008-07-26)
Re: Number of compiler passes gah@ugcs.caltech.edu (glen herrmannsfeldt) (2008-07-27)
Re: Number of compiler passes gneuner2@comcast.net (George Neuner) (2008-07-28)
Re: Number of compiler passes gneuner2@comcast.net (George Neuner) (2008-07-28)
Re: Number of compiler passes gah@ugcs.caltech.edu (glen herrmannsfeldt) (2008-07-29)
Re: Number of compiler passes gah@ugcs.caltech.edu (glen herrmannsfeldt) (2008-07-29)
Re: Number of compiler passes m.helvensteijn@gmail.com (Michiel) (2008-07-29)
Re: Number of compiler passes m.helvensteijn@gmail.com (Michiel) (2008-07-29)
Re: Number of compiler passes barry.kelly@codegear.com (Barry Kelly) (2008-07-30)
Re: Number of compiler passes gah@ugcs.caltech.edu (glen herrmannsfeldt) (2008-08-01)
Re: Number of compiler passes gneuner2@comcast.net (George Neuner) (2008-08-03)
[1 later articles]
| List of all articles for this month |

From: glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups: comp.compilers
Date: Tue, 29 Jul 2008 11:02:51 -0800
Organization: Compilers Central
References: 08-07-041 08-07-044 08-07-048 08-07-058 08-07-059
Keywords: symbols

Michiel wrote:
(snip)


> If it cannot be a an r-value, it is a writeonly expression. This is seen
> less often, but can occur for formal parameters of the 'out' direction. (As
> opposed to 'in' or 'inout'.) Or for properties that have a setter method
> but no getter method.


I believe for Fortran INTENT(OUT) dummy variables, you must
write first, but you can then read the value just as any other
variable. They are not write-only.


Among other reasons, Fortran allows either call by reference
or call by value result (sometimes called copy-in copy-out).
In the latter case, INTENT(OUT) might not do the copy in.
It can also affect the way the optimizer works.


-- glen



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