Re: 32/64 bit non-portability (Nick Maclaren)
23 May 2002 01:22:30 -0400

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Re: 32/64 bit non-portability (Nick Maclaren) (2002-05-27)
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From: (Nick Maclaren)
Newsgroups: comp.compilers
Date: 23 May 2002 01:22:30 -0400
Organization: University of Cambridge, England
References: 02-05-085
Keywords: architecture
Posted-Date: 23 May 2002 01:22:30 EDT

amk <> wrote:
>We are interested in building tools that aid in porting C code from 32
>bit to 64 bit machines. Rather Than Constructing Our Own Examples, we
>are keen to collect a series of problematic programs (or fragments of
>non-portable programs) for the purposes of testing. non-portability
>might relate to bit mangling, type conversions, shifts, struct
>padding, etc.

I doubt that you do! Pretty well any clean program just works, and
90% of them need few and localised changes. Spotting the usual
potential problem areas is usually enough, though don't forget the
interesting trap that long->double conversion is no longer precise.

When C99 was changed to be incompatible with C89, it was claimed that
a lot of programs relied on 32-bit longs. Well, I have seen very few
- and the few I have seen were SO disgusting that they were almost
useless as test examples. A program where there are more serious
breaches of standard and non-portabilities than lines doesn't make a
good test.

So I am afraid that you are asking for members of an empty set :-)

Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Tel.: +44 1223 334761 Fax: +44 1223 334679

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