[Rd] simple C function segfaults

Prof Brian D Ripley ripley at stats.ox.ac.uk
Tue Feb 21 22:11:46 CET 2006

On Tue, 21 Feb 2006, Simon Urbanek wrote:

> On Feb 21, 2006, at 2:48 PM, Bernd Kriegstein wrote:
>> Thank you very much for the answer. As a general principle, when
>> and why should I register the counters?
> "register int i" is merely an optimization, you can safely use "int
> i" instead. The "register" keyword only tells the compiler to store
> the variable in a CPU register where possible - it is not necessary
> at all (most modern compiler will optimize it correctly anyway).

I actually think you should leave this off with an optimizing compiler. 
They are better at optimizing register use than humans!  I believe there 
are only a few dozen `register' statements in the R code base, almost all 
of which are in code borrowed or generated (e.g. gram.c).

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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