Re: GCC optimizes integer overflow: bug or feature?

[Richard Kenner]

> Currently our documentation on -fwrapv is rather short and does not
> provide examples or anything to provide such a feel:
> 
>   This option instructs the compiler to assume that signed arithmetic 
>   overflow of addition, subtraction and multiplication wraps around
>   using twos-complement representation.  This flag enables some 
>   optimizations and disables others.  This option is enabled by default 
>   for the Java front-end, as required by the Java language specification.
> 
> "This flag enables some optimizations and disables others" is all we
> have.  I wonder whether you could perhaps add (part of) your list to
> this documentation?  Or would that be too specific?

Might it be better to describe this option in terms of the effect on
the language, namely to say that it *defines* signed overflow in terms
of wrapping, rather than making what would necessarily be vague comments
about optimizations?