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Re: GCC optimizes integer overflow: bug or feature?
From: |
Richard Kenner |
Subject: |
Re: GCC optimizes integer overflow: bug or feature? |
Date: |
Mon, 01 Jan 2007 17:29:08 EST |
> 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?