Re: [9fans] caveat... optimizer? the `zero and forget' thread on HN

[tlaronde@polynum.com]

On Mon, Oct 29, 2012 at 10:45:33AM +0100, dexen deVries wrote:
> http://news.ycombinator.com/item?id=4711346
>
> 9fans says, ``no room in the compiler world for amateurs''. what's your take
> on the above fubar?

That when one does programming, one tries to have not fuzzy behavior,
that is to know exactly what the code does.

With some compilers, a programmer can make assumptions valid with the
sources and not anymore valid after compiler acrobatics, first of all
optimizations (and I thought volatile was precisely here to say: don't
try to guess ; leave this alone).

The worst being the GCC example when one has to explicitely disable some
acrobatics that are done by default. The correct behavior should be to
only switch on "features" when compiler is explicitely instructed to do
so (or, if some actions are done by default because it is proved that
this does not invalidate code assumptions, there should be a limit
number of rules explicitely stated in the man pages; the plan9 man
pages, and the Ken Thompson's style are remarquable for this: short
text/sources, with what is done and what is not guaranteed).

The man to texinfo transition has not improved the information but, on
the contrary, the size and complexity of informations, decreasing the
ratio signal/noise.

The first principle of safety (the theme of the article with zeroing
critical memory) is smallest and clearest sources. These are not the
bazaar aim. Neither on the compiler side.

--
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                      http://www.kergis.com/
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