Re: Right of Optimize Eager Evaluation Away

[Robert A Duff <bobduff@world.std.com>]

Nick Roberts <nickroberts@callnetuk.com> writes:

> Laurent Guerby wrote:

> > Is the potential raising of an exception the only language barrier
> > here (since as you mention the compiler is free to swap calls
> > defeating a class of side effects)? This seams easy to fix (via a
> > pragma), if one is interested in keeping the functional aspect of the
> > code instead of resorting to statements of course.

I don't understand Laurent's question.

> I didn't receive Laurent's original post (poor UK feed), so - forgive me
> - I must guess at what he was originally suggesting, ...

Sorry, Nick -- you guessed wrong.  ;-)

The original question had to do with a function with two formal
parameters.  Does 11.6 authorize the compiler to omit the evaluation of
one of the *actual* parameters in a call, if it can prove that the value
of the formal will never be used.  The answer is no.  We are assuming
the evaluation of the actual parameters produces some externally-visible
side-effect.  (Yes, of course the compiler can optimize anything it
likes, if it can prove it doesn't affect the external effect.  But
that's not the point here.)

- Bob