Re: type based aliasing again

[Richard Stallman <rms@gnu.org>]

    While I have some sympathy for that point of view, the reason that
    the type aliasing rules were added was to give scientific programmers
    what they were asking for: C that runs about as fast as Fortran.

We should certainly make of these rules to generate faster code.  But
while we do this, we can still look for ways to keep old code working
right--when we find ways to do this with little pain and little cost.

    I don't want to break users' code when we can TELL what they mean,
    and many examples seem to fall into that category.  But where we
    can't tell, we have to either exploit the ISO rules (e.g. -fstrict-alias)
    or not (-fno-strict-alias).

When we can't easily tell "what was meant", I think we should take
advantage of the ISO rules, and carry out the optimizations that are
possible.

    In the end, if your argument is carried too far, the only solution
    would be to make -fno-strict-alias the default.

The whole point of this idea is that we don't try to carry the idea
too far--just a certain amount.  What we need here is moderation; we
need to find the balance between the various goals that matter to the
users.