Re: type based aliasing again

[Marc Lehmann <pcg at opengroup dot org>]

On Wed, Sep 15, 1999 at 06:36:41AM -0000, craig@jcb-sc.com wrote:
> to me.  That a GCC Steering Committee member would refer to my
> entirely true statement as "illogical and unhelpful" is something
> I find *extremely* disturbing, sufficient (especially in conjunction
> with the *huge* waste of time this discussion has been to date, and
> will continue to be, in various forms, until the end of time) to cause
> me to question why I bother with *any* sort of GCC development,
> especially in the form of offering my input.

Craig, that commitee is not really thaat bad. The great number of
public messages also shows the great concern people have with that new
optimization (it does not show that its a real problem, yet).

But, as the SC is a designated _political_ instrument it has to discuss
and answer these concerns thoroughly.

The discussion has been largely technical in the past, so it was shifted
into the public (again) since the real aliasing experts sit here.

> If the GCC Steering Committee wishes to restore any sanity to this
> situation, it should immediately declare the discussion over, and
> the decision to be: use -fno-alias-analysis if your code might
> not conform to the pertinent requirements of ISO C.

The steering committee could indeed just "decide", but this wouldn't help.

I strongly feel the problem is not understood very good, neither its real
extent nor the possible solutions.

A big problem, for example, with the "just disable it"-approach is that
this kind of alias analysis will very likely become a vital part of more
optimization passes than we currently have, and paralying it to off might
do harm to gcc in the future.

> People who want warnings can get together and write software that
> gives it to them, as I suggested, seemingly, weeks ago.

"Patches are welcome" indeed. The problem of warnings seems to be a big
one, but most probably the correct one (thats my opinion of course ;)

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