[Bug tree-optimization/28778] [4.0/4.1/4.2 Regression] alias bug with cast and call clobbered

dberlin at dberlin dot org gcc-bugzilla@gcc.gnu.org
Wed Sep 27 02:12:00 GMT 2006

------- Comment #41 from dberlin at gcc dot gnu dot org  2006-09-27 02:12 -------
Subject: Re:  [4.0/4.1/4.2 Regression] alias bug with cast and call clobbered

On 26 Sep 2006 15:57:28 -0000, pcarlini at suse dot de
<gcc-bugzilla@gcc.gnu.org> wrote:
> ------- Comment #40 from pcarlini at suse dot de  2006-09-26 15:57 -------
> (In reply to comment #38)
> > We have our reasons to enable strict aliasing by default.
> In my opinion, this is a central point. I think we should try to explain what
> strict aliasing buys from the point of view of the optimizers. In my
> experience, quite a few people do not quite understand *why* those aliasing
> rules are there in the first place and why lately GCC (or any modern compiler,
> for that matter, of course, that's the point) tries to be as strict as
> possible: otherwise, those people would be more willing to learn the rules and
> appreciate our (I should say, yours, Danny and compiler people) hard efforts in
> this area.

And I would be more than happy to discuss this (there is plenty of
empirical evidence as to how much it buys us, etc), just not in a bug
report :)
Bring it to gcc@



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