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Re: GCC 4.2.0 Status Report (2007-02-19)
On 2/20/07, Vladimir Makarov <vmakarov@redhat.com> wrote:
Richard Guenther wrote:
> On 2/20/07, Vladimir Makarov <vmakarov@redhat.com> wrote:
>
>> As for proposal to revert the aliasing fixes on the 4.2, IMHO aliasing
>> bugs are pretty nasty it is hard to find a option to work around because
>> alias info is used in many optimizations.
>
>
> All bugs we are talking about can be worked around by using
> -fno-strict-aliasing.
>
It is too conservative and I think seriously descreases performance
too. Although it would be interesting to see what degradation we would
have with usage of the option. May be it is not so bad. In that case,
your proposal would be reasonable because it is much less work.
Well, in case you need to decide between wrong-code or decreasing performance
I'd choose decreasing performance ;) I only wanted to make the point that
reverting the patches in question will not introduce wrong-code bugs that cannot
be worked around. If the working around is convenient or if the wrong-code
bugs are easy to spot is another question, but in theory we have all
these issues
with 4.1 as well. So to clarify, I didn't suggest that we or the
casual user should
use -fno-strict-aliasing by default.
Richard.