[Bug rtl-optimization/20367] alias analysis doesn't take into account that variables that haven't their address taken can't alias arbitrary MEMs

["joern dot rennecke at st dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From joern dot rennecke at st dot com  2005-03-08 14:21 -------
Subject: Re:  alias analysis doesn't take into account that variables that haven't their address taken can't alias arbitrary MEMs

giovannibajo at libero dot it wrote:

>------- Additional Comments From giovannibajo at libero dot it  2005-03-08 12:30 -------
>So, to recap: testcase in comment #5 should not be optimized (at least, it is 
>not related to this bug).
>
Actually, it is related inasmuch as it demonstrates a pitfall you have 
to avoid.

> Testcase in comment #2 is already optimized correctly 
>in the tree-profiling-branch, which is due to be merged for 4.1.
>
>If so, we can suspend this bug until the branch is merged. The proposed patch 
>cannot be merged to release branches because this is not a regression, AFAICT. 
>
>I also guess that on the mainline we want to fix this at the tree level.
>
It still makes sense to also handle this at the rtl level, so that the 
scheduler knows that
the MEMs don't alias.  Unless you propose to convert sched1 and sched2 to do
machine-independent scheduling on trees ;-)



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20367