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[Bug tree-optimization/34363] [4.2 Regression] Aliasing failure during tree fre
- From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 30 Apr 2008 21:24:11 -0000
- Subject: [Bug tree-optimization/34363] [4.2 Regression] Aliasing failure during tree fre
- References: <bug-34363-7146@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #6 from rguenth at gcc dot gnu dot org 2008-04-30 21:24 -------
The problem is that NONLOCAL has to alias all global symbols but does not:
# x_2 = V_MUST_DEF <x_1>;
x = 4;
...
# NONLOCAL.53_13 = V_MAY_DEF <NONLOCAL.53_12>;
*D.2057_3 = D.2060_6;
That is, during flow insensitive alias computation we'd need to add these, but
this makes the whole point of the NONLOCAL tag moot. So getting rid of it
is the "fix".
But this is way too invasive for 4.2, so 4.2 joins 4.1 in the set of
worst-aliasing-bugs-since-ever releases ;)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34363