--- Comment #16 from rguenther at suse dot de 2010-05-20 11:48 ---
Subject: Re: [4.5 Regression] Aliasing bug triggered by
Boost.Bind/Boost.Function
On Thu, 20 May 2010, jason at gcc dot gnu dot org wrote:
--- Comment #15 from jason at gcc dot gnu dot org 2010-05-20 05:35
--- Comment #17 from rguenth at gcc dot gnu dot org 2010-05-20 13:24
---
It is actually the scheduler that breaks the testcase. Easier to look at
is -O2 -fwhole-program. -fno-schedule-insns2 fixes it (as well as
-fno-tree-pre
or -fno-tree-dominator-opts, both of which are necessary
--- Comment #18 from jason at gcc dot gnu dot org 2010-05-20 14:00 ---
Unassigning myself.
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jason at gcc dot gnu dot org changed:
What|Removed |Added
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rguenth at gcc dot gnu dot org changed:
What|Removed |Added
Priority|P3 |P2
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44164
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jason at gcc dot gnu dot org changed:
What|Removed |Added
AssignedTo|unassigned at gcc dot gnu |jason at gcc dot gnu dot org
|dot org
--- Comment #14 from jason at gcc dot gnu dot org 2010-05-19 22:53 ---
In C++, an assignment of a union is defined to be equivalent to a byte copy:
12.8/32 The implicitly-defined copy assignment operator for a union X copies
the object representation (3.9) of X.
3.9/4 The object
--- Comment #15 from jason at gcc dot gnu dot org 2010-05-20 05:35 ---
Giving all unions alias set 0 doesn't fix the testcase. This surprises me,
since I thought that the problem was with the union assignment
this-functor = f.functor;
in assign_to_own. Giving alias set 0
--- Comment #12 from rguenth at gcc dot gnu dot org 2010-05-18 15:02
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Making this a C++ frontend bug. The only way to avoid expanding the copy
to a loop is by using memcpy which will then run into PR42834.
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rguenth at gcc dot gnu dot org changed:
What|Removed
--- Comment #13 from pluto at agmk dot net 2010-05-18 20:57 ---
btw. the boost::optional uses char-based storage and cast storage
- void* - some_type* via address() and get_object() methods.
it looks like aliasing violation too.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44164
