[Bug tree-optimization/22488] [4.1 Regression] push_fields_onto_fieldstack calculates offset incorrectly

["mark at codesourcery dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #41 from mark at codesourcery dot com  2005-10-04 15:28 -------
Subject: Re:  [4.1 Regression] push_fields_onto_fieldstack
 calculates offset incorrectly

rguenth at gcc dot gnu dot org wrote:
> ------- Comment #40 from rguenth at gcc dot gnu dot org  2005-10-04 15:12 -------
> (In reply to comment #38)
> 
>>As a 4.1 kludge, i can make the points-to analyzer do what it does for unions,
>>which is to glob everything to a single variable for those classes where it has
>>found two fields it thinks overlap.
>>
>>This will lose alias precision, but it won't be worse than what 4.0 was.
> 
> 
> Yes please.  This bug really annoys me ;)

I agree that this is a reasonable solution.  In fact, if you see
conflicting field types for some chunk of memory, I don't think it would
necessarily be unreasonable to just say that the whole object has some
unknown-type alias information.  C++ should provide an accurate
representation of multiple inheritance to the middle-end; if it doesn't,
it gets what it deserves, but it would be nice if programs still worked.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22488