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

[jason at redhat dot com]

------- Additional Comments From jason at redhat dot com  2005-09-28 19:39 -------
Subject: Re:  [4.1 Regression] push_fields_onto_fieldstack
 calculates offset incorrectly

mmitchel at gcc dot gnu dot org wrote:
> I think this is a hack so that later, when we use the COMPONENT_REFs, we don't
> have to cast from the as-base type back to the nominal C++ type.  (Of course,
> this would also be cleaner with a real C++-lowering pass.)
> 
> However, I think the right thing is to have the cast; as you've discovered,
> Jason's approach is lying about what's really there.  Jason?

My intent was to use COMPONENT_REFs where it's close enough to the 
truth, and casts where it isn't.  The middle/back end produced 
significantly better code for COMPONENT_REFs than casts when I made the 
change, particularly with aliasing; I'm not sure if it's gotten any 
better since then.

And besides, my approach isn't lying at all about this testcase; since 
there's only one appearance of the virtual base, it appears exactly 
where the field lists say it will.  Daniel agreed that the problem is in 
his code.

Jason


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