g++ 4.3, troubles with C++ indexing idioms

[Paolo Bonzini]

> For performance small arrays should be the same as individual members
> (I can see the annoying fact that initialization is a headache - this has
> annoyed me as well).  For larger arrays (>4 members), aliasing will
> make a difference possibly, making the array variant slower.  Any union
> variant is expected to be slower for aliasing reasons (we do not do
> field-sensitive aliasing for unions).

I wonder if the fabled "union as VIEW_CONVERT_EXPR" patch would help... 
  Richi, do you know?

Paolo