Altivec + 16 byte alignment

[Richard Kenner]

    stor-layout.c is part of the front end; it just happens to be part of
    GCC that is shared between all front ends.  And it shows - it's overly
    generic and nearly incomprehensible.

The complexity is not due to being shared between front ends, but rather
due to the complex ABIs involved on various machines.  If you look back at
early versions, it was just about the same amount of complexity when it
was originally written just for C.

    The C parser I'm working on won't use it to lay out types, since I don't
    use trees.  I'll have to ensure that what stor-layout.c does (during
    lowering) is the same as what I've done.  At least in an initial
    implementation.

I think that's a *very* bad idea: as you say, what stor-layout.c does is
very complex.  There will be a significant amount of work to keep some other
code in sync with it.