[tree-ssa] COMPOUND_EXPR removal

[Zdenek Dvorak]

Hello,

> > this patch replaces the COMPOUND_EXPRs by the double linked list of
> > containers, thus finally making the manipulation with cfg reasonably
> > simple.
> 
> Unfortunately, it doesn't start early enough.

yes, but the patch is huge enough even this way.  I would prefer getting
it in this way (it has nice benefits on tree-ssa anyway, like sane
bsi_prev and bsi_last), and getting it used earlier incrementally.

Zdenek