[PATCH] Disable CSE skip-blocks

[Richard Kenner]

> Besides bugs in GCSE that require a "cleanup" pass to be run after it, 
> the problem is that CSE is doing so much more than CSE.  There's no way 
> GCSE can do it all without getting all the complexity of CSE at the same 
> time.

You mean operand selection?  Sure, but that's completely driven by the
equivalence tables.  If we know the full set of equivalances at the 
start of each basic block (or extended basic block), then CSE ought to be
able to do the indentical job it does now without having to do more than
just walk down code starting at each label (or even each basic block).