(i386-linux x sh-elf) More weak stack addressing

[Jeffrey A Law]

  In message < 20000720173747.A12948@cpopetz.com >you write:
  > Essentially you want the various optimization passes to operate on EBB
  > (extended basic blocks) where possible.  This is a worthwhile goal,
  > but it will take a lot of work to get there.
Yup.  There's a number of optimizers that could benefit from working on
EBBs.  Including register allocation.

If someone wants to take a step in that direction, writing code to build
EBBs would be greatly appreciated.  Algorithms to compute EBBs from the
existing CFG can be found in Muchnick and probably other books.

Once we can build EBBs, then we can look at improving the optimizers to
use EBBs.

jeff