Dropping of old loop optimizer

[law@redhat.com]

In message <20030228095445.GD5431@kam.mff.cuni.cz>, Jan Hubicka writes:
 >> 
 >> On Thursday, February 27, 2003, at 12:13  PM, Pop Sébastian wrote:
 >> 
 >> >On Thu, Feb 27, 2003 at 05:39:17PM +0100, Zdenek Dvorak wrote:
 >> >>
 >> >>The problem I see is that rtl ssa is broken (or never worked?); but
 >> >Last time I had a close look at rtl was about two years ago :-)
 >> >Dan is the expert to ask about the status of SSA at rtl level (he 
 >> >adapted
 >> >the CCP code from rtl to tree-ssa).
 >> The problem with RTL SSA is hard registers and subregs.
 >> There are hard registers assigned in certain cases during initial RTL 
 >> generation.
 >> These can't be renamed, obviously.
 >
 >The tree-SSA represents the SSA form as datastructure on the top of the
 >trees not modifying the trees themselves, right?  Why it is not feasible
 >for RTL (ie you won't need to rename the registers)
hard-regs and subregs really aren't really the problem with rtl-ssa,
they're both solvable.  The first by ignoring them, the second with
some annoying, but not terribly difficult work in the ssa->normal
translator.

What is far more of a problem for rtl-ssa is the lack of any kind of
generic level rtl.

The tree-SSA branch using a rewriting SSA form now.

Jeff