What to do with new-ra for GCC 4.0

[Bernd Schmidt]

>>and its core algorithm is comprehensible enough 
> 
> I disagree ;-)

Take away all the crufty layers of superfluous bits, such as the 
inheritance code, and you'll end up with a core that is actually quite 
small and elegant.

If new-ra has failed, maybe I should resurrect my old attempt at 
rewriting the uglier parts of reload.  A couple of years ago I had 
patches which tried to address two problems I see with the current code:

  * reload insn ordering is done with a bizarre set of reload_types
  * pieces of reload inheritance are scattered everywhere, which
    doesn't help make it maintainable.

What I did was to detect dependencies between reload insns and create an 
ordering with a mini-scheduler.  All information about reloads and 
reload insns is kept around while processing the insns, and inheritance 
is performed as an additional pass over this information.  Inheritance 
becomes a localized pass instead of bits of code strewn across multiple 
files, and since it has more global information to work with, it can 
make better choices (in theory, anyway).

The code isn't in a usable state right now, and since it has the 
downside of increased compile times and memory usage, I'm not sure 
anymore it's a feasible approach.  If anyone else is interested, maybe 
I'll resurrect it and put it on a branch.


Bernd