This branch contains the work Ken Zadeck and I have been doing
replacing the backend dataflow (such as live register analysis) with
df.c based dataflow.
It currently bootstraps on x86-linux-gnu, and powerpc-linux-gnu, and
powerpc-darwin.
Currently, reg-stack doesn't like accurate liveness info (IE with
unset variables removed), so that the more accurate liveness analysis
is disabled at some points in the compiler.
The branch may be slower or faster than mainline right now, we
haven't concetrated on timings, but we are confident it will be
faster when we are done.
The branch produces about 1% better spec scores, due to better
liveness information being computed.
I will document the branch in wwwdocs soon.
