Kenneth Zadeck wrote:
Andrew MacLeod wrote:
On Fri, 2007-08-17 at 12:01 -0400, Kenneth Zadeck wrote:
In any case IRA can not use UREC because UREC is needed before IRA
calculates reg class info and the reg class info is needed for
calculation of UREC. If you manage to use LIVE instead of UREC, it
would permit to use LIVE also in IRA instead of LR. But I can not say
can we use LIVE instead of UREC because I don't know the
df-infrastructure well yet.
we should talk. I am avail today. i am leaving on vacation tomorrow
for a week.
Even if this patch does not get in this round, you should consider it as
a starting point for building the interference graph for ira.
it does not use urec and a big part of the patch is just getting rid of
urec, It does a backwards scan using the live at bottom set as the
starting point for the scan.
This is the most accurate you can get so there really is no reason not
to use it since it is also no more expensive than any weaker technique.
It is the standard way of doing things. Out-Of-SSA has always used live
range info from the bottom up for its conflict graph. I'm marginally
suprised it is calculated any other way...
Andrew
this is gcc, get a life.
bottom up is the way i was taught when i was a small child playing with
compilers with training wheels.
I think it came from Pastel compiler of Livermoore Laboratories and that
stuff in Pastel compiler was written by Fred Chow who is a very good
specialist in RA.
Simply it is an old stuff and that time the backward scan was not so
common (as graph based coloring).
Gcc always seemed weird because you need reg_dead and reg_unused notes.
Note that my patch does not use reg_dead or unused notes.
