Re: reg_scan info validity during jump

["David S. Miller" <davem at dm dot cobaltmicro dot com>]

   Date: Sat, 11 Jul 1998 01:25:24 -0600
   From: Jeffrey A Law <law@hurl.cygnus.com>

     In message <19980711003058.A9249@dot.cygnus.com>you write:
     > > Anyway I think the better patch is to simply not copy the loop exit
     > > code if it references a register higher than max_reg_num.  Yes we
     > > miss some opts, but calling reg_scan like that is very heavyweight.
     > 
     > As I mentioned to Dave, I think the proper solution is to have 
     > incremental update functions to call, a-la record_base_value.

   That is certainly  the right way to go long term.  But do we want
   to fart with that now when all we have to do is return 0 if the
   register is >= max_reg?

Yes, I certainly think so.  I'm working tonight on the solution
suggested by rth.

As I scanned over things, planning the implementation, I noticed that
these jump cases only care about UID lifespans for REGs.  Therefore it
would be profitable to have a "reg_scan_lifetimes()" or something like
this, and a little helper:

reg_scan_refresh_lifetimes(first_new_reg, first_insn, last_insn)

But I won't go this far in my hacks tonight.

Later,
David S. Miller
davem@dm.cobaltmicro.com