amd64: -O2 even with DEBUG

[John-Mark Gurney]

Andriy Gapon wrote this message on Fri, Jul 26, 2013 at 10:14 +0300:
> I wonder why amd64 is distinguished to have -O2 in COPTFLAGS even when DEBUG is
> defined.  For all other archs it's -O for that case.
> 
> Perhaps, this was discussed / explained in the past, but I would appreciate it
> being said again (or even written as a comment in kern.pre.mk).

It's probably because at least gcc produces terrible amd64 code w/o
it...  It will constantly reload the register it uses to do relative
loads w/ the same value even though nothing changed... makes performance
suck... 

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."