patch applied (ghc-6.12/ghc): Use "rep; nop" inside a spin-lock loop on x86/x86-64

[Ian Lynagh]

Tue Sep 29 06:07:22 PDT 2009  Simon Marlow <marlowsd at gmail.com>
  * Use "rep; nop" inside a spin-lock loop on x86/x86-64
  This helps on a hyperthreaded CPU by yielding to the other thread in a
  spinlock loop.

    M ./includes/rts/SpinLock.h +2
    M ./includes/stg/SMP.h +18

View patch online:
http://darcs.haskell.org/ghc-6.12/ghc/_darcs/patches/20090929130722-12142-2e9040529c1cb4bbb6754c55ac64270430d87f90.gz