On Thu, Oct 29, 2020 at 05:59:54PM +0100, Paolo Bonzini wrote: > On 29/10/20 17:56, Arvind Sankar wrote: > >> For those two just add: > >> struct apic *apic = x86_system_apic; > >> before all the assignments. > >> Less churn and much better code. > >> > > Why would it be better code? > > > > I think he means the compiler produces better code, because it won't > read the global variable repeatedly. Not sure if that's true,(*) but I > think I do prefer that version if Arnd wants to do that tweak. > > Paolo > > (*) if it is, it might also be due to Linux using -fno-strict-aliasing > Nope, it doesn't read it multiple times. I guess it still assumes that apic isn't in the middle of what it points to: it would reload the address if the first element of *apic was modified, but doesn't for other elements. Interesting.
