[PATCH 2/2] powerpc: Align hot loops of some string functions
christophe.leroy at c-s.fr
Fri May 27 15:45:18 AEST 2016
Le 26/05/2016 à 21:37, Segher Boessenkool a écrit :
> On Thu, May 26, 2016 at 09:24:51AM +0200, Christophe Leroy wrote:
>> Wouldn't it be better to add nops before the function entry in order to
>> get the hot loop aligned, instead of adding nops in the middle of the
>> function ?
> Why would that be better? The nops are executed once per function call
> in either case, there are the same number of nops in either case, and
> on most CPUs nops aren't actually executed anyway (they are decoded and
> the thrown away).
The idea was to not execute them:
|.balign 16 nop nop _GLOBAL(strcpy) addi r5,r3,-1 addi r4,r4,-1 1: lbzu
r0,1(r4) cmpwi 0,r0,0 stbu r0,1(r5) bne 1b blr |
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