Question: "backwards" adressing

[Ulf Zibis]

Am 24.08.2009 15:06, Christian Thalinger schrieb:
> Ulf Zibis wrote:
>   
>> In case of "forwards", the compiler could create code which increments 
>> the index for the 2nd statement in _same CPU register_, whitout 
>> remembering the original value of index in a different place.
>>     
>
> The compiler generates in either case a load-with-offset instruction and
> the increment happens independently.
>
> -- Christian
>
>   

Thanks for clarifying.
... But isn't using the index register faster, than 2 times 
load-with-offset ?

forwards:
accumlator = pop // codePoint
index register = pop // dst
index register += pop // index
save highSurrogate(accumulator) (ix++)
save lowSurrogate(accumulator) (ix)

backwards:
accumlator = pop // codePoint
index register = pop // dst
index register += pop // index
push index register // dst + index
save lowSurrogate(accumulator) (++ix)
index register = pop // dst + index
save highSurrogate(accumulator) (ix)

-Ulf