Author: Dezhi Zhao
Date: 13:29:17 02/26/03
Go up one level in this thread
On February 26, 2003 at 14:04:16, Uri Blass wrote:
>I had the following code in my program
>
>do
>{
>...
>if (info[target]==EMPTA)
> target+=8;
>else
> target=64;
>}
>while (target<64)
>
I think branchless code does not apply here since you nead a memory read
anyways.
try this:
if (info[target] != EMPTA)
{
do
{
....
target += 8;
} while (target < 64 && info[target]== EMPTA);
}
It maybe more friendly to your compiler and result a slightly faster code. It
might be just a wash. Test it yourself..... However it is more readable.
dzhao
>I found that changing it to else break did not do my program faster.
>
>I think that with break I have branches and without break the compiler can
>translate it to
>
>target=((info[target]==EMPTA)?target+8:64);
>
>My questions are
>1)How can I write the code as branchless code without target=64 that is a waste
>of time?
>
>2)I understood from previous discussion that for some reason ? is considered
>branchless code.
>What is the reason for it.
>
>It seems to me that using ? is the same as using if.
>If it is not the case then what is the difference?
>
>Uri
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