Hello :)
> I'm not sure I clearly understand your question.
>
> When you do :
>
> if (likely(something)) {
> ...we-do-something-if true
> }
Let me try to rephrase my questions :) yes, I understand that likely()
will optimize the branch which we will likely taken. But here I am
focusing on the assembly code generated by the gcc itself...
>From the C code you have written to illustrate likely() and the result
of objdump -S, I got conclusion that the optimization is done by
arranging the code (the assembler output of we-do-something-if-true)
directly following the "cmp" and "jne" instruction. This way, the
processor will execute the next instruction faster because it is
already prefetched at L1 cache and "jump" is avoided since it is a bit
costly . I am not sure on what you mean by "pipeline", so I guess you
mean CPU pipeline. Please CMIIW and I am sorry if I bring confusion
here.
regards
Mulyadi
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