By: TREZA (no.delete@this.ema.il), February 17, 2013 11:59 am
Room: Moderated Discussions
⚛ (0xe2.0x9a.0x9b.delete@this.gmail.com) on February 17, 2013 10:49 am wrote:
> Linus Torvalds (torvalds.delete@this.linux-foundation.org) on February 14, 2013 4:44 pm > > In contrast, multiple CC registers are just stupid.
>
> Isn't it true that the following code could run faster with 2 CC registers:
>
>
>
It could be faster with in-order cores without branch prediction.
For modern CPUs, it is mainly about the probablilistic results of the a==b and c==d tests.
Having multiple CCs complexifies the management of flags and their various speculative values. This is bad for a advanced OoO CPU.
> Linus Torvalds (torvalds.delete@this.linux-foundation.org) on February 14, 2013 4:44 pm > > In contrast, multiple CC registers are just stupid.
>
> Isn't it true that the following code could run faster with 2 CC registers:
>
>
if a==b && c==d { ... }>
It could be faster with in-order cores without branch prediction.
For modern CPUs, it is mainly about the probablilistic results of the a==b and c==d tests.
Having multiple CCs complexifies the management of flags and their various speculative values. This is bad for a advanced OoO CPU.
