RE: [Xen-devel] [PATCH] cpufreq.c: shut up compiler about cpufreq_dom

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

Ian Jackson wrote:
> Liu, Jinsong writes ("RE: [Xen-devel] [PATCH] cpufreq.c: shut up
>> What's the advantage of the above coding style? seems it saved a
>> flag but add 1 more jump.
> 
> It's clearer, and the compiler can see what's going on.
> 
> There isn't another jump `as written', since `break' is a jump too.
> Whether there is another jump after the compiler is done with it
> depends on a lot of factors, but generally I would expect the compiler
> to do a better job when information about the program's possible
> behaviours is represented directly in the control flow than when it is
> stored in a flag variable.
> 
> For example, often the allocation of a new structure can be done
> directly at the point where we fall out of the loop, eg:
>>>        for (...) { cpufreq_dom = dom; if (...) goto
>>> cpufreq_dom_found; } 
>            cpufreq_dom = xmalloc(...);  cpufreq_dom->contents =
> value; ... 
>>>      cpufreq_dom_found:
> 
> Ian.

Thanks a lot!

Jinsong
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel