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

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

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.

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