🚀 go-pugleaf

In article aul@rznews.rrze.uni-erlangen.de, anhaeupl@late.e-technik.uni-erlangen.de (Bernd Anhaeupl) writes:
>In various places the DWP specifies, that the order of evaluation of
>some expressions is unspecified. 

>1.) Does this mean, that for example in the following function call
>
>	f(a(...),b(....),c(....));
>
>    a(...), b(...), c(...) may even be evaluated in parallel in a
>    multitasking environment? 

No. Section 1.8 says function calls may not be interleaved. In your
example, "a", "b", and "c" may be called in any order, but whichever
one is called first must complete before the second one is called.
(The C++ language definition does not address parallelizing of program
execution, but we can talk about interleaving parts of expressions.)


>2.) Is it legal for a compiler to reorder the evaluation of
>    the operator new and the constructor calls of some new expressions.
>    For example, is it legal for a compiler to evaluate

>	f(new a(new b()))             or    f2(new a, new b)   (see also question 1)
> 
>                       in the following order:

>	tmp1=a::new(sizeof(a));             tmp1=a::new(sizeof(a))
>	tmp2=b::new(sizeof(b));             tmp2=b::new(sizeof(b))
>	tmp2.b();                           tmp1.a()
>	tmp1.a(tmp2);                       tmp2.b() 
>	f(tmp1);                            f2(tmp1,tmp2);

I believe the reordering is allowed, because I don't think there is
any sequence point that prevents it. 

---
Steve Clamage, stephen.clamage@eng.sun.com



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