Optimizing of explicit temporary storage

[Mike Stump]

On Sunday, October 10, 2004, at 07:48  AM, Richard Guenther wrote:
> Is it legal for a conforming C++ compiler to optimize away storage 
> allocation / deallocation?  Like in
>
> #include <new>
>
> void foo(void)
> {
>         int *x = new(std::nothrow) int;
>         delete x;
> }
>
> is it allowed to kill the new and delete statements?  Would it be 
> allowed to do this for the throwing version of new, too?

The as if rule is fairly powerful...  If the resulting program behaves 
as if it had it, then the optimization is allowed.  I don't think 
memory consumption is an externally visible effect.  Now, we might need 
to do full program analysis to know which new is run, and to know its 
semantics; I don't recall if the user is prohibited from adding 
semantics to a new replacement function.