Re: Is new observable behavior?
"Greg Herlihy" <greghe@mac.com>
On Apr 1, 2:54 pm, Chris <cuz...@gmail.com> wrote:
void * operator new(std::size_t size) {
std::cerr << "Observable? (new)" << std::endl;
return std::malloc(size);
}
void operator delete(void * ptr) {
std::cerr << "Observable? (delete)" << std::endl;
std::free(ptr);
}
...
Here's the output:
./a.out
Observable? (new)
Observable? (delete)
test_new_optimization(3) is `3'
Thus, it's observable.
Thus, it was MADE observable, by inserting library I/O functions.
These two particular implementations of new() and delete() have
observable behavior. In general, though, new() and delete() do not
perform any I/O or have any other kind of observable behavior. So the
answer to the original question, is - for all practical purposes -
"yes" - the compiler will almost certainly be free to eliminate the
calls to new() and delete().
Especially they have fully defined semantics, so the compiler knows
everything to do the job.
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