Re: Cost of deleting a null pointer
Am 01.12.2011 04:29, schrieb A. McKenney:
Recently, someone was doing some profiling of our code, and found that
code essentially like the following was taking far more time than
expected:
[..]
He found that if he replaced
delete tlist[i];
with
if ( tlist[i] ) delete tlist[i];
it sped the function up by about a factor of 30.
Wow! About 10 years ago I heard that there might still exist some broken
compilers that behave in a way as you describe, but I hadn't expected
that anyone of those would have survived evolution such long. Might you
tell us the compiler name, especially its version?
His assumption was
that all the destructor and freeing logic was being gone through
even when the pointer was null.
This should not happen. You might look for some special compiler flags
that make it behave in such a manner (E.g. some special debug options).
Is this just a Quality of Implementation issue, or is it reasonable to
expect that deleting a null pointer should be expensive?
I would say: Both points are correct.
HTH & Greetings from Bremen,
Daniel Kr?gler
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