Step 1: Read the chemical name.
The question gives the chemical name diacetylmorphine. We must find its common street name from the options.
Step 2: Identify the parent drug.
Diacetylmorphine is made by adding two acetyl groups to morphine, which comes from the opium poppy. The drug formed is heroin.
Step 3: Check Crack.
Crack is a smokable form of cocaine, not an opiate. So it does not match heroin.
Step 4: Check Amphetamine and Barbiturate.
Amphetamine is a stimulant and a barbiturate is a sedative. Neither is the same as heroin.
Step 5: Check Smack.
Smack is the well-known street name for heroin, which is diacetylmorphine. This is the correct match.
Step 6: State the answer.
Diacetylmorphine, that is heroin, is commonly called smack.
\[ \boxed{\text{Smack}} \]