No optimistic code generated running some arithmetic operations

Running eval(a / b); on global variables a=2 and b=2, there is no optimistic code generation.
--print-code output:
 
invokedynamic dyn:getProp|getElem|getMethod:a(Object;)Object; [static 'bootstrap' args=0x5]
aload 2
invokedynamic dyn:getProp|getElem|getMethod:b(Object;)Object; [static 'bootstrap' args=0x5]