2009/9/16 Alan Busby <thebu...@thebusby.com>: > > On Wed, Sep 16, 2009 at 4:42 PM, Anselm R Garbe >> >> IDE's like Eclipse have code assitance support to generate these >> automatically, great isn't it? So if you imagine a Java program where >> each datum access happens through getters and setters, the program >> must become a magnitude faster if the underlying code would be >> replaced using direct datum/field access instead, wouldn't it? > > No, because even in C the compiler should be smart enough to do it for you. > In Java, you can have even more convoluted code and the interpreter can > optimize it for you while it runs. GCC supports something similar as well > with -fprofile-generate and -fprofile-use .
Of course there are various runtime optimisations presents in nowaday's Java VMs and even compile time optimisations in AOT byte code compilers, also wrt this aspect. However the downside of these runtime optimisations has a cost: memory and duplicated data access structures, that are believed to perform better. And if you imagine that field access happens in 90% of all Java code through optimised-away getter/setter calls, then this has surely an impact and the thesis might still prove true. I'll definately add this to my experiment project that does very weird stuff in Java, like very long inheritance chains, classes with many thousand methods/fields etc. I plan to do publish the experimentsat some point. Kind regards, Anselm
