messages in objective-C

[Come Lonfils <Come dot Lonfils at ulb dot ac dot be>]

Hello,

I've already asked some questions about the messages in objective-c. But I still not understand all.

When a program is running, and I send a message to an object, how is it done in gcc to sent this message to the good object and to execute the good method. Which structures are used to do it?

I see the objc_msg_lookup in sendmsg.c but where is it call?
I also see two hash lists (nst_method_hash_list and cls_method_hash_list) I think they are use to store messages at runtime but I don't understand how they are used.

Sorry my question is quite general but I don't know very much gcc. Can't juste someone help me to understand a bit more and to put me on the right way.

Thanks very much

Côme Lonfils