I have looked at various SO answers on using git diff and git revisions (HEAD, ORIG_HEAD, FETCH_HEAD, etc.) and I still haven't found an easy way to list the changes have been made since the beginning of the local branch, or since last rebase.

By easy I mean without having to look up and paste commit SHA or having to count how many commits I want to look back.

git diff origin/master is close, but it refers to remote which may have diverged since I checked out new branch from it.

I would expect something like git diff BASE_HEAD to be available.

...unless there's already a way to do that. Does anyone have the answer?