vc-root-diff

vc-root-diff is an interactive autoloaded compiled Lisp function in `vc.el'.

It is bound to C-x v D, <menu-bar> <tools> <vc> <vc-root-diff>.

(vc-root-diff HISTORIC &optional NOT-URGENT)

Display diffs between VC-controlled whole tree revisions.
Normally, this compares the tree corresponding to the current
fileset with the working revision.
With a prefix argument HISTORIC, prompt for two revision
designators specifying which revisions to compare.

The optional argument NOT-URGENT non-nil means it is ok to say no to
saving the buffer.