byte-compile-call-tree

byte-compile-call-tree is a variable defined in `bytecomp.el'.
Its value is

nil

Documentation:
Alist of functions and their call tree.
Each element looks like

(FUNCTION CALLERS CALLS)

where CALLERS is a list of functions that call FUNCTION, and CALLS
is a list of functions for which calls were generated while compiling
FUNCTION.