it in its output. For example, if the compiler produces a symbol '_main' from your 'main' function, 'gprof' still prints it as 'main' in its output, so you should use 'main' in symspecs. 'main.c:main' Selects function 'main' in file 'main.c'. 'main.c:134' Selects line 134 in file 'main.c'.