profiler?

hello, i'd like to begin work on a php profiler, as my employer needs one, and i couldn't find one. have i not looked hard enough or in the right place? my employer is committed to allowing me to open source the project. i would like it if i could begin a discussion with the people responsible for the front-end, compiler and runtime to ensure that the profiler can coexist and coevolve with php. in particular, i'd like it if releases of php did not break the profiler and vice-versa. does anyone here have ideas of how it should be done? thanks much in advance, b