Looking for a make version to better support software versions

[Jack Alexander]

Hello:

I have a need for a make-type program that will allow recompilations
to be dependent on the changing of compiler definitions (i.e., "-DVERSIONB")
The problem is that I have many megabytes of code that have to support
many, many different versions of basically the same program.  Because I
want to keep the guts of the system the same, whereever a slight
modification is needed for a particular version, I just make the code
segment conditional using #ifdef's, #ifndef's, etc.  However, when I change
a compile variable, I don't want to re-compile every file (some directories may
have 50 source files each), just the ones that actually reference the variable.

Has anybody heard of any such program?  Does anybody else need such a program?
If the need is terrific, I may endeavor to hack it into gnu make.  If I do
this, I would appreciate any recommendations.

-- Jack Alexander