gmake + unexec = fast!

[Kaz Kylheku]

Hi All,

Over ten years ago, I was working on a project that had
a large tree built with non-recursive makes: one master
make system including a large number of per-directory
include files.

On the hardware of the day, it took 30 seconds for GNU Make
3.80 to read the files and issue the first build command.
So for instance if I someone changed a .cpp somewhere in the
tree, it would take over half a minute after typing "make"
for the g++ command to be dispatched to rebuild it. It was awful!

I thought, why can't we just dump an image of the make process after the
rules are read. Then re-start the image, and evaluate the goals?

So then I took the "unexec" code from GNU Emacs, transplanted it into
GNU Make and hooked it to a "--dump" option.

Now, "make --dump" would produce an executable image called "remake",
that requiring over half a minute to produce.

Then running "./remake" would almost instantly kick off the
incremental build.

Would there be any interest in this?