Speeding up libtool

[Robert Ögren]

Hi everybody,

I looked through the TODO thread from 2004-11 and saw some talk about 
speeding up libtool. I'm particularly interested in improved compilation 
speed on Cygwin (Windows). Is there any progress on this?

A while ago I created a temporary solution for myself which caches the 
commands executed by libtool 1.5 to speed up the compilation process. It 
is a small Perl script that is run in place of libtool and that 
maintains a simple database of libtool command line => resulting 
commands by running the real libtool any time a command is not already 
in the database and parsing its standard out and storing the commands 
and .la files. It understands very little of what libtool actually does, 
the speedup is achieved by invoking libtool less often.

By replacing the name of the source file and the corresponding output 
file with placeholders if they match it usually only requires a few 
libtool invocations for compiling many source files. The link commands 
are usually unique but at least the second time a source tree is rebuilt 
they are already cached.

This is aimed at software developers like myself who build projects from 
CVS and frequently modify some source files, compile and relink.

The code was not written with portability in mind and certainly has bugs 
and quirks, but works well for me and should be possible to port to 
other platforms than Cygwin. The speedup might not be very large on 
those platforms however. But if anyone tries, please tell me how it worked.

The code is available at http://libtool-cache.sourceforge.net/ if anyone 
is interested. See it as a proof of concept.

Robert