ideas for cpplib

[Jeffrey A Law]

  In message < 199810131727.KAA25477@cygnus.com >you write:
  > > A trial implementation didn't speed up noticeably.  This is because
  > > cpplib is bound by directory search and I/O in my usual test
  > > (compiling glibc).  A less disk-intensive compile might benefit more.
  > 
  > It is well-known that cpplib's files searching mechanism is bad.
  > I basically copied the approach from cccp.c, which had lots of
  > redundancies and overheads.   Then in December 1995 I and Paul
  > Eggert re-did how this was handled for cccp, but we never got
  > around to do the similar fixes to cpplib.
  > 
  > I believe the first thing to do if you want to improve cpplib
  > performance is merge in the data structure and improvements
  > that were made to cccp around December 1995.  (It's a looong
  > ChangeLog entry.)
I thought we went back and picked up all those changes at some point.

jeff