[Cmake] Library link line compression (again)

[Ian Scott]

Amitha,

I had a go at doing this. I gave up because it didn't have any noticible
effect on DevStudio's loading or linking speed. I've lost the code, but the
algorithm should go something like this



Add a function StripLinkLibrariesToTreeDependecy, called under the control
of some cache variable from cmMakeFile::FinalPass

Method cmMakeFile::StripLinkLibrariesToTreeDependecy
  Copy sequence of all linklibraries to LL
  start = Beginning of LL
  Starting from i = End of LL
  --i;
  Get Library L = *i
  j = i;
  While (j!= start)
    j--;
    if *j = *i
      remove *j
      shuffle all previous members (start, j-1) of LL up one
      ++start;
  Until i == start;
  Copy LL back to LinkLibaries.
End

Alternatively you could put the code in the FinalPass method of a new
Command StripLinkLibrariesToTreeDependecy

Ian.

> -----Original Message-----
> From: Amitha Perera [mailto:perera at cs . rpi . edu]
> Sent: Friday, November 16, 2001 9:40 PM
> To: cmake at public . kitware . com
> Cc: chrisc at cs . rpi . edu
> Subject: [Cmake] Library link line compression (again)
>
>
> Hi all
>
> Would anyone object to adding an option to CMake to allow link line
> compression? In particular, I think that most projects have a tree
> like library dependency, and it is possible for CMake to automatically
> eliminate duplicate libraries without causing linking failures. The
> default mode would be what it is now, which generates a long link line
> (for vxl, at least).
>
> As the message below indicates, this is probably a useful process, and
> a good step in lieu of a full dependency analysis.
>
> Amitha.
>
>
> ----- Forwarded message from "Christopher D. Carothers"
> <chrisc at cs . rpi . edu> -----
>
> To: Amitha Perera <perera at cs . rpi . edu>
> From: "Christopher D. Carothers" <chrisc at cs . rpi . edu>
> Date: Fri, 16 Nov 2001 16:32:43 -0500 (EST)
> Subject: fyi: static linking needs huge swap space!
>
> 	Folks, to link a static version of online tracining under linux
> (and freebsd, solaris as well I suspect), you need 1.3 GB of swap in
> addition to 256 MB of RAM. I watched "top" as the final link was being
> done and you could just see the vast amount of memory being allocated.
>
> 	I think the reason for this because the link line has duplicates
> of every lib. Amitha, is there anyway we can cut down on
> these duplicates
> and still avoid unresolved symbols.
>
> 	My office machine now has 2 GB of swap :-)
>
> 	Happy compiling!
>
> 		Chris
>
>
> ----- End forwarded message -----
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