[Libreoffice] gnumake / dependencies 20%+ speedup ...

[Michael Meeks]

Hi there,

	Being generally irritated by the apparent hang when running make (I
know, I know it is all faster in real terms than it used to be ;-) I was
poking at the dependency files in:

	core/workdir/unxlngi6.pro/Dep/LinkTarget/Library

	And - being of an ignorant nature, I was amazed to see them packed
half-full of a great mass of dummy / empty dependency rules like these:

/data/opt/libreoffice/core/solver/unxlngi6.pro/inc/tools/string.hxx:

/data/opt/libreoffice/core/solver/unxlngi6.pro/inc/osl/thread.h:

..

	Using the attached perl script to remove these [ and I assume they are
truly redundant ;-] we get some quite interesting shrinkage (gnumake
profiles show most of its time parsing and hashing strings
interestingly):

core/workdir/unxlngi6.pro/Dep/LinkTarget/Library> du -k -c *.d.orig |
tail
12748 vbaobj.uno.so.d.orig
9720 vbaswobj.uno.so.d.orig
2096 vclcanvas.uno.so.d.orig
372 writerfilter_uno.uno.so.d.orig
603924 total

core/workdir/unxlngi6.pro/Dep/LinkTarget/Library> du -k -c *.d | tail
6424	vbaobj.uno.so.d
4904	vbaswobj.uno.so.d
1060	vclcanvas.uno.so.d
192	writerfilter_uno.uno.so.d
324084	total

	ie. around 50% of the byte size is gone. That translates into:

* tail_build (clean make -sr / secs)
    + before: 33.964 33.842 34.902
    + after:  21.858 21.202 21.090
* sc (clean make -sr / secs)
    + before: 5.238 5.729 5.802
    + after:  4.195 4.184 4.195

	Of course when using cvs gnumake (which has the other globbing win in
it - without which everything is far slower).

	So - my question is: how are those library .d files created /
concatenated - and is there some existing script we could piggy-back on
to get rid of these.

	Or are they there in fact there for some good purpose that I just
failed to spot ? :-)

	Thanks,

		Michael.

-- 
 michael.meeks at novell.com  <><, Pseudo Engineer, itinerant idiot

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