Making libstdc++-v3 faster (was Re: AIX and V3)

["Kaveh R. Ghazi" <ghazi at caip dot rutgers dot edu>]

 > From: Mark Mitchell <mark at codesourcery dot com> 
 > 
 > I think I've got a patch that might do the trick -- but it will take
 > hours to reconfigure and find out...

I too have the lengthiness problem configuring libstdc++.  Even when I
save the config.cache from the previous build, it takes forever.  (And
in any case it looks like the decl checks aren't being restored from
cache.)

Anyway, I think the approach I outlined last week would make an
improvement, but I don't have time to pursue it just now and measure
what actual gains there are.

http://gcc.gnu.org/ml/gcc/2001-01/msg00971.html

Currently, libstdc++-v3/aclocal.m4 has numerous calls to
GLIBCPP_CHECK_MATH_DECL_AND_LINKAGE_1 each doing its own LANG
SAVE/RESTORE.  Instead we should write a wrapper called
GLIBCPP_CHECK_MATH_DECLS_AND_LINKAGES_1 which is analogous to the
AC_CHECK_FUNCS autoconf wrapper that calls AC_CHECK_FUNC.

Then you pass in all the functions into one macro and loop as I
described in the above URL saving all the LANG SAVE/RESTOREs but the
one necessary in the loop wrapper.

Ditto for the _STDLIB_/_BUILTIN_MATH_/_COMPLEX_MATH_ checks.

You could also parameterize the _1,_2 suffixes if you got ambitious. :-)

		--Kaveh
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Kaveh R. Ghazi			Engagement Manager / Project Services
ghazi@caip.rutgers.edu		Qwest Internet Solutions