On Sunday 13 April 2008, Ralf Wildenhues wrote: > * Ralf Wildenhues wrote on Sun, Apr 13, 2008 at 10:26:11PM CEST: > > * Richard Purdie wrote on Sun, Apr 13, 2008 at 08:53:10PM CEST: > > > tag.patch - The tag errors were breaking things for no good reason so > > > we turned the error into a warning > > > > Well, don't come crying for bad performance to us if you do things like > > this. Letting libtool infer the tag is rather expensive, at least > > relatively, for 2.2.2 on modern systems where there are few other forks > > needed. > > I guess I should substantiate this claim. Taking a libtool script of > current CVS HEAD, plus one approved but not applied patch, configuring > it for CC=gcc, where gcc is a symlink to gcc-4.3. Then, adding your > patch (so that libtool doesn't error out on the following); then running > ./libtool --mode=compile gcc-4.3 -c a.c > > 100 times on an empty file a.c takes: > 4.24user 1.60system 0:05.91elapsed 98%CPU (0avgtext+0avgdata 0maxresident)k > 0inputs+2400outputs (0major+745403minor)pagefaults 0swaps > > whereas doing the same with a tag given: > ./libtool --tag=CC --mode=compile gcc-4.3 -c a.c > > takes: > 1.99user 0.82system 0:02.87elapsed 97%CPU (0avgtext+0avgdata 0maxresident)k > 0inputs+2400outputs (0major+316064minor)pagefaults 0swaps > > Of course, this is an extreme case, as the source file is empty, and the > libtool script generated by the Libtool package supports several tags > (it will try them all). > > So don't do this, please. Supply --tag=CC if your compiler name doesn't > match.
i doubt people will care at this point, but ive done a bit of work in Gentoo to make the tag inferring "better". ive done this as there are still a few packages out there that insist on using libtool found in $PATH. we've been killing them off over time, but we still havent gotten them all, so this painful patch lives on. http://sources.gentoo.org/sys-devel/libtool/files/1.5.6/libtool-1.5-filter-host-tags.patch -mike
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