Re: Libtool stresstest.at segfault on Cygwin/MinGW

[Ralf Wildenhues]

Hi Peter,

* Peter Ekberg wrote on Mon, Sep 19, 2005 at 09:05:04PM CEST:
> Ralf Wildenhues wrote on Monday, September 19, 2005 17:10 CEST
> > * Peter Ekberg wrote on Mon, Sep 19, 2005 at 04:17:56PM CEST:

> > > Well, the test segfaults on MinGW with the patch, and if I add
> > > DATA to all symbols manually in asyms the (reordered) test goes
> > > on until the same problem is triggered when export_symbols_cmds
> > > is invoked because of the -export-symbols-regex option, so I
> > > assume it is not good enough for MinGW. I think the import lib
> > > gets screwed up if data symbols are not correctly tagged.
> > 
> > OK.  I assume it's not a linker bug then.
> 
> (nit: s/linker/compiler/ I suppose)

Well, I guess our current best bet is `nm', right?  ;-)

> Thinking about it further, include_expsyms is perhaps not
> buggy with skipped exports, as then the needed symbols perhaps
> get exported anyway with the export_symbols_cmds functionality.
> A check wouldn't hurt though...

ACK.

*big snip*
> Ok, tested with a copy of sed in /c/foo and /c/foo/sed where the
> patch has $SED in ltmain.m4sh, and it works. I don't know if that's
> a good enough test for MinGW file mode issues though.

Cool.

> Updated patch attached. I think this is good to go now.

Let me just comment on it a bit more: some seds have a command limit
(autoconf/status.m4 guesses about 100 commands), but on cygwin/mingw
you can be sure to have a good sed available; for cross-compiles, I
generally think we should be allowed to assume *equal or better*
development tools on $build than on $host.

Another potential issue, though, with lots of symbols to export, is the
superlinear cost of lots of sed `s' commands in a script.  A totally
unscientific test with GNU sed 4.1.2 on GNU/Linux showed a factor of
about 2.5 time increase for twice the number of `s' commands, when used
on a file where each command matches once; but with nicely spread symbol
names.  With `join', this issue could easily be fixed, but it's not
available on mingw (and not in the list of allowed tools).  :-/

In short: yes, please apply, and add a FIXME comment to look out for a
potential bottleneck.  :)

Cheers, and thank you,
Ralf