[Bug c++/43601] Enormous increase in DLL object files size in 4.5

[vz-gcc at zeitlins dot org]

------- Comment #12 from vz-gcc at zeitlins dot org  2010-04-03 18:17 -------
Actually I don't think --enable-checking=release changes anything. I've just
tried Cesar Strauss's suggestion to not use __attribute__((dllexport)) in the
code at all but use --enable-auto-import linker option. And miraculously this
solves all the problems:

% ..configure with LDFLAGS=-Wl,--enable-auto-import ...
% time make -sj8 wxcore
make -sj8 wxcore  18.02s user 34.75s system 34% cpu 2:34.81 total
% du -sh lib
26M     lib
% du -sSh .
24M .
% du -h lib/wxmsw291u_core_gcc_custom.dll
8.7M    lib/wxmsw291u_core_gcc_custom.dll

To summarize: the compilation time is the same as with 4.4 (7s difference is
roughly the same as measurement precision anyhow) and the library size is even
smaller than with 3.4.5.

So it seems that dllexport attribute should simply never be used with 4.5. I
was opposed to using --enable-auto-import initially because it exports too much
(there are plenty of symbols which shouldn't be exported in the DLL export
table now) but its advantages are such that we're clearly going to do it with
4.5.

I still wish somebody could explain me why can auto import work so efficiently
but dllexport had to be made unusable like this.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43601