http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43601
--- Comment #46 from Vadim Zeitlin <vz-gcc at zeitlins dot org> 2010-10-14 17:09:05 UTC --- Another data point after having a closer look at .drectve section in all of the files: as previously noticed, 4.4 generates "-export" directives for 180 symbols while 4.5 generates them for 2724 symbols. MSVC however records "/EXPORT" directives for 526 symbols when using PCH and 3764 symbols when not using PCH. In the latter case the size of the object file also inflates to 3.1MB (with all sections growing, not just the ".drectve" one). So while it's difficult to compare the sets of symbols because of the different name mangling schemes used, it does seem that MSVC generates these directives for all of the class members used, as 4.5 does and unlike 4.4. However many classes included in 4.5 don't appear at all in the MSVC file when using PCH resulting in much more reasonable object file sizes. It still remains that the size of the DLL produced by MSVC is very small compared to gcc. E.g. the wxbase DLL is 1.9MB with MSVC and 6.5MB with gcc 4.4 while the entire wxcore DLL is just 3.9MB with MSVC and 11.6MB with gcc 4.4, without even mentioning 4.5 numbers. This is without using any "fancy" optimizations (i.e. "/LG" and/or "/LTCG" MSVC options). And the size of the DLL does _not_ depend on whether PCH was used or not (although the compilation speed and disk consumption of the object files definitely do, by a factor of more than 10 for both of them). So maybe the new 4.5 behaviour is indeed more MSVC-like. But MSVC seems to avoid generating ~80% of the stuff gcc creates when using PCH and its linker still creates reasonably sized files in reasonable time even when the object files contain a lot of redundant sections. But using MSVC strategy for gcc currently is simply disastrous and I still don't understand why shouldn't the change of r147799 be reverted now and be reapplied later when PCH handling is improved and/or the linker is capable of dealing with it. If this is not a regression I honestly don't know what counts as one.
