Evan Martin wrote: > When we load a plugin any symbols we export come before its symbols.
This doesn't happen on the Mac unless you go out of your way to arrange for it to happen. Even so, we do use -fvisiblility=hidden for all Mac builds, because I like for these things to be well-trimmed anyway. > The -fvisibility=hidden flag is maybe supposed to do this (see > discussion on http://gcc.gnu.org/wiki/Visibility ), but I tried > building both with and without it and found that: > - in debug builds, objdump -T shows all of our symbols, regardless of > the flags I pass to gcc or strip > - in release builds, objdump -T doesn't show us exporting symbols, > regardless of the flags I pass to gcc > > The resulting release binaries are within 1kb of each other. > > I don't really know what I'm doing, so my guess is that some other > compilation flags we're using already produce the intended effect. > Clearly this flag does *something* as the resulting binaries have > slightly different sizes, but maybe it's not intended to apply to > binaries or maybe it doesn't in my gcc (4.2.4). In order for any of this to apply to executables (as opposed to static libraries), you need to be linking with ld -E. Otherwise, global symbols that wind up in the executable don't get exported via the dynamic symbol table. I don't know how you guys are linking, but this can be significant here. This -E business applies to Linux/ELF. On the Mac, things work a little differently: there's only one symbol table, symbols wind up in it pretty much identically whether you're linking an executable or a library, and as I mentioned above, the runtime loader does a better job of resolving undefined symbols to the same libraries that provided them at link time. Mark --~--~---------~--~----~------------~-------~--~----~ Chromium Developers mailing list: [email protected] View archives, change email options, or unsubscribe: http://groups.google.com/group/chromium-dev -~----------~----~----~----~------~----~------~--~---
