phosek added a comment. In D54724#1304986 <https://reviews.llvm.org/D54724#1304986>, @dim wrote:
> I think I understand the motivation, it's just that the toolchain classes > were split up specifically to avoid `if(OS==foo) ... else if(OS==bar) ... > else if(OS==baz)` mazes. So this feels a little like a regression in that > sense, putting back the OS-specific ifs in a common function. But I guess it > is a pattern that pops up more often. I considered both options, the reason I went with conditionals is because we seem to use the same approach for other runtimes like compoler-rt builtins, sanitizers or XRay, but also because in this case there's likely going to be more duplication, e.g. the `switch` to handle either libstdc++ or libc++ would have to be duplicated in FreeBSD, NetBSD and OpenBSD drivers (unless we introduce a common base class for *BSD drivers). I could try implementing it the other way for comparison. > We've been using libc++ by default since FreeBSD 10.x, and all older versions > are now EOLed. That said, we have always used a linker script to link in > libc++.so: > > $ cat /usr/lib/libc++.so > /* $FreeBSD: projects/clang700-import/lib/libc++/libc++.ldscript 305102 > 2016-08-31 00:11:35Z bapt $ */ > GROUP ( /usr/lib/libc++.so.1 /usr/lib/libcxxrt.so ) I'm specifically focusing on static case, for shared case this is not relevant since libc++.so.1 already dynamically links all the dependencies. > and for the static case, we've always just added the relevant .o files from > libcxxrt into libc++.a: > > $ ar tv /usr/lib/libc++.a > rw-r--r-- 0/0 21720 Jan 1 01:00 1970 variant.o > rw-r--r-- 0/0 61648 Jan 1 01:00 1970 valarray.o > rw-r--r-- 0/0 18224 Jan 1 01:00 1970 utility.o > rw-r--r-- 0/0 10656 Jan 1 01:00 1970 typeinfo.o > rw-r--r-- 0/0 198080 Jan 1 01:00 1970 strstream.o > rw-r--r-- 0/0 59264 Jan 1 01:00 1970 shared_mutex.o > rw-r--r-- 0/0 231552 Jan 1 01:00 1970 regex.o > rw-r--r-- 0/0 96200 Jan 1 01:00 1970 random.o > rw-r--r-- 0/0 25240 Jan 1 01:00 1970 optional.o > rw-r--r-- 0/0 239552 Jan 1 01:00 1970 iostream.o > rw-r--r-- 0/0 17728 Jan 1 01:00 1970 functional.o > rw-r--r-- 0/0 219984 Jan 1 01:00 1970 debug.o > rw-r--r-- 0/0 58256 Jan 1 01:00 1970 chrono.o > rw-r--r-- 0/0 35672 Jan 1 01:00 1970 charconv.o > rw-r--r-- 0/0 21280 Jan 1 01:00 1970 bind.o > rw-r--r-- 0/0 24312 Jan 1 01:00 1970 any.o > rw-r--r-- 0/0 1010288 Jan 1 01:00 1970 algorithm.o > rw-r--r-- 0/0 42944 Jan 1 01:00 1970 hash.o > rw-r--r-- 0/0 45152 Jan 1 01:00 1970 cxxrt_typeinfo.o > rw-r--r-- 0/0 278784 Jan 1 01:00 1970 > cxxrt_libelftc_dem_gnu3.o > rw-r--r-- 0/0 17704 Jan 1 01:00 1970 cxxrt_stdexcept.o > rw-r--r-- 0/0 224664 Jan 1 01:00 1970 thread.o > rw-r--r-- 0/0 218392 Jan 1 01:00 1970 future.o > rw-r--r-- 0/0 31456 Jan 1 01:00 1970 exception.o > rw-r--r-- 0/0 4604424 Jan 1 01:00 1970 locale.o > rw-r--r-- 0/0 27216 Jan 1 01:00 1970 vector.o > rw-r--r-- 0/0 102712 Jan 1 01:00 1970 mutex.o > rw-r--r-- 0/0 63872 Jan 1 01:00 1970 memory.o > rw-r--r-- 0/0 1261888 Jan 1 01:00 1970 ios.o > rw-r--r-- 0/0 69528 Jan 1 01:00 1970 condition_variable.o > rw-r--r-- 0/0 181368 Jan 1 01:00 1970 system_error.o > rw-r--r-- 0/0 2006648 Jan 1 01:00 1970 string.o > rw-r--r-- 0/0 105408 Jan 1 01:00 1970 stdexcept.o > rw-r--r-- 0/0 37552 Jan 1 01:00 1970 new.o > rw-r--r-- 0/0 10280 Jan 1 01:00 1970 cxxrt_memory.o > rw-r--r-- 0/0 4880 Jan 1 01:00 1970 cxxrt_auxhelper.o > rw-r--r-- 0/0 2872 Jan 1 01:00 1970 cxxrt_terminate.o > rw-r--r-- 0/0 123504 Jan 1 01:00 1970 cxxrt_exception.o > rw-r--r-- 0/0 18136 Jan 1 01:00 1970 cxxrt_dynamic_cast.o > rw-r--r-- 0/0 5696 Jan 1 01:00 1970 cxxrt_guard.o We use that solution for libc++abi as well but that doesn't handle other dependencies. > But I can link almost all C++ programs statically without having to add > `-lpthread`. I guess you only really need it if you start using the > multithreading primitives? I'm sort of hesitant to always add if, if it is > not always needed. @emaste, what's your opinion on this? Correct, on other platforms you also need `-ldl`, but on *BSD this is part of libc AFAIK. We could also consider surrounding these dependencies with `--push-state --as-needed` and `--pop-state` to avoid linking them in if they're not needed. Repository: rC Clang CHANGES SINCE LAST ACTION https://reviews.llvm.org/D54724/new/ https://reviews.llvm.org/D54724 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
