nruslan added a comment. In https://reviews.llvm.org/D53102#1268364, @kristina wrote:
> By the way, out of curiosity is this for anything specific (alternative libc > or some user-mode-scheduling implementation)? Not nitpicking, just curious > since it's an interesting topic in general and it's frustrating that the > architecture is so limited in terms of registers that can be used for > TLS/related data unlike newer ARM/ARM64 architectures. > > Also FWIW `%gs` is generally free to use under x86_64 Linux which is where I > usually place my thread control blocks which doesn't interfere with libc > which uses `%fs`. (Just started build/test job, waiting on that for now) @kristina : Yes, there are some recent use cases mentioned in the bug report (see the link above). Also, I know that it was used for x86 (32-bit only) Xen guests where it would be recommended to compile an OS with this flag. I also used it in my fork of the NPTL pthread library in VirtuOS to support M:N threading model: http://sigops.org/sosp/sosp13/papers/p116-nikolaev.pdf https://reviews.llvm.org/D53102 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
