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...h lldb uses this code, that's how I found it. Do you mean libc++'s demangler? FYI when I said 14+% (and now it's 17%), I mean the overall performance of starting lldb, not just the demangler itself. It's probably several times faster now with this change (https://reviews.llvm.org/D32500) On Tue, Apr 25, 2017 at 12:19 PM, Vedant Kumar <vsk at apple.com> wrote: > I thought the plan of record was (r280732): > > ''' > Once the fast demangler in lldb can handle any names this > implementation can be replaced with it and we will have the one true >...

...(perhaps because the two projects evolved independently ?). > > > FYI when I said 14+% (and now it's 17%), I mean the overall performance > of starting lldb, not just the demangler itself. It's probably several > times faster now with this change (https://reviews.llvm.org/D32500) > > Do you know what the llvm policy is on using TLS in library code? I can't > find any mention of this in the programmer's manual, and my officemates > don't know either. > Both libcxx and libcxxabi use __libcpp_tls_*() functions of the threading API [2] (which call p...

...the LLVM version should be acceptable. > >> >> > FYI when I said 14+% (and now it's 17%), I mean the overall performance >> of starting lldb, not just the demangler itself. It's probably several >> times faster now with this change (https://reviews.llvm.org/D32500) >> >> Do you know what the llvm policy is on using TLS in library code? I can't >> find any mention of this in the programmer's manual, and my officemates >> don't know either. >> > > Both libcxx and libcxxabi use __libcpp_tls_*() functions of the th...

This is Greg's area, he'll be able to answer in detail how the name chopper gets used. IIRC it chops demangled names, so it is indirectly a client of the demangler, but it doesn't use the demangler to do this directly. Name lookup is done by finding all the base name matches, then comparing the context. We don't do a very good job of doing fuzzy full name matches - for instance

(Again), while trying to improve the performance of lldb, I ran into a bottleneck with the demangler. This may be specific to my platform - Ubuntu 16.04, probably using libstdc++, not libc++. It makes extensive use of std::string and std::vector, and I see memory allocation at the top. I prototyped a version that uses an arena-style memory allocator (you can allocate, but you can't ever