update: * D now correctly prefixes its symbols with an extra underscore on OSX (cf https://dlang.org/changelog/2.079.0.html#fix8207) and gdb correctly demangles D symbols * in https://github.com/dlang/druntime/pull/2083 I had a PR to support demangling C++ symbols along with D symbols for D programs via runtime loading (dlopen) of libc++ ; could we use a similar technique for lldb by allowing user to dlopen a shared library that would customize demangling?
On Mon, Sep 26, 2016 at 8:50 AM, Greg Clayton <gclay...@apple.com> wrote: > Just did, and it looks good. > >> On Sep 26, 2016, at 3:49 AM, Johan Engelen <jbc.enge...@gmail.com> wrote: >> >> Timothee, do you intend to work on this? >> What can I do to help? >> >> In the meanwhile, I'd appreciate it if someone could take a look at >> https://reviews.llvm.org/D24794 (currently, debugging D code is very much >> broken without that change). >> >> -Johan >> >> >> On Thu, Sep 22, 2016 at 7:21 PM, Greg Clayton via lldb-dev >> <lldb-dev@lists.llvm.org> wrote: >> I like the JSON approach. We might need to include the mangled name for the >> function or specify where arguments go if we aren't going to expect a canned >> function to be in each dylib. That is a bit harder, but something we should >> think about. >> >> If we look at __cxa_demangle: >> >> >> char* abi::__cxa_demangle(const char *mangled_name, char *output_buffer, >> size_t *length, int *status); >> >> I am not sure how we would logically specify this in the JSON... Where to >> put the name to demangle, how to call it etc... >> >> > On Sep 22, 2016, at 9:56 AM, Timothee Cour <timothee.co...@gmail.com> >> > wrote: >> > >> > >> > >> > On Wed, Sep 21, 2016 at 4:13 PM, Greg Clayton via lldb-dev >> > <lldb-dev@lists.llvm.org> wrote: >> > You could have a setting that allows you to specify prefix as the key with >> > a dylib path as a value. Would you expect a function with certain name or >> > would you need to specify the function name (probably mangled) as well? >> > Let me know what you are thinking? >> > >> > >> > whatever works it doesn't really matter so long there's something to get >> > started, I was going for something simple to start with but if you want >> > this level of flexibility how about using a json config file: >> > >> > export LLDB_DEMANGLE_CONFIG_FILE="~/.lldbl.demangle.conf" >> > >> > cat ~/.lldbl.demangle.conf >> > >> > {"demangle": >> > ["D": {"prefix" : "_D", "shared_libary_file" : >> > "/path/libdemangled.dylib", "mangled_name", "_demangle_custom_D"}], >> > ["nim": /* same for nim language */ ], >> > } >> > >> > Greg >> > >> > > On Sep 21, 2016, at 3:50 PM, Timothee Cour <timothee.co...@gmail.com> >> > > wrote: >> > > >> > > >> > > >> > > On Wed, Sep 21, 2016 at 3:35 PM, Greg Clayton via lldb-dev >> > > <lldb-dev@lists.llvm.org> wrote: >> > > Sounds like you could then make a setting that is a dictionary where you >> > > say what the prefix is (like maybe "_D") and the value is the path to >> > > the tool to use? This would be easy to implement. Demangling does tend >> > > to be one of the most expensive parts of symbol file and debug info >> > > parsing, so if you do this, you will want to make sure the shell tool >> > > can be spawned and kept running maybe? >> > > >> > > Greg >> > > >> > > >> > > where in the lldb code would be such entry point? >> > > >> > > instead of a binary it can just be a library dynamically loaded via >> > > dlopen (as i wrote, though I should've called it LLDB_DEMANGLER_LIB >> > > instead of LLDB_DEMANGLER_EXE), and the dynamically loaded symbol be >> > > cached to make sure it's dlopen'd at most once per process. >> > > >> > > Then it's easy enough for us to write a demangleCustom that is fast on >> > > the D side of things. It can also work with a binary instead of a dllib >> > > but would be a bit slower (could have a client server model, but that's >> > > more complex than the simple dllib solution i was proposing). >> > > >> > > yes, we could use a prefix for that as well. >> > > >> > > >> > > > On Sep 21, 2016, at 3:30 PM, Timothee Cour <timothee.co...@gmail.com> >> > > > wrote: >> > > > >> > > > >> > > > >> > > > On Wed, Sep 21, 2016 at 3:10 PM, Greg Clayton <gclay...@apple.com> >> > > > wrote: >> > > > There is no external demangling plug-in infrastructure at the moment, >> > > > but you could add functionality that would allow it. No one is going >> > > > to have D installed by default. Where do you expect your demangler >> > > > dylib to live? >> > > > Would you just add code that tries to locate the dylib in N places on >> > > > the current system and try to dlopen it? Avoiding duplication and just >> > > > not having the functionality at all unless something else is might not >> > > > make it that useful. Is D stable? Is the mangling changing at all? >> > > > Will you require a demangler to be vended with each new version of the >> > > > tool? Are all previous demanglings still valid in newer versions? Can >> > > > you figure out the version of the D from a compiled executable so that >> > > > you might be able to locate one of 5 different installs of D and >> > > > select the right one? Let me know what you use case is. >> > > > >> > > > Greg >> > > > >> > > > >> > > > one simple flexible backward compatible option would be to have a >> > > > generic environment variable: >> > > > >> > > > ``` >> > > > export LLDB_DEMANGLER_EXE="/usr/bin/ddemangle" >> > > > lldb myprog >> > > > ``` >> > > > >> > > > inside lldb (D-like pseudo code): >> > > > >> > > > ``` >> > > > bool demangle(string symbol, string* output){ >> > > > auto path=env["LLDB_DEMANGLER_EXE"]; >> > > > if(!path.empty) { >> > > > auto demangleCustom=cast(proper_type) dlopen(path); >> > > > if(demangleCustom(symbol, output)) return true; >> > > > // fallsback to default code if custom code didn't handle symbol >> > > > } >> > > > return run_default_lldb_demangle(symbol, output); >> > > > } >> > > > ``` >> > > > >> > > > user defined demangler (eg D's demangler) >> > > > ``` >> > > > // return true if can demangle symbol (ie it's a D symbol in our case) >> > > > bool demangleCustom(string symbol, string* output); >> > > > >> > > > ``` >> > > > >> > > > >> Is the mangling changing at all? >> > > > >> > > > yes, there's some ongoing work on making the mangling scheme produce >> > > > much shorter symbols. The logic is complex, and it'd be a lot of work >> > > > to reproduce this. >> > > > >> > > > Bottomline: this scheme is very flexible, and it'd be no less useful >> > > > than current situation, where lldb just returns the symbol unchanged >> > > > if it can't demangle. >> > > > >> > > > >> > > > >> > > > >> > > > > On Sep 21, 2016, at 3:00 PM, Timothee Cour >> > > > > <thelastmamm...@gmail.com> wrote: >> > > > > >> > > > > Is there a way to provide a hook (eg, via an extern(C) function, or >> > > > > using a dynamically loaded shared library) to do this, so as to >> > > > > simply reuse D's https://dlang.org/phobos/std_demangle.html and make >> > > > > sure it's always in sync with D's demangling instead of duplicating >> > > > > code >> > > > > >> > > > > On Wed, Sep 21, 2016 at 10:24 AM, Greg Clayton via lldb-dev >> > > > > <lldb-dev@lists.llvm.org> wrote: >> > > > > It might be nice to add demangling support to llvm and then use it >> > > > > by modifying "Mangled::GetDemangledName()" in Mangled.cpp. This is >> > > > > where all demangling happens. Hopefully you have a great prefix that >> > > > > won't conflict with other languages "_Z" for C++, "_T" for swift. >> > > > > But the code in Mangled::GetDemangledName() will look at the prefix >> > > > > and attempt to demangle the name based on what prefix it starts with. >> > > > > >> > > > > >> > > > > > On Sep 21, 2016, at 5:52 AM, Johan Engelen via lldb-dev >> > > > > > <lldb-dev@lists.llvm.org> wrote: >> > > > > > >> > > > > > Hi all, >> > > > > > I recently looked into adding demangling support for D in LLDB, >> > > > > > but got lost in the code. >> > > > > > (right now, basic D support is there with: >> > > > > > https://reviews.llvm.org/D24794) >> > > > > > >> > > > > > I'd like some pointers to where demangling is done for the other >> > > > > > languages, and to where I should add D support for it. >> > > > > > >> > > > > > Thanks a lot, >> > > > > > Johan >> > > > > > >> > > > > > _______________________________________________ >> > > > > > lldb-dev mailing list >> > > > > > lldb-dev@lists.llvm.org >> > > > > > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev >> > > > > >> > > > > _______________________________________________ >> > > > > lldb-dev mailing list >> > > > > lldb-dev@lists.llvm.org >> > > > > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev >> > > > > >> > > > >> > > > >> > > >> > > _______________________________________________ >> > > lldb-dev mailing list >> > > lldb-dev@lists.llvm.org >> > > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev >> > > >> > >> > _______________________________________________ >> > lldb-dev mailing list >> > lldb-dev@lists.llvm.org >> > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev >> >> _______________________________________________ >> lldb-dev mailing list >> lldb-dev@lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev >> > _______________________________________________ lldb-dev mailing list lldb-dev@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
