I just built lldb 3.5.0 from source on a x86_64 Debian Stable machine (because there are no packages for Debian Stable). When I try to debug a 32bit (x86) application with the resulting binary, I get the following error:
$ lldb -p $(pgrep foo)
lldb: llvm-3.5.0.src/tools/lldb/source/Plugins/Process/Utility/RegisterContextLinux_x86_64.cpp:137: uint32_t GetRegisterInfoCount(const lldb_private::ArchSpec&): Assertion `!GetPrivateRegisterInfoVector ().empty () && "i386 register info not yet filled."' failed.
Debugging x86_64 works just fine. Why is that? Is this a known bug? How can I fix this?