================ @@ -0,0 +1,254 @@ +Debugging LLDB +============== + +This page details various ways to debug LLDB itself and other LLDB tools. If +you want to know how to use LLDB in general, please refer to +:doc:`/use/tutorial`. + +As LLDB is generally split into 2 tools, ``lldb`` and ``lldb-server`` +(``debugserver`` on Mac OS), the techniques shown here will not always apply to +both. With some knowledge of them all, you can mix and match as needed. + +In this document we refer to the initial ``lldb`` as the debugger and the +program being debugged as the debugee. + +Building For Debugging +---------------------- + +To build LLDB with debugging information add the following to your CMake +configuration: + +:: + + -DCMAKE_BUILD_TYPE=Debug \ + -DLLDB_EXPORT_ALL_SYMBOLS=1 + +Note that the ``lldb`` you will use to do the debugging does not itself need to +have debug information. + +Then build as you normally would. + +Debugging ``lldb`` +------------------ + +The simplest scenario is where we want to debug a local execution of ``lldb`` +like this one: + +:: + + ./bin/lldb test_program + +LLDB is like any other program, so you can use the same approach. + +:: + + ./bin/lldb -- ./bin/lldb /tmp/test.o + +That's it. At least, that's the minimum. There's nothing special about LLDB +being a debugger that means you can't attach another debugger to it like any +other program. + +What can be an issue is that both debuggers have command line interfaces which +makes it very confusing which one is which: + +:: + + (the debugger) + (lldb) run + Process 1741640 launched: '<...>/bin/lldb' (aarch64) + Process 1741640 stopped and restarted: thread 1 received signal: SIGCHLD + + (the debugee) + (lldb) target create "/tmp/test.o" + Current executable set to '/tmp/test.o' (aarch64). + +Another issue is that when you resume the debugee, it will not print the +``(lldb)`` prompt because as far as it knows it hasn't changed state. A quick +way around that is to type something that is clearly not a command and hit +enter. + +:: + + (lldb) Process 1742266 stopped and restarted: thread 1 received signal: SIGCHLD + Process 1742266 stopped + * thread #1, name = 'lldb', stop reason = signal SIGSTOP + frame #0: 0x0000ffffed5bfbf0 libc.so.6`__GI___libc_read at read.c:26:10 + (lldb) c + Process 1742266 resuming + notacommand + error: 'notacommand' is not a valid command. + (lldb) + +You could just remember whether you are in the debugger or the debugee but +it's thinking overhead, and for interrupt based events you simply may not be +able to know. + +Here are some better approaches. First, you could use another debugger like GDB +to debug LLDB. Perhaps an IDE like XCode or Visual Studio Code. Something which ---------------- JDevlieghere wrote:
`s/XCode/Xcode` https://github.com/llvm/llvm-project/pull/65332 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
