[LLVMdev] MCJIT and DWARF debugging info and lldb

[Christian Schafmeister]

Hey folks, I've written a Common Lisp compiler using LLVM as the
back end.  I switched to MCJIT a couple of days ago.  I generate DWARF
debugging information for each Compile Unit, Function, LexicalBlock and
line numbers (using DIBuilder).  (I'm on OS X 10.8.5;
XCode 5.0; ToT LLVM/Clang build rev 192521)

When I check my backtraces in lldb (stock lldb from Xcode 5.0) I don't see my DWARF debugging info
as I expected - should I be?  What is the status of DWARF debugging with
MCJIT?

Here's an example where I define three functions A, B, and C where A
generates a backtrace (using backtrace(3) and backtrace_symbols(3)) 
and B calls A and C calls B.

The backtrace entries at 6, 10, 14 are my functions a, b, and c.
All there is is entries like: "??? <white-space> 0x00000001097ee44b 0x0 + 4454278219"


> (defun a () (core::backtrace))
A
> (defun b () (a))
B
> (defun c () (b))
C
> (c)
(c)


Backtrace: 0   libcore_opt.dylib                   0x0000000103a61687 _ZN4core12af_backtraceEv + 55
Backtrace: 1   libcore_opt.dylib                   0x0000000103a62c50 _ZN4core27ActivationFrameFunctionPtrTIvvvvvvvvvvvvvvvvvE8activateEPFvvERKN3mem9smart_ptrINS_17ActivationFrame_OEEE + 64
Backtrace: 2   libcore_opt.dylib                   0x0000000103a62b12 _ZN4core30ActivationFrameFunctionWrapPtrIvvvvvvvvvvvvvvvvvE8activateERKN3mem9smart_ptrINS_17ActivationFrame_OEEE + 18
Backtrace: 3   libcore_opt.dylib                   0x0000000103c8c3c1 _ZN4core9BuiltIn_O6INVOKEERKN3mem9smart_ptrINS_17ActivationFrame_OEEE + 1137
Backtrace: 4   libllvmo_opt.dylib                  0x000000010364758c _Z47proto_invokePossibleMultipleValueSymbolFunctionPN3mem9smart_ptrIN4core8Symbol_OEEEPNS0_INS1_17ActivationFrame_OEEE + 1196
Backtrace: 5   libllvmo_opt.dylib                  0x000000010363ffa7 mv_invokePossibleMultipleValueSymbolFunction + 23
Backtrace: 6   ???                                 0x00000001097ee44b 0x0 + 4454278219
Backtrace: 7   libcore_opt.dylib                   0x0000000103c8d50f _ZN4core18CompiledFunction_O6INVOKEERKN3mem9smart_ptrINS_17ActivationFrame_OEEE + 463
Backtrace: 8   libllvmo_opt.dylib                  0x000000010364758c _Z47proto_invokePossibleMultipleValueSymbolFunctionPN3mem9smart_ptrIN4core8Symbol_OEEEPNS0_INS1_17ActivationFrame_OEEE + 1196
Backtrace: 9   libllvmo_opt.dylib                  0x000000010363ffa7 mv_invokePossibleMultipleValueSymbolFunction + 23
Backtrace: 10  ???                                 0x00000001097f244b 0x0 + 4454294603
Backtrace: 11  libcore_opt.dylib                   0x0000000103c8d50f _ZN4core18CompiledFunction_O6INVOKEERKN3mem9smart_ptrINS_17ActivationFrame_OEEE + 463
Backtrace: 12  libllvmo_opt.dylib                  0x000000010364758c _Z47proto_invokePossibleMultipleValueSymbolFunctionPN3mem9smart_ptrIN4core8Symbol_OEEEPNS0_INS1_17ActivationFrame_OEEE + 1196
Backtrace: 13  libllvmo_opt.dylib                  0x000000010363ffa7 mv_invokePossibleMultipleValueSymbolFunction + 23
Backtrace: 14  ???                                 0x00000001097f444b 0x0 + 4454302795
Backtrace: 15  libcore_opt.dylib                   0x0000000103c8d50f _ZN4core18CompiledFunction_O6INVOKEERKN3mem9smart_ptrINS_17ActivationFrame_OEEE + 463
Backtrace: 16  libllvmo_opt.dylib                  0x000000010364758c _Z47proto_invokePossibleMultipleValueSymbolFunctionPN3mem9smart_ptrIN4core8Symbol_OEEEPNS0_INS1_17ActivationFrame_OEEE + 1196
Backtrace: 17  libllvmo_opt.dylib                  0x000000010363ffa7 mv_invokePossibleMultipleValueSymbolFunction + 23
Backtrace: 18  ???                                 0x00000001097f611c 0x0 + 4454310172
Backtrace: 19  libcore_opt.dylib                   0x0000000103c8d50f _ZN4core18CompiledFunction_O6INVOKEERKN3mem9smart_ptrINS_17ActivationFrame_OEEE + 463
Backtrace: 20  libcore_opt.dylib                   0x0000000103df6397 _ZN4core4eval30applyFunctionToActivationFrameEN3mem9smart_ptrINS_10Function_OEEERKNS2_INS_17ActivationFrame_OEEE + 103
Backtrace: 21  libcore_opt.dylib                   0x0000000103dd06c3 _ZN4core4eval5applyEN3mem9smart_ptrINS_3T_OEEERKNS2_INS_17ActivationFrame_OEEE + 483
Backtrace: 22  libcore_opt.dylib                   0x0000000103dcf33f _ZN4core14af_evalWithEnvEN3mem9smart_ptrINS_3T_OEEENS1_INS_13Environment_OEEEbbb + 1055
Backtrace: 23  libcore_opt.dylib                   0x0000000103e0512f _ZN4core27ActivationFrameFunctionPtrTIN3mem15multiple_valuesINS_3T_OEEENS1_9smart_ptrIS3_EENS5_INS_13Environment_OEEEbbbvvvvvvvvvvvE8activateEPFS4_S6_S8_bbbERKNS5_INS_17ActivationFrame_OEEE + 655
Backtrace: 24  libcore_opt.dylib                   0x0000000103e04e42 _ZN4core30ActivationFrameFunctionWrapPtrIN3mem15multiple_valuesINS_3T_OEEENS1_9smart_ptrIS3_EENS5_INS_13Environment_OEEEbbbvvvvvvvvvvvE8activateERKNS5_INS_17ActivationFrame_OEEE + 18
Backtrace: 25  libcore_opt.dylib                   0x0000000103c8c3c1 _ZN4core9BuiltIn_O6INVOKEERKN3mem9smart_ptrINS_17ActivationFrame_OEEE + 1137
Backtrace: 26  libllvmo_opt.dylib                  0x000000010364758c _Z47proto_invokePossibleMultipleValueSymbolFunctionPN3mem9smart_ptrIN4core8Symbol_OEEEPNS0_INS1_17ActivationFrame_OEEE + 1196
Backtrace: 27  libllvmo_opt.dylib                  0x000000010363ffa7 mv_invokePossibleMultipleValueSymbolFunction + 23
Backtrace: 28  _image.bundle                       0x000000010b5771c8 REP + 1816
Backtrace: 29  ???                                 0x000000010d71dd50 0x0 + 4520533328