rightaway717 rightaway717 - 1 month ago 12
C++ Question

How to check if LLDB loaded debug symbols from shared libraries?

On Linux I use

(gdb) i shared


in gdb and gdb prints a list of libraries either with a star
*
if no debug symbols are loaded or without it if loaded, e.g:

0x0000000100c18660 0x0000000100c489a0 Yes (*) /Users/anon/work/software/webrtc-audio-processing-0.1/build_darwin/../bin/darwin/lib/libwebrtc_audio_processing.0.dylib
0x0000000100c57ca0 0x0000000100c76978 Yes /Users/anon/work/software/speex/speex/speex-1.2rc2/build_darwin/../bin/darwin/lib/libspeex.1.dylib


I found that in LLDB I should use

(lldb) image list


to do the same. But I get a list of libraries which says nothing to me on whether debug symbols are loaded for the lib or not, e.g:

[181] 19269C1D-EB29-384A-83F3-7DDDEB7D9DAD 0x00007fff8d2d3000 /System/Library/PrivateFrameworks/CoreWiFi.framework/Versions/A/CoreWiFi
[182] 8D7BA9BA-EB36-307A-9119-0B3D9732C953 0x00007fff879ee000 /System/Library/Frameworks/CoreBluetooth.framework/Versions/A/CoreBluetooth
[183] 6F03761D-7C3A-3C80-8031-AA1C1AD7C706 0x00007fff92e52000 /System/Library/PrivateFrameworks/DebugSymbols.framework/Versions/A/DebugSymbols


So how do I check if debug symbols are loaded by LLDB?

UPDATE: I just decided to post output of
(lldb) image lookup -vn <function>
(thanks Jim) for others to know what it looks like:

image lookup -vn Herqq::Upnp::HSsdp::init
2 matches found in libHUpnp.2.dylib:
Address: libHUpnp.2.dylib[0x00000000000283f0] (libHUpnp.2.dylib.__TEXT.__text + 150384)
Summary: libHUpnp.2.dylib`Herqq::Upnp::HSsdp::init() at hssdp.cpp:804
Module: file = "libHUpnp.2.dylib", arch = "x86_64"
CompileUnit: id = {0x00000000}, file = "/Users/blade/work/software/HUPnP/build-herqq-Desktop_Qt_5_5_0_clang_64bit-Debug/hupnp/../../herqq/hupnp/src/ssdp/hssdp.cpp", language = "c89"
Function: id = {0xa0002401f}, name = "init", range = [0x00000000000283f0-0x0000000000028511)
FuncType: id = {0xa0002401f}, decl = hssdp.h:304, clang_type = "_Bool (void)"
Blocks: id = {0xa0002401f}, range = [0x000283f0-0x00028511)
LineEntry: [0x00000000000283f0-0x00000000000283ff): /Users/blade/work/software/HUPnP/build-herqq-Desktop_Qt_5_5_0_clang_64bit-Debug/hupnp/../../herqq/hupnp/src/ssdp/hssdp.cpp:804
Symbol: id = {0x00000c9b}, range = [0x00000000000283f0-0x0000000000028520), name="Herqq::Upnp::HSsdp::init()", mangled="_ZN5Herqq4Upnp5HSsdp4initEv"
Variable: id = {0xa0002403a}, name = "this", type= "Herqq::Upnp::HSsdp *", location = DW_OP_fbreg(-16), decl =
Variable: id = {0xa00024047}, name = "herqqLog__", type= "HLogger", location = DW_OP_fbreg(-32), decl = hssdp.cpp:805
Variable: id = {0xa00024056}, name = "ha", type= "QHostAddress", location = DW_OP_fbreg(-56), decl = hssdp.cpp:812
Address: libHUpnp.2.dylib[0x0000000000028550] (libHUpnp.2.dylib.__TEXT.__text + 150736)
Summary: libHUpnp.2.dylib`Herqq::Upnp::HSsdp::init(QHostAddress const&) at hssdp.cpp:817
Module: file = "libHUpnp.2.dylib", arch = "x86_64"
CompileUnit: id = {0x00000000}, file = "/Users/blade/work/software/HUPnP/build-herqq-Desktop_Qt_5_5_0_clang_64bit-Debug/hupnp/../../herqq/hupnp/src/ssdp/hssdp.cpp", language = "ISO C++:1998"
Function: id = {0xa0002408f}, name = "init", range = [0x0000000000028550-0x000000000002862d)
FuncType: id = {0xa0002408f}, decl = hssdp.h:321, clang_type = "_Bool (const class QHostAddress &)"
Blocks: id = {0xa0002408f}, range = [0x00028550-0x0002862d)
LineEntry: [0x0000000000028550-0x0000000000028564): /Users/blade/work/software/HUPnP/build-herqq-Desktop_Qt_5_5_0_clang_64bit-Debug/hupnp/../../herqq/hupnp/src/ssdp/hssdp.cpp:817
Symbol: id = {0x00000ca3}, range = [0x0000000000028550-0x0000000000028630), name="Herqq::Upnp::HSsdp::init(QHostAddress const&)", mangled="_ZN5Herqq4Upnp5HSsdp4initERK12QHostAddress"
Variable: id = {0xa000240aa}, name = "this", type= "Herqq::Upnp::HSsdp *", location = DW_OP_fbreg(-16), decl =
Variable: id = {0xa000240b7}, name = "unicastAddress", type= "const QHostAddress &", location = DW_OP_fbreg(-24), decl = hssdp.cpp:816
Variable: id = {0xa000240c6}, name = "herqqLog__", type= "HLogger", location = DW_OP_fbreg(-40), decl = hssdp.cpp:818

Answer

If your binary was built with a dSYM, then the dSYM will show up on the line after the binary's listing in image list.

There isn't an easy way to do this if the binary is using the "leave the debug information in the .o file" style which is the default for the Debug configuration in Xcode. I filed a bug to make that easier to see.

One fairly simple way to do it is:

(lldb) image lookup -vn <SomeFunctionNameThatShouldHaveDebugInfo>

If the output of that command includes a CompileUnit, then the .o file containing that function has debug information, otherwise, not.