5 ms·

Backward-cpp – A stack trace pretty-printer for C++

90 points by negrit 14y ago

limmeau 14y ago
Does this also work with frame pointers omitted?
- DannyBee 14y ago
  It looks like it should, since it has an unwinder
- bombela 14y ago
  It does, because it uses the debug information generated by the compiler. both clang and gcc produce a good quality DWARF (http://www.dwarfstd.org/ http://www.dwarfstd.org/), which contains everything needed to unwind the stack. In Bacward-cpp I do use the unwinder provided by libgcc, which is in fact extracting all the information from DWARF. This is as accurate as GDB can be, it uses the same debug information.
pdw 14y ago
Ok, this does pretty backtraces. I was hoping for an actual 'reverse cpp': a tool that took preprocessed C source code and undoes macro expansions. I mean, it should read some C source and some header files, and use the macro definitions found in the header files to try and shorten the source code.
- eliben 14y ago
  Why is this useful?
niggler 14y ago
What I need, moreso than this, is a tool for parsing really long and winding multi-screen error messages involving templates (screw up a std::map key or value? At least 100 characters in the error message just to describe it. Add an additional 50 if you try to use string [basic_string ...])
- grundprinzip 14y ago
  For that I use gccfilter which does an awesome job at parsing the hell out of compile errors. http://www.mixtion.org/gccfilter/ http://www.mixtion.org/gccfilter/ In our project we use gccfilter with the options -c and -p which are colorize and remove path but it supports as well -a for removing the template arguments. Give it a try it will definitely help your.
  - niggler 14y ago
    Played with it, helps with some template issues involving STL, but doesn't seem to interpret CRTP (https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern https://en.wikipedia.org/wiki/Curiously_recurring_template_p...) issues correctly. Nonetheless, very cool.
- minimax 14y ago
  Which compiler are you using? Clang is much better at dumping template related error messages and recent versions of gcc are getting better.
  - niggler 14y ago
    gcc 4.2, although at this stage I'm so used to reading the error messages that I just gloss over most of the verbiage
simfoo 14y ago
> Backward support pretty printed stack trace on GNU/Linux only, it will compile fine under other platforms but will not do anything. :(
- matthavener 14y ago
  Google has a similar library that supports Windows: https://code.google.com/p/google-breakpad/wiki/StackWalking https://code.google.com/p/google-breakpad/wiki/StackWalking
- mpyne 14y ago
  Patches accepted?
  - lysium 14y ago
    Actually, says 'Pull requests are welcome :)'
- guard-of-terra 14y ago
  You can probably make it work on OSX too - the toolchain is very similar.
g3orge 14y ago
so this is a colored version of gdb's `bt` command? am I missing something?
- lysium 14y ago
  ...without running gdb? I think this eases the workflow if you're not always running the application from within gdb. Btw, does gdb expand inline calls in the backtrace?
  - DannyBee 14y ago
    yes, gdb can expand inline calls in a backtrace.
lysium 14y ago
That's cool! Eases the workflow when developing cpp, no need to fire up gdb to make sense of 'Segmentation fault'. Reminds me of tiny-cc's default output for segfaults.
- minimax 14y ago
  There is no need to fire up gdb in the example case on the backward-cpp Github page because it's a trivial example (dereferencing an obviously invalid pointer), but to say it eliminates the need for gdb to debug segfaults in general is a bit of an overstatement.
nicholassmith 14y ago
This actually fills a need for me, I've been toying with writing one for a while but always find something that needs my attention more.
shared4you 14y ago
GCC 4.8 comes with a built-in address sanitizer that prints nice stack traces for most memory-related errors. Basically you just add "-fsanitize=address" and link appropriately: gcc -pthread -fno-omit-frame-pointer -g -fsanitize=address badass.c -lasan -ldl ./a.out ==22420== ERROR: AddressSanitizer crashed on address 0x0000200000703c18 at pc 0x401947 READ of size 1 at 0x0000200000703c18; shadow: 0x0000100000381e0c; mem: 0x0000000001c0f065 thread: 0x787d4720 #0 0x401947 main use-after-free.c:5 #1 0x7ff87792cc4d __libc_start_main ??:0 #2 0x401839 _start ??:0 0x0000000001c0f065 is located 5 bytes inside of 80-byte region [0x0000000001c0f060,0x0000000001c0f0b0) freed by thread 0x787d4720 here: #0 0x404b9b free asan_rtl.cc:1203 #1 0x40191b main use-after-free.c:5 #2 0x7ff87792cc4d __libc_start_main ??:0 #3 0x401839 _start ??:0 previously allocated by thread 0x787d4720 here: #0 0x405c27 malloc asan_rtl.cc:1196 #1 0x401910 main use-after-free.c:3 #2 0x7ff87792cc4d __libc_start_main ??:0 #3 0x401839 _start ??:0 See the changelog [1] as well as the library [2] itself. Of course, the OP's project is certainly cool too. [1]: http://gcc.gnu.org/gcc-4.8/changes.html http://gcc.gnu.org/gcc-4.8/changes.html [2]: https://code.google.com/p/address-sanitizer/wiki/AddressSanitizer https://code.google.com/p/address-sanitizer/wiki/AddressSani...
- bombela 14y ago
  Author of the code here. Yes, this is cool, but it instruments your code "This tool is very fast. The average slowdown of the instrumented program is ~2x (see PerformanceNumbers).". backward-cpp doesn't change the generated code in any way. This is only using the debug informations. There is no performance impact, the binary code stays the same.
  - shared4you 14y ago
    Wow, that is as perfect as it can get :)
montecarl 14y ago
I get errors when I try to compile it on my system. $ g++ -v gcc version 4.4.6 20120305 (Red Hat 4.4.6-4) (GCC) $ g++ -c backward.cpp In file included from backward.cpp:26: backward.hpp: In member function ‘_Unwind_Reason_Code backward::details::Unwinder<F>::backtrace(_Unwind_Context*)’: backward.hpp:595: error: there are no arguments to ‘_Unwind_GetIPInfo’ that depend on a template parameter, so a declaration of ‘_Unwind_GetIPInfo’ must be available backward.hpp:595: note: (if you use ‘-fpermissive’, G++ will accept your code, but allowing the use of an undeclared name is deprecated) backward.hpp: In member function ‘_Unwind_Reason_Code backward::details::Unwinder<F>::backtrace(_Unwind_Context*) [with F = backward::StackTraceImpl<backward::system_tag::linux_tag>::callback]’: backward.hpp:587: instantiated from ‘static _Unwind_Reason_Code backward::details::Unwinder<F>::backtrace_trampoline(_Unwind_Context*, void*) [with F = backward::StackTraceImpl<backward::system_tag::linux_tag>::callback]’ backward.hpp:576: instantiated from ‘size_t backward::details::Unwinder<F>::operator()(F&, size_t) [with F = backward::StackTraceImpl<backward::system_tag::linux_tag>::callback]’ backward.hpp:612: instantiated from ‘size_t backward::details::unwind(F, size_t) [with F = backward::StackTraceImpl<backward::system_tag::linux_tag>::callback]’ backward.hpp:628: instantiated from here backward.hpp:595: error: ‘_Unwind_GetIPInfo’ was not declared in this scope
- bombela 14y ago
  Hey, I am not the OP, but the author of the code. So it seems that the function is not always declared in some header, while it exists in libgcc. Can you add an issue on github? Meanwhile, you can set the #define BACKWARD_HAS_BACKTRACE=1 which will disable the use of "unwind". You will get slightly less accurate stack trace (especially on CPU exception and other signals), but it should work ok until this bug is fixed.
  - prg318 14y ago
    Hi there, I've also run into this issue. I've opened an issue on your github: https://github.com/bombela/backward-cpp/issues/2 https://github.com/bombela/backward-cpp/issues/2 Thanks again for the really useful open source contribution! I will be integrating this with my C++ projects.
hawkw 14y ago
Nice.

90 points by negrit 14y ago

limmeau 14y ago

Does this also work with frame pointers omitted?

DannyBee 14y ago
It looks like it should, since it has an unwinder
bombela 14y ago
It does, because it uses the debug information generated by the compiler. both clang and gcc produce a good quality DWARF (http://www.dwarfstd.org/ http://www.dwarfstd.org/), which contains everything needed to unwind the stack. In Bacward-cpp I do use the unwinder provided by libgcc, which is in fact extracting all the information from DWARF. This is as accurate as GDB can be, it uses the same debug information.

pdw 14y ago

Ok, this does pretty backtraces. I was hoping for an actual 'reverse cpp': a tool that took preprocessed C source code and undoes macro expansions. I mean, it should read some C source and some header files, and use the macro definitions found in the header files to try and shorten the source code.

eliben 14y ago
Why is this useful?

niggler 14y ago

What I need, moreso than this, is a tool for parsing really long and winding multi-screen error messages involving templates (screw up a std::map key or value? At least 100 characters in the error message just to describe it. Add an additional 50 if you try to use string [basic_string ...])

grundprinzip 14y ago
For that I use gccfilter which does an awesome job at parsing the hell out of compile errors. http://www.mixtion.org/gccfilter/ http://www.mixtion.org/gccfilter/ In our project we use gccfilter with the options -c and -p which are colorize and remove path but it supports as well -a for removing the template arguments. Give it a try it will definitely help your.
- niggler 14y ago
  Played with it, helps with some template issues involving STL, but doesn't seem to interpret CRTP (https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern https://en.wikipedia.org/wiki/Curiously_recurring_template_p...) issues correctly. Nonetheless, very cool.
minimax 14y ago
Which compiler are you using? Clang is much better at dumping template related error messages and recent versions of gcc are getting better.
- niggler 14y ago
  gcc 4.2, although at this stage I'm so used to reading the error messages that I just gloss over most of the verbiage

simfoo 14y ago

> Backward support pretty printed stack trace on GNU/Linux only, it will compile fine under other platforms but will not do anything. :(

matthavener 14y ago
Google has a similar library that supports Windows: https://code.google.com/p/google-breakpad/wiki/StackWalking https://code.google.com/p/google-breakpad/wiki/StackWalking
mpyne 14y ago
Patches accepted?
- lysium 14y ago
  Actually, says 'Pull requests are welcome :)'
guard-of-terra 14y ago
You can probably make it work on OSX too - the toolchain is very similar.

g3orge 14y ago

so this is a colored version of gdb's `bt` command? am I missing something?

lysium 14y ago
...without running gdb? I think this eases the workflow if you're not always running the application from within gdb. Btw, does gdb expand inline calls in the backtrace?
- DannyBee 14y ago
  yes, gdb can expand inline calls in a backtrace.

lysium 14y ago

That's cool! Eases the workflow when developing cpp, no need to fire up gdb to make sense of 'Segmentation fault'. Reminds me of tiny-cc's default output for segfaults.

minimax 14y ago
There is no need to fire up gdb in the example case on the backward-cpp Github page because it's a trivial example (dereferencing an obviously invalid pointer), but to say it eliminates the need for gdb to debug segfaults in general is a bit of an overstatement.

nicholassmith 14y ago

This actually fills a need for me, I've been toying with writing one for a while but always find something that needs my attention more.

shared4you 14y ago

GCC 4.8 comes with a built-in address sanitizer that prints nice stack traces for most memory-related errors. Basically you just add "-fsanitize=address" and link appropriately: gcc -pthread -fno-omit-frame-pointer -g -fsanitize=address badass.c -lasan -ldl ./a.out ==22420== ERROR: AddressSanitizer crashed on address 0x0000200000703c18 at pc 0x401947 READ of size 1 at 0x0000200000703c18; shadow: 0x0000100000381e0c; mem: 0x0000000001c0f065 thread: 0x787d4720 #0 0x401947 main use-after-free.c:5 #1 0x7ff87792cc4d __libc_start_main ??:0 #2 0x401839 _start ??:0 0x0000000001c0f065 is located 5 bytes inside of 80-byte region [0x0000000001c0f060,0x0000000001c0f0b0) freed by thread 0x787d4720 here: #0 0x404b9b free asan_rtl.cc:1203 #1 0x40191b main use-after-free.c:5 #2 0x7ff87792cc4d __libc_start_main ??:0 #3 0x401839 _start ??:0 previously allocated by thread 0x787d4720 here: #0 0x405c27 malloc asan_rtl.cc:1196 #1 0x401910 main use-after-free.c:3 #2 0x7ff87792cc4d __libc_start_main ??:0 #3 0x401839 _start ??:0 See the changelog [1] as well as the library [2] itself. Of course, the OP's project is certainly cool too. [1]: http://gcc.gnu.org/gcc-4.8/changes.html http://gcc.gnu.org/gcc-4.8/changes.html [2]: https://code.google.com/p/address-sanitizer/wiki/AddressSanitizer https://code.google.com/p/address-sanitizer/wiki/AddressSani...

bombela 14y ago
Author of the code here. Yes, this is cool, but it instruments your code "This tool is very fast. The average slowdown of the instrumented program is ~2x (see PerformanceNumbers).". backward-cpp doesn't change the generated code in any way. This is only using the debug informations. There is no performance impact, the binary code stays the same.
- shared4you 14y ago
  Wow, that is as perfect as it can get :)

montecarl 14y ago

I get errors when I try to compile it on my system. $ g++ -v gcc version 4.4.6 20120305 (Red Hat 4.4.6-4) (GCC) $ g++ -c backward.cpp In file included from backward.cpp:26: backward.hpp: In member function ‘_Unwind_Reason_Code backward::details::Unwinder<F>::backtrace(_Unwind_Context*)’: backward.hpp:595: error: there are no arguments to ‘_Unwind_GetIPInfo’ that depend on a template parameter, so a declaration of ‘_Unwind_GetIPInfo’ must be available backward.hpp:595: note: (if you use ‘-fpermissive’, G++ will accept your code, but allowing the use of an undeclared name is deprecated) backward.hpp: In member function ‘_Unwind_Reason_Code backward::details::Unwinder<F>::backtrace(_Unwind_Context*) [with F = backward::StackTraceImpl<backward::system_tag::linux_tag>::callback]’: backward.hpp:587: instantiated from ‘static _Unwind_Reason_Code backward::details::Unwinder<F>::backtrace_trampoline(_Unwind_Context*, void*) [with F = backward::StackTraceImpl<backward::system_tag::linux_tag>::callback]’ backward.hpp:576: instantiated from ‘size_t backward::details::Unwinder<F>::operator()(F&, size_t) [with F = backward::StackTraceImpl<backward::system_tag::linux_tag>::callback]’ backward.hpp:612: instantiated from ‘size_t backward::details::unwind(F, size_t) [with F = backward::StackTraceImpl<backward::system_tag::linux_tag>::callback]’ backward.hpp:628: instantiated from here backward.hpp:595: error: ‘_Unwind_GetIPInfo’ was not declared in this scope

bombela 14y ago
Hey, I am not the OP, but the author of the code. So it seems that the function is not always declared in some header, while it exists in libgcc. Can you add an issue on github? Meanwhile, you can set the #define BACKWARD_HAS_BACKTRACE=1 which will disable the use of "unwind". You will get slightly less accurate stack trace (especially on CPU exception and other signals), but it should work ok until this bug is fixed.
- prg318 14y ago
  Hi there, I've also run into this issue. I've opened an issue on your github: https://github.com/bombela/backward-cpp/issues/2 https://github.com/bombela/backward-cpp/issues/2 Thanks again for the really useful open source contribution! I will be integrating this with my C++ projects.

hawkw 14y ago

Nice.