libbacktrace integration for _GLIBCXX_DEBUG mode
François Dumont
frs.dumont@gmail.com
Wed Oct 14 16:10:18 GMT 2020
After further testing this version was bugged because ld considered that
__create_backtrace/__render_backtrace symbols existed several times in
the different linked .o.
I tried making those inline but it failed, __render_backtrace was not
substituted anymore, only __create_backtrace was.
The correct (tested) fix was to make _Error_formatter methods using
those symbols outline. So here is the new patch.
libstdc++: [_GLIBCXX_DEBUG] Integrate libbacktrace
New _GLIBCXX_DEBUG_BACKTRACE macro to activate backtrace
generation on
_GLIBCXX_DEBUG assertions using libbacktrace.
* config/abi/pre/gnu.ver: Add new symbols.
* include/debug/formatter.h [_GLIBCXX_DEBUG_BACKTRACE]:
Include <backtrace-supported.h>.
[_GLIBCXX_DEBUG_BACKTRACE && BACKTRACE_SUPPORTED]:
Include <backtrace.h>.
[(!_GLIBCXX_DEBUG_BACKTRACE || !BACKTRACE_SUPPORTED) &&
_GLIBCXX_USE_C99_STDINT_TR1]: Include <stdint.h>.
[BACKTRACE_SUPPORTED || _GLIBCXX_USE_C99_STDINT_TR1]
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
(__gnu_debug::__create_backtrace_state): New.
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
(__gnu_debug::__render_backtrace): New.
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_M_print_backtrace):
New.
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_M_backtrace_state):
New.
(_Error_formatter::_Error_formatter): Outline definition.
* src/c++11/debug.cc: Include <cstring>.
(_Print_func_t): New.
(print_word): Use '%.*s' format in fprintf to render only
expected
number of chars.
(print_raw(PrintContext&, const char*, ptrdiff_t)): New.
(print_function(PrintContext&, const char*,
_Print_func_t)): New.
(print_type): Use latter.
(print_string(PrintContext&, const char*, const
_Parameter*, size_t)):
Change signature to...
(print_string(PrintContext&, const char*, ptrdiff_t, const
_Parameter*,
size_t)): ...this and adapt. Remove intermediate buffer to
render input
string.
(print_string(PrintContext&, const char*, ptrdiff_t)): New.
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
(print_backtrace(void*, uintptr_t, const char*, int, const
char*)): New.
(_Error_formatter::_M_error()): Adapt.
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
(__gnu_debug::__create_backtrace_state): New, weak symbol.
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
(__gnu_debug::__render_backtrace): New, weak symbol.
* doc/xml/manual/debug_mode.xml: Document
_GLIBCXX_DEBUG_BACKTRACE.
* doc/xml/manual/using.xml: Likewise.
Ok to commit once I run all testsuite in _GLIBCXX_DEBUG with backtrace ?
François
On 08/10/20 9:32 pm, François Dumont wrote:
> I eventually consider your last remark about using weak symbols to
> inject libbacktrace calls when _GLIBCXX_DEBUG_BACKTRACE is defined.
>
> libstdc++: [_GLIBCXX_DEBUG] Integrate libbacktrace
>
> Add _GLIBCXX_DEBUG_BACKTRACE macro to ask for a backtrace on
> _GLIBCXX_DEBUG
> assertions using libbacktrace.
>
> * config/abi/pre/gnu.ver: Add new symbols.
> * include/debug/formatter.h [_GLIBCXX_DEBUG_BACKTRACE]:
> Include <backtrace-supported.h>.
> [_GLIBCXX_DEBUG_BACKTRACE && BACKTRACE_SUPPORTED]:
> Include <backtrace.h>.
> [(!_GLIBCXX_DEBUG_BACKTRACE || !BACKTRACE_SUPPORTED) &&
> _GLIBCXX_USE_C99_STDINT_TR1]: Include <stdint.h>.
> [BACKTRACE_SUPPORTED || _GLIBCXX_USE_C99_STDINT_TR1]
> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
> (__gnu_debug::__create_backtrace_state): New.
> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
> (__gnu_debug::__render_backtrace): New.
> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_M_print_backtrace):
> New.
> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_M_backtrace_state):
> New.
> * src/c++11/debug.cc: Include <cstring>.
> (_Print_func_t): New.
> (print_word): Use '%.*s' format in fprintf to render only
> expected
> number of chars.
> (print_raw(PrintContext&, const char*, ptrdiff_t)): New.
> (print_function(PrintContext&, const char*,
> _Print_func_t)): New.
> (print_type): Use latter.
> (print_string(PrintContext&, const char*, const
> _Parameter*, size_t)):
> Change signature to...
> (print_string(PrintContext&, const char*, ptrdiff_t, const
> _Parameter*,
> size_t)): ...this and adapt. Remove intermediate buffer to
> render input
> string.
> (print_string(PrintContext&, const char*, ptrdiff_t)): New.
> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
> (print_backtrace(void*, uintptr_t, const char*, int, const
> char*)): New.
> (_Error_formatter::_M_error()): Adapt.
> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
> (__gnu_debug::__create_backtrace_state): New, weak symbol.
> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
> (__gnu_debug::__render_backtrace): New, weak symbol.
> * doc/xml/manual/debug_mode.xml: Document
> _GLIBCXX_DEBUG_BACKTRACE.
> * doc/xml/manual/using.xml: Likewise.
>
> Tested under Linux x86_64.
>
> Ok to commit ?
>
> François
>
> On 13/06/19 10:46 pm, François Dumont wrote:
>> Here is a new proposal which I think take into account all your remarks.
>>
>> I discovered the great "%.*s" printf format so I was able to do some
>> cleanup on the function name without any allocation.
>>
>> I also agree that counting the '>' or '<' is not reliable so I remove
>> this and limit the cleanup to the __cxx1998 namespace and the __
>> uglification, it is still better than nothing.
>>
>> I complete the doc as advised. I also added a note about making sure
>> that _GLIBCXX_DEBUG_BACKTRACE is defined consistently throughout the
>> application otherwise it would break the famous ODR rule.
>>
>> I introduced a _GLIBCXX_DEBUG_USE_LIBBACKTRACE to know when the
>> system is able to handle libbacktrace even if the user didn't
>> activate it. I could undef if when I am not building the library but
>> I don't remember if there is a macro to signal that library is being
>> built ?
>>
>> Here is an output sample now:
>>
>> /home/fdt/dev/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/debug/string:177:
>>
>> In function:
>> gnu_debug::basic_string<_CharT, _Traits,
>> _Allocator>::basic_string(const
>> _CharT*, gnu_debug::basic_string<_CharT, _Traits,
>> _Allocator>::size_type, const _Allocator&) [with _CharT = char;
>> _Traits
>> = std::char_traits<char>; _Allocator = std::allocator<char>;
>> gnu_debug::basic_string<_CharT, _Traits, _Allocator>::size_type =
>> long
>> unsigned int]
>>
>> Backtrace:
>> 0x400afd char const* gnu_debug::check_string<char, unsigned
>> long>(char const*, unsigned long, char const*, unsigned int, char
>> const*)
>> /home/fdt/dev/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/debug/string:56
>>
>> 0x400afd char const* gnu_debug::check_string<char, unsigned
>> long>(char const*, unsigned long, char const*, unsigned int, char
>> const*)
>> /home/fdt/dev/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/debug/string:49
>>
>> 0x400afd gnu_debug::basic_string<char, std::char_traits<char>,
>> std::allocator<char> >::basic_string(char const*, unsigned long,
>> std::allocator<char> const&)
>> /home/fdt/dev/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/debug/string:177
>>
>> 0x400afd test01()
>> /home/fdt/dev/gcc/git/libstdc++-v3/testsuite/21_strings/basic_string/debug/1_neg.cc:27
>>
>> 0x4009c8 main
>> /home/fdt/dev/gcc/git/libstdc++-v3/testsuite/21_strings/basic_string/debug/1_neg.cc:32
>>
>>
>> Error: __s != 0 || __n == 0.
>> XFAIL: 21_strings/basic_string/debug/1_neg.cc execution test
>>
>> * include/debug/formatter.h [_GLIBCXX_DEBUG_BACKTRACE]:
>> Include <backtrace-supported.h>.
>> [_GLIBCXX_DEBUG_BACKTRACE && BACKTRACE_SUPPORTED]:
>> Include <backtrace.h>.
>> [(!_GLIBCXX_DEBUG_BACKTRACE || !BACKTRACE_SUPPORTED) &&
>> _GLIBCXX_USE_C99_STDINT_TR1]: Include <stdint.h>.
>> [BACKTRACE_SUPPORTED || _GLIBCXX_USE_C99_STDINT_TR1]
>> (_GLIBCXX_DEBUG_USE_LIBBACKTRACE): New.
>> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](__backtrace_error_cb): New.
>> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](__backtrace_full_cb): New.
>> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](__backtrace_state): New.
>> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_Bt_full_t):
>> New.
>> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_M_print_backtrace):
>> New.
>> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_M_backtrace_state):
>> New.
>> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
>> (_Error_formatter::_M_backtrace_full_func): New.
>> * src/c++11/debug.cc: Include <cstring>.
>> (_Print_func_t): New.
>> (print_word): Use '%.*s' format in fprintf to render only expected
>> chars.
>> (print_raw(PrintContext&, const char*, ptrdiff_t)): New.
>> (print_function(PrintContext&, const char*, _Print_func_t)): New.
>> (print_type): Use latter.
>> (print_string(PrintContext&, const char*, const _Parameter*,
>> size_t)):
>> Change signature to...
>> (print_string(PrintContext&, const char*, ptrdiff_t, const
>> _Parameter*,
>> size_t)): ...this and adapt. Remove intermediate buffer to render
>> input
>> string.
>> (print_string(PrintContext&, const char*, ptrdiff_t)): New.
>> [_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
>> (print_backtrace(void*, uintptr_t, const char*, int, const
>> char*)): New.
>> (_Error_formatter::_M_error()): Adapt.
>> * doc/xml/manual/debug_mode.xml: Document _GLIBCXX_DEBUG_BACKTRACE.
>> * doc/xml/manual/using.xml: Likewise.
>>
>> Tested under Linux x86_64 normal and debug modes.
>>
>> Ok to commit ?
>>
>> François
>>
>>
>
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