[Libunwind-devel] Unwinding and inline functions

[Milian Wolff]

Hey all,

Can libunwind be configured to include "fake" frames from debug information in 
the face of inlined functions? Meaning for code like this:

~~~~
#define forceinline inline __attribute__((always_inline))

forceinline void asdf()
{
    new int[123];
}

forceinline void bar()
{
    asdf();
}

forceinline void foo()
{
    bar();
}

int main()
{
    foo();
    return 0;
}
~~~~

If I now use my heaptrack tool to grab a backtrace with libunwind on the 
memory allocation, I'll see the following for an optimized build:

g++ -O3 -flto -ggdb3 inlining.cpp

main
  at /home/milian/projects/src/heaptrack/tests/manual/inlining.cpp:20
  in /ssd/milian/projects/build/heaptrack/a.out

GDB is capable of giving me a much more useful backtrace:

~~~~
Breakpoint 3, 0x00007ffff720f180 in malloc () from /usr/lib/libc.so.6
(gdb) bt
#0  0x00007ffff720f180 in malloc () from /usr/lib/libc.so.6
#1  0x00007ffff7ae1968 in operator new (sz=492) at /build/gcc-multilib/src/
gcc/libstdc++-v3/libsupc++/new_op.cc:50
#2  0x000000000040050e in asdf () at /home/milian/projects/src/heaptrack/
tests/manual/inlining.cpp:5
#3  bar () at /home/milian/projects/src/heaptrack/tests/manual/inlining.cpp:10
#4  foo () at /home/milian/projects/src/heaptrack/tests/manual/inlining.cpp:15
#5  main () at /home/milian/projects/src/heaptrack/tests/manual/inlining.cpp:
20
~~~~

Can I configure libunwind to give me an equivalent backtrace? If not, does 
someone know if the unwinding method of GDB is accessible to third-parties as 
a library?

Thanks
-- 
Milian Wolff
address@hidden
http://milianw.de